Removing the dependency on GraphicsContext for drawing images in 2D canvas

Source/platform/graphics/BitmapImage.cpp

Index: Source/platform/graphics/BitmapImage.cpp
diff --git a/Source/platform/graphics/BitmapImage.cpp b/Source/platform/graphics/BitmapImage.cpp
index 8ffafb8cb36399ff81cda5afcf3153a0b66f22b8..7f990014462eb2d2f801cf4c04a5c7a44f9331f8 100644
--- a/Source/platform/graphics/BitmapImage.cpp
+++ b/Source/platform/graphics/BitmapImage.cpp
@@ -280,57 +280,67 @@ String BitmapImage::filenameExtension() const
     return m_source.filenameExtension();
 }
 
-void BitmapImage::draw(GraphicsContext* ctxt, const FloatRect& dstRect, const FloatRect& srcRect, SkXfermode::Mode compositeOp, RespectImageOrientationEnum shouldRespectImageOrientation)
+bool BitmapImage::isLazyDecodedBitmap()
+{
+    SkBitmap bitmap;
+    if (!bitmapForCurrentFrame(&bitmap))
+        return false;
+    return DeferredImageDecoder::isLazyDecoded(bitmap);
+}
+
+bool BitmapImage::isImmutableBitmap()
+{
+    SkBitmap bitmap;
+    if (!bitmapForCurrentFrame(&bitmap))
+        return false;
+    return bitmap.isImmutable();
+}
+
+void BitmapImage::draw(SkCanvas* canvas, const SkPaint& paint, const FloatRect& dstRect, const FloatRect& srcRect, RespectImageOrientationEnum shouldRespectImageOrientation, ImageClampingMode clampMode)

[Noel Gordon, 2015/06/10 12:21:15]

Previously, this routine created its SkPaint internally (line 332 left). 
Curious about why it needs to be passed in as a parameter now, and why const?

[Justin Novosad, 2015/06/10 13:46:01]

The old code required a GraphicsContext object for setting-up the SkPaint (line
324). With the removal of the dependency on GraphicsContext, that is no longer
possible.  The SkPaint that is passed in is now how drawing parameters are
communicated to this function, instead of the call to
GraphicsContext::preparePaintForDrawRectToRect that existed before

 {
     TRACE_EVENT0("skia", "BitmapImage::draw");
+
+    ASSERT(dstRect.width() >= 0 && dstRect.height() >= 0);
+    ASSERT(srcRect.width() >= 0 && srcRect.height() >= 0);
     SkBitmap bitmap;
     if (!bitmapForCurrentFrame(&bitmap))
         return; // It's too early and we don't have an image yet.
 
-    FloatRect normDstRect = adjustForNegativeSize(dstRect);
-    FloatRect normSrcRect = adjustForNegativeSize(srcRect);
-    normSrcRect.intersect(FloatRect(0, 0, bitmap.width(), bitmap.height()));
+    FloatRect adjustedSrcRect = srcRect;
+    adjustedSrcRect.intersect(FloatRect(0, 0, bitmap.width(), bitmap.height()));
 
-    if (normSrcRect.isEmpty() || normDstRect.isEmpty())
+    if (adjustedSrcRect.isEmpty() || dstRect.isEmpty())
         return; // Nothing to draw.
 
     ImageOrientation orientation = DefaultImageOrientation;
     if (shouldRespectImageOrientation == RespectImageOrientation)
         orientation = frameOrientationAtIndex(m_currentFrame);
 
-    GraphicsContextStateSaver saveContext(*ctxt, false);
+    int initialSaveCount = canvas->getSaveCount();
+    FloatRect adjustedDstRect = dstRect;
     if (orientation != DefaultImageOrientation) {
-        saveContext.save();
+        canvas->save();
 
         // ImageOrientation expects the origin to be at (0, 0)
-        ctxt->translate(normDstRect.x(), normDstRect.y());
-        normDstRect.setLocation(FloatPoint());
+        canvas->translate(adjustedDstRect.x(), adjustedDstRect.y());
+        adjustedDstRect.setLocation(FloatPoint());
 
-        ctxt->concatCTM(orientation.transformFromDefault(normDstRect.size()));
+        canvas->concat(affineTransformToSkMatrix(orientation.transformFromDefault(adjustedDstRect.size())));
 
         if (orientation.usesWidthAsHeight()) {
             // The destination rect will have it's width and height already reversed for the orientation of
             // the image, as it was needed for page layout, so we need to reverse it back here.
-            normDstRect = FloatRect(normDstRect.x(), normDstRect.y(), normDstRect.height(), normDstRect.width());
+            adjustedDstRect = FloatRect(adjustedDstRect.x(), adjustedDstRect.y(), adjustedDstRect.height(), adjustedDstRect.width());
         }
     }
 
-    bool isLazyDecoded = DeferredImageDecoder::isLazyDecoded(bitmap);
-    bool isOpaque = bitmap.isOpaque();
-
-    {
-        SkPaint paint;
-        SkRect skSrcRect = normSrcRect;
-        int initialSaveCount = ctxt->preparePaintForDrawRectToRect(&paint, skSrcRect, normDstRect, compositeOp, !isOpaque, isLazyDecoded, bitmap.isImmutable());
-        // We want to filter it if we decided to do interpolation above, or if
-        // there is something interesting going on with the matrix (like a rotation).
-        // Note: for serialization, we will want to subset the bitmap first so we
-        // don't send extra pixels.
-        ctxt->drawBitmapRect(bitmap, &skSrcRect, normDstRect, &paint);
-        ctxt->canvas()->restoreToCount(initialSaveCount);
-    }
+    SkRect skSrcRect = adjustedSrcRect;

[Noel Gordon, 2015/06/10 12:21:15]

Anyho, as we are discussion on another bug, I can interpolate an appropriate
SkColorFilter about here, and add it to the SkPaint ...

[Justin Novosad, 2015/06/10 13:46:01]

Yes, just create a local non-const copy of paint, and add the filter to it.

+    SkCanvas::DrawBitmapRectFlags flags =
+        clampMode == ClampImageToSourceRect ? SkCanvas::kNone_DrawBitmapRectFlag : SkCanvas::kBleed_DrawBitmapRectFlag;
+    canvas->drawBitmapRectToRect(bitmap, &skSrcRect, adjustedDstRect, &paint, flags);

[Noel Gordon, 2015/06/10 12:21:15]

... and the drawBitmapRectToRect records the SkPaint.  Hence, my SkColorFilter
gets sent to the impl-side where it is applied to this bitmap image, right?

[Justin Novosad, 2015/06/10 13:46:01]

Yes

+    canvas->restoreToCount(initialSaveCount);
 
-    if (isLazyDecoded)
+    if (DeferredImageDecoder::isLazyDecoded(bitmap))
         PlatformInstrumentation::didDrawLazyPixelRef(bitmap.getGenerationID());
 
     if (ImageObserver* observer = imageObserver())