SkImageSource

src/core/SkReadBuffer.cpp

 
 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkErrorInternals.h"
+#include "SkImage.h"
+#include "SkImageGenerator.h"
 #include "SkReadBuffer.h"
 #include "SkStream.h"
 #include "SkTypeface.h"
 
 static uint32_t default_flags() {
     uint32_t flags = 0;
     flags |= SkReadBuffer::kScalarIsFloat_Flag;
     if (8 == sizeof(void*)) {
         flags |= SkReadBuffer::kPtrIs64Bit_Flag;
     }
@@ skipping 246 matching lines @@
             return true;
         } else if (SkBitmap::ReadRawPixels(this, bitmap)) {
             return true;
         }
     }
     // Could not read the SkBitmap. Use a placeholder bitmap.
     bitmap->setInfo(SkImageInfo::MakeUnknown(width, height));
     return false;
 }
 
+namespace {
+
+// This generator intentionally should always fail on all attempts to get its pixels,
+// simulating a bad or empty codec stream.
+class EmptyImageGenerator final : public SkImageGenerator {
+public:
+    EmptyImageGenerator(const SkImageInfo& info) : INHERITED(info) { }
+
+private:
+    typedef SkImageGenerator INHERITED;
+};
+
+} // anonymous namespace
+
+SkImage* SkReadBuffer::readImage() {
+    int width = this->read32();
+    int height = this->read32();
+    if (width <= 0 || height <= 0) {    // SkImage never has a zero dimension
+        this->validate(false);
+        return nullptr;
+    }
+
+    SkAutoTUnref<SkData> encoded(this->readByteArrayAsData());
+    if (encoded->size() == 0) {
+        // The image could not be encoded at serialization time - return an empty placeholder.
+        return SkImage::NewFromGenerator(
+            new EmptyImageGenerator(SkImageInfo::MakeN32Premul(width, height)));
+    }
+
+    int originX = this->read32();
+    int originY = this->read32();
+    if (originX < 0 || originY < 0) {
+        this->validate(false);
+        return nullptr;
+    }
+
+    const SkIRect subset = SkIRect::MakeXYWH(originX, originY, width, height);
+    return SkImage::NewFromEncoded(encoded, &subset);
+}
+
 SkTypeface* SkReadBuffer::readTypeface() {
 
     uint32_t index = fReader.readU32();
     if (0 == index || index > (unsigned)fTFCount) {
         if (index) {
             SkDebugf("====== typeface index %d\n", index);
         }
         return nullptr;
     } else {
         SkASSERT(fTFArray);
@@ skipping 64 matching lines @@
             return;
         }
     } else {
         if (nullptr == this->readFunctionPtr()) {
             return;
         }
     }
     uint32_t sizeRecorded = fReader.readU32();
     fReader.skip(sizeRecorded);
 }