PixelPaint: Start working on a custom layer list widget

Instead of using a TableView to show the layer stack, let's build a new
custom widget for this purpose and give it some neat features!

This patch also introduces an ImageClient interface for Image to notify
interested parties about things happening. The LayerListWidget is the
first ImageClient and listens for "layer added" and "layer removed"
notifications. :^)

Applications/PixelPaint/CMakeLists.txt

@@ -6,6 +6,7 @@ set(SOURCES
     Image.cpp
     ImageEditor.cpp
     Layer.cpp
+    LayerListWidget.cpp
     LayerModel.cpp
     LineTool.cpp
     main.cpp

Applications/PixelPaint/Image.cpp

@@ -67,6 +67,9 @@ void Image::add_layer(NonnullRefPtr<Layer> layer)
         ASSERT(&existing_layer != layer.ptr());
     }
     m_layers.append(move(layer));
+
+    for (auto* client : m_clients)
+        client->image_did_add_layer(m_layers.size() - 1);
 }
 
 GUI::Model& Image::layer_model()
@@ -126,6 +129,21 @@ void Image::remove_layer(Layer& layer)
     NonnullRefPtr<Layer> protector(layer);
     auto index = index_of(layer);
     m_layers.remove(index);
+
+    for (auto* client : m_clients)
+        client->image_did_remove_layer(index);
+}
+
+void Image::add_client(ImageClient& client)
+{
+    ASSERT(!m_clients.contains(&client));
+    m_clients.set(&client);
+}
+
+void Image::remove_client(ImageClient& client)
+{
+    ASSERT(m_clients.contains(&client));
+    m_clients.remove(&client);
 }
 
 }

Applications/PixelPaint/Image.h

@@ -26,6 +26,7 @@
 
 #pragma once
 
+#include <AK/HashTable.h>
 #include <AK/NonnullRefPtrVector.h>
 #include <AK/RefCounted.h>
 #include <AK/RefPtr.h>
@@ -39,6 +40,13 @@ namespace PixelPaint {
 
 class Layer;
 
+class ImageClient {
+public:
+    virtual void image_did_add_layer(size_t) { }
+    virtual void image_did_remove_layer(size_t) { }
+    virtual void image_did_update_layer(size_t) { }
+};
+
 class Image : public RefCounted<Image> {
 public:
     static RefPtr<Image> create_with_size(const Gfx::Size&);
@@ -61,6 +69,9 @@ public:
     void move_layer_down(Layer&);
     void remove_layer(Layer&);
 
+    void add_client(ImageClient&);
+    void remove_client(ImageClient&);
+
 private:
     explicit Image(const Gfx::Size&);
 
@@ -69,6 +80,8 @@ private:
     Gfx::Size m_size;
     NonnullRefPtrVector<Layer> m_layers;
     RefPtr<GUI::Model> m_layer_model;
+
+    HashTable<ImageClient*> m_clients;
 };
 
 }

Applications/PixelPaint/LayerListWidget.cpp

@@ -0,0 +1,147 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "LayerListWidget.h"
+#include "Image.h"
+#include "Layer.h"
+#include <LibGUI/Model.h>
+#include <LibGUI/Painter.h>
+#include <LibGfx/Palette.h>
+
+namespace PixelPaint {
+
+LayerListWidget::LayerListWidget()
+{
+}
+
+LayerListWidget::~LayerListWidget()
+{
+    if (m_image)
+        m_image->remove_client(*this);
+}
+
+void LayerListWidget::set_image(Image* image)
+{
+    if (m_image == image)
+        return;
+    if (m_image)
+        m_image->remove_client(*this);
+    m_image = image;
+    if (m_image)
+        m_image->add_client(*this);
+
+    m_gadgets.clear();
+
+    if (m_image) {
+        for (size_t layer_index = 0; layer_index < m_image->layer_count(); ++layer_index) {
+            m_gadgets.append({ layer_index, {} });
+        }
+    }
+
+    relayout_gadgets();
+}
+
+void LayerListWidget::resize_event(GUI::ResizeEvent& event)
+{
+    Widget::resize_event(event);
+    relayout_gadgets();
+}
+
+void LayerListWidget::paint_event(GUI::PaintEvent& event)
+{
+    GUI::Painter painter(*this);
+    painter.add_clip_rect(event.rect());
+
+    painter.fill_rect(event.rect(), palette().button());
+
+    if (!m_image)
+        return;
+
+    painter.fill_rect(event.rect(), palette().button());
+
+    for (auto& gadget : m_gadgets) {
+        painter.draw_rect(gadget.rect, Color::Black);
+        auto& layer = m_image->layer(gadget.layer_index);
+
+        Gfx::Rect thumbnail_rect { gadget.rect.x(), gadget.rect.y(), gadget.rect.height(), gadget.rect.height() };
+        thumbnail_rect.shrink(8, 8);
+        painter.draw_scaled_bitmap(thumbnail_rect, layer.bitmap(), layer.bitmap().rect());
+
+        Gfx::Rect text_rect { thumbnail_rect.right() + 10, gadget.rect.y(), gadget.rect.width(), gadget.rect.height() };
+        text_rect.intersect(gadget.rect);
+
+        painter.draw_text(text_rect, layer.name(), Gfx::TextAlignment::CenterLeft);
+    }
+}
+
+void LayerListWidget::mousedown_event(GUI::MouseEvent& event)
+{
+    (void)event;
+}
+
+void LayerListWidget::mousemove_event(GUI::MouseEvent& event)
+{
+    (void)event;
+}
+
+void LayerListWidget::mouseup_event(GUI::MouseEvent& event)
+{
+    (void)event;
+}
+
+void LayerListWidget::image_did_add_layer(size_t layer_index)
+{
+    Gadget gadget { layer_index, {} };
+    m_gadgets.insert(layer_index, move(gadget));
+    relayout_gadgets();
+}
+
+void LayerListWidget::image_did_remove_layer(size_t layer_index)
+{
+    m_gadgets.remove(layer_index);
+    relayout_gadgets();
+}
+
+void LayerListWidget::image_did_update_layer(size_t layer_index)
+{
+    update(m_gadgets[layer_index].rect);
+}
+
+void LayerListWidget::relayout_gadgets()
+{
+    constexpr int gadget_height = 30;
+    constexpr int gadget_spacing = 1;
+    int y = 0;
+
+    for (auto& gadget : m_gadgets) {
+        gadget.rect = { 0, y, width(), gadget_height };
+        y += gadget_height + gadget_spacing;
+    }
+
+    update();
+}
+
+}

Applications/PixelPaint/LayerListWidget.h

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include "Image.h"
+#include <LibGUI/Widget.h>
+
+namespace PixelPaint {
+
+class LayerListWidget final
+    : public GUI::Widget
+    , ImageClient {
+    C_OBJECT(LayerListWidget);
+
+public:
+    virtual ~LayerListWidget() override;
+
+    void set_image(Image*);
+
+private:
+    explicit LayerListWidget();
+
+    virtual void paint_event(GUI::PaintEvent&) override;
+    virtual void mousedown_event(GUI::MouseEvent&) override;
+    virtual void mousemove_event(GUI::MouseEvent&) override;
+    virtual void mouseup_event(GUI::MouseEvent&) override;
+    virtual void resize_event(GUI::ResizeEvent&) override;
+
+    virtual void image_did_add_layer(size_t) override;
+    virtual void image_did_remove_layer(size_t) override;
+    virtual void image_did_update_layer(size_t);
+
+    void relayout_gadgets();
+
+    struct Gadget {
+        size_t layer_index { 0 };
+        Gfx::Rect rect;
+    };
+
+    Vector<Gadget> m_gadgets;
+    RefPtr<Image> m_image;
+};
+
+}

Applications/PixelPaint/main.cpp

@@ -28,6 +28,7 @@
 #include "Image.h"
 #include "ImageEditor.h"
 #include "Layer.h"
+#include "LayerListWidget.h"
 #include "PaletteWidget.h"
 #include "Tool.h"
 #include "ToolboxWidget.h"
@@ -84,12 +85,15 @@ int main(int argc, char** argv)
     vertical_container.add<PixelPaint::PaletteWidget>(image_editor);
 
     auto& right_panel = horizontal_container.add<GUI::Widget>();
+    right_panel.set_fill_with_background_color(true);
     right_panel.set_size_policy(GUI::SizePolicy::Fixed, GUI::SizePolicy::Fill);
     right_panel.set_preferred_size(230, 0);
     right_panel.set_layout<GUI::VerticalBoxLayout>();
 
     auto& layer_table_view = right_panel.add<GUI::TableView>();
 
+    auto& layer_list_widget = right_panel.add<PixelPaint::LayerListWidget>();
+
     window->show();
 
     auto menubar = GUI::MenuBar::construct();
@@ -123,58 +127,74 @@ int main(int argc, char** argv)
     });
 
     auto& layer_menu = menubar->add_menu("Layer");
-    layer_menu.add_action(GUI::Action::create("Create new layer...", { Mod_Ctrl | Mod_Shift, Key_N }, [&](auto&) {
+    layer_menu.add_action(GUI::Action::create(
-        auto dialog = PixelPaint::CreateNewLayerDialog::construct(image_editor.image()->size(), window);
+        "Create new layer...", { Mod_Ctrl | Mod_Shift, Key_N }, [&](auto&) {
-        if (dialog->exec() == GUI::Dialog::ExecOK) {
+            auto dialog = PixelPaint::CreateNewLayerDialog::construct(image_editor.image()->size(), window);
-            auto layer = PixelPaint::Layer::create_with_size(dialog->layer_size(), dialog->layer_name());
+            if (dialog->exec() == GUI::Dialog::ExecOK) {
-            if (!layer) {
+                auto layer = PixelPaint::Layer::create_with_size(dialog->layer_size(), dialog->layer_name());
-                GUI::MessageBox::show_error(String::format("Unable to create layer with size %s", dialog->size().to_string().characters()));
+                if (!layer) {
-                return;
+                    GUI::MessageBox::show_error(String::format("Unable to create layer with size %s", dialog->size().to_string().characters()));
+                    return;
+                }
+                image_editor.image()->add_layer(layer.release_nonnull());
+                image_editor.layers_did_change();
             }
-            image_editor.image()->add_layer(layer.release_nonnull());
+        },
-            image_editor.layers_did_change();
+        window));
-        }
-    }, window));
 
     layer_menu.add_separator();
-    layer_menu.add_action(GUI::Action::create("Select previous layer", { 0, Key_PageUp }, [&](auto&) {
+    layer_menu.add_action(GUI::Action::create(
-        layer_table_view.move_selection(1);
+        "Select previous layer", { 0, Key_PageUp }, [&](auto&) {
-    }, window));
+            layer_table_view.move_selection(1);
-    layer_menu.add_action(GUI::Action::create("Select next layer", { 0, Key_PageDown }, [&](auto&) {
+        },
-        layer_table_view.move_selection(-1);
+        window));
-    }, window));
+    layer_menu.add_action(GUI::Action::create(
-    layer_menu.add_action(GUI::Action::create("Select top layer", { 0, Key_Home }, [&](auto&) {
+        "Select next layer", { 0, Key_PageDown }, [&](auto&) {
-        layer_table_view.selection().set(layer_table_view.model()->index(image_editor.image()->layer_count() - 1));
+            layer_table_view.move_selection(-1);
-    }, window));
+        },
-    layer_menu.add_action(GUI::Action::create("Select bottom layer", { 0, Key_End }, [&](auto&) {
+        window));
-        layer_table_view.selection().set(layer_table_view.model()->index(0));
+    layer_menu.add_action(GUI::Action::create(
-    }, window));
+        "Select top layer", { 0, Key_Home }, [&](auto&) {
+            layer_table_view.selection().set(layer_table_view.model()->index(image_editor.image()->layer_count() - 1));
+        },
+        window));
+    layer_menu.add_action(GUI::Action::create(
+        "Select bottom layer", { 0, Key_End }, [&](auto&) {
+            layer_table_view.selection().set(layer_table_view.model()->index(0));
+        },
+        window));
     layer_menu.add_separator();
-    layer_menu.add_action(GUI::Action::create("Move active layer up", { Mod_Ctrl, Key_PageUp }, [&](auto&) {
+    layer_menu.add_action(GUI::Action::create(
-        auto active_layer = image_editor.active_layer();
+        "Move active layer up", { Mod_Ctrl, Key_PageUp }, [&](auto&) {
-        if(!active_layer)
+            auto active_layer = image_editor.active_layer();
-            return;
+            if (!active_layer)
-        image_editor.image()->move_layer_up(*active_layer);
+                return;
-        layer_table_view.move_selection(1);
+            image_editor.image()->move_layer_up(*active_layer);
-        image_editor.layers_did_change();
+            layer_table_view.move_selection(1);
-    }, window));
+            image_editor.layers_did_change();
-    layer_menu.add_action(GUI::Action::create("Move active layer down", { Mod_Ctrl, Key_PageDown }, [&](auto&) {
+        },
-        auto active_layer = image_editor.active_layer();
+        window));
-        if(!active_layer)
+    layer_menu.add_action(GUI::Action::create(
-            return;
+        "Move active layer down", { Mod_Ctrl, Key_PageDown }, [&](auto&) {
-        image_editor.image()->move_layer_down(*active_layer);
+            auto active_layer = image_editor.active_layer();
-        layer_table_view.move_selection(-1);
+            if (!active_layer)
-        image_editor.layers_did_change();
+                return;
-    }, window));
+            image_editor.image()->move_layer_down(*active_layer);
+            layer_table_view.move_selection(-1);
+            image_editor.layers_did_change();
+        },
+        window));
     layer_menu.add_separator();
-    layer_menu.add_action(GUI::Action::create("Remove active layer", { Mod_Ctrl , Key_D }, [&](auto&) {
+    layer_menu.add_action(GUI::Action::create(
-        auto active_layer = image_editor.active_layer();
+        "Remove active layer", { Mod_Ctrl, Key_D }, [&](auto&) {
-        if(!active_layer)
+            auto active_layer = image_editor.active_layer();
-            return;
+            if (!active_layer)
-        image_editor.image()->remove_layer(*active_layer);
+                return;
-        image_editor.set_active_layer(nullptr);
+            image_editor.image()->remove_layer(*active_layer);
-        image_editor.layers_did_change();
+            image_editor.set_active_layer(nullptr);
-    }, window));
+            image_editor.layers_did_change();
+        },
+        window));
 
     auto& help_menu = menubar->add_menu("Help");
     help_menu.add_action(GUI::Action::create("About", [&](auto&) {
@@ -196,6 +216,16 @@ int main(int argc, char** argv)
     image->add_layer(*bg_layer);
     bg_layer->bitmap().fill(Color::White);
 
+    auto fg_layer1 = PixelPaint::Layer::create_with_size({ 200, 200 }, "FG Layer 1");
+    fg_layer1->set_location({ 50, 50 });
+    image->add_layer(*fg_layer1);
+    fg_layer1->bitmap().fill(Color::Yellow);
+
+    auto fg_layer2 = PixelPaint::Layer::create_with_size({ 100, 100 }, "FG Layer 2");
+    fg_layer2->set_location({ 300, 300 });
+    image->add_layer(*fg_layer2);
+    fg_layer2->bitmap().fill(Color::Blue);
+
     layer_table_view.set_model(image->layer_model());
     layer_table_view.on_selection_change = [&] {
         auto index = layer_table_view.selection().first();
@@ -205,6 +235,8 @@ int main(int argc, char** argv)
             image_editor.set_active_layer(nullptr);
     };
 
+    layer_list_widget.set_image(image);
+
     image_editor.set_image(image);
     image_editor.set_active_layer(bg_layer);