Allow choosing merge diff parent

gitg/gitg-commit-action-create-patch.vala

@@ -107,7 +107,7 @@ class CommitActionCreatePatch : GitgExt.UIElement, GitgExt.Action, GitgExt.Commi
 		opts.n_context_lines = nc;
 		opts.n_interhunk_lines = nc;
 
-		return commit.get_diff(opts);
+		return commit.get_diff(opts, 0);
 	}
 
 	private void create_patch(File file) throws Error

libgitg/gitg-commit.vala

@@ -111,7 +111,7 @@ public class Commit : Ggit.Commit
 		}
 	}
 
-	public Ggit.Diff get_diff(Ggit.DiffOptions? options)
+	public Ggit.Diff get_diff(Ggit.DiffOptions? options, int parent)
 	{
 		Ggit.Diff? diff = null;
 
@@ -121,9 +121,9 @@ public class Commit : Ggit.Commit
 		{
 			var parents = get_parents();
 
-			// Create a new diff from the parents to the commit tree
 			if (parents.size == 0)
 			{
+				// No parents, initial commit?
 				diff = new Ggit.Diff.tree_to_tree(repo,
 				                                  null,
 				                                  get_tree(),
@@ -131,27 +131,15 @@ public class Commit : Ggit.Commit
 			}
 			else
 			{
-				for (var i = 0; i < parents.size; ++i)
+				if (parent >= parents.size)
 				{
-					var parent = parents[i];
-
-					if (i == 0)
-					{
-						diff = new Ggit.Diff.tree_to_tree(repo,
-						                                  parent.get_tree(),
-						                                  get_tree(),
-						                                  options);
-					}
-					else
-					{
-						var d = new Ggit.Diff.tree_to_tree(repo,
-						                                   parent.get_tree(),
-						                                   get_tree(),
-						                                   options);
-
-						diff.merge(d);
-					}
+					parent = (int)parents.size - 1;
 				}
+
+				diff = new Ggit.Diff.tree_to_tree(repo,
+						                              parents[parent].get_tree(),
+						                              get_tree(),
+						                              options);
 			}
 		}
 		catch (Error e)

libgitg/gitg-diff-view.vala

@@ -42,6 +42,9 @@ namespace Gitg
 						case "load-parent":
 							d_view.load_parent(parameter("value"));
 							break;
+						case "select-parent":
+							d_view.select_parent(parameter("value"));
+							break;
 					}
 
 					return false;
@@ -58,6 +61,7 @@ namespace Gitg
 		private Settings? d_fontsettings;
 		private bool d_has_selection;
 		private Ggit.DiffOptions? d_options;
+		private string? d_parent;
 
 		private static Gee.HashMap<string, DiffView> s_diff_map;
 		private static uint64 s_diff_id;
@@ -103,6 +107,7 @@ namespace Gitg
 			{
 				d_diff = value;
 				d_commit = null;
+				d_parent = null;
 
 				update();
 			}
@@ -113,8 +118,12 @@ namespace Gitg
 			get { return d_commit; }
 			set
 			{
-				d_commit = value;
-				d_diff = null;
+				if (d_commit != value)
+				{
+					d_commit = value;
+					d_diff = null;
+					d_parent = null;
+				}
 
 				update();
 			}
@@ -230,6 +239,7 @@ namespace Gitg
 			o.set_boolean_member("debug", Environment.get_variable("GITG_GTK_DIFF_VIEW_DEBUG") != null);
 			o.set_boolean_member("changes_inline", changes_inline);
 			o.set_boolean_member("show_parents", show_parents);
+			o.set_string_member("parent", d_parent);
 
 			var strings = new Json.Object();
 
@@ -238,6 +248,7 @@ namespace Gitg
 			strings.set_string_member("loading_diff", _("Loading diff…"));
 			strings.set_string_member("notes", _("Notes:"));
 			strings.set_string_member("parents", _("Parents:"));
+			strings.set_string_member("diff_against", _("Diff against:"));
 
 			o.set_object_member("strings", strings);
 
@@ -512,7 +523,24 @@ namespace Gitg
 
 			if (d_commit != null)
 			{
-				d_diff = d_commit.get_diff(options);
+				int parent = 0;
+				var parents = d_commit.get_parents();
+
+				if (d_parent != null)
+				{
+					for (var i = 0; i < parents.size; i++)
+					{
+						var id = parents.get_id(i);
+
+						if (id.to_string() == d_parent)
+						{
+							parent = i;
+							break;
+						}
+					}
+				}
+
+				d_diff = d_commit.get_diff(options, parent);
 			}
 
 			if (d_diff != null)
@@ -540,6 +568,12 @@ namespace Gitg
 			request_select_commit(id);
 		}
 
+		public void select_parent(string id)
+		{
+			d_parent = id;
+			update();
+		}
+
 		private PatchSet parse_patchset(Json.Node node)
 		{
 			PatchSet ret = new PatchSet();

libgitg/resources/diff-view.css

@@ -244,6 +244,15 @@ div.commit .note_message {
   margin-bottom: 5px;
 }
 
+div.commit .parent-chooser {
+  float: right;
+}
+
+div.commit .parent-chooser select {
+  margin-left: 6px;
+  padding: 1px;
+}
+
 a {
   color: #3465a4;
 }

libgitg/resources/diff-view.html

@@ -35,6 +35,8 @@
     <div id="diff">
       <div id="diff_header">
         <div class="commit">
+          <div class="parent-chooser" data-id="parent_chooser">
+          </div>
           <img class="avatar" data-id="avatar" src="gitg-diff:/icon/avatar-default-symbolic?size=50"/>
           <p>
             <span class="author" data-id="author"></span><br/>

libgitg/resources/diff-view.js

@@ -27,7 +27,8 @@ var settings = {
 		unstage: 'unstage',
 		loading_diff: 'Loading diff...',
 		notes: 'Notes:',
-		parents: 'Parents:'
+		parents: 'Parents:',
+		diff_against: 'Diff against:'
 	},
 };
 
@@ -165,6 +166,33 @@ function write_commit(content, commit)
 		elems.notes_container.hide();
 	}
 
+	if (commit.parents.length > 1)
+	{
+		var span = $('<span/>').text(settings.strings.diff_against);
+		var chooser = $('<select/>');
+
+		for (var i = 0; i < commit.parents.length; i++)
+		{
+			var parent = commit.parents[i];
+			var elem = $('<option/>', {
+				value: parent.id
+			}).text(parent.id.slice(0, 6));
+
+			if (parent.id === settings.parent)
+			{
+				elem.attr('selected', 'selected');
+			}
+
+			chooser.append(elem);
+		}
+
+		chooser.on('change', function() {
+			xhr_get('internal', {'action': 'select-parent', 'value': chooser.val()});
+		});
+
+		elems.parent_chooser.html([span, chooser]);
+	}
+
 	if (commit.parents.length > 1 && settings.show_parents)
 	{
 		var d = $('<div/>');