SkImage-only bitmap patterns

Source/platform/graphics/BitmapPatternBase.cpp

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "config.h"
-#include "platform/graphics/BitmapPatternBase.h"
-
-#include "platform/graphics/skia/SkiaUtils.h"
-#include "third_party/skia/include/core/SkCanvas.h"
-#include "third_party/skia/include/core/SkShader.h"
-
-namespace blink {
-
-BitmapPatternBase::BitmapPatternBase(RepeatMode repeatMode, int64_t externalMemoryAllocated) : Pattern(repeatMode, externalMemoryAllocated) { }
-
-BitmapPatternBase::~BitmapPatternBase() { }
-
-PassRefPtr<SkShader> BitmapPatternBase::createShader()
-{
-    // Skia does not have a "draw the tile only once" option. Clamp_TileMode
-    // repeats the last line of the image after drawing one tile. To avoid
-    // filling the space with arbitrary pixels, this workaround forces the
-    // image to have a line of transparent pixels on the "repeated" edge(s),
-    // thus causing extra space to be transparent filled.
-    SkShader::TileMode tileModeX = isRepeatX() ? SkShader::kRepeat_TileMode : SkShader::kClamp_TileMode;
-    SkShader::TileMode tileModeY = isRepeatY() ? SkShader::kRepeat_TileMode : SkShader::kClamp_TileMode;
-    int expandW = isRepeatX() ? 0 : 1;
-    int expandH = isRepeatY() ? 0 : 1;
-
-    // Create a transparent bitmap 1 pixel wider and/or taller than the
-    // original, then copy the orignal into it.
-    // FIXME: Is there a better way to pad (not scale) an image in skia?
-    SkImageInfo info = this->getBitmapInfo();
-    // we explicitly require non-opaquness, since we are going to add a transparent strip.
-    info = SkImageInfo::Make(info.width() + expandW, info.height() + expandH, info.colorType(), kPremul_SkAlphaType);
-
-    SkBitmap bm2;
-    bm2.allocPixels(info);
-    bm2.eraseColor(SK_ColorTRANSPARENT);
-    SkCanvas canvas(bm2);
-
-    SkPaint paint;
-    paint.setXfermodeMode(SkXfermode::kSrc_Mode);
-
-    this->drawBitmapToCanvas(canvas, paint);
-
-    paint.setARGB(0x00, 0x00, 0x00, 0x00);
-    paint.setStyle(SkPaint::kFill_Style);
-
-    if (!isRepeatX())
-        canvas.drawRect(SkRect::MakeXYWH(info.width() - 1, 0, 1, info.height()), paint);
-
-    if (!isRepeatY())
-        canvas.drawRect(SkRect::MakeXYWH(0, info.height() - 1, info.width(), 1), paint);
-
-    bm2.setImmutable();
-
-    adjustExternalMemoryAllocated(bm2.getSafeSize());
-
-    SkMatrix localMatrix = affineTransformToSkMatrix(m_patternSpaceTransformation);
-
-    return adoptRef(SkShader::CreateBitmapShader(bm2, tileModeX, tileModeY, &localMatrix));
-}
-
-} // namespace