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/*
* Copyright (c) 2008, 2009, Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "XBMImageDecoder.h"
#include "ASCIICType.h"
#include <algorithm>
#include <cstdio>
namespace WebCore {
XBMImageDecoder::XBMImageDecoder()
: m_decodeOffset(0)
, m_allDataReceived(false)
, m_decodedHeader(false)
, m_dataType(Unknown)
, m_bitsDecoded(0)
{
}
void XBMImageDecoder::setData(SharedBuffer* data, bool allDataReceived)
{
ImageDecoder::setData(data, allDataReceived);
m_xbmString = data->buffer();
m_xbmString.append('\0');
m_allDataReceived = allDataReceived;
}
bool XBMImageDecoder::isSizeAvailable()
{
if (!ImageDecoder::isSizeAvailable() && !m_failed)
decode(true);
return ImageDecoder::isSizeAvailable();
}
RGBA32Buffer* XBMImageDecoder::frameBufferAtIndex(size_t index)
{
if (index)
return 0;
if (m_frameBufferCache.isEmpty())
m_frameBufferCache.resize(1);
// Attempt to get the size if we don't have it yet.
if (!ImageDecoder::isSizeAvailable())
decode(true);
// Initialize the framebuffer if needed.
RGBA32Buffer& buffer = m_frameBufferCache[0];
if (!failed() && ImageDecoder::isSizeAvailable()
&& (buffer.status() == RGBA32Buffer::FrameEmpty)) {
if (!buffer.setSize(size().width(), size().height())) {
m_failed = true;
return 0;
}
buffer.setStatus(RGBA32Buffer::FramePartial);
// For XBMs, the frame always fills the entire image.
buffer.setRect(IntRect(IntPoint(), size()));
}
// Keep trying to decode until we've got the entire image.
if (buffer.status() == RGBA32Buffer::FramePartial)
decode(false);
return &buffer;
}
bool XBMImageDecoder::decodeHeader()
{
ASSERT(m_decodeOffset <= m_xbmString.size());
ASSERT(!m_decodedHeader);
const char* input = m_xbmString.data();
// At least 2 "#define <string> <unsigned>" sequences are required. These
// specify the width and height of the image.
int width, height;
if (!ImageDecoder::isSizeAvailable()) {
int count;
if (sscanf(&input[m_decodeOffset], "#define %*s %i #define %*s %i%n",
&width, &height, &count) != 2)
return false;
// The width and height need to follow some rules.
if (width < 0 || width > maxDimension || height < 0 || height > maxDimension) {
// If this happens, decoding should not continue.
setFailed();
return false;
}
if (!setSize(width, height)) {
setFailed();
return false;
}
m_decodeOffset += count;
ASSERT(m_decodeOffset <= m_xbmString.size());
}
ASSERT(ImageDecoder::isSizeAvailable());
// Now we're looking for something that tells us that we've seen all of the
// "#define <string> <unsigned>" sequences that we're going to. Mozilla
// just looks for " char " or " short ". We'll do the same.
if (m_dataType == Unknown) {
const char* x11hint = " char ";
const char* x11HintLocation = strstr(&input[m_decodeOffset], x11hint);
if (x11HintLocation) {
m_dataType = X11;
m_decodeOffset += ((x11HintLocation - &input[m_decodeOffset]) + strlen(x11hint));
} else {
const char* x10hint = " short ";
const char* x10HintLocation = strstr(&input[m_decodeOffset], x10hint);
if (x10HintLocation) {
m_dataType = X10;
m_decodeOffset += ((x10HintLocation - &input[m_decodeOffset]) + strlen(x10hint));
} else
return false;
}
ASSERT(m_decodeOffset <= m_xbmString.size());
}
// Find the start of the data. Again, we do what mozilla does and just
// look for a '{' in the input.
const char* found = strchr(&input[m_decodeOffset], '{');
if (!found)
return false;
// Advance to character after the '{'
m_decodeOffset += ((found - &input[m_decodeOffset]) + 1);
ASSERT(m_decodeOffset <= m_xbmString.size());
m_decodedHeader = true;
return true;
}
// The data in an XBM file is provided as an array of either "char" or "short"
// values. These values are decoded one at a time using strtoul() and the bits
// are used to set the alpha value for the image.
//
// The value for the color is always set to RGB(0,0,0), the alpha value takes
// care of whether or not the pixel shows up.
//
// Since the data may arrive in chunks, and many prefixes of valid numbers are
// themselves valid numbers, this code needs to check to make sure that the
// value is not truncated. This is done by consuming space after the value
// read until a ',' or a '}' occurs. In a valid XBM, one of these characters
// will occur after each value.
//
// The checks after strtoul are based on Mozilla's nsXBMDecoder.cpp.
bool XBMImageDecoder::decodeDatum(uint16_t* result)
{
const char* input = m_xbmString.data();
char* endPtr;
const uint16_t value = strtoul(&input[m_decodeOffset], &endPtr, 0);
// End of input or couldn't decode anything, can't go any further.
if (endPtr == &input[m_decodeOffset] || !*endPtr)
return false;
// Possibly a hex value truncated at "0x". Need more data.
if (value == 0 && (*endPtr == 'x' || *endPtr == 'X'))
return false;
// Skip whitespace
while (*endPtr && isASCIISpace(*endPtr))
++endPtr;
// Out of input, don't know what comes next.
if (!*endPtr)
return false;
// If the next non-whitespace character is not one of these, it's an error.
// Every valid entry in the data array needs to be followed by ',' or '}'.
if (*endPtr != ',' && *endPtr != '}') {
setFailed();
return false;
}
// At this point we have a value.
*result = value;
// Skip over the decoded value plus the delimiter (',' or '}').
m_decodeOffset += ((endPtr - &input[m_decodeOffset]) + 1);
ASSERT(m_decodeOffset <= m_xbmString.size());
return true;
}
bool XBMImageDecoder::decodeData()
{
ASSERT(m_decodeOffset <= m_xbmString.size());
ASSERT(m_decodedHeader && !m_frameBufferCache.isEmpty());
RGBA32Buffer& frame = m_frameBufferCache[0];
ASSERT(frame.status() == RGBA32Buffer::FramePartial);
const int bitsPerRow = size().width();
ASSERT(m_dataType != Unknown);
while (m_bitsDecoded < (size().width() * size().height())) {
uint16_t value;
if (!decodeDatum(&value))
return false;
int x = m_bitsDecoded % bitsPerRow;
const int y = m_bitsDecoded / bitsPerRow;
// How many bits will be written?
const int bits = std::min(bitsPerRow - x, (m_dataType == X11) ? 8 : 16);
// Only the alpha channel matters here, so the color values are always
// set to 0.
for (int i = 0; i < bits; ++i)
frame.setRGBA(x++, y, 0, 0, 0, value & (1 << i) ? 255 : 0);
m_bitsDecoded += bits;
}
frame.setStatus(RGBA32Buffer::FrameComplete);
return true;
}
// Decode as much as we can of the XBM file.
void XBMImageDecoder::decode(bool sizeOnly)
{
if (failed())
return;
bool decodeResult = false;
if (!m_decodedHeader)
decodeResult = decodeHeader();
if (m_decodedHeader && !sizeOnly)
decodeResult = decodeData();
// The header or the data could not be decoded, but there is no more
// data: decoding has failed.
if (!decodeResult && m_allDataReceived)
setFailed();
}
} // namespace WebCore
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