Bug 557159 - [OS/2] Optimize Cairo/Thebes surfaces. Surface Part 3 - nsWindow. r= Peter Weilbacher, a=NPOTB

widget/src/os2/nsWindow.cpp

@@ -222,6 +222,7 @@ nsWindow::nsWindow() : nsBaseWidget()
   mOnDestroyCalled    = PR_FALSE;
   mIsDestroying       = PR_FALSE;
   mInSetFocus         = PR_FALSE;
+  mNoPaint            = PR_FALSE;
   mDragHps            = 0;
   mDragStatus         = 0;
   mClipWnd            = 0;
@@ -399,6 +400,15 @@ NS_METHOD nsWindow::Create(nsIWidget* aParent,
   if (aInitData) {
     mWindowType = aInitData->mWindowType;
     mBorderStyle = aInitData->mBorderStyle;
+
+    // Suppress creation of a Thebes surface for windows that will never
+    // be painted because they're always covered by another window.
+    if (mWindowType == eWindowType_toplevel ||
+        mWindowType == eWindowType_invisible ||
+        (mWindowType == eWindowType_child &&
+         aInitData->mContentType == eContentTypeContent)) {
+      mNoPaint = PR_TRUE;
+    }
   }
 
   // For toplevel windows, create an instance of our helper class,
@@ -701,6 +711,19 @@ gfxASurface* nsWindow::GetThebesSurface()
   return mThebesSurface;
 }
 
+//-----------------------------------------------------------------------------
+// Internal-only method that suppresses creation of a Thebes surface
+// for windows that aren't supposed to be visible.  If one was created
+// by an external call to GetThebesSurface(), it will be returned.
+
+gfxASurface* nsWindow::ConfirmThebesSurface()
+{
+  if (!mThebesSurface && !mNoPaint && mWnd) {
+    mThebesSurface = new gfxOS2Surface(mWnd);
+  }
+  return mThebesSurface;
+}
+
 //-----------------------------------------------------------------------------
 // Return some native data according to aDataType.
 
@@ -1970,12 +1993,10 @@ PRBool nsWindow::OnReposition(PSWP pSwp)
     mBounds.width  = pSwp->cx;
     mBounds.height = pSwp->cy;
 
-    // Resize the thebes surface to the new size.  The first time we do
-    // a resize, we may need to create a thebes surface for the window.
-    if (!mThebesSurface) {
-      mThebesSurface = new gfxOS2Surface(mWnd);
+    // If the window is supposed to have a thebes surface, resize it.
+    if (ConfirmThebesSurface()) {
+        mThebesSurface->Resize(gfxIntSize(mBounds.width, mBounds.height));
     }
-    mThebesSurface->Resize(gfxIntSize(mBounds.width, mBounds.height));
 
     result = DispatchResizeEvent(mBounds.width, mBounds.height);
   }
@@ -2026,8 +2047,16 @@ do {
   WinQueryUpdateRegion(mWnd, hrgn);
   WinBeginPaint(mWnd, hPS, &rcl);
 
-  // Exit if the update rect is empty or mThebesSurface is null.
-  if (WinIsRectEmpty(0, &rcl) || !GetThebesSurface()) {
+  // Exit if the update rect is empty.
+  if (WinIsRectEmpty(0, &rcl)) {
+    break;
+  }
+
+  // Exit if a thebes surface can not/should not be created,
+  // but first fill the area with the default background color
+  // to erase any visual artifacts.
+  if (!ConfirmThebesSurface()) {
+    WinDrawBorder(hPS, &rcl, 0, 0, 0, 0, DB_INTERIOR | DB_AREAATTRS);
     break;
   }
 
@@ -2044,6 +2073,15 @@ do {
   nsRefPtr<gfxContext> thebesContext = new gfxContext(mThebesSurface);
   thebesContext->SetFlag(gfxContext::FLAG_DESTINED_FOR_SCREEN);
 
+  // Intersect the update region with the paint rectangle to clip areas
+  // that aren't visible (e.g. offscreen or covered by another window).
+  HRGN hrgnPaint;
+  hrgnPaint = GpiCreateRegion(hPS, 1, &rcl);
+  if (hrgnPaint) {
+    GpiCombineRegion(hPS, hrgn, hrgn, hrgnPaint, CRGN_AND);
+    GpiDestroyRegion(hPS, hrgnPaint);
+  }
+
   // See how many rects comprise the update region.  If there are 8
   // or fewer, update them individually.  If there are more or the call
   // failed, update the bounding rectangle returned by WinBeginPaint().

widget/src/os2/nsWindow.h

@@ -228,6 +228,7 @@ protected:
                                      HWND aParentWnd,
                                      const nsIntRect& aRect,
                                      nsWidgetInitData* aInitData);
+  gfxASurface*          ConfirmThebesSurface();
   HWND                  GetMainWindow();
   static nsWindow*      GetNSWindowPtr(HWND aWnd);
   static PRBool         SetNSWindowPtr(HWND aWnd, nsWindow* aPtr);
@@ -286,6 +287,7 @@ protected:
   PRInt32       mWindowState;       // current nsWindowState_* value
   PRBool        mIsDestroying;      // in destructor
   PRBool        mInSetFocus;        // prevent recursive calls
+  PRBool        mNoPaint;           // true if window is never visible
   HPS           mDragHps;           // retrieved by DrgGetPS() during a drag
   PRUint32      mDragStatus;        // set when object is being dragged over
   HWND          mClipWnd;           // used to clip plugin windows