Image generator-backed SkPictureShader

src/core/SkPictureShader.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPictureShader.h"
 
 #include "SkBitmap.h"
 #include "SkBitmapProcShader.h"
 #include "SkCanvas.h"
+#include "SkImageGenerator.h"
 #include "SkMatrixUtils.h"
 #include "SkPicture.h"
 #include "SkReadBuffer.h"
 #include "SkResourceCache.h"
 
 #if SK_SUPPORT_GPU
 #include "GrContext.h"
 #include "GrCaps.h"
 #endif
 
@@ skipping 54 matching lines @@
     }
     const char* getCategory() const override { return "bitmap-shader"; }
     SkDiscardableMemory* diagnostic_only_getDiscardable() const override { return nullptr; }
 
     static bool Visitor(const SkResourceCache::Rec& baseRec, void* contextShader) {
         const BitmapShaderRec& rec = static_cast<const BitmapShaderRec&>(baseRec);
         SkAutoTUnref<SkShader>* result = reinterpret_cast<SkAutoTUnref<SkShader>*>(contextShader);
 
         result->reset(SkRef(rec.fShader.get()));
 
-        SkBitmap tile;
-        if (rec.fShader.get()->isABitmap(&tile, nullptr, nullptr)) {
-            // FIXME: this doesn't protect the pixels from being discarded as soon as we unlock.
-            // Should be handled via a pixel ref generator instead
-            // (https://code.google.com/p/skia/issues/detail?id=3220).
-            SkAutoLockPixels alp(tile, true);
-            return tile.getPixels() != nullptr;
-        }
-        return false;
+        // The bitmap shader is backed by an image generator, thus it can always re-generate its
+        // pixels if discarded.
+        return true;
     }
 };
 
-static bool cache_try_alloc_pixels(SkBitmap* bitmap) {
-    SkBitmap::Allocator* allocator = SkResourceCache::GetAllocator();
-
-    return nullptr != allocator
-        ? allocator->allocPixelRef(bitmap, nullptr)
-        : bitmap->tryAllocPixels();
-}
-
 } // namespace
 
 SkPictureShader::SkPictureShader(const SkPicture* picture, TileMode tmx, TileMode tmy,
                                  const SkMatrix* localMatrix, const SkRect* tile)
     : INHERITED(localMatrix)
     , fPicture(SkRef(picture))
     , fTile(tile ? *tile : picture->cullRect())
     , fTmx(tmx)
     , fTmy(tmy) {
 }
 
-SkPictureShader::~SkPictureShader() {
-    fPicture->unref();
-}
-
 SkShader* SkPictureShader::Create(const SkPicture* picture, TileMode tmx, TileMode tmy,
                                          const SkMatrix* localMatrix, const SkRect* tile) {
     if (!picture || picture->cullRect().isEmpty() || (tile && tile->isEmpty())) {
         return SkShader::CreateEmptyShader();
     }
     return new SkPictureShader(picture, tmx, tmy, localMatrix, tile);
 }
 
 SkFlattenable* SkPictureShader::CreateProc(SkReadBuffer& buffer) {
     SkMatrix lm;
@@ skipping 93 matching lines @@
 
     SkAutoTUnref<SkShader> tileShader;
     BitmapShaderKey key(fPicture->uniqueID(),
                         fTile,
                         fTmx,
                         fTmy,
                         tileScale,
                         this->getLocalMatrix());
 
     if (!SkResourceCache::Find(key, BitmapShaderRec::Visitor, &tileShader)) {
+        SkMatrix matrix;
+        matrix.setRectToRect(fTile, SkRect::MakeIWH(tileSize.width(), tileSize.height()),
+                             SkMatrix::kFill_ScaleToFit);
         SkBitmap bm;
-        bm.setInfo(SkImageInfo::MakeN32Premul(tileSize));
-        if (!cache_try_alloc_pixels(&bm)) {
-            return SkShader::CreateEmptyShader();
+        if (!SkInstallDiscardablePixelRef(
+            SkImageGenerator::NewFromPicture(tileSize, fPicture, &matrix, nullptr), &bm)) {
+            return nullptr;
         }
-        bm.eraseColor(SK_ColorTRANSPARENT);
-
-        // Always disable LCD text, since we can't assume our image will be opaque.
-        SkCanvas canvas(bm, SkSurfaceProps(0, kUnknown_SkPixelGeometry));
-
-        canvas.scale(tileScale.width(), tileScale.height());
-        canvas.translate(-fTile.x(), -fTile.y());
-        canvas.drawPicture(fPicture);
 
         SkMatrix shaderMatrix = this->getLocalMatrix();
         shaderMatrix.preScale(1 / tileScale.width(), 1 / tileScale.height());
         tileShader.reset(CreateBitmapShader(bm, fTmx, fTmy, &shaderMatrix));
 
         SkResourceCache::Add(new BitmapShaderRec(key, tileShader.get(), bm.getSize()));
     }
 
     return tileShader.detach();
 }
@@ skipping 59 matching lines @@
     fBitmapShaderContext->shadeSpan16(x, y, dstC, count);
 }
 
 #ifndef SK_IGNORE_TO_STRING
 void SkPictureShader::toString(SkString* str) const {
     static const char* gTileModeName[SkShader::kTileModeCount] = {
         "clamp", "repeat", "mirror"
     };
 
     str->appendf("PictureShader: [%f:%f:%f:%f] ",
-                 fPicture ? fPicture->cullRect().fLeft : 0,
-                 fPicture ? fPicture->cullRect().fTop : 0,
-                 fPicture ? fPicture->cullRect().fRight : 0,
-                 fPicture ? fPicture->cullRect().fBottom : 0);
+                 fPicture->cullRect().fLeft,
+                 fPicture->cullRect().fTop,
+                 fPicture->cullRect().fRight,
+                 fPicture->cullRect().fBottom);
 
     str->appendf("(%s, %s)", gTileModeName[fTmx], gTileModeName[fTmy]);
 
     this->INHERITED::toString(str);
 }
 #endif
 
 #if SK_SUPPORT_GPU
 const GrFragmentProcessor* SkPictureShader::asFragmentProcessor(
                                                     GrContext* context,
                                                     const SkMatrix& viewM,
                                                     const SkMatrix* localMatrix,
                                                     SkFilterQuality fq,
                                                     GrProcessorDataManager* procDataManager) const {
     int maxTextureSize = 0;
     if (context) {
         maxTextureSize = context->caps()->maxTextureSize();
     }
     SkAutoTUnref<SkShader> bitmapShader(this->refBitmapShader(viewM, localMatrix, maxTextureSize));
     if (!bitmapShader) {
         return nullptr;
     }
     return bitmapShader->asFragmentProcessor(context, viewM, nullptr, fq, procDataManager);
 }
 #endif