size_t FrontBufferedStream::readDirectlyFromStream(char* dst, size_t size) {
SkASSERT(size > 0);
// If we get here, we have buffered all that can be buffered.
SkASSERT(fBufferSize == fBufferedSoFar && fOffset >= fBufferSize);
const size_t bytesReadDirectly = fStream->read(dst, size);
fOffset += bytesReadDirectly;
// If we have read past the end of the buffer, rewinding is no longer
// supported, so we can go ahead and free the memory.
if (bytesReadDirectly > 0) {
sk_free(fBuffer.detach());
}
return bytesReadDirectly;
}
size_t FrontBufferedStream::bufferAndWriteTo(char* dst, size_t size) {
SkASSERT(size > 0);
SkASSERT(fOffset >= fBufferedSoFar);
SkASSERT(fBuffer);
// Data needs to be buffered. Buffer up to the lesser of the size requested
// and the remainder of the max buffer size.
const size_t bytesToBuffer = SkTMin(size, fBufferSize - fBufferedSoFar);
char* buffer = fBuffer + fOffset;
const size_t buffered = fStream->read(buffer, bytesToBuffer);
fBufferedSoFar += buffered;
fOffset = fBufferedSoFar;
SkASSERT(fBufferedSoFar <= fBufferSize);
// Copy the buffer to the destination buffer and update the amount read.
if (dst != NULL) {
memcpy(dst, buffer, buffered);
}
return buffered;
}