Bug 590294, part 6: Add a window.setResolution(xres, yres) API to control the number of backing pixels allocated to scalable content. r=roc sr=dbaron

dom/base/nsDOMWindowUtils.cpp

@@ -278,6 +278,18 @@ nsDOMWindowUtils::SetDisplayPort(float aXPx, float aYPx,
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsDOMWindowUtils::SetResolution(float aXResolution, float aYResolution)
+{
+  if (!IsUniversalXPConnectCapable()) {
+    return NS_ERROR_DOM_SECURITY_ERR;
+  }
+
+  nsIPresShell* presShell = GetPresShell();
+  return presShell ? presShell->SetResolution(aXResolution, aYResolution)
+                   : NS_ERROR_FAILURE;
+}
+
 NS_IMETHODIMP
 nsDOMWindowUtils::SendMouseEvent(const nsAString& aType,
                                  float aX,

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -53,7 +53,7 @@ interface nsIDOMEvent;
 interface nsITransferable;
 interface nsIQueryContentEventResult;
 
-[scriptable, uuid(b6628355-e72f-4d1d-9b83-ffc2740536b5)]
+[scriptable, uuid(d0d23c20-16ca-4c0f-b2d2-74ae4c7b858b)]
 interface nsIDOMWindowUtils : nsISupports {
 
   /**
@@ -139,6 +139,32 @@ interface nsIDOMWindowUtils : nsISupports {
   void setDisplayPort(in float aXPx, in float aYPx,
                       in float aWidthPx, in float aHeightPx);
 
+  /**
+   * Get/set the resolution at which rescalable web content is drawn.
+   * Currently this is only (some) thebes content.
+   *
+   * Setting a new resolution does *not* trigger reflow.  This API is
+   * entirely separate from textZoom and fullZoom; a resolution scale
+   * can be applied together with both textZoom and fullZoom.
+   *
+   * The effect of is API for gfx code to allocate more or fewer
+   * pixels for rescalable content by a factor of |resolution| in
+   * either or both dimensions.  setResolution() together with
+   * setDisplayport() can be used to implement a non-reflowing
+   * scale-zoom in concert with another entity that can draw with a
+   * scale.  For example, to scale a content |window| inside a
+   * <browser> by a factor of 2.0
+   *
+   *   window.setDisplayport(x, y, oldW / 2.0, oldH / 2.0);
+   *   window.setResolution(2.0, 2.0);
+   *   // elsewhere
+   *   browser.setViewportScale(2.0, 2.0);
+   *
+   * The caller of this method must have UniversalXPConnect
+   * privileges.
+   */
+  void setResolution(in float aXResolution, in float aYResolution);
+
   /** Synthesize a mouse event. The event types supported are:
    *    mousedown, mouseup, mousemove, mouseover, mouseout, contextmenu
    *

layout/base/nsIPresShell.h

@@ -1089,6 +1089,19 @@ public:
     return mDisplayPort;
   }
 
+   /**
+   * Set a "resolution" for the document, which if not 1.0 will
+   * allocate more or fewer pixels for rescalable content by a factor
+   * of |resolution| in both dimensions.  Return NS_OK iff the
+   * resolution bounds are sane, and the resolution of this was
+   * actually updated.
+   *
+   * The resolution defaults to 1.0.
+   */
+  virtual nsresult SetResolution(float aXResolution, float aYResolution) = 0;
+  float GetXResolution() { return mXResolution; }
+  float GetYResolution() { return mYResolution; }
+
   /**
    * Refresh observer management.
    */
@@ -1201,6 +1214,11 @@ protected:
   // maintain.
   nsRect                    mDisplayPort;
 
+  // Used to force allocation and rendering of proportionally more or
+  // less pixels in the given dimension.
+  float                     mXResolution;
+  float                     mYResolution;
+
   // Live pres shells, for memory and other tracking
   typedef nsPtrHashKey<nsIPresShell> PresShellPtrKey;
   static nsTHashtable<PresShellPtrKey> *sLiveShells;

layout/base/nsPresShell.cpp

@@ -831,6 +831,8 @@ public:
 
   virtual void SetDisplayPort(const nsRect& aDisplayPort);
 
+  virtual nsresult SetResolution(float aXResolution, float aYResolution);
+
   //nsIViewObserver interface
 
   NS_IMETHOD Paint(nsIView* aDisplayRoot,
@@ -1023,9 +1025,13 @@ protected:
     RenderingState(PresShell* aPresShell) 
       : mRenderFlags(aPresShell->mRenderFlags)
       , mDisplayPort(aPresShell->mDisplayPort)
+      , mXResolution(aPresShell->mXResolution)
+      , mYResolution(aPresShell->mYResolution)
     { }
     PRUint32 mRenderFlags;
     nsRect mDisplayPort;
+    float mXResolution;
+    float mYResolution;
   };
 
   struct AutoSaveRestoreRenderingState {
@@ -1038,6 +1044,8 @@ protected:
     {
       mPresShell->mRenderFlags = mOldState.mRenderFlags;
       mPresShell->mDisplayPort = mOldState.mDisplayPort;
+      mPresShell->mXResolution = mOldState.mXResolution;
+      mPresShell->mYResolution = mOldState.mYResolution;
     }
 
     PresShell* mPresShell;
@@ -1651,6 +1659,8 @@ PresShell::PresShell()
   mPresArenaAllocCount = 0;
 #endif
   mRenderFlags = 0;
+  mXResolution = 1.0;
+  mYResolution = 1.0;
 
   static bool registeredReporter = false;
   if (!registeredReporter) {
@@ -5944,6 +5954,21 @@ void PresShell::SetDisplayPort(const nsRect& aDisplayPort)
   SetRenderingState(state);
 }
 
+nsresult PresShell::SetResolution(float aXResolution, float aYResolution)
+{
+  if (!(aXResolution > 0.0 && aXResolution > 0.0)) {
+    return NS_ERROR_ILLEGAL_VALUE;
+  }
+  if (aXResolution == mXResolution && aYResolution == mYResolution) {
+    return NS_OK;
+  }
+  RenderingState state(this);
+  state.mXResolution = aXResolution;
+  state.mYResolution = aYResolution;
+  SetRenderingState(state);
+  return NS_OK;
+ }
+
 void PresShell::SetRenderingState(const RenderingState& aState)
 {
   if (mRenderFlags != aState.mRenderFlags) {
@@ -5961,6 +5986,8 @@ void PresShell::SetRenderingState(const RenderingState& aState)
   } else {
     mDisplayPort = nsRect();
   }
+  mXResolution = aState.mXResolution;
+  mYResolution = aState.mYResolution;
 
   nsIFrame* rootFrame = FrameManager()->GetRootFrame();
   if (rootFrame) {