Changeset 19876 in webkit

Timestamp:

Feb 26, 2007, 9:23:22 PM (18 years ago)

Author:

oliver

Message:

2007-02-26 Oliver Hunt <​oliver@apple.com>

Reviewed by Maciej.

Fix for <rdar://problem/4827378>: Canvas with large height
uses lots of memory, computer almost stops responding

Put cap on maximum area of canvas, size is similar too the
maximum size allowed by firefox (firefox seems to to cut off
at area == 32767 * 9358).

Also protect renderer against the possibility of a null context
(this was triggering a CG warning)

• html/HTMLCanvasElement.cpp: (WebCore::HTMLCanvasElement::createDrawingContext):

Apply maximum canvas area

(WebCore::HTMLCanvasElement::createPlatformImage):

Protect against null CG Context

Location:

trunk/WebCore

Files:

• ChangeLog (modified) (1 diff)
• html/HTMLCanvasElement.cpp (modified) (3 diffs)

trunk/WebCore/ChangeLog

@@ +1 @@
+2007-02-26  Oliver Hunt  <oliver@apple.com>
+
+        Reviewed by Maciej.
+
+        Fix for <rdar://problem/4827378>: Canvas with large height 
+        uses lots of memory, computer almost stops responding
+         
+        Put cap on maximum area of canvas, size is similar too the 
+        maximum size allowed by firefox (firefox seems to to cut off 
+        at area == 32767 * 9358). 
+
+        Also protect renderer against the possibility of a null context
+        (this was triggering a CG warning)
+
+        * html/HTMLCanvasElement.cpp:
+        (WebCore::HTMLCanvasElement::createDrawingContext):
+           Apply maximum canvas area
+        (WebCore::HTMLCanvasElement::createPlatformImage):
+           Protect against null CG Context
+
 2007-02-26  Mitz Pettel  <mitz@webkit.org>
 

trunk/WebCore/html/HTMLCanvasElement.cpp

@@ -50 +50 @@
 const int defaultHeight = 150;
 
+// Firefox limits width/height to 32767 pixels, but slows down dramatically before it 
+// reaches that limit we limit by area instead, giving us larger max dimensions, in exchange 
+// for reduce maximum canvas size.
+const float maxCanvasArea = 32768 * 8192; // Maximum canvas area in CSS pixels
+
 HTMLCanvasElement::HTMLCanvasElement(Document* doc)
     : HTMLElement(canvasTag, doc)
@@ -179 +184 @@
     float hf = ceilf(unscaledHeight * pageScaleFactor);
     
-    if (!(wf > 0 && wf < UINT_MAX && hf > 0 && hf < UINT_MAX))
+    if (!(wf >= 1 && hf >= 1 && wf * hf <= maxCanvasArea))
         return;
         
@@ -215 +220 @@
     if (!context)
         return 0;
-    CGContextFlush(context->platformContext());
-    return CGBitmapContextCreateImage(context->platformContext());
+    
+    CGContextRef contextRef = context->platformContext();
+    if (!contextRef)
+        return 0;
+    
+    CGContextFlush(contextRef);
+    
+    return CGBitmapContextCreateImage(contextRef);
 }