Add command to change the layer opacity

data/gui.xml

@@ -223,6 +223,17 @@
         <param name="action" value="in" />
       </key>
 
+      <!-- Layer opacity -->
+      <key command="LayerOpacity"><param name="opacity" value="0" /></key>
+      <key command="LayerOpacity"><param name="opacity" value="32" /></key>
+      <key command="LayerOpacity" shortcut="Shift+1"><param name="opacity" value="64" /></key>
+      <key command="LayerOpacity"><param name="opacity" value="96" /></key>
+      <key command="LayerOpacity" shortcut="Shift+2"><param name="opacity" value="128" /></key>
+      <key command="LayerOpacity"><param name="opacity" value="160" /></key>
+      <key command="LayerOpacity" shortcut="Shift+3"><param name="opacity" value="192" /></key>
+      <key command="LayerOpacity"><param name="opacity" value="224" /></key>
+      <key command="LayerOpacity" shortcut="Shift+4"><param name="opacity" value="255" /></key>
+
       <!-- Scroll to center -->
       <key command="ScrollCenter" shortcut="Shift+C" />
       <key command="FitScreen" shortcut="Ctrl+0" mac="Cmd+0" />

src/app/CMakeLists.txt

@@ -225,6 +225,7 @@ add_library(app-lib
   commands/cmd_keyboard_shortcuts.cpp
   commands/cmd_launch.cpp
   commands/cmd_layer_from_background.cpp
+  commands/cmd_layer_opacity.cpp
   commands/cmd_layer_properties.cpp
   commands/cmd_layer_visibility.cpp
   commands/cmd_link_cels.cpp

src/app/commands/cmd_layer_opacity.cpp

@@ -0,0 +1,111 @@
+// Aseprite
+// Copyright (C) 2016  David Capello
+//
+// This program is distributed under the terms of
+// the End-User License Agreement for Aseprite.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "app/app.h"
+#include "app/cmd/set_layer_opacity.h"
+#include "app/commands/command.h"
+#include "app/commands/params.h"
+#include "app/context.h"
+#include "app/context_access.h"
+#include "app/modules/gui.h"
+#include "app/transaction.h"
+#include "app/ui/timeline.h"
+#include "base/convert_to.h"
+#include "doc/layer.h"
+
+#include <string>
+
+namespace app {
+
+class LayerOpacityCommand : public Command {
+public:
+  LayerOpacityCommand();
+
+protected:
+  void onLoadParams(const Params& params) override;
+  bool onEnabled(Context* context) override;
+  void onExecute(Context* context) override;
+  std::string onGetFriendlyName() const override;
+
+private:
+  int m_opacity;
+};
+
+LayerOpacityCommand::LayerOpacityCommand()
+  : Command("LayerOpacity",
+            "Layer Opacity",
+            CmdUIOnlyFlag)
+{
+  m_opacity = 255;
+}
+
+void LayerOpacityCommand::onLoadParams(const Params& params)
+{
+  m_opacity = params.get_as<int>("opacity");
+  m_opacity = MID(0, m_opacity, 255);
+}
+
+bool LayerOpacityCommand::onEnabled(Context* context)
+{
+  return context->checkFlags(ContextFlags::ActiveDocumentIsWritable |
+                             ContextFlags::HasActiveLayer);
+}
+
+void LayerOpacityCommand::onExecute(Context* context)
+{
+  ContextWriter writer(context);
+  Layer* layer = writer.layer();
+  if (!layer ||
+      !layer->isImage() ||
+      static_cast<LayerImage*>(layer)->opacity() == m_opacity)
+    return;
+
+  {
+    Transaction transaction(writer.context(), "Set Layer Opacity");
+
+    // TODO the range of selected frames should be in doc::Site.
+    auto range = App::instance()->timeline()->range();
+    if (range.enabled()) {
+      for (LayerIndex layerIdx = range.layerBegin(); layerIdx <= range.layerEnd(); ++layerIdx) {
+        Layer* layer = writer.sprite()->indexToLayer(layerIdx);
+        if (!layer->isImage())
+          continue;
+
+        transaction.execute(
+          new cmd::SetLayerOpacity(static_cast<LayerImage*>(layer), m_opacity));
+      }
+    }
+    else {
+      transaction.execute(
+        new cmd::SetLayerOpacity(static_cast<LayerImage*>(writer.layer()), m_opacity));
+    }
+
+    transaction.commit();
+  }
+
+  update_screen_for_document(writer.document());
+}
+
+std::string LayerOpacityCommand::onGetFriendlyName() const
+{
+  std::string text = "Set Layer Opacity to ";
+  text += base::convert_to<std::string>(m_opacity);
+  text += " (";
+  text += base::convert_to<std::string>(int(100.0 * m_opacity / 255.0));
+  text += "%)";
+  return text;
+}
+
+Command* CommandFactory::createLayerOpacityCommand()
+{
+  return new LayerOpacityCommand;
+}
+
+} // namespace app

src/app/commands/commands_list.h

@@ -61,6 +61,7 @@ FOR_EACH_COMMAND(InvertMask)
 FOR_EACH_COMMAND(KeyboardShortcuts)
 FOR_EACH_COMMAND(Launch)
 FOR_EACH_COMMAND(LayerFromBackground)
+FOR_EACH_COMMAND(LayerOpacity)
 FOR_EACH_COMMAND(LayerProperties)
 FOR_EACH_COMMAND(LayerVisibility)
 FOR_EACH_COMMAND(LinkCels)