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This CL generated by |sed -i '/sky\/engine\/config.h/d'| and a manual sweep to catch some oddballs. TBR=eseidel@chromium.org Review URL: https://codereview.chromium.org/1206763002.
801 lines
33 KiB
C++
801 lines
33 KiB
C++
/*
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* Copyright (c) 2008, 2009, Google Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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* * Neither the name of Google Inc. nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "platform/image-decoders/bmp/BMPImageReader.h"
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namespace {
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// See comments on m_lookupTableAddresses in the header.
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const uint8_t nBitTo8BitlookupTable[] = {
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// 1 bit
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0, 255,
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// 2 bits
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0, 85, 170, 255,
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// 3 bits
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0, 36, 73, 109, 146, 182, 219, 255,
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// 4 bits
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0, 17, 34, 51, 68, 85, 102, 119, 136, 153, 170, 187, 204, 221, 238, 255,
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// 5 bits
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0, 8, 16, 25, 33, 41, 49, 58, 66, 74, 82, 90, 99, 107, 115, 123,
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132, 140, 148, 156, 165, 173, 181, 189, 197, 206, 214, 222, 230, 239, 247, 255,
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// 6 bits
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0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 45, 49, 53, 57, 61,
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65, 69, 73, 77, 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125,
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130, 134, 138, 142, 146, 150, 154, 158, 162, 166, 170, 174, 178, 182, 186, 190,
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194, 198, 202, 206, 210, 215, 219, 223, 227, 231, 235, 239, 243, 247, 251, 255,
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// 7 bits
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0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30,
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32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62,
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64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94,
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96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126,
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129, 131, 133, 135, 137, 139, 141, 143, 145, 147, 149, 151, 153, 155, 157, 159,
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161, 163, 165, 167, 169, 171, 173, 175, 177, 179, 181, 183, 185, 187, 189, 191,
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193, 195, 197, 199, 201, 203, 205, 207, 209, 211, 213, 215, 217, 219, 221, 223,
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225, 227, 229, 231, 233, 235, 237, 239, 241, 243, 245, 247, 249, 251, 253, 255,
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};
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}
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namespace blink {
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BMPImageReader::BMPImageReader(ImageDecoder* parent, size_t decodedAndHeaderOffset, size_t imgDataOffset, bool isInICO)
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: m_parent(parent)
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, m_buffer(0)
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, m_decodedOffset(decodedAndHeaderOffset)
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, m_headerOffset(decodedAndHeaderOffset)
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, m_imgDataOffset(imgDataOffset)
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, m_isOS21x(false)
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, m_isOS22x(false)
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, m_isTopDown(false)
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, m_needToProcessBitmasks(false)
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, m_needToProcessColorTable(false)
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, m_seenNonZeroAlphaPixel(false)
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, m_seenZeroAlphaPixel(false)
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, m_isInICO(isInICO)
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, m_decodingAndMask(false)
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{
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// Clue-in decodeBMP() that we need to detect the correct info header size.
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memset(&m_infoHeader, 0, sizeof(m_infoHeader));
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}
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bool BMPImageReader::decodeBMP(bool onlySize)
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{
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// Calculate size of info header.
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if (!m_infoHeader.biSize && !readInfoHeaderSize())
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return false;
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// Read and process info header.
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if ((m_decodedOffset < (m_headerOffset + m_infoHeader.biSize)) && !processInfoHeader())
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return false;
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// processInfoHeader() set the size, so if that's all we needed, we're done.
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if (onlySize)
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return true;
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// Read and process the bitmasks, if needed.
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if (m_needToProcessBitmasks && !processBitmasks())
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return false;
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// Read and process the color table, if needed.
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if (m_needToProcessColorTable && !processColorTable())
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return false;
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// Initialize the framebuffer if needed.
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ASSERT(m_buffer); // Parent should set this before asking us to decode!
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if (m_buffer->status() == ImageFrame::FrameEmpty) {
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if (!m_buffer->setSize(m_parent->size().width(), m_parent->size().height()))
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return m_parent->setFailed(); // Unable to allocate.
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m_buffer->setStatus(ImageFrame::FramePartial);
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// setSize() calls eraseARGB(), which resets the alpha flag, so we force
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// it back to false here. We'll set it true below in all cases where
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// these 0s could actually show through.
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m_buffer->setHasAlpha(false);
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// For BMPs, the frame always fills the entire image.
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m_buffer->setOriginalFrameRect(IntRect(IntPoint(), m_parent->size()));
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if (!m_isTopDown)
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m_coord.setY(m_parent->size().height() - 1);
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}
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// Decode the data.
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if (!m_decodingAndMask && !pastEndOfImage(0)) {
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if ((m_infoHeader.biCompression != RLE4) && (m_infoHeader.biCompression != RLE8) && (m_infoHeader.biCompression != RLE24)) {
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const ProcessingResult result = processNonRLEData(false, 0);
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if (result != Success)
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return (result == Failure) ? m_parent->setFailed() : false;
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} else if (!processRLEData())
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return false;
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}
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// If the image has an AND mask and there was no alpha data, process the
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// mask.
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if (m_isInICO && !m_decodingAndMask && !m_buffer->hasAlpha()) {
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// Reset decoding coordinates to start of image.
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m_coord.setX(0);
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m_coord.setY(m_isTopDown ? 0 : (m_parent->size().height() - 1));
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// The AND mask is stored as 1-bit data.
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m_infoHeader.biBitCount = 1;
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m_decodingAndMask = true;
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}
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if (m_decodingAndMask) {
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const ProcessingResult result = processNonRLEData(false, 0);
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if (result != Success)
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return (result == Failure) ? m_parent->setFailed() : false;
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}
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// Done!
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m_buffer->setStatus(ImageFrame::FrameComplete);
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return true;
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}
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bool BMPImageReader::readInfoHeaderSize()
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{
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// Get size of info header.
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ASSERT(m_decodedOffset == m_headerOffset);
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if ((m_decodedOffset > m_data->size()) || ((m_data->size() - m_decodedOffset) < 4))
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return false;
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m_infoHeader.biSize = readUint32(0);
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// Don't increment m_decodedOffset here, it just makes the code in
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// processInfoHeader() more confusing.
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// Don't allow the header to overflow (which would be harmless here, but
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// problematic or at least confusing in other places), or to overrun the
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// image data.
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if (((m_headerOffset + m_infoHeader.biSize) < m_headerOffset) || (m_imgDataOffset && (m_imgDataOffset < (m_headerOffset + m_infoHeader.biSize))))
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return m_parent->setFailed();
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// See if this is a header size we understand:
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// OS/2 1.x: 12
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if (m_infoHeader.biSize == 12)
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m_isOS21x = true;
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// Windows V3: 40
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else if ((m_infoHeader.biSize == 40) || isWindowsV4Plus())
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;
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// OS/2 2.x: any multiple of 4 between 16 and 64, inclusive, or 42 or 46
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else if ((m_infoHeader.biSize >= 16) && (m_infoHeader.biSize <= 64) && (!(m_infoHeader.biSize & 3) || (m_infoHeader.biSize == 42) || (m_infoHeader.biSize == 46)))
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m_isOS22x = true;
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else
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return m_parent->setFailed();
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return true;
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}
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bool BMPImageReader::processInfoHeader()
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{
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// Read info header.
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ASSERT(m_decodedOffset == m_headerOffset);
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if ((m_decodedOffset > m_data->size()) || ((m_data->size() - m_decodedOffset) < m_infoHeader.biSize) || !readInfoHeader())
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return false;
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m_decodedOffset += m_infoHeader.biSize;
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// Sanity-check header values.
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if (!isInfoHeaderValid())
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return m_parent->setFailed();
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// Set our size.
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if (!m_parent->setSize(m_infoHeader.biWidth, m_infoHeader.biHeight))
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return false;
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// For paletted images, bitmaps can set biClrUsed to 0 to mean "all
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// colors", so set it to the maximum number of colors for this bit depth.
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// Also do this for bitmaps that put too large a value here.
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if (m_infoHeader.biBitCount < 16) {
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const uint32_t maxColors = static_cast<uint32_t>(1) << m_infoHeader.biBitCount;
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if (!m_infoHeader.biClrUsed || (m_infoHeader.biClrUsed > maxColors))
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m_infoHeader.biClrUsed = maxColors;
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}
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// For any bitmaps that set their BitCount to the wrong value, reset the
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// counts now that we've calculated the number of necessary colors, since
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// other code relies on this value being correct.
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if (m_infoHeader.biCompression == RLE8)
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m_infoHeader.biBitCount = 8;
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else if (m_infoHeader.biCompression == RLE4)
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m_infoHeader.biBitCount = 4;
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// Tell caller what still needs to be processed.
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if (m_infoHeader.biBitCount >= 16)
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m_needToProcessBitmasks = true;
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else if (m_infoHeader.biBitCount)
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m_needToProcessColorTable = true;
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return true;
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}
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bool BMPImageReader::readInfoHeader()
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{
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// Pre-initialize some fields that not all headers set.
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m_infoHeader.biCompression = RGB;
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m_infoHeader.biClrUsed = 0;
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if (m_isOS21x) {
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m_infoHeader.biWidth = readUint16(4);
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m_infoHeader.biHeight = readUint16(6);
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ASSERT(!m_isInICO); // ICO is a Windows format, not OS/2!
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m_infoHeader.biBitCount = readUint16(10);
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return true;
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}
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m_infoHeader.biWidth = readUint32(4);
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m_infoHeader.biHeight = readUint32(8);
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if (m_isInICO)
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m_infoHeader.biHeight /= 2;
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m_infoHeader.biBitCount = readUint16(14);
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// Read compression type, if present.
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if (m_infoHeader.biSize >= 20) {
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uint32_t biCompression = readUint32(16);
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// Detect OS/2 2.x-specific compression types.
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if ((biCompression == 3) && (m_infoHeader.biBitCount == 1)) {
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m_infoHeader.biCompression = HUFFMAN1D;
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m_isOS22x = true;
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} else if ((biCompression == 4) && (m_infoHeader.biBitCount == 24)) {
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m_infoHeader.biCompression = RLE24;
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m_isOS22x = true;
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} else if (biCompression > 5)
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return m_parent->setFailed(); // Some type we don't understand.
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else
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m_infoHeader.biCompression = static_cast<CompressionType>(biCompression);
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}
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// Read colors used, if present.
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if (m_infoHeader.biSize >= 36)
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m_infoHeader.biClrUsed = readUint32(32);
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// Windows V4+ can safely read the four bitmasks from 40-56 bytes in, so do
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// that here. If the bit depth is less than 16, these values will be ignored
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// by the image data decoders. If the bit depth is at least 16 but the
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// compression format isn't BITFIELDS, the RGB bitmasks will be ignored and
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// overwritten in processBitmasks(). (The alpha bitmask will never be
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// overwritten: images that actually want alpha have to specify a valid
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// alpha mask. See comments in processBitmasks().)
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//
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// For non-Windows V4+, m_bitMasks[] et. al will be initialized later
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// during processBitmasks().
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if (isWindowsV4Plus()) {
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m_bitMasks[0] = readUint32(40);
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m_bitMasks[1] = readUint32(44);
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m_bitMasks[2] = readUint32(48);
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m_bitMasks[3] = readUint32(52);
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}
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// Detect top-down BMPs.
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if (m_infoHeader.biHeight < 0) {
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m_isTopDown = true;
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m_infoHeader.biHeight = -m_infoHeader.biHeight;
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}
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return true;
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}
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bool BMPImageReader::isInfoHeaderValid() const
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{
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// Non-positive widths/heights are invalid. (We've already flipped the
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// sign of the height for top-down bitmaps.)
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if ((m_infoHeader.biWidth <= 0) || !m_infoHeader.biHeight)
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return false;
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// Only Windows V3+ has top-down bitmaps.
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if (m_isTopDown && (m_isOS21x || m_isOS22x))
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return false;
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// Only bit depths of 1, 4, 8, or 24 are universally supported.
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if ((m_infoHeader.biBitCount != 1) && (m_infoHeader.biBitCount != 4) && (m_infoHeader.biBitCount != 8) && (m_infoHeader.biBitCount != 24)) {
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// Windows V3+ additionally supports bit depths of 0 (for embedded
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// JPEG/PNG images), 16, and 32.
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if (m_isOS21x || m_isOS22x || (m_infoHeader.biBitCount && (m_infoHeader.biBitCount != 16) && (m_infoHeader.biBitCount != 32)))
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return false;
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}
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// Each compression type is only valid with certain bit depths (except RGB,
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// which can be used with any bit depth). Also, some formats do not support
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// some compression types.
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switch (m_infoHeader.biCompression) {
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case RGB:
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if (!m_infoHeader.biBitCount)
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return false;
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break;
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case RLE8:
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// Supposedly there are undocumented formats like "BitCount = 1,
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// Compression = RLE4" (which means "4 bit, but with a 2-color table"),
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// so also allow the paletted RLE compression types to have too low a
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// bit count; we'll correct this later.
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if (!m_infoHeader.biBitCount || (m_infoHeader.biBitCount > 8))
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return false;
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break;
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case RLE4:
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// See comments in RLE8.
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if (!m_infoHeader.biBitCount || (m_infoHeader.biBitCount > 4))
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return false;
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break;
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case BITFIELDS:
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// Only valid for Windows V3+.
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if (m_isOS21x || m_isOS22x || ((m_infoHeader.biBitCount != 16) && (m_infoHeader.biBitCount != 32)))
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return false;
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break;
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case JPEG:
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case PNG:
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// Only valid for Windows V3+.
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if (m_isOS21x || m_isOS22x || m_infoHeader.biBitCount)
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return false;
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break;
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case HUFFMAN1D:
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// Only valid for OS/2 2.x.
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if (!m_isOS22x || (m_infoHeader.biBitCount != 1))
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return false;
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break;
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case RLE24:
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// Only valid for OS/2 2.x.
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if (!m_isOS22x || (m_infoHeader.biBitCount != 24))
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return false;
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break;
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default:
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// Some type we don't understand. This should have been caught in
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// readInfoHeader().
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ASSERT_NOT_REACHED();
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return false;
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}
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// Top-down bitmaps cannot be compressed; they must be RGB or BITFIELDS.
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if (m_isTopDown && (m_infoHeader.biCompression != RGB) && (m_infoHeader.biCompression != BITFIELDS))
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return false;
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// Reject the following valid bitmap types that we don't currently bother
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// decoding. Few other people decode these either, they're unlikely to be
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// in much use.
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// TODO(pkasting): Consider supporting these someday.
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// * Bitmaps larger than 2^16 pixels in either dimension (Windows
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// probably doesn't draw these well anyway, and the decoded data would
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// take a lot of memory).
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if ((m_infoHeader.biWidth >= (1 << 16)) || (m_infoHeader.biHeight >= (1 << 16)))
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return false;
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// * Windows V3+ JPEG-in-BMP and PNG-in-BMP bitmaps (supposedly not found
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// in the wild, only used to send data to printers?).
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if ((m_infoHeader.biCompression == JPEG) || (m_infoHeader.biCompression == PNG))
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return false;
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// * OS/2 2.x Huffman-encoded monochrome bitmaps (see
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// http://www.fileformat.info/mirror/egff/ch09_05.htm , re: "G31D"
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// algorithm).
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if (m_infoHeader.biCompression == HUFFMAN1D)
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return false;
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return true;
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}
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bool BMPImageReader::processBitmasks()
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{
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// Create m_bitMasks[] values for R/G/B.
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if (m_infoHeader.biCompression != BITFIELDS) {
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// The format doesn't actually use bitmasks. To simplify the decode
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// logic later, create bitmasks for the RGB data. For Windows V4+,
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// this overwrites the masks we read from the header, which are
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// supposed to be ignored in non-BITFIELDS cases.
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// 16 bits: MSB <- xRRRRRGG GGGBBBBB -> LSB
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// 24/32 bits: MSB <- [AAAAAAAA] RRRRRRRR GGGGGGGG BBBBBBBB -> LSB
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const int numBits = (m_infoHeader.biBitCount == 16) ? 5 : 8;
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for (int i = 0; i <= 2; ++i)
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m_bitMasks[i] = ((static_cast<uint32_t>(1) << (numBits * (3 - i))) - 1) ^ ((static_cast<uint32_t>(1) << (numBits * (2 - i))) - 1);
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} else if (!isWindowsV4Plus()) {
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// For Windows V4+ BITFIELDS mode bitmaps, this was already done when
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// we read the info header.
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// Fail if we don't have enough file space for the bitmasks.
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static const size_t SIZEOF_BITMASKS = 12;
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if (((m_headerOffset + m_infoHeader.biSize + SIZEOF_BITMASKS) < (m_headerOffset + m_infoHeader.biSize)) || (m_imgDataOffset && (m_imgDataOffset < (m_headerOffset + m_infoHeader.biSize + SIZEOF_BITMASKS))))
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return m_parent->setFailed();
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// Read bitmasks.
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if ((m_data->size() - m_decodedOffset) < SIZEOF_BITMASKS)
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return false;
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m_bitMasks[0] = readUint32(0);
|
|
m_bitMasks[1] = readUint32(4);
|
|
m_bitMasks[2] = readUint32(8);
|
|
|
|
m_decodedOffset += SIZEOF_BITMASKS;
|
|
}
|
|
|
|
// Alpha is a poorly-documented and inconsistently-used feature.
|
|
//
|
|
// Windows V4+ has an alpha bitmask in the info header. Unlike the R/G/B
|
|
// bitmasks, the MSDN docs don't indicate that it is only valid for the
|
|
// BITFIELDS compression format, so we respect it at all times.
|
|
//
|
|
// To complicate things, Windows V3 BMPs, which lack this mask, can specify
|
|
// 32bpp format, which to any sane reader would imply an 8-bit alpha
|
|
// channel -- and for BMPs-in-ICOs, that's precisely what's intended to
|
|
// happen. There also exist standalone BMPs in this format which clearly
|
|
// expect the alpha channel to be respected. However, there are many other
|
|
// BMPs which, for example, fill this channel with all 0s, yet clearly
|
|
// expect to not be displayed as a fully-transparent rectangle.
|
|
//
|
|
// If these were the only two types of Windows V3, 32bpp BMPs in the wild,
|
|
// we could distinguish between them by scanning the alpha channel in the
|
|
// image, looking for nonzero values, and only enabling alpha if we found
|
|
// some. (It turns out we have to do this anyway, because, crazily, there
|
|
// are also Windows V4+ BMPs with an explicit, non-zero alpha mask, which
|
|
// then zero-fill their alpha channels! See comments in
|
|
// processNonRLEData().)
|
|
//
|
|
// Unfortunately there are also V3 BMPs -- indeed, probably more than the
|
|
// number of 32bpp, V3 BMPs which intentionally use alpha -- which specify
|
|
// 32bpp format, use nonzero (and non-255) alpha values, and yet expect to
|
|
// be rendered fully-opaque. And other browsers do so.
|
|
//
|
|
// So it's impossible to display every BMP in the way its creators intended,
|
|
// and we have to choose what to break. Given the paragraph above, we match
|
|
// other browsers and ignore alpha in Windows V3 BMPs except inside ICO
|
|
// files.
|
|
if (!isWindowsV4Plus())
|
|
m_bitMasks[3] = (m_isInICO && (m_infoHeader.biCompression != BITFIELDS) && (m_infoHeader.biBitCount == 32)) ? static_cast<uint32_t>(0xff000000) : 0;
|
|
|
|
// We've now decoded all the non-image data we care about. Skip anything
|
|
// else before the actual raster data.
|
|
if (m_imgDataOffset)
|
|
m_decodedOffset = m_imgDataOffset;
|
|
m_needToProcessBitmasks = false;
|
|
|
|
// Check masks and set shift and LUT address values.
|
|
for (int i = 0; i < 4; ++i) {
|
|
// Trim the mask to the allowed bit depth. Some Windows V4+ BMPs
|
|
// specify a bogus alpha channel in bits that don't exist in the pixel
|
|
// data (for example, bits 25-31 in a 24-bit RGB format).
|
|
if (m_infoHeader.biBitCount < 32)
|
|
m_bitMasks[i] &= ((static_cast<uint32_t>(1) << m_infoHeader.biBitCount) - 1);
|
|
|
|
// For empty masks (common on the alpha channel, especially after the
|
|
// trimming above), quickly clear the shift and LUT address and
|
|
// continue, to avoid an infinite loop in the counting code below.
|
|
uint32_t tempMask = m_bitMasks[i];
|
|
if (!tempMask) {
|
|
m_bitShiftsRight[i] = 0;
|
|
m_lookupTableAddresses[i] = 0;
|
|
continue;
|
|
}
|
|
|
|
// Make sure bitmask does not overlap any other bitmasks.
|
|
for (int j = 0; j < i; ++j) {
|
|
if (tempMask & m_bitMasks[j])
|
|
return m_parent->setFailed();
|
|
}
|
|
|
|
// Count offset into pixel data.
|
|
for (m_bitShiftsRight[i] = 0; !(tempMask & 1); tempMask >>= 1)
|
|
++m_bitShiftsRight[i];
|
|
|
|
// Count size of mask.
|
|
size_t numBits = 0;
|
|
for (; tempMask & 1; tempMask >>= 1)
|
|
++numBits;
|
|
|
|
// Make sure bitmask is contiguous.
|
|
if (tempMask)
|
|
return m_parent->setFailed();
|
|
|
|
// Since RGBABuffer tops out at 8 bits per channel, adjust the shift
|
|
// amounts to use the most significant 8 bits of the channel.
|
|
if (numBits >= 8) {
|
|
m_bitShiftsRight[i] += (numBits - 8);
|
|
numBits = 0;
|
|
}
|
|
|
|
// Calculate LUT address.
|
|
m_lookupTableAddresses[i] = numBits ? (nBitTo8BitlookupTable + (1 << numBits) - 2) : 0;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool BMPImageReader::processColorTable()
|
|
{
|
|
size_t tableSizeInBytes = m_infoHeader.biClrUsed * (m_isOS21x ? 3 : 4);
|
|
|
|
// Fail if we don't have enough file space for the color table.
|
|
if (((m_headerOffset + m_infoHeader.biSize + tableSizeInBytes) < (m_headerOffset + m_infoHeader.biSize)) || (m_imgDataOffset && (m_imgDataOffset < (m_headerOffset + m_infoHeader.biSize + tableSizeInBytes))))
|
|
return m_parent->setFailed();
|
|
|
|
// Read color table.
|
|
if ((m_decodedOffset > m_data->size()) || ((m_data->size() - m_decodedOffset) < tableSizeInBytes))
|
|
return false;
|
|
m_colorTable.resize(m_infoHeader.biClrUsed);
|
|
for (size_t i = 0; i < m_infoHeader.biClrUsed; ++i) {
|
|
m_colorTable[i].rgbBlue = m_data->data()[m_decodedOffset++];
|
|
m_colorTable[i].rgbGreen = m_data->data()[m_decodedOffset++];
|
|
m_colorTable[i].rgbRed = m_data->data()[m_decodedOffset++];
|
|
// Skip padding byte (not present on OS/2 1.x).
|
|
if (!m_isOS21x)
|
|
++m_decodedOffset;
|
|
}
|
|
|
|
// We've now decoded all the non-image data we care about. Skip anything
|
|
// else before the actual raster data.
|
|
if (m_imgDataOffset)
|
|
m_decodedOffset = m_imgDataOffset;
|
|
m_needToProcessColorTable = false;
|
|
|
|
return true;
|
|
}
|
|
|
|
bool BMPImageReader::processRLEData()
|
|
{
|
|
if (m_decodedOffset > m_data->size())
|
|
return false;
|
|
|
|
// RLE decoding is poorly specified. Two main problems:
|
|
// (1) Are EOL markers necessary? What happens when we have too many
|
|
// pixels for one row?
|
|
// http://www.fileformat.info/format/bmp/egff.htm says extra pixels
|
|
// should wrap to the next line. Real BMPs I've encountered seem to
|
|
// instead expect extra pixels to be ignored until the EOL marker is
|
|
// seen, although this has only happened in a few cases and I suspect
|
|
// those BMPs may be invalid. So we only change lines on EOL (or Delta
|
|
// with dy > 0), and fail in most cases when pixels extend past the end
|
|
// of the line.
|
|
// (2) When Delta, EOL, or EOF are seen, what happens to the "skipped"
|
|
// pixels?
|
|
// http://www.daubnet.com/formats/BMP.html says these should be filled
|
|
// with color 0. However, the "do nothing" and "don't care" comments
|
|
// of other references suggest leaving these alone, i.e. letting them
|
|
// be transparent to the background behind the image. This seems to
|
|
// match how MSPAINT treats BMPs, so we do that. Note that when we
|
|
// actually skip pixels for a case like this, we need to note on the
|
|
// framebuffer that we have alpha.
|
|
|
|
// Impossible to decode row-at-a-time, so just do things as a stream of
|
|
// bytes.
|
|
while (true) {
|
|
// Every entry takes at least two bytes; bail if there isn't enough
|
|
// data.
|
|
if ((m_data->size() - m_decodedOffset) < 2)
|
|
return false;
|
|
|
|
// For every entry except EOF, we'd better not have reached the end of
|
|
// the image.
|
|
const uint8_t count = m_data->data()[m_decodedOffset];
|
|
const uint8_t code = m_data->data()[m_decodedOffset + 1];
|
|
if ((count || (code != 1)) && pastEndOfImage(0))
|
|
return m_parent->setFailed();
|
|
|
|
// Decode.
|
|
if (!count) {
|
|
switch (code) {
|
|
case 0: // Magic token: EOL
|
|
// Skip any remaining pixels in this row.
|
|
if (m_coord.x() < m_parent->size().width())
|
|
m_buffer->setHasAlpha(true);
|
|
moveBufferToNextRow();
|
|
|
|
m_decodedOffset += 2;
|
|
break;
|
|
|
|
case 1: // Magic token: EOF
|
|
// Skip any remaining pixels in the image.
|
|
if ((m_coord.x() < m_parent->size().width()) || (m_isTopDown ? (m_coord.y() < (m_parent->size().height() - 1)) : (m_coord.y() > 0)))
|
|
m_buffer->setHasAlpha(true);
|
|
return true;
|
|
|
|
case 2: { // Magic token: Delta
|
|
// The next two bytes specify dx and dy. Bail if there isn't
|
|
// enough data.
|
|
if ((m_data->size() - m_decodedOffset) < 4)
|
|
return false;
|
|
|
|
// Fail if this takes us past the end of the desired row or
|
|
// past the end of the image.
|
|
const uint8_t dx = m_data->data()[m_decodedOffset + 2];
|
|
const uint8_t dy = m_data->data()[m_decodedOffset + 3];
|
|
if (dx || dy)
|
|
m_buffer->setHasAlpha(true);
|
|
if (((m_coord.x() + dx) > m_parent->size().width()) || pastEndOfImage(dy))
|
|
return m_parent->setFailed();
|
|
|
|
// Skip intervening pixels.
|
|
m_coord.move(dx, m_isTopDown ? dy : -dy);
|
|
|
|
m_decodedOffset += 4;
|
|
break;
|
|
}
|
|
|
|
default: { // Absolute mode
|
|
// |code| pixels specified as in BI_RGB, zero-padded at the end
|
|
// to a multiple of 16 bits.
|
|
// Because processNonRLEData() expects m_decodedOffset to
|
|
// point to the beginning of the pixel data, bump it past
|
|
// the escape bytes and then reset if decoding failed.
|
|
m_decodedOffset += 2;
|
|
const ProcessingResult result = processNonRLEData(true, code);
|
|
if (result == Failure)
|
|
return m_parent->setFailed();
|
|
if (result == InsufficientData) {
|
|
m_decodedOffset -= 2;
|
|
return false;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
} else { // Encoded mode
|
|
// The following color data is repeated for |count| total pixels.
|
|
// Strangely, some BMPs seem to specify excessively large counts
|
|
// here; ignore pixels past the end of the row.
|
|
const int endX = std::min(m_coord.x() + count, m_parent->size().width());
|
|
|
|
if (m_infoHeader.biCompression == RLE24) {
|
|
// Bail if there isn't enough data.
|
|
if ((m_data->size() - m_decodedOffset) < 4)
|
|
return false;
|
|
|
|
// One BGR triple that we copy |count| times.
|
|
fillRGBA(endX, m_data->data()[m_decodedOffset + 3], m_data->data()[m_decodedOffset + 2], code, 0xff);
|
|
m_decodedOffset += 4;
|
|
} else {
|
|
// RLE8 has one color index that gets repeated; RLE4 has two
|
|
// color indexes in the upper and lower 4 bits of the byte,
|
|
// which are alternated.
|
|
size_t colorIndexes[2] = {code, code};
|
|
if (m_infoHeader.biCompression == RLE4) {
|
|
colorIndexes[0] = (colorIndexes[0] >> 4) & 0xf;
|
|
colorIndexes[1] &= 0xf;
|
|
}
|
|
for (int which = 0; m_coord.x() < endX; ) {
|
|
// Some images specify color values past the end of the
|
|
// color table; set these pixels to black.
|
|
if (colorIndexes[which] < m_infoHeader.biClrUsed)
|
|
setI(colorIndexes[which]);
|
|
else
|
|
setRGBA(0, 0, 0, 255);
|
|
which = !which;
|
|
}
|
|
|
|
m_decodedOffset += 2;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
BMPImageReader::ProcessingResult BMPImageReader::processNonRLEData(bool inRLE, int numPixels)
|
|
{
|
|
if (m_decodedOffset > m_data->size())
|
|
return InsufficientData;
|
|
|
|
if (!inRLE)
|
|
numPixels = m_parent->size().width();
|
|
|
|
// Fail if we're being asked to decode more pixels than remain in the row.
|
|
const int endX = m_coord.x() + numPixels;
|
|
if (endX > m_parent->size().width())
|
|
return Failure;
|
|
|
|
// Determine how many bytes of data the requested number of pixels
|
|
// requires.
|
|
const size_t pixelsPerByte = 8 / m_infoHeader.biBitCount;
|
|
const size_t bytesPerPixel = m_infoHeader.biBitCount / 8;
|
|
const size_t unpaddedNumBytes = (m_infoHeader.biBitCount < 16) ? ((numPixels + pixelsPerByte - 1) / pixelsPerByte) : (numPixels * bytesPerPixel);
|
|
// RLE runs are zero-padded at the end to a multiple of 16 bits. Non-RLE
|
|
// data is in rows and is zero-padded to a multiple of 32 bits.
|
|
const size_t alignBits = inRLE ? 1 : 3;
|
|
const size_t paddedNumBytes = (unpaddedNumBytes + alignBits) & ~alignBits;
|
|
|
|
// Decode as many rows as we can. (For RLE, where we only want to decode
|
|
// one row, we've already checked that this condition is true.)
|
|
while (!pastEndOfImage(0)) {
|
|
// Bail if we don't have enough data for the desired number of pixels.
|
|
if ((m_data->size() - m_decodedOffset) < paddedNumBytes)
|
|
return InsufficientData;
|
|
|
|
if (m_infoHeader.biBitCount < 16) {
|
|
// Paletted data. Pixels are stored little-endian within bytes.
|
|
// Decode pixels one byte at a time, left to right (so, starting at
|
|
// the most significant bits in the byte).
|
|
const uint8_t mask = (1 << m_infoHeader.biBitCount) - 1;
|
|
for (size_t byte = 0; byte < unpaddedNumBytes; ++byte) {
|
|
uint8_t pixelData = m_data->data()[m_decodedOffset + byte];
|
|
for (size_t pixel = 0; (pixel < pixelsPerByte) && (m_coord.x() < endX); ++pixel) {
|
|
const size_t colorIndex = (pixelData >> (8 - m_infoHeader.biBitCount)) & mask;
|
|
if (m_decodingAndMask) {
|
|
// There's no way to accurately represent an AND + XOR
|
|
// operation as an RGBA image, so where the AND values
|
|
// are 1, we simply set the framebuffer pixels to fully
|
|
// transparent, on the assumption that most ICOs on the
|
|
// web will not be doing a lot of inverting.
|
|
if (colorIndex) {
|
|
setRGBA(0, 0, 0, 0);
|
|
m_buffer->setHasAlpha(true);
|
|
} else
|
|
m_coord.move(1, 0);
|
|
} else {
|
|
// See comments near the end of processRLEData().
|
|
if (colorIndex < m_infoHeader.biClrUsed)
|
|
setI(colorIndex);
|
|
else
|
|
setRGBA(0, 0, 0, 255);
|
|
}
|
|
pixelData <<= m_infoHeader.biBitCount;
|
|
}
|
|
}
|
|
} else {
|
|
// RGB data. Decode pixels one at a time, left to right.
|
|
while (m_coord.x() < endX) {
|
|
const uint32_t pixel = readCurrentPixel(bytesPerPixel);
|
|
|
|
// Some BMPs specify an alpha channel but don't actually use it
|
|
// (it contains all 0s). To avoid displaying these images as
|
|
// fully-transparent, decode as if images are fully opaque
|
|
// until we actually see a non-zero alpha value; at that point,
|
|
// reset any previously-decoded pixels to fully transparent and
|
|
// continue decoding based on the real alpha channel values.
|
|
// As an optimization, avoid setting "hasAlpha" to true for
|
|
// images where all alpha values are 255; opaque images are
|
|
// faster to draw.
|
|
int alpha = getAlpha(pixel);
|
|
if (!m_seenNonZeroAlphaPixel && !alpha) {
|
|
m_seenZeroAlphaPixel = true;
|
|
alpha = 255;
|
|
} else {
|
|
m_seenNonZeroAlphaPixel = true;
|
|
if (m_seenZeroAlphaPixel) {
|
|
m_buffer->zeroFillPixelData();
|
|
m_seenZeroAlphaPixel = false;
|
|
} else if (alpha != 255)
|
|
m_buffer->setHasAlpha(true);
|
|
}
|
|
|
|
setRGBA(getComponent(pixel, 0), getComponent(pixel, 1),
|
|
getComponent(pixel, 2), alpha);
|
|
}
|
|
}
|
|
|
|
// Success, keep going.
|
|
m_decodedOffset += paddedNumBytes;
|
|
if (inRLE)
|
|
return Success;
|
|
moveBufferToNextRow();
|
|
}
|
|
|
|
// Finished decoding whole image.
|
|
return Success;
|
|
}
|
|
|
|
void BMPImageReader::moveBufferToNextRow()
|
|
{
|
|
m_coord.move(-m_coord.x(), m_isTopDown ? 1 : -1);
|
|
}
|
|
|
|
} // namespace blink
|