Make BMP decoder not depend on call to getLength.

src/images/SkImageDecoder_libbmp.cpp

 
 /*
  * Copyright 2007 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "bmpdecoderhelper.h"
@@ skipping 75 matching lines @@
     const uint8_t* rgb() const { return fRGB.begin(); }
 
 private:
     SkTDArray<uint8_t> fRGB;
     int fWidth;
     int fHeight;
     bool fJustBounds;
 };
 
 bool SkBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
+    // First read the entire stream, so that all of the data can be passed to
+    // the BmpDecoderHelper.
 
-    size_t length = stream->getLength();
-    SkAutoMalloc storage(length);
+    // Byte length of all of the data.
+    size_t length;
+    // Allocated space used to hold the data.
+    SkAutoMalloc storage;
 
-    if (stream->read(storage.get(), length) != length) {
-        return false;
+    if (stream->hasLength()) {
+        length = stream->getLength();
+        void* dst = storage.reset(length);
+        if (stream->read(dst, length) != length) {
+            return false;
+        }
+    } else {
+        SkDynamicMemoryWStream tempStream;
+        // Arbitrary buffer size.
+        const size_t bufferSize = 256 * 1024; // 256 KB
+        char buffer[bufferSize];
+        length = 0;
+        do {
+            size_t bytesRead = stream->read(buffer, bufferSize);
+            tempStream.write(buffer, bytesRead);
+            length += bytesRead;
+            SkASSERT(tempStream.bytesWritten() == length);
+        } while (!stream->isAtEnd());
+        void* dst = storage.reset(length);
+        tempStream.copyTo(dst);
     }
 
     const bool justBounds = SkImageDecoder::kDecodeBounds_Mode == mode;
     SkBmpDecoderCallback callback(justBounds);
 
     // Now decode the BMP into callback's rgb() array [r,g,b, r,g,b, ...]
     {
         image_codec::BmpDecoderHelper helper;
         const int max_pixels = 16383*16383; // max width*height
         if (!helper.DecodeImage((const char*)storage.get(), length,
@@ skipping 39 matching lines @@
     const int dstHeight = sampler.scaledHeight();
     const uint8_t* srcRow = callback.rgb();
 
     srcRow += sampler.srcY0() * srcRowBytes;
     for (int y = 0; y < dstHeight; y++) {
         sampler.next(srcRow);
         srcRow += sampler.srcDY() * srcRowBytes;
     }
     return true;
 }