Add auto-fit screen option (fix #789, fix #2267)

data/pref.xml

@@ -160,6 +160,10 @@
       <option id="straight_line_preview" type="bool" default="true" />
       <option id="play_once" type="bool" default="false" />
       <option id="play_all" type="bool" default="false" />
+      <!-- TODO this would be nice to be "true" but we have to fix
+           some performance issue rendering huge sprites with small
+           zoom levels -->
+      <option id="auto_fit" type="bool" default="false" />
     </section>
     <section id="cursor">
       <option id="use_native_cursor" type="bool" default="false" />

data/strings/en.ini

@@ -1068,6 +1068,7 @@ zoom_from_center_with_keys = Zoom from center with keys
 show_scrollbars = Show scroll-bars in sprite editor
 show_scrollbars_tooltip = Show scroll-bars in all sprite editors.
 auto_scroll = Auto-scroll on editor edges
+auto_fit = Auto-fit screen when a sprite is open
 straight_line_preview = Preview straight line immediately on Pencil tool
 straight_line_preview_tooltip = <<<END
 On Pencil tool you can draw straight lines

data/widgets/options.xml

@@ -203,6 +203,8 @@
           <check text="@.zoom_from_center_with_keys" id="zoom_from_center_with_keys" />
           <check text="@.show_scrollbars" id="show_scrollbars" tooltip="@.show_scrollbars_tooltip" />
           <check text="@.auto_scroll" id="auto_scroll" />
+          <check text="@.auto_fit" id="auto_fit"
+                 pref="editor.auto_fit" />
           <check text="@.straight_line_preview" id="straight_line_preview" tooltip="@.straight_line_preview_tooltip" />
           <check text="@.discard_brush" id="discard_brush" />
           <hbox>

src/app/commands/cmd_scroll_center.cpp

@@ -37,7 +37,7 @@ bool ScrollCenterCommand::onEnabled(Context* context)
 
 void ScrollCenterCommand::onExecute(Context* context)
 {
-  current_editor->setDefaultScroll();
+  current_editor->setScrollToCenter();
 }
 
 Command* CommandFactory::createScrollCenterCommand()

src/app/ui/editor/editor.cpp

@@ -417,6 +417,14 @@ void Editor::setZoom(const render::Zoom& zoom)
 }
 
 void Editor::setDefaultScroll()
+{
+  if (Preferences::instance().editor.autoFit())
+    setScrollAndZoomToFitScreen();
+  else
+    setScrollToCenter();
+}
+
+void Editor::setScrollToCenter()
 {
   View* view = View::getView(this);
   Rect vp = view->viewportBounds();

src/app/ui/editor/editor.h

@@ -155,6 +155,7 @@ namespace app {
 
     void setZoom(const render::Zoom& zoom);
     void setDefaultScroll();
+    void setScrollToCenter();
     void setScrollAndZoomToFitScreen();
     void setEditorScroll(const gfx::Point& scroll);
     void setEditorZoom(const render::Zoom& zoom);