Fix some problems updating the StatusBar cel opacity slider

Now the StatusBar observes changes in the cel opacity to update the
slider (e.g. when we change the cel opacity through Cel > Properties
menu, the StatusBar refresh its slider).

src/app/cmd/set_pixel_format.cpp

@@ -20,6 +20,7 @@
 #include "doc/cel.h"
 #include "doc/cels_range.h"
 #include "doc/document.h"
+#include "doc/document_event.h"
 #include "doc/layer.h"
 #include "doc/palette.h"
 #include "doc/sprite.h"
@@ -124,6 +125,11 @@ void SetPixelFormat::setFormat(PixelFormat format)
   // Regenerate extras
   static_cast<app::Document*>(sprite->document())
     ->destroyExtraCel();
+
+  // Generate notification
+  DocumentEvent ev(sprite->document());
+  ev.sprite(sprite);
+  sprite->document()->notifyObservers<DocumentEvent&>(&DocumentObserver::onPixelFormatChanged, ev);
 }
 
 } // namespace cmd

src/app/ui/status_bar.cpp

@@ -33,6 +33,7 @@
 #include "app/util/range_utils.h"
 #include "base/bind.h"
 #include "doc/cel.h"
+#include "doc/document_event.h"
 #include "doc/image.h"
 #include "doc/layer.h"
 #include "doc/sprite.h"
@@ -137,7 +138,7 @@ StatusBar* StatusBar::m_instance = NULL;
 StatusBar::StatusBar()
   : Widget(statusbar_type())
   , m_color(app::Color::fromMask())
-  , m_hasDoc(false)
+  , m_doc(nullptr)
 {
   m_instance = this;
 
@@ -172,7 +173,7 @@ StatusBar::StatusBar()
     setup_mini_look(m_newFrame);
     setup_mini_look(m_slider);
 
-    m_slider->Change.connect(Bind<void>(&StatusBar::onCelOpacityChange, this));
+    m_slider->Change.connect(Bind<void>(&StatusBar::onCelOpacitySliderChange, this));
     m_slider->setMinSize(gfx::Size(ui::display_w()/5, 0));
 
     box1->setBorder(gfx::Border(2, 1, 2, 2)*guiscale());
@@ -199,10 +200,12 @@ StatusBar::StatusBar()
     Bind<void>(&StatusBar::onCurrentToolChange, this));
 
   UIContext::instance()->addObserver(this);
+  UIContext::instance()->documents().addObserver(this);
 }
 
 StatusBar::~StatusBar()
 {
+  UIContext::instance()->documents().removeObserver(this);
   UIContext::instance()->removeObserver(this);
 
   delete m_tipwindow;           // widget
@@ -334,7 +337,7 @@ void StatusBar::onResize(ResizeEvent& ev)
     rc.x += rc.w - prefWidth - border.right() - toolBarWidth;
     rc.w = prefWidth;
 
-    m_commandsBox->setVisible(true && m_hasDoc);
+    m_commandsBox->setVisible(m_doc != nullptr);
     m_commandsBox->setBounds(rc);
   }
   else
@@ -421,7 +424,7 @@ bool StatusBar::CustomizedTipWindow::onProcessMessage(Message* msg)
   return ui::TipWindow::onProcessMessage(msg);
 }
 
-void StatusBar::onCelOpacityChange()
+void StatusBar::onCelOpacitySliderChange()
 {
   try {
     ContextWriter writer(UIContext::instance(), 500);
@@ -449,8 +452,20 @@ void StatusBar::onCelOpacityChange()
 
 void StatusBar::onActiveSiteChange(const doc::Site& site)
 {
+  if (m_doc && site.document() != m_doc) {
+    m_doc->removeObserver(this);
+    m_doc = nullptr;
+  }
+
   if (site.document() && site.sprite()) {
-    m_hasDoc = true;
+    if (!m_doc) {
+      m_doc = const_cast<doc::Document*>(site.document());
+      m_doc->addObserver(this);
+    }
+    else {
+      ASSERT(m_doc == site.document());
+    }
+
     m_commandsBox->setVisible(true);
 
     // Current frame
@@ -472,11 +487,38 @@ void StatusBar::onActiveSiteChange(const doc::Site& site)
     }
   }
   else {
-    m_hasDoc = false;
+    ASSERT(m_doc == nullptr);
     m_commandsBox->setVisible(false);
   }
 }
 
+void StatusBar::onRemoveDocument(doc::Document* doc)
+{
+  if (m_doc &&
+      m_doc == doc) {
+    m_doc->removeObserver(this);
+    m_doc = nullptr;
+  }
+}
+
+void StatusBar::onCelOpacityChanged(doc::DocumentEvent& ev)
+{
+  ASSERT(m_doc);
+  ASSERT(m_doc == const_cast<doc::Document*>(ev.document()));
+  ASSERT(ev.cel());
+
+  if (m_doc &&
+      m_doc == const_cast<doc::Document*>(ev.document()) &&
+      ev.cel()) {
+    m_slider->setValue(MID(0, ev.cel()->opacity(), 255));
+  }
+}
+
+void StatusBar::onPixelFormatChanged(DocumentEvent& ev)
+{
+  onActiveSiteChange(UIContext::instance()->activeSite());
+}
+
 void StatusBar::newFrame()
 {
   Command* cmd = CommandsModule::instance()->getCommandByName(CommandId::NewFrame);

src/app/ui/status_bar.h

@@ -12,6 +12,8 @@
 #include "app/color.h"
 #include "base/observers.h"
 #include "doc/context_observer.h"
+#include "doc/document_observer.h"
+#include "doc/documents_observer.h"
 #include "doc/layer_index.h"
 #include "ui/base.h"
 #include "ui/widget.h"
@@ -38,7 +40,9 @@ namespace app {
   }
 
   class StatusBar : public ui::Widget
-                  , public doc::ContextObserver {
+                  , public doc::ContextObserver
+                  , public doc::DocumentsObserver
+                  , public doc::DocumentObserver {
     static StatusBar* m_instance;
   public:
     static StatusBar* instance() { return m_instance; }
@@ -61,9 +65,16 @@ namespace app {
     // ContextObserver impl
     void onActiveSiteChange(const doc::Site& site) override;
 
+    // DocumentObservers impl
+    void onRemoveDocument(doc::Document* doc) override;
+
+    // DocumentObserver impl
+    void onCelOpacityChanged(doc::DocumentEvent& ev) override;
+    void onPixelFormatChanged(DocumentEvent& ev) override;
+
   private:
     void onCurrentToolChange();
-    void onCelOpacityChange();
+    void onCelOpacitySliderChange();
     void newFrame();
 
     enum State { SHOW_TEXT, SHOW_COLOR, SHOW_TOOL };
@@ -84,7 +95,7 @@ namespace app {
     ui::Slider* m_slider;             // Opacity slider
     ui::Entry* m_currentFrame;        // Current frame and go to frame entry
     ui::Button* m_newFrame;           // Button to create a new frame
-    bool m_hasDoc;
+    doc::Document* m_doc;      // Document used to show the cel slider
 
     // Tip window
     class CustomizedTipWindow;

src/doc/document_observer.h

@@ -1,5 +1,5 @@
 // Aseprite Document Library
-// Copyright (c) 2001-2014 David Capello
+// Copyright (c) 2001-2015 David Capello
 //
 // This file is released under the terms of the MIT license.
 // Read LICENSE.txt for more information.
@@ -22,6 +22,8 @@ namespace doc {
     // anything in the document could be changed.
     virtual void onGeneralUpdate(DocumentEvent& ev) { }
 
+    virtual void onPixelFormatChanged(DocumentEvent& ev) { }
+
     virtual void onAddLayer(DocumentEvent& ev) { }
     virtual void onAddFrame(DocumentEvent& ev) { }
     virtual void onAddCel(DocumentEvent& ev) { }