We assume that each SkDevice is our custom PlatformDevice. This assumption is not valid when usin...

skia/ext/platform_canvas.cc

Index: skia/ext/platform_canvas.cc
===================================================================
--- skia/ext/platform_canvas.cc	(revision 83722)
+++ skia/ext/platform_canvas.cc	(working copy)
@@ -5,13 +5,21 @@
 #include "skia/ext/platform_canvas.h"
 
 #include "skia/ext/bitmap_platform_device.h"
+#include "third_party/skia/include/core/SkMetaData.h"
 #include "third_party/skia/include/core/SkTypes.h"
 
 namespace {
+static const char* kPlatformDeviceIdentifier = "CrPlatformDevice";

[Jeff Timanus, 2011/05/04 21:22:47]

Style guide nit/question.  Does static have any meaning in an unnamed
named-space in a .cc translation unit?

+
 skia::PlatformDevice* GetTopPlatformDevice(const SkCanvas* canvas) {
-  // All of our devices should be our special PlatformDevice.
   SkCanvas::LayerIter iter(const_cast<SkCanvas*>(canvas), false);
-  return static_cast<skia::PlatformDevice*>(iter.device());
+  SkDevice* device = iter.device();
+  // Check if this device is our custom PlatformDevice.
+  // The custom devices are tagged with meta-data named
+  // kPlatformDeviceIdentifier.
+  SkMetaData& meta_data = device->getMetaData();
+  return meta_data.findBool(kPlatformDeviceIdentifier) ?
+      static_cast<skia::PlatformDevice*>(device) : NULL;
 }
 }
 
@@ -38,10 +46,15 @@
   return 4 * width;
 }
 
-bool PlatformCanvas::initializeWithDevice(SkDevice* device) {
+bool PlatformCanvas::initializeWithDevice(PlatformDevice* device) {
   if (!device)
     return false;
 
+  // Set meta-data on the device indicating that this device is our custom
+  // platform device.
+  SkMetaData& meta_data = device->getMetaData();
+  meta_data.setBool(kPlatformDeviceIdentifier, true);
+
   setDevice(device);
   device->unref();  // Was created with refcount 1, and setDevice also refs.
   return true;
@@ -52,9 +65,8 @@
 }
 
 bool SupportsPlatformPaint(const SkCanvas* canvas) {
-  // TODO(alokp): Rename PlatformDevice::IsNativeFontRenderingAllowed after
-  // removing these calls from WebKit.
-  return GetTopPlatformDevice(canvas)->IsNativeFontRenderingAllowed();
+  skia::PlatformDevice* device = GetTopPlatformDevice(canvas);
+  return device ? device->IsNativeFontRenderingAllowed() : false;
 }
 
 PlatformDevice::PlatformSurface BeginPlatformPaint(SkCanvas* canvas) {