Add image->bitmap

BUG=skia:

patch from issue 1212163012 at patchset 1 (http://crrev.com/1212163012#ps1)

Review URL: https://codereview.chromium.org/1208993017

include/core/SkImage.h

@@ -264,6 +264,24 @@ public:
     SkImage* newImage(int newWidth, int newHeight, const SkIRect* subset = NULL,
                       SkFilterQuality = kNone_SkFilterQuality) const;
 
+    // Helper functions to convert to SkBitmap
+
+    enum LegacyBitmapMode {
+        kRO_LegacyBitmapMode,
+        kRW_LegacyBitmapMode,
+    };
+
+    /**
+     *  Attempt to create a bitmap with the same pixels as the image. The result will always be
+     *  a raster-backed bitmap (texture-backed bitmaps are DEPRECATED, and not supported here).
+     *
+     *  If the mode is kRO (read-only), the resulting bitmap will be marked as immutable.
+     *
+     *  On succcess, returns true. On failure, returns false and the bitmap parameter will be reset
+     *  to empty.
+     */
+    bool asLegacyBitmap(SkBitmap*, LegacyBitmapMode) const;
+    
 protected:
     SkImage(int width, int height) :
         fWidth(width),

src/image/SkImage.cpp

@@ -257,6 +257,29 @@ SkImage* SkImage::NewFromBitmap(const SkBitmap& bm) {
     return SkNewImageFromRasterBitmap(bm, false, NULL);
 }
 
+bool SkImage::asLegacyBitmap(SkBitmap* bitmap, LegacyBitmapMode mode) const {
+    return as_IB(this)->onAsLegacyBitmap(bitmap, mode);
+}
+
+bool SkImage_Base::onAsLegacyBitmap(SkBitmap* bitmap, LegacyBitmapMode mode) const {
+    // As the base-class, all we can do is make a copy (regardless of mode).
+    // Subclasses that want to be more optimal should override.
+    SkImageInfo info = SkImageInfo::MakeN32(this->width(), this->height(),
+                                    this->isOpaque() ? kOpaque_SkAlphaType : kPremul_SkAlphaType);
+    if (!bitmap->tryAllocPixels(info)) {
+        return false;
+    }
+    if (!this->readPixels(bitmap->info(), bitmap->getPixels(), bitmap->rowBytes(), 0, 0)) {
+        bitmap->reset();
+        return false;
+    }
+
+    if (kRO_LegacyBitmapMode == mode) {
+        bitmap->setImmutable();
+    }
+    return true;
+}
+
 //////////////////////////////////////////////////////////////////////////////////////
 
 #if !SK_SUPPORT_GPU

src/image/SkImage_Base.h

@@ -61,6 +61,8 @@ public:
                                 SkFilterQuality) const;
     virtual SkData* onRefEncoded() const { return NULL; }
 
+    virtual bool onAsLegacyBitmap(SkBitmap*, LegacyBitmapMode) const;
+
 private:
     const SkSurfaceProps fProps;
 

src/image/SkImage_Raster.cpp

@@ -79,6 +79,7 @@ public:
                           const SkMatrix* localMatrix) const override;
 
     bool isOpaque() const override;
+    bool onAsLegacyBitmap(SkBitmap*, LegacyBitmapMode) const override;
 
     SkImage_Raster(const SkBitmap& bm, const SkSurfaceProps* props)
         : INHERITED(bm.width(), bm.height(), props)
@@ -262,3 +263,17 @@ bool SkImage_Raster::isOpaque() const {
     return fBitmap.isOpaque();
 }
 
+bool SkImage_Raster::onAsLegacyBitmap(SkBitmap* bitmap, LegacyBitmapMode mode) const {
+    if (kRO_LegacyBitmapMode == mode) {
+        // When we're a snapshot from a surface, our bitmap may not be marked immutable
+        // even though logically always we are, but in that case we can't physically share our
+        // pixelref since the caller might call setImmutable() themselves
+        // (thus changing our state).
+        if (fBitmap.isImmutable()) {
+            bitmap->setInfo(fBitmap.info());
+            bitmap->setPixelRef(fBitmap.pixelRef(), fBitmap.pixelRefOrigin());
+            return true;
+        }
+    }
+    return this->INHERITED::onAsLegacyBitmap(bitmap, mode);
+}

tests/SurfaceTest.cpp

@@ -407,6 +407,33 @@ static void test_image_readpixels(skiatest::Reporter* reporter, SkImage* image,
     REPORTER_ASSERT(reporter, has_pixels(&pixels[1], w*h - 1, notExpected));
 }
 
+static void test_legacy_bitmap(skiatest::Reporter* reporter, const SkImage* image) {
+    const SkImage::LegacyBitmapMode modes[] = {
+        SkImage::kRO_LegacyBitmapMode,
+        SkImage::kRW_LegacyBitmapMode,
+    };
+    for (size_t i = 0; i < SK_ARRAY_COUNT(modes); ++i) {
+        SkBitmap bitmap;
+        REPORTER_ASSERT(reporter, image->asLegacyBitmap(&bitmap, modes[i]));
+
+        REPORTER_ASSERT(reporter, image->width() == bitmap.width());
+        REPORTER_ASSERT(reporter, image->height() == bitmap.height());
+        REPORTER_ASSERT(reporter, image->isOpaque() == bitmap.isOpaque());
+
+        bitmap.lockPixels();
+        REPORTER_ASSERT(reporter, bitmap.getPixels());
+
+        const SkImageInfo info = SkImageInfo::MakeN32(1, 1, bitmap.alphaType());
+        SkPMColor imageColor;
+        REPORTER_ASSERT(reporter, image->readPixels(info, &imageColor, sizeof(SkPMColor), 0, 0));
+        REPORTER_ASSERT(reporter, imageColor == *bitmap.getAddr32(0, 0));
+
+        if (SkImage::kRO_LegacyBitmapMode == modes[i]) {
+            REPORTER_ASSERT(reporter, bitmap.isImmutable());
+        }
+    }
+}
+
 static void test_imagepeek(skiatest::Reporter* reporter, GrContextFactory* factory) {
     static const struct {
         ImageType   fType;
@@ -450,6 +477,8 @@ static void test_imagepeek(skiatest::Reporter* reporter, GrContextFactory* facto
             REPORTER_ASSERT(reporter, NULL == releaseCtx.fData);  // we ignored the context
         }
 
+        test_legacy_bitmap(reporter, image);
+
         const void* addr = image->peekPixels(&info, &rowBytes);
         bool success = SkToBool(addr);
         REPORTER_ASSERT(reporter, gRec[i].fPeekShouldSucceed == success);