Merge branch 'wip/mahmoudkhalil11/adds-compare-activity-to-compare-branches-or-commits' into 'master'

WIP: Creates A New Compare Activity That Handles Comparing Between Two Different Branches/Commits

See merge request GNOME/gitg!156

gitg/compare/gitg-compare-branch-view.vala

@@ -0,0 +1,41 @@
+/*
+ * This file is part of gitg
+ *
+ * Copyright (C) 2020 - Mahmoud Ahmed Khalil
+ *
+ * gitg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * gitg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gitg. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace GitgCompare
+{
+	[GtkTemplate (ui = "/org/gnome/gitg/ui/gitg-compare-branch-view.ui")]
+	public class BranchView : Gtk.Paned
+	{
+		[GtkChild]
+		private Gitg.CommitListView d_commit_list_view;
+
+		[GtkChild]
+		private Gitg.DiffView d_diff_view;
+
+		public Gitg.CommitListView commit_list_view
+		{
+			get { return d_commit_list_view; }
+		}
+
+		public Gitg.DiffView diff_view
+		{
+			get { return d_diff_view; }
+		}
+	}
+}

gitg/compare/gitg-compare-commits-view.vala

@@ -0,0 +1,49 @@
+/*
+ * This file is part of gitg
+ *
+ * Copyright (C) 2020 - Mahmoud Ahmed Khalil
+ *
+ * gitg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * gitg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gitg. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace GitgCompare
+{
+	[GtkTemplate (ui = "/org/gnome/gitg/ui/gitg-compare-commits-view.ui")]
+	public class CommitsView : Gtk.Box
+	{
+		[GtkChild]
+		private Gitg.CommitListView d_source_commit_list_view;
+
+		[GtkChild]
+		private Gitg.CommitListView d_target_commit_list_view;
+
+		[GtkChild]
+		private Gitg.DiffView d_diff_view;
+
+		public Gitg.CommitListView source_commit_list_view
+		{
+			get { return d_source_commit_list_view; }
+		}
+
+		public Gitg.CommitListView target_commit_list_view
+		{
+			get { return d_target_commit_list_view; }
+		}
+
+		public Gitg.DiffView diff_view
+		{
+			get { return d_diff_view; }
+		}
+	}
+}

gitg/compare/gitg-compare-main-view.vala

@@ -0,0 +1,135 @@
+/*
+ * This file is part of gitg
+ *
+ * Copyright (C) 2020 - Mahmoud Ahmed Khalil
+ *
+ * gitg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * gitg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gitg. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace GitgCompare
+{
+	[GtkTemplate (ui = "/org/gnome/gitg/ui/gitg-compare-main-view.ui")]
+	public class MainView : Gtk.Grid
+	{
+		[GtkChild]
+		private Gtk.MenuButton d_first_branch;
+
+		[GtkChild]
+		private Gtk.Label d_first_branch_label;
+
+		[GtkChild]
+		private Gtk.MenuButton d_second_branch;
+
+		[GtkChild]
+		private Gtk.Label d_second_branch_label;
+
+		[GtkChild]
+		private Gtk.Button d_compare_branches;
+
+		[GtkChild]
+		private Gtk.Button d_compare_commits;
+
+		[GtkChild]
+		private Gtk.Label d_indicator_label;
+
+		[GtkChild]
+		private Gtk.Label d_compare_label;
+
+		private Gitg.BranchesPopover d_first_branch_popover;
+		private Gitg.BranchesPopover d_second_branch_popover;
+
+		public Gtk.MenuButton first_branch
+		{
+			get
+			{
+				return d_first_branch;
+			}
+		}
+
+		public Gtk.MenuButton second_branch
+		{
+			get
+			{
+				return d_second_branch;
+			}
+		}
+
+		public Gtk.Label first_branch_label
+		{
+			get
+			{
+				return d_first_branch_label;
+			}
+		}
+
+		public Gtk.Label second_branch_label
+		{
+			get
+			{
+				return d_second_branch_label;
+			}
+		}
+
+		public Gtk.Button compare_branches
+		{
+			get { return d_compare_branches; }
+		}
+
+		public Gtk.Button compare_commits
+		{
+			get { return d_compare_commits; }
+		}
+
+		public Gitg.BranchesPopover first_branch_popover
+		{
+			get
+			{
+				return d_first_branch_popover;
+			}
+		}
+
+		public Gitg.BranchesPopover second_branch_popover
+		{
+			get
+			{
+				return d_second_branch_popover;
+			}
+		}
+
+		public Gtk.Label indicator_label
+		{
+			get
+			{
+				return d_indicator_label;
+			}
+		}
+
+		public Gtk.Label compare_label
+		{
+			get
+			{
+				return d_compare_label;
+			}
+		}
+
+		construct
+		{
+			d_first_branch_popover = new Gitg.BranchesPopover();
+			d_second_branch_popover = new Gitg.BranchesPopover();
+
+			d_first_branch.popover = d_first_branch_popover;
+			d_second_branch.popover = d_second_branch_popover;
+		}
+	}
+}

gitg/compare/gitg-compare-stack.vala

@@ -0,0 +1,49 @@
+/*
+ * This file is part of gitg
+ *
+ * Copyright (C) 2020 - Mahmoud Ahmed Khalil
+ *
+ * gitg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * gitg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gitg. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace GitgCompare
+{
+	[GtkTemplate (ui = "/org/gnome/gitg/ui/gitg-compare-stack.ui")]
+	public class Stack : Gtk.Stack
+	{
+		[GtkChild]
+		private MainView d_main_view;
+
+		[GtkChild]
+		private BranchView d_branch_view;
+
+		[GtkChild]
+		private CommitsView d_commits_view;
+
+		public MainView main_view
+		{
+			get { return d_main_view; }
+		}
+
+		public BranchView branch_view
+		{
+			get { return d_branch_view; }
+		}
+
+		public CommitsView commits_view
+		{
+			get { return d_commits_view; }
+		}
+	}
+}

gitg/compare/gitg-compare.vala

@@ -0,0 +1,753 @@
+/*
+ * This file is part of gitg
+ *
+ * Copyright (C) 2020 - Mahmoud Ahmed Khalil
+ *
+ * gitg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * gitg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gitg. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace GitgCompare
+{
+	public enum CurrentView
+	{
+		MAIN,
+		BRANCH,
+		COMMIT
+	}
+
+	/*
+	 * Compare View, this view can be used to compare any two different branches/commits
+	 */
+	public class Activity : Object, GitgExt.UIElement, GitgExt.Activity
+	{
+		// Do this to pull in config.h before glib.h (for gettext...)
+		private const string version = Gitg.Config.VERSION;
+
+		private int d_current_view;
+		private Stack? d_main;
+
+		private string[] d_mainline;
+		private Gitg.Ref[] d_branches; // used to load current branches(local and upstream)
+
+		private Gitg.Ref d_source_ref;
+		private Gitg.Ref d_target_ref;
+
+		public Gitg.Ref source_ref
+		{
+			get
+			{
+				return d_source_ref;
+			}
+
+			set
+			{
+				if(value != null)
+				{
+					d_source_ref = value;
+
+					reload_main_view();
+				}
+			}
+		}
+
+		public Gitg.Ref target_ref
+		{
+			get
+			{
+				return d_target_ref;
+			}
+
+			set
+			{
+				if(value != null)
+				{
+					d_target_ref = value;
+
+					reload_main_view();
+				}
+			}
+		}
+
+		private Ggit.RevisionWalker? d_walker;
+		private Gitg.CommitModel d_commits_view_source_model;
+		private Gitg.CommitModel d_commits_view_target_model;
+		private Gitg.CommitModel d_branch_view_model;
+
+		private ulong d_externally_changed_id;
+		private ulong d_commits_changed_id;
+		private uint d_walker_update_idle_id;
+
+		private Gitg.WhenMapped d_reload_when_mapped;
+
+		public GitgExt.Application? application { owned get; construct set; }
+
+		public Activity(GitgExt.Application application)
+		{
+			Object(application: application);
+		}
+
+		public int current_view
+		{
+			get { return d_current_view; }
+
+			set
+			{
+				if(value < 3)
+				{
+					d_current_view = value;
+					reload_ui();
+				}
+			}
+		}
+
+		construct
+		{
+			application.bind_property("repository", this,
+			                          "repository", BindingFlags.DEFAULT);
+
+			d_externally_changed_id = application.repository_changed_externally.connect(repository_changed_externally);
+			d_commits_changed_id = application.repository_commits_changed.connect(repository_commits_changed);
+
+			d_commits_view_source_model = new Gitg.CommitModel(null);
+			d_commits_view_target_model = new Gitg.CommitModel(null);
+			d_branch_view_model = new Gitg.CommitModel(null);
+
+			d_commits_view_source_model.finished.connect(on_commits_view_source_model_finished);
+			d_commits_view_source_model.begin_clear.connect(on_commits_view_source_model_begin_clear);
+
+			d_commits_view_target_model.finished.connect(on_commits_view_target_model_finished);
+			d_commits_view_target_model.begin_clear.connect(on_commits_view_target_model_begin_clear);
+
+			d_branch_view_model.finished.connect(on_branch_view_model_finished);
+			d_branch_view_model.begin_clear.connect(on_branch_view_model_begin_clear);
+		}
+
+		private void update_commits_view_diff()
+		{
+			Gitg.Commit? source_commit = null;
+			Gitg.Commit? target_commit = null;
+
+			d_main.commits_view.diff_view.diff = null;
+
+			d_main.commits_view.source_commit_list_view.get_selection().selected_foreach((model, path, iter) => {
+				source_commit = d_commits_view_source_model.commit_from_iter(iter);
+			});
+
+			d_main.commits_view.target_commit_list_view.get_selection().selected_foreach((model, path, iter) => {
+				target_commit = d_commits_view_target_model.commit_from_iter(iter);
+			});
+
+			if(source_commit != null && target_commit != null)
+			{
+				try
+				{
+					d_main.commits_view.diff_view.diff = new Ggit.Diff.tree_to_tree(application.repository,
+																					target_commit.get_tree(),
+																					source_commit.get_tree(),
+																					null);
+				}
+				catch {}
+			}
+			else if(source_commit != null)
+			{
+				d_main.commits_view.diff_view.diff = source_commit.get_diff(null, 0);
+			}
+			else if(target_commit != null)
+			{
+				d_main.commits_view.diff_view.diff = target_commit.get_diff(null, 0);
+			}
+		}
+
+		private void on_commits_view_source_model_begin_clear()
+		{
+			d_main.commits_view.source_commit_list_view.model = null;
+		}
+
+		private void on_commits_view_source_model_finished()
+		{
+			d_main.commits_view.source_commit_list_view.model = d_commits_view_source_model;
+
+			var path = path_for_ref(d_source_ref, d_commits_view_source_model);
+
+			if(path == null)
+			{
+				return;
+			}
+
+			d_main.commits_view.source_commit_list_view.get_selection().select_path(path);
+
+			if(d_source_ref.get_name() == d_target_ref.get_name())
+			{
+				d_main.commits_view.target_commit_list_view.model = null;
+
+				d_commits_view_target_model = d_commits_view_source_model;
+				d_main.commits_view.target_commit_list_view.model = d_commits_view_target_model;
+			}
+			else
+			{
+				update_walker_idle(d_commits_view_target_model, d_target_ref, null);
+			}
+		}
+
+		private void on_commits_view_target_model_begin_clear()
+		{
+			d_main.commits_view.target_commit_list_view.model = null;
+		}
+
+		private void on_commits_view_target_model_finished()
+		{
+			d_main.commits_view.target_commit_list_view.model = d_commits_view_target_model;
+
+			var path = path_for_ref(d_target_ref, d_commits_view_target_model);
+
+			if(path == null)
+			{
+				return;
+			}
+
+			d_main.commits_view.target_commit_list_view.get_selection().select_path(path);
+		}
+
+		private void on_branch_view_selection_changed(Gtk.TreeSelection sel)
+		{
+			if(d_branch_view_model == null)
+			{
+				return;
+			}
+
+			// using selected_foreach() to only get the first selected commit (if there is any)
+			sel.selected_foreach((model, path, iter) => {
+				var selected_commit = d_branch_view_model.commit_from_iter(iter);
+
+				if(selected_commit == null)
+				{
+					return;
+				}
+
+				d_main.branch_view.diff_view.diff = selected_commit.get_diff(null, 0);
+			});
+		}
+
+		private void on_branch_view_model_begin_clear()
+		{
+			d_main.branch_view.commit_list_view.model = null;
+		}
+
+		private void on_branch_view_model_finished()
+		{
+			d_main.branch_view.commit_list_view.model = d_branch_view_model;
+
+			var path = path_for_ref(d_source_ref, d_branch_view_model);
+
+			if(path == null)
+			{
+				return;
+			}
+
+			d_main.branch_view.commit_list_view.get_selection().select_path(path);
+		}
+
+		private void repository_changed_externally(GitgExt.ExternalChangeHint hint)
+		{
+			var repository = application.repository;
+			if(repository == null)
+			{
+				return;
+			}
+
+			if(d_main != null && (hint & GitgExt.ExternalChangeHint.REFS) != 0)
+			{
+				reload_when_mapped();
+			}
+		}
+
+		private void repository_commits_changed()
+		{
+			if (d_main != null)
+			{
+				reload_when_mapped();
+			}
+		}
+
+		private void reload_when_mapped()
+		{
+			if(d_main == null)
+			{
+				return;
+			}
+
+			d_reload_when_mapped = new Gitg.WhenMapped(d_main);
+
+			d_reload_when_mapped.update(() => {
+				reload();
+			}, this);
+		}
+
+		private void reload()
+		{
+			d_reload_when_mapped = null;
+
+			d_source_ref = null;
+			d_target_ref = null;
+
+			var repository = application.repository;
+			if(repository == null)
+			{
+				return;
+			}
+
+			if(d_walker_update_idle_id != 0)
+			{
+				Source.remove(d_walker_update_idle_id);
+				d_walker_update_idle_id = 0;
+			}
+
+			try
+			{
+				d_walker = new Ggit.RevisionWalker(repository);
+			}
+			catch(Error err)
+			{
+				stderr.printf("Couldn't load walker: %s\n", err.message);
+				return;
+			}
+
+			// mainline is already reloaded, configured, and saved in the history activity
+			// that's why I'm assuming we should only read it here
+			try
+			{
+				d_mainline = repository.get_config().snapshot().get_string("gitg.mainline").split(",");
+			}
+			catch(Error err)
+			{
+				stderr.printf("Could reload mainlin: %s\n", err.message);
+				d_mainline = new string[] {"refs/heads/master"};
+			}
+
+			// reload branches
+			d_branches = new Gitg.Ref[0];
+
+			try
+			{
+				var uniq_id = new Gee.HashSet<Ggit.OId>((Gee.HashDataFunc)Ggit.OId.hash,
+	                                        			(Gee.EqualDataFunc)Ggit.OId.equal);
+
+				repository.references_foreach((reference) => {
+					if(reference.is_branch() || reference.is_remote())
+					{
+						try
+						{
+							reference = reference.resolve();
+							var id = reference.get_target();
+
+							if(id != null && uniq_id.add(id))
+							{
+								var r = reference as Gitg.Ref;
+								d_branches += r;
+
+								// setting the source/target refs to master
+								if(source_ref == null && target_ref == null)
+								{
+									d_source_ref = r;
+									d_target_ref = r;
+									debug("source/target are set");
+								}
+							}
+						}
+						catch(Error err)
+						{
+							stderr.printf("Error while resolving reference: %s\n", err.message);
+						}
+					}
+
+					return 0;
+				});
+			}
+			catch(Error err)
+			{
+				stderr.printf("Error while looking up references: %s\n", err.message);
+			}
+
+			// resetting all models, we only need to keep track of the models used in the selected view(branch/commits)
+			// so this should be called whenever we change the views or reload the repositories
+			reset_models();
+
+			// reloading ui elements
+			reload_ui();
+		}
+
+		private void reset_models()
+		{
+			d_commits_view_source_model.repository = null;
+			d_commits_view_source_model.walker = null;
+
+			d_commits_view_target_model.repository = null;
+			d_commits_view_target_model.walker = null;
+
+			d_branch_view_model.repository = null;
+			d_branch_view_model.walker = null;
+		}
+
+		private void reload_ui()
+		{
+			if(d_main == null)
+			{
+				return;
+			}
+
+			var commits_view = d_main.commits_view;
+			var branch_view = d_main.branch_view;
+
+			commits_view.diff_view.diff = null;
+			commits_view.source_commit_list_view.model = null;
+			commits_view.target_commit_list_view.model = null;
+
+			branch_view.diff_view.diff = null;
+			branch_view.commit_list_view.model = null;
+
+			switch(d_current_view)
+			{
+				case CurrentView.MAIN:
+					d_main.set_visible_child(d_main.main_view);
+					reload_main_view();
+					break;
+				case CurrentView.BRANCH:
+					d_main.set_visible_child(d_main.branch_view);
+					reload_branch_view();
+					break;
+				case CurrentView.COMMIT:
+					reload_commits_view();
+					break;
+			}
+		}
+
+		private void reload_main_view()
+		{
+			if(d_main == null)
+			{
+				return;
+			}
+
+			d_main.main_view.first_branch_popover.set_branches(d_branches);
+			d_main.main_view.second_branch_popover.set_branches(d_branches);
+
+			// if the d_source_ref and d_target_ref are not set, that means that this
+			// is a bare repository and no branches created yet
+			if(d_source_ref == null && d_target_ref == null)
+			{
+				d_main.main_view.first_branch.visible = false;
+				d_main.main_view.second_branch.visible = false;
+				d_main.main_view.compare_branches.visible = false;
+				d_main.main_view.compare_commits.visible = false;
+				d_main.main_view.compare_label.visible = false;
+
+				d_main.main_view.indicator_label.visible = true;
+			}
+			else
+			{
+				d_main.main_view.first_branch.visible = true;
+				d_main.main_view.second_branch.visible = true;
+				d_main.main_view.compare_branches.visible = true;
+				d_main.main_view.compare_commits.visible = true;
+				d_main.main_view.compare_label.visible = true;
+
+				d_main.main_view.indicator_label.visible = false;
+
+				d_main.main_view.first_branch_label.label = d_source_ref.parsed_name.shortname;
+				d_main.main_view.second_branch_label.label = d_target_ref.parsed_name.shortname;
+			}
+		}
+
+		private void reload_commits_view()
+		{
+			d_commits_view_source_model.repository = application.repository;
+			d_commits_view_source_model.walker = d_walker;
+			d_commits_view_source_model.limit = 1000;
+
+			d_commits_view_target_model.repository = application.repository;
+			d_commits_view_target_model.walker = d_walker;
+			d_commits_view_target_model.limit = 1000;
+
+			update_walker_idle(d_commits_view_source_model, d_source_ref, null);
+		}
+
+		private void reload_branch_view()
+		{
+			d_branch_view_model.repository = application.repository;
+			d_branch_view_model.walker = d_walker;
+
+			update_walker_idle(d_branch_view_model, d_source_ref, d_target_ref);
+		}
+
+		private void build_ui()
+		{
+			d_main = new Stack();
+
+			d_main.main_view.compare_commits.clicked.connect(on_compare_commits);
+			d_main.main_view.compare_branches.clicked.connect(on_compare_branches);
+
+			d_main.main_view.first_branch_popover.on_selected.connect((reference) => {
+				d_main.main_view.first_branch_label.label = reference.parsed_name.shortname;
+				d_source_ref = reference;
+			});
+
+			d_main.main_view.second_branch_popover.on_selected.connect((reference) => {
+				d_main.main_view.second_branch_label.label = reference.parsed_name.shortname;
+				d_target_ref = reference;
+			});
+
+			d_main.branch_view.commit_list_view.get_selection().set_mode(Gtk.SelectionMode.SINGLE);
+			d_main.branch_view.commit_list_view.get_selection().changed.connect(on_branch_view_selection_changed);
+
+			d_main.commits_view.source_commit_list_view.get_selection().set_mode(Gtk.SelectionMode.SINGLE);
+			d_main.commits_view.source_commit_list_view.get_selection().changed.connect(update_commits_view_diff);
+			d_main.commits_view.target_commit_list_view.get_selection().set_mode(Gtk.SelectionMode.SINGLE);
+			d_main.commits_view.target_commit_list_view.get_selection().changed.connect(update_commits_view_diff);
+
+			application.bind_property("repository", d_main.commits_view.diff_view, "repository", BindingFlags.SYNC_CREATE);
+			application.bind_property("repository", d_main.branch_view.diff_view, "repository", BindingFlags.SYNC_CREATE);
+
+			d_current_view = CurrentView.MAIN;
+
+			reload_main_view();
+		}
+
+		private void on_compare_commits()
+		{
+			reset_models();
+
+			d_current_view = CurrentView.COMMIT;
+
+			reload_commits_view();
+			d_main.set_visible_child(d_main.commits_view);
+		}
+
+		private void on_compare_branches()
+		{
+			reset_models();
+
+			d_current_view = CurrentView.BRANCH;
+
+			reload_branch_view();
+			d_main.set_visible_child(d_main.branch_view);
+		}
+
+		private Gtk.TreePath? path_for_ref(Ggit.Ref r, Gitg.CommitModel model)
+		{
+			Gtk.TreePath? path = null;
+
+			if(model == null)
+			{
+				return null;
+			}
+
+			var selected_commit_oid = id_for_ref(r);
+
+			try
+			{
+				var selected_commit = application.repository.lookup_commit(selected_commit_oid) as Gitg.Commit;
+				var selected_commit_path = model.path_from_commit(selected_commit);
+				path = selected_commit_path;
+			}
+			catch(Error err)
+			{
+				stderr.printf("Error while retrieving path for ref: %s\n", err.message);
+			}
+
+			return path;
+		}
+
+		private Ggit.OId? id_for_ref(Ggit.Ref r)
+		{
+			Ggit.OId? id = null;
+
+			try
+			{
+				var resolved = r.resolve();
+
+				if (resolved.is_tag())
+				{
+					var t = application.repository.lookup<Ggit.Tag>(resolved.get_target());
+
+					id = t.get_target_id();
+				}
+				else
+				{
+					id = resolved.get_target();
+				}
+			}
+			catch {}
+
+			return id;
+		}
+
+		private void update_walker(Gitg.CommitModel model, Gitg.Ref src, Gitg.Ref? target)
+		{
+			if(application.repository == null)
+			{
+				return;
+			}
+
+			if(model == null || src == null)
+			{
+				return;
+			}
+
+			var include = new Gee.HashSet<Ggit.OId>((Gee.HashDataFunc)Ggit.OId.hash,
+			                                        (Gee.EqualDataFunc)Ggit.OId.equal);
+
+            var exclude = new Gee.HashSet<Ggit.OId>((Gee.HashDataFunc)Ggit.OId.hash,
+        											(Gee.EqualDataFunc)Ggit.OId.equal);
+
+			var perm_uniq = new Gee.HashSet<Ggit.OId>((Gee.HashDataFunc)Ggit.OId.hash,
+			                                          (Gee.EqualDataFunc)Ggit.OId.equal);
+
+			var permanent = new Ggit.OId[0];
+
+			foreach (var ml in d_mainline)
+			{
+				Ggit.OId id;
+
+				try
+				{
+					id = id_for_ref(application.repository.lookup_reference(ml));
+				} catch { continue; }
+
+				if (id != null && perm_uniq.add(id))
+				{
+					permanent += id;
+				}
+			}
+
+			var id = id_for_ref(src);
+
+			if (id != null)
+			{
+				include.add(id);
+			}
+
+			if(target != null)
+			{
+				id = id_for_ref(target);
+
+				if(id != null)
+				{
+					exclude.add(id);
+				}
+			}
+
+			model.set_permanent_lanes(permanent);
+			model.set_include(include.to_array());
+			model.set_exclude(exclude.to_array());
+			model.reload();
+		}
+
+		private void update_walker_idle(Gitg.CommitModel model, Gitg.Ref src, Gitg.Ref? target)
+		{
+			if (application.repository == null)
+			{
+				return;
+			}
+
+			if (d_walker_update_idle_id == 0)
+			{
+				d_walker_update_idle_id = Idle.add(() => {
+					d_walker_update_idle_id = 0;
+					update_walker(model, src, target);
+					return false;
+				});
+			}
+		}
+
+		public Gitg.Repository repository
+		{
+			set
+			{
+				d_current_view = CurrentView.MAIN;
+				reload();
+			}
+		}
+
+		public override void dispose()
+		{
+			if (d_externally_changed_id != 0)
+			{
+				application.disconnect(d_externally_changed_id);
+				d_externally_changed_id = 0;
+			}
+
+			if(d_walker_update_idle_id != 0)
+			{
+				Source.remove(d_walker_update_idle_id);
+				d_walker_update_idle_id = 0;
+			}
+
+			if (d_commits_changed_id != 0)
+			{
+				application.disconnect(d_commits_changed_id);
+				d_commits_changed_id = 0;
+			}
+
+			d_mainline = null;
+			d_branches = null;
+
+			reset_models();
+
+			base.dispose();
+		}
+
+		public string id
+		{
+			owned get { return "/org/gnome/gitg/Activities/Compare"; }
+		}
+
+		public string display_name
+		{
+			owned get { return C_("Activity", "Compare"); }
+		}
+
+		public string description
+		{
+			owned get { return null; }
+		}
+
+		public string? icon
+		{
+			owned get { return null; }
+		}
+
+		public Gtk.Widget? widget
+		{
+			owned get
+			{
+				if (d_main == null)
+				{
+					build_ui();
+				}
+
+				return d_main;
+			}
+		}
+
+		public bool available
+		{
+			get { return true; }
+		}
+
+		public bool enabled
+		{
+			get { return true; }
+		}
+	}
+}

gitg/gitg-ref-action-compare.vala

@@ -0,0 +1,77 @@
+/*
+ * This file is part of gitg
+ *
+ * Copyright (C) 2020 - Mahmoud Ahmed Khalil
+ *
+ * gitg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * gitg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gitg. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace Gitg
+{
+
+class RefActionCompare : GitgExt.UIElement, GitgExt.Action, GitgExt.RefAction, Object
+{
+	// Do this to pull in config.h before glib.h (for gettext...)
+	private const string version = Gitg.Config.VERSION;
+
+	public GitgExt.Application? application { owned get; construct set; }
+	public GitgExt.RefActionInterface action_interface { get; construct set; }
+	public Gitg.Ref reference { get; construct set; }
+
+	public RefActionCompare(GitgExt.Application        application,
+	                        GitgExt.RefActionInterface action_interface,
+	                        Gitg.Ref                   reference)
+	{
+		Object(application:      application,
+		       action_interface: action_interface,
+		       reference:        reference);
+	}
+
+	public string id
+	{
+		owned get { return "/org/gnome/gitg/ref-actions/compare"; }
+	}
+
+	public string display_name
+	{
+		owned get { return _("Compare branches/commits"); }
+	}
+
+	public string description
+	{
+		owned get { return _("Compare the selected branch with other repository branches"); }
+	}
+
+	public bool enabled
+	{
+		get
+		{
+			return reference.is_branch() || reference.is_remote();
+		}
+	}
+
+	public void activate()
+	{
+		var compare_id = "/org/gnome/gitg/Activities/Compare";
+
+		var activity = application.get_activity_by_id(compare_id) as GitgCompare.Activity;
+		activity.source_ref = reference;
+
+		application.set_activity_by_id(compare_id);
+	}
+}
+
+}
+
+// ex:set ts=4 noet

gitg/gitg-window.vala

@@ -180,6 +180,20 @@ public class Window : Gtk.ApplicationWindow, GitgExt.Application, Initable
 	[GtkCallback]
 	private void dash_button_clicked(Gtk.Button dash)
 	{
+		var elems = d_activities.get_available_elements();
+
+		if(d_activities.current == elems[2])
+		{
+			var compare_activity = d_activities.current as GitgCompare.Activity;
+
+			if(compare_activity.current_view != GitgCompare.CurrentView.MAIN)
+			{
+				compare_activity.current_view = GitgCompare.CurrentView.MAIN;
+
+				return;
+			}
+		}
+
 		repository = null;
 	}
 
@@ -966,7 +980,8 @@ public class Window : Gtk.ApplicationWindow, GitgExt.Application, Initable
 
 		var builtins = new GitgExt.Activity[] {
 			new GitgHistory.Activity(this),
-			new GitgCommit.Activity(this)
+			new GitgCommit.Activity(this),
+			new GitgCompare.Activity(this)
 		};
 
 		var extset = new Peas.ExtensionSet(engine,

gitg/history/gitg-history.vala

@@ -884,6 +884,7 @@ namespace GitgHistory
 			add_ref_action(actions, new Gitg.RefActionRename(application, af, reference));
 			add_ref_action(actions, new Gitg.RefActionDelete(application, af, reference));
 			add_ref_action(actions, new Gitg.RefActionCopyName(application, af, reference));
+			add_ref_action(actions, new Gitg.RefActionCompare(application, af, reference));
 
 			var fetch = new Gitg.RefActionFetch(application, af, reference);
 

gitg/meson.build

@@ -13,6 +13,11 @@ sources = gitg_sources + files(
   'commit/gitg-commit-submodule-history-view.vala',
   'commit/gitg-commit-submodule-info.vala',
   'commit/gitg-commit.vala',
+  'compare/gitg-compare.vala',
+  'compare/gitg-compare-branch-view.vala',
+  'compare/gitg-compare-commits-view.vala',
+  'compare/gitg-compare-main-view.vala',
+  'compare/gitg-compare-stack.vala',
   'history/gitg-history-action-interface.vala',
   'history/gitg-history-command-line.vala',
   'history/gitg-history-paned.vala',
@@ -43,6 +48,7 @@ sources = gitg_sources + files(
   'gitg-popup-menu.vala',
   'gitg-recursive-monitor.vala',
   'gitg-recursive-scanner.vala',
+  'gitg-ref-action-compare.vala',
   'gitg-ref-action-copy-name.vala',
   'gitg-ref-action-create-branch.vala',
   'gitg-ref-action-create-patch.vala',
@@ -106,6 +112,10 @@ resource_data = files(
   'resources/ui/gitg-commit-submodule-diff-view.ui',
   'resources/ui/gitg-commit-submodule-history-view.ui',
   'resources/ui/gitg-commit-submodule-info.ui',
+  'resources/ui/gitg-compare-branch-view.ui',
+  'resources/ui/gitg-compare-commits-view.ui',
+  'resources/ui/gitg-compare-main-view.ui',
+  'resources/ui/gitg-compare-stack.ui',
   'resources/ui/gitg-create-branch-dialog.ui',
   'resources/ui/gitg-create-tag-dialog.ui',
   'resources/ui/gitg-dash-view.ui',

gitg/resources/gitg-resources.xml.in

@@ -10,6 +10,10 @@
     <file compressed="true" preprocess="xml-stripblanks">ui/gitg-commit-submodule-diff-view.ui</file>
     <file compressed="true" preprocess="xml-stripblanks">ui/gitg-commit-submodule-info.ui</file>
     <file compressed="true" preprocess="xml-stripblanks">ui/gitg-commit-dialog.ui</file>
+    <file compressed="true" preprocess="xml-stripblanks">ui/gitg-compare-main-view.ui</file>
+    <file compressed="true" preprocess="xml-stripblanks">ui/gitg-compare-branch-view.ui</file>
+    <file compressed="true" preprocess="xml-stripblanks">ui/gitg-compare-commits-view.ui</file>
+    <file compressed="true" preprocess="xml-stripblanks">ui/gitg-compare-stack.ui</file>
     <file compressed="true" preprocess="xml-stripblanks">ui/gitg-create-branch-dialog.ui</file>
     <file compressed="true" preprocess="xml-stripblanks">ui/gitg-create-tag-dialog.ui</file>
     <file compressed="true" preprocess="xml-stripblanks">ui/gitg-dash-view.ui</file>

gitg/resources/ui/gitg-compare-branch-view.ui

@@ -0,0 +1,79 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <!-- interface-requires gtk+ 3.3 -->
+  <!-- interface-requires gitg 0.0 -->
+  <!-- interface-requires gd 1.0 -->
+  <template class="GitgCompareBranchView" parent="GtkPaned">
+    <property name="visible">True</property>
+    <property name="can_focus">True</property>
+    <property name="orientation">vertical</property>
+    <child>
+      <object class="GtkScrolledWindow" id="d_scrolled_window_commit_list">
+        <property name="visible">True</property>
+        <property name="hexpand">True</property>
+        <property name="vexpand">True</property>
+        <property name="can_focus">True</property>
+        <property name="shadow-type">none</property>
+        <child>
+          <object class="GitgCommitListView" id="d_commit_list_view">
+            <property name="visible">True</property>
+            <property name="can_focus">True</property>
+            <property name="has_focus">True</property>
+            <property name="fixed-height-mode">True</property>
+            <property name="headers-visible">False</property>
+            <property name="enable-search">False</property>
+            <child>
+              <object class="GtkTreeViewColumn" id="column_commit_list_subject">
+                <property name="title" translatable="yes">Subject</property>
+                <property name="sizing">fixed</property>
+                <property name="resizable">True</property>
+                <property name="expand">True</property>
+                <property name="fixed-width">400</property>
+                <child>
+                  <object class="GitgCellRendererLanes" id="renderer_commit_list_subject">
+                    <property name="ellipsize">end</property>
+                  </object>
+                  <attributes>
+                    <attribute name="text">1</attribute>
+                  </attributes>
+                </child>
+              </object>
+            </child>
+            <child>
+              <object class="GtkTreeViewColumn" id="column_commit_list_author_date">
+                <property name="title" translatable="yes">Date</property>
+                <property name="sizing">fixed</property>
+                <property name="resizable">True</property>
+                <property name="fixed-width">150</property>
+                <child>
+                  <object class="GtkCellRendererText" id="renderer_commit_list_author_date">
+                    <property name="ellipsize">end</property>
+                  </object>
+                  <attributes>
+                    <attribute name="text">6</attribute>
+                  </attributes>
+                </child>
+              </object>
+            </child>
+          </object>
+        </child>
+      </object>
+      <packing>
+        <property name="resize">True</property>
+        <property name="shrink">True</property>
+      </packing>
+    </child>
+    <child>
+      <object class="GitgDiffView" id="d_diff_view">
+        <property name="visible">True</property>
+        <property name="hexpand">True</property>
+        <property name="vexpand">True</property>
+        <property name="can_focus">True</property>
+        <property name="handle_selection">True</property>
+      </object>
+      <packing>
+        <property name="shrink">True</property>
+      </packing>
+    </child>
+  </template>
+</interface>

gitg/resources/ui/gitg-compare-commits-view.ui

@@ -0,0 +1,114 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <!-- interface-requires gtk+ 3.3 -->
+  <!-- interface-requires gitg 0.0 -->
+  <!-- interface-requires gd 1.0 -->
+  <template class="GitgCompareCommitsView" parent="GtkBox">
+    <property name="visible">True</property>
+    <property name="can_focus">True</property>
+    <property name="orientation">vertical</property>
+    <child>
+      <object class="GtkPaned">
+        <property name="visible">True</property>
+        <property name="can-focus">True</property>
+        <property name="orientation">vertical</property>
+        <child>
+          <object class="GtkBox" id="d_commit_lists_box">
+            <property name="visible">True</property>
+            <property name="can-focus">True</property>
+            <property name="hexpand">True</property>
+            <property name="vexpand">True</property>
+            <property name="orientation">horizontal</property>
+            <property name="spacing">12</property>
+            <child>
+              <object class="GtkScrolledWindow">
+                <property name="can-focus">True</property>
+                <property name="visible">True</property>
+                <property name="hexpand">True</property>
+                <property name="vexpand">True</property>
+                <child>
+                  <object class="GitgCommitListView" id="d_source_commit_list_view">
+                    <property name="can-focus">True</property>
+                    <property name="visible">True</property>
+                    <property name="fixed-height-mode">True</property>
+                    <property name="headers-visible">False</property>
+                    <property name="enable-search">False</property>
+                    <property name="hexpand">True</property>
+                    <child>
+                      <object class="GtkTreeViewColumn">
+                        <property name="title" translatable="yes">Subject</property>
+                        <property name="resizable">True</property>
+                        <property name="sizing">fixed</property>
+                        <property name="expand">True</property>
+                        <property name="fixed-width">400</property>
+                        <child>
+                          <object class="GitgCellRendererLanes">
+                            <property name="ellipsize">none</property>
+                          </object>
+                          <attributes>
+                            <attribute name="text">1</attribute>
+                          </attributes>
+                        </child>
+                      </object>
+                    </child>
+                  </object>
+                </child>
+              </object>
+            </child>
+            <child>
+              <object class="GtkScrolledWindow">
+                <property name="visible">True</property>
+                <property name="can-focus">True</property>
+                <property name="hexpand">True</property>
+                <property name="vexpand">True</property>
+                <child>
+                  <object class="GitgCommitListView" id="d_target_commit_list_view">
+                    <property name="can-focus">True</property>
+                    <property name="visible">True</property>
+                    <property name="fixed-height-mode">True</property>
+                    <property name="headers-visible">False</property>
+                    <property name="enable-search">False</property>
+                    <property name="hexpand">True</property>
+                    <child>
+                      <object class="GtkTreeViewColumn">
+                        <property name="title" translatable="yes">Subject</property>
+                        <property name="resizable">True</property>
+                        <property name="sizing">fixed</property>
+                        <property name="expand">True</property>
+                        <property name="fixed-width">400</property>
+                        <child>
+                          <object class="GitgCellRendererLanes">
+                            <property name="ellipsize">none</property>
+                          </object>
+                          <attributes>
+                            <attribute name="text">1</attribute>
+                          </attributes>
+                        </child>
+                      </object>
+                    </child>
+                  </object>
+                </child>
+              </object>
+            </child>
+          </object>
+          <packing>
+            <property name="resize">True</property>
+            <property name="shrink">False</property>
+          </packing>
+        </child>
+        <child>
+          <object class="GitgDiffView" id="d_diff_view">
+            <property name="visible">True</property>
+            <property name="hexpand">True</property>
+            <property name="can_focus">True</property>
+            <property name="handle_selection">True</property>
+          </object>
+          <packing>
+            <property name="resize">True</property>
+            <property name="shrink">True</property>
+          </packing>
+        </child>
+      </object>
+    </child>
+  </template>
+</interface>

gitg/resources/ui/gitg-compare-main-view.ui

@@ -0,0 +1,163 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <!-- interface-requires gtk+ 3.3 -->
+  <!-- interface-requires gitg 0.0 -->
+  <!-- interface-requires gd 1.0 -->
+  <template class="GitgCompareMainView" parent="GtkGrid">
+    <property name="visible">True</property>
+    <property name="can_focus">False</property>
+    <property name="row_homogeneous">True</property>
+    <property name="column_homogeneous">True</property>
+    <property name="width_request">450</property>
+    <property name="halign">center</property>
+    <child>
+      <object class="GtkImage">
+        <property name="visible">True</property>
+        <property name="can_focus">False</property>
+        <property name="pixel_size">256</property>
+        <property name="icon_name">org.gnome.gitg-symbolic</property>
+      </object>
+      <packing>
+        <property name="left_attach">0</property>
+        <property name="top_attach">0</property>
+      </packing>
+    </child>
+    <child>
+      <object class="GtkBox">
+        <property name="visible">True</property>
+        <property name="can_focus">False</property>
+        <property name="orientation">vertical</property>
+        <property name="spacing">12</property>
+        <child>
+          <object class="GtkLabel" id="d_compare_label">
+            <property name="visible">True</property>
+            <property name="can_focus">False</property>
+            <property name="label" translatable="yes">Choose two branches to compare</property>
+            <property name="justify">center</property>
+            <attributes>
+              <attribute name="font-desc" value="Cantarell Bold 12"/>
+              <attribute name="weight" value="bold"/>
+              <attribute name="foreground" value="#88888a8a8585"/>
+            </attributes>
+          </object>
+          <packing>
+            <property name="position">0</property>
+          </packing>
+        </child>
+        <child>
+          <object class="GtkLabel" id="d_indicator_label">
+            <property name="visible">True</property>
+            <property name="can_focus">False</property>
+            <property name="label" translatable="yes">Bare repository, nothing yet to compare</property>
+            <property name="justify">center</property>
+            <attributes>
+              <attribute name="font-desc" value="Cantarell Bold 16"/>
+              <attribute name="weight" value="bold"/>
+              <attribute name="foreground" value="#88888a8a8585"/>
+            </attributes>
+          </object>
+          <packing>
+            <property name="position">1</property>
+          </packing>
+        </child>
+        <child>
+          <object class="GtkMenuButton" id="d_first_branch">
+            <property name="visible">True</property>
+            <property name="can_focus">False</property>
+            <child>
+              <object class="GtkBox">
+                <property name="visible">True</property>
+                <property name="can-focus">True</property>
+                <child>
+                  <object class="GtkLabel" id="d_first_branch_label">
+                    <property name="visible">True</property>
+                    <property name="hexpand">True</property>
+                    <property name="halign">start</property>
+                    <property name="max-width-chars">50</property>
+                    <property name="wrap">True</property>
+                    <property name="ellipsize">PANGO_ELLIPSIZE_END</property>
+                  </object>
+                </child>
+                <child>
+                  <object class="GtkImage">
+                    <property name="visible">True</property>
+                    <property name="icon-name">go-down-symbolic</property>
+                  </object>
+                </child>
+              </object>
+            </child>
+          </object>
+          <packing>
+            <property name="position">2</property>
+          </packing>
+        </child>
+        <child>
+          <object class="GtkMenuButton" id="d_second_branch">
+            <property name="visible">True</property>
+            <property name="can_focus">False</property>
+            <child>
+              <object class="GtkBox">
+                <property name="visible">True</property>
+                <property name="can-focus">True</property>
+                <child>
+                  <object class="GtkLabel" id="d_second_branch_label">
+                    <property name="visible">True</property>
+                    <property name="hexpand">True</property>
+                    <property name="halign">start</property>
+                    <property name="max-width-chars">50</property>
+                    <property name="wrap">True</property>
+                    <property name="ellipsize">PANGO_ELLIPSIZE_END</property>
+                  </object>
+                </child>
+                <child>
+                  <object class="GtkImage">
+                    <property name="visible">True</property>
+                    <property name="icon-name">go-down-symbolic</property>
+                  </object>
+                </child>
+              </object>
+            </child>
+          </object>
+          <packing>
+            <property name="position">3</property>
+          </packing>
+        </child>
+        <child>
+          <object class="GtkBox">
+            <property name="visible">True</property>
+            <property name="can_focus">False</property>
+            <property name="halign">end</property>
+            <property name="spacing">5</property>
+            <child>
+              <object class="GtkButton" id="d_compare_branches">
+                <property name="label" translatable="yes">Compare Branches</property>
+                <property name="visible">True</property>
+                <property name="can_focus">True</property>
+              </object>
+              <packing>
+                <property name="position">0</property>
+              </packing>
+            </child>
+            <child>
+              <object class="GtkButton" id="d_compare_commits">
+                <property name="label" translatable="yes">Compare Commits</property>
+                <property name="visible">True</property>
+                <property name="can_focus">True</property>
+              </object>
+              <packing>
+                <property name="position">1</property>
+              </packing>
+            </child>
+          </object>
+          <packing>
+            <property name="position">4</property>
+          </packing>
+        </child>
+      </object>
+      <packing>
+        <property name="left_attach">0</property>
+        <property name="top_attach">1</property>
+      </packing>
+    </child>
+  </template>
+</interface>

gitg/resources/ui/gitg-compare-stack.ui

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <!-- interface-requires gtk+ 3.3 -->
+  <!-- interface-requires gitg 0.0 -->
+  <!-- interface-requires gd 1.0 -->
+  <template class="GitgCompareStack" parent="GtkStack">
+    <property name="visible">True</property>
+    <property name="can_focus">False</property>
+    <child>
+      <object class="GitgCompareMainView" id="d_main_view">
+        <property name="visible">True</property>
+        <property name="can_focus">False</property>
+        <property name="receives_default">True</property>
+      </object>
+      <packing>
+        <property name="name">Compare Main View</property>
+        <property name="position">0</property>
+      </packing>
+    </child>
+    <child>
+      <object class="GitgCompareBranchView" id="d_branch_view">
+        <property name="visible">True</property>
+        <property name="can_focus">False</property>
+      </object>
+      <packing>
+        <property name="name">Compare Branch View</property>
+        <property name="position">1</property>
+      </packing>
+    </child>
+    <child>
+      <object class="GitgCompareCommitsView" id="d_commits_view">
+        <property name="visible">True</property>
+        <property name="can-focus">True</property>
+      </object>
+      <packing>
+        <property name="name">Compare Commits View</property>
+        <property name="position">2</property>
+      </packing>
+    </child>
+  </template>
+</interface>

gitg/resources/ui/gitg-window.ui

@@ -263,6 +263,7 @@
                         </child>
                         <child>
                           <object class="GtkButton" id="d_search_up_button">
+                            <property name="tooltip-text" translatable="yes">Previous result</property>
                             <property name="visible">True</property>
                             <property name="can_focus">False</property>
                             <signal name="clicked" handler="search_up_clicked" swapped="no"/>
@@ -278,6 +279,7 @@
                         </child>
                         <child>
                           <object class="GtkButton" id="d_search_down_button">
+                            <property name="tooltip-text" translatable="yes">Next result</property>
                             <property name="visible">True</property>
                             <property name="can_focus">False</property>
                             <signal name="clicked" handler="search_down_clicked" swapped="no"/>

libgitg/gitg-branches-popover.vala

@@ -0,0 +1,194 @@
+/*
+ * This file is part of gitg
+ *
+ * Copyright (C) 2020 - Mahmoud Ahmed Khalil
+ *
+ * gitg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * gitg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gitg. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace Gitg
+{
+	[GtkTemplate (ui = "/org/gnome/gitg/ui/gitg-branches-popover.ui")]
+	public class BranchesPopover : Gtk.Popover
+	{
+		public signal void on_selected(Gitg.Ref r);
+
+		[GtkChild]
+		private Gtk.SearchEntry d_search_entry;
+
+		[GtkChild]
+		private Gtk.ListBox d_listbox;
+
+		private Gitg.Ref[] d_branches;
+		private GLib.ListStore d_model;
+
+		public void set_branches(Gitg.Ref[] branches)
+		{
+			if(branches == null)
+			{
+				return;
+			}
+
+			d_branches = branches;
+			purge_model.begin();
+		}
+
+		construct
+		{
+			d_model = new GLib.ListStore(typeof(Gitg.Ref));
+		}
+
+		private async void purge_model()
+		{
+			d_model.remove_all();
+
+			foreach(var branch in d_branches)
+			{
+				d_model.append(branch);
+			}
+
+			d_listbox.bind_model(d_model, (item) => {
+				var branch = item as Gitg.Ref;
+
+				var entry = new ListEntry();
+				entry.reference = branch;
+
+				return entry;
+			});
+		}
+
+		[GtkCallback]
+		private async void on_search_entry_changed()
+		{
+			var text = d_search_entry.get_text ();
+		    if (text.length == 0) {
+		        yield purge_model ();
+
+		        return;
+		    } else {
+		        d_model.remove_all ();
+		    }
+
+		    d_listbox.select_row (null);
+
+		    var query = canonicalize_for_search (text);
+		    var nresults = 6;
+		    foreach (var branch in d_branches) {
+		        if (nresults == 0)
+		            return;
+
+		        var name = canonicalize_for_search (branch.parsed_name.shortname);
+		        if (query in name) {
+		            d_model.append (branch);
+
+		            nresults -= 1;
+		        }
+		    }
+
+		}
+
+		[GtkCallback]
+		private void on_listbox_row_activated()
+		{
+			var row = d_listbox.get_selected_row();
+
+			if(row == null)
+			{
+				return;
+			}
+
+			var entry = row.get_child() as ListEntry;
+			if(entry == null)
+			{
+				return;
+			}
+
+			on_selected(entry.reference);
+
+			d_listbox.unselect_row(row);
+			this.popdown();
+		}
+
+		private string canonicalize_for_search (string str)
+		{
+		    unowned string s;
+		    var buf = new unichar[18];
+		    var res = new StringBuilder();
+
+		    for (s = str; s[0] != 0; s = s.next_char()) {
+		        var c = strip_char (s.get_char());
+		        if (c != 0) {
+		            var size = c.fully_decompose(false, buf);
+		            if (size > 0)
+		                res.append_unichar(buf[0]);
+		        }
+		    }
+		    return res.str;
+		}
+
+		private unichar strip_char(unichar ch)
+		{
+		    switch (ch.type ())
+		    {
+				case UnicodeType.CONTROL:
+				case UnicodeType.FORMAT:
+				case UnicodeType.UNASSIGNED:
+				case UnicodeType.NON_SPACING_MARK:
+				case UnicodeType.COMBINING_MARK:
+				case UnicodeType.ENCLOSING_MARK:
+				    /* Ignore those */
+				    return 0;
+				default:
+				    return ch.tolower ();
+		    }
+		}
+
+	}
+
+	private class ListEntry : Gtk.Box
+	{
+		private Gitg.Ref d_reference;
+
+		public Gitg.Ref reference
+		{
+			get
+			{
+				return d_reference;
+			}
+
+			set
+			{
+				if(value != null)
+				{
+					d_reference = value;
+					update_entry();
+				}
+			}
+		}
+
+		private Gtk.Label d_label;
+
+		private void update_entry()
+		{
+			d_label.label = d_reference.parsed_name.shortname;
+			d_label.visible = true;
+			add(d_label);
+		}
+
+		construct
+		{
+			d_label = new Gtk.Label(null);
+		}
+	}
+}

libgitg/gitg-commit-model.vala

@@ -83,6 +83,17 @@ namespace Gitg
 
 		public uint limit { get; set; }
 
+		public Ggit.RevisionWalker walker
+		{
+			set
+			{
+				if(value != null)
+				{
+					d_walker = value;
+				}
+			}
+		}
+
 		public Ggit.SortMode sort_mode
 		{
 			get { return d_sortmode; }

libgitg/gitg-diff-view.vala

@@ -57,6 +57,8 @@ public class Gitg.DiffView : Gtk.Grid
 	private uint d_reveal_options_timeout;
 	private uint d_unreveal_options_timeout;
 
+	private uint d_update_diff_id;
+
 	private static Gee.HashSet<string> s_image_mime_types;
 
 	public Ggit.DiffOptions options
@@ -231,6 +233,12 @@ public class Gitg.DiffView : Gtk.Grid
 			d_cancellable.cancel();
 		}
 
+		if(d_update_diff_id != 0)
+		{
+			Source.remove(d_update_diff_id);
+			d_update_diff_id = 0;
+		}
+
 		base.dispose();
 	}
 
@@ -590,7 +598,22 @@ public class Gitg.DiffView : Gtk.Grid
 
 		if (d_diff != null)
 		{
-			update_diff(d_diff, preserve_expanded, d_cancellable);
+			if(d_update_diff_id != 0)
+			{
+				Source.remove(d_update_diff_id);
+				d_update_diff_id = 0;
+			}
+
+			d_update_diff_id = Idle.add(() => {
+				update_diff.begin(d_diff,
+								  preserve_expanded,
+								  d_cancellable,
+								  (obj, res) => {
+								  	d_update_diff_id = 0;
+								  });
+
+				return false;
+			});
 		}
 	}
 
@@ -693,7 +716,7 @@ public class Gitg.DiffView : Gtk.Grid
 		return "";
 	}
 
-	private void update_diff(Ggit.Diff diff, bool preserve_expanded, Cancellable? cancellable)
+	private async void update_diff(Ggit.Diff diff, bool preserve_expanded, Cancellable? cancellable)
 	{
 		var nqueries = 0;
 		var finished = false;

libgitg/meson.build

@@ -24,6 +24,7 @@ sources = files(
   'gitg-avatar-cache.vala',
   'gitg-branch-base.vala',
   'gitg-branch.vala',
+  'gitg-branches-popover.vala',
   'gitg-cell-renderer-lanes.vala',
   'gitg-color.vala',
   'gitg-commit-list-view.vala',
@@ -77,6 +78,7 @@ sources = files(
 
 resource_data = files(
   'resources/ui/gitg-authentication-dialog.ui',
+  'resources/ui/gitg-branches-popover.ui',
   'resources/ui/gitg-diff-view-commit-details.ui',
   'resources/ui/gitg-diff-view-file-renderer-binary.ui',
   'resources/ui/gitg-diff-view-file-renderer-image.ui',

libgitg/resources/resources.xml

@@ -2,6 +2,7 @@
 <gresources>
   <gresource prefix="/org/gnome/gitg">
     <file compressed="true" preprocess="xml-stripblanks">ui/gitg-repository-list-box-row.ui</file>
+    <file compressed="true" preprocess="xml-stripblanks">ui/gitg-branches-popover.ui</file>
     <file compressed="true" preprocess="xml-stripblanks">ui/gitg-authentication-dialog.ui</file>
     <file compressed="true" preprocess="xml-stripblanks">ui/gitg-diff-view.ui</file>
     <file compressed="true" preprocess="xml-stripblanks">ui/gitg-diff-view-file.ui</file>

libgitg/resources/ui/gitg-branches-popover.ui

@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <template class="GitgBranchesPopover" parent="GtkPopover">
+    <property name="modal">True</property>
+    <property name="position">bottom</property>
+    <property name="can_focus">False</property>
+    <property name="width-request">450</property>
+    <property name="height-request">300</property>
+
+    <child>
+      <object class="GtkBox">
+        <property name="visible">True</property>
+        <property name="border-width">5</property>
+        <property name="spacing">10</property>
+        <property name="orientation">vertical</property>
+
+        <child>
+          <object class="GtkSearchEntry" id="d_search_entry">
+            <property name="visible">True</property>
+            <property name="placeholder-text" translatable="yes">Search for branch...</property>
+            <signal name="search-changed" handler="on_search_entry_changed" />
+          </object>
+        </child>
+
+        <child>
+          <object class="GtkScrolledWindow" id="d_scrolled_window">
+            <property name="visible">True</property>
+            <property name="can-focus">True</property>
+            <child>
+              <object class="GtkListBox" id="d_listbox">
+                <property name="visible">True</property>
+                <property name="vexpand">True</property>
+                <property name="hexpand">True</property>
+                <property name="selection-mode">single</property>
+                <signal name="row-activated" handler="on_listbox_row_activated"/>
+              </object>
+            </child>
+          </object>
+        </child>
+
+      </object>
+    </child>
+
+  </template>
+</interface>
+