| /* |
| * 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 "platform/image-decoders/bmp/BMPImageReader.h" |
| |
| namespace { |
| |
| // See comments on lookup_table_addresses_ in the header. |
| const uint8_t nBitTo8BitlookupTable[] = { |
| // 1 bit |
| 0, 255, |
| // 2 bits |
| 0, 85, 170, 255, |
| // 3 bits |
| 0, 36, 73, 109, 146, 182, 219, 255, |
| // 4 bits |
| 0, 17, 34, 51, 68, 85, 102, 119, 136, 153, 170, 187, 204, 221, 238, 255, |
| // 5 bits |
| 0, 8, 16, 25, 33, 41, 49, 58, 66, 74, 82, 90, 99, 107, 115, 123, 132, 140, |
| 148, 156, 165, 173, 181, 189, 197, 206, 214, 222, 230, 239, 247, 255, |
| // 6 bits |
| 0, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 45, 49, 53, 57, 61, 65, 69, 73, 77, |
| 81, 85, 89, 93, 97, 101, 105, 109, 113, 117, 121, 125, 130, 134, 138, 142, |
| 146, 150, 154, 158, 162, 166, 170, 174, 178, 182, 186, 190, 194, 198, 202, |
| 206, 210, 215, 219, 223, 227, 231, 235, 239, 243, 247, 251, 255, |
| // 7 bits |
| 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, |
| 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, |
| 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, |
| 112, 114, 116, 118, 120, 122, 124, 126, 129, 131, 133, 135, 137, 139, 141, |
| 143, 145, 147, 149, 151, 153, 155, 157, 159, 161, 163, 165, 167, 169, 171, |
| 173, 175, 177, 179, 181, 183, 185, 187, 189, 191, 193, 195, 197, 199, 201, |
| 203, 205, 207, 209, 211, 213, 215, 217, 219, 221, 223, 225, 227, 229, 231, |
| 233, 235, 237, 239, 241, 243, 245, 247, 249, 251, 253, 255, |
| }; |
| |
| } // namespace |
| |
| namespace blink { |
| |
| BMPImageReader::BMPImageReader(ImageDecoder* parent, |
| size_t decoded_and_header_offset, |
| size_t img_data_offset, |
| bool is_in_ico) |
| : parent_(parent), |
| buffer_(nullptr), |
| fast_reader_(nullptr), |
| decoded_offset_(decoded_and_header_offset), |
| header_offset_(decoded_and_header_offset), |
| img_data_offset_(img_data_offset), |
| is_os21x_(false), |
| is_os22x_(false), |
| is_top_down_(false), |
| need_to_process_bitmasks_(false), |
| need_to_process_color_table_(false), |
| seen_non_zero_alpha_pixel_(false), |
| seen_zero_alpha_pixel_(false), |
| is_in_ico_(is_in_ico), |
| decoding_and_mask_(false) { |
| // Clue-in decodeBMP() that we need to detect the correct info header size. |
| memset(&info_header_, 0, sizeof(info_header_)); |
| } |
| |
| bool BMPImageReader::DecodeBMP(bool only_size) { |
| // Defensively clear the FastSharedBufferReader's cache, as another caller |
| // may have called SharedBuffer::MergeSegmentsIntoBuffer(). |
| fast_reader_.ClearCache(); |
| |
| // Calculate size of info header. |
| if (!info_header_.bi_size && !ReadInfoHeaderSize()) |
| return false; |
| |
| const size_t header_end = header_offset_ + info_header_.bi_size; |
| // Read and process info header. |
| if ((decoded_offset_ < header_end) && !ProcessInfoHeader()) |
| return false; |
| |
| // ProcessInfoHeader() set the size, so if that's all we needed, we're done. |
| if (only_size) |
| return true; |
| |
| // Read and process the bitmasks, if needed. |
| if (need_to_process_bitmasks_ && !ProcessBitmasks()) |
| return false; |
| |
| // Read and process the color table, if needed. |
| if (need_to_process_color_table_ && !ProcessColorTable()) |
| return false; |
| |
| // Initialize the framebuffer if needed. |
| DCHECK(buffer_); // Parent should set this before asking us to decode! |
| if (buffer_->GetStatus() == ImageFrame::kFrameEmpty) { |
| if (!buffer_->AllocatePixelData(parent_->Size().Width(), |
| parent_->Size().Height(), |
| parent_->ColorSpaceForSkImages())) { |
| return parent_->SetFailed(); // Unable to allocate. |
| } |
| buffer_->ZeroFillPixelData(); |
| buffer_->SetStatus(ImageFrame::kFramePartial); |
| // SetSize() calls EraseARGB(), which resets the alpha flag, so we force |
| // it back to false here. We'll set it true below in all cases where |
| // these 0s could actually show through. |
| buffer_->SetHasAlpha(false); |
| |
| // For BMPs, the frame always fills the entire image. |
| buffer_->SetOriginalFrameRect(IntRect(IntPoint(), parent_->Size())); |
| |
| if (!is_top_down_) |
| coord_.SetY(parent_->Size().Height() - 1); |
| } |
| |
| // Decode the data. |
| if (!decoding_and_mask_ && !PastEndOfImage(0) && |
| !DecodePixelData((info_header_.bi_compression != RLE4) && |
| (info_header_.bi_compression != RLE8) && |
| (info_header_.bi_compression != RLE24))) |
| return false; |
| |
| // If the image has an AND mask and there was no alpha data, process the |
| // mask. |
| if (is_in_ico_ && !decoding_and_mask_ && |
| ((info_header_.bi_bit_count < 16) || !bit_masks_[3] || |
| !seen_non_zero_alpha_pixel_)) { |
| // Reset decoding coordinates to start of image. |
| coord_.SetX(0); |
| coord_.SetY(is_top_down_ ? 0 : (parent_->Size().Height() - 1)); |
| |
| // The AND mask is stored as 1-bit data. |
| info_header_.bi_bit_count = 1; |
| |
| decoding_and_mask_ = true; |
| } |
| if (decoding_and_mask_ && !DecodePixelData(true)) |
| return false; |
| |
| // Done! |
| buffer_->SetStatus(ImageFrame::kFrameComplete); |
| return true; |
| } |
| |
| bool BMPImageReader::DecodePixelData(bool non_rle) { |
| const IntPoint coord(coord_); |
| const ProcessingResult result = |
| non_rle ? ProcessNonRLEData(false, 0) : ProcessRLEData(); |
| if (coord_ != coord) |
| buffer_->SetPixelsChanged(true); |
| return (result == kFailure) ? parent_->SetFailed() : (result == kSuccess); |
| } |
| |
| bool BMPImageReader::ReadInfoHeaderSize() { |
| // Get size of info header. |
| DCHECK_EQ(decoded_offset_, header_offset_); |
| if ((decoded_offset_ > data_->size()) || |
| ((data_->size() - decoded_offset_) < 4)) |
| return false; |
| info_header_.bi_size = ReadUint32(0); |
| // Don't increment decoded_offset here, it just makes the code in |
| // ProcessInfoHeader() more confusing. |
| |
| // Don't allow the header to overflow (which would be harmless here, but |
| // problematic or at least confusing in other places), or to overrun the |
| // image data. |
| const size_t header_end = header_offset_ + info_header_.bi_size; |
| if ((header_end < header_offset_) || |
| (img_data_offset_ && (img_data_offset_ < header_end))) |
| return parent_->SetFailed(); |
| |
| // See if this is a header size we understand: |
| // OS/2 1.x: 12 |
| if (info_header_.bi_size == 12) |
| is_os21x_ = true; |
| // Windows V3: 40 |
| else if ((info_header_.bi_size == 40) || IsWindowsV4Plus()) |
| ; |
| // OS/2 2.x: any multiple of 4 between 16 and 64, inclusive, or 42 or 46 |
| else if ((info_header_.bi_size >= 16) && (info_header_.bi_size <= 64) && |
| (!(info_header_.bi_size & 3) || (info_header_.bi_size == 42) || |
| (info_header_.bi_size == 46))) |
| is_os22x_ = true; |
| else |
| return parent_->SetFailed(); |
| |
| return true; |
| } |
| |
| bool BMPImageReader::ProcessInfoHeader() { |
| // Read info header. |
| DCHECK_EQ(decoded_offset_, header_offset_); |
| if ((decoded_offset_ > data_->size()) || |
| ((data_->size() - decoded_offset_) < info_header_.bi_size) || |
| !ReadInfoHeader()) |
| return false; |
| decoded_offset_ += info_header_.bi_size; |
| |
| // Sanity-check header values. |
| if (!IsInfoHeaderValid()) |
| return parent_->SetFailed(); |
| |
| // Set our size. |
| if (!parent_->SetSize(info_header_.bi_width, info_header_.bi_height)) |
| return false; |
| |
| // For paletted images, bitmaps can set biClrUsed to 0 to mean "all |
| // colors", so set it to the maximum number of colors for this bit depth. |
| // Also do this for bitmaps that put too large a value here. |
| if (info_header_.bi_bit_count < 16) { |
| const uint32_t max_colors = static_cast<uint32_t>(1) |
| << info_header_.bi_bit_count; |
| if (!info_header_.bi_clr_used || (info_header_.bi_clr_used > max_colors)) |
| info_header_.bi_clr_used = max_colors; |
| } |
| |
| // For any bitmaps that set their BitCount to the wrong value, reset the |
| // counts now that we've calculated the number of necessary colors, since |
| // other code relies on this value being correct. |
| if (info_header_.bi_compression == RLE8) |
| info_header_.bi_bit_count = 8; |
| else if (info_header_.bi_compression == RLE4) |
| info_header_.bi_bit_count = 4; |
| |
| // Tell caller what still needs to be processed. |
| if (info_header_.bi_bit_count >= 16) |
| need_to_process_bitmasks_ = true; |
| else if (info_header_.bi_bit_count) |
| need_to_process_color_table_ = true; |
| |
| return true; |
| } |
| |
| bool BMPImageReader::ReadInfoHeader() { |
| // Pre-initialize some fields that not all headers set. |
| info_header_.bi_compression = RGB; |
| info_header_.bi_clr_used = 0; |
| |
| if (is_os21x_) { |
| info_header_.bi_width = ReadUint16(4); |
| info_header_.bi_height = ReadUint16(6); |
| DCHECK(!is_in_ico_); // ICO is a Windows format, not OS/2! |
| info_header_.bi_bit_count = ReadUint16(10); |
| return true; |
| } |
| |
| info_header_.bi_width = ReadUint32(4); |
| info_header_.bi_height = ReadUint32(8); |
| if (is_in_ico_) |
| info_header_.bi_height /= 2; |
| info_header_.bi_bit_count = ReadUint16(14); |
| |
| // Read compression type, if present. |
| if (info_header_.bi_size >= 20) { |
| uint32_t bi_compression = ReadUint32(16); |
| |
| // Detect OS/2 2.x-specific compression types. |
| if ((bi_compression == 3) && (info_header_.bi_bit_count == 1)) { |
| info_header_.bi_compression = HUFFMAN1D; |
| is_os22x_ = true; |
| } else if ((bi_compression == 4) && (info_header_.bi_bit_count == 24)) { |
| info_header_.bi_compression = RLE24; |
| is_os22x_ = true; |
| } else if (bi_compression > 5) |
| return parent_->SetFailed(); // Some type we don't understand. |
| else |
| info_header_.bi_compression = |
| static_cast<CompressionType>(bi_compression); |
| } |
| |
| // Read colors used, if present. |
| if (info_header_.bi_size >= 36) |
| info_header_.bi_clr_used = ReadUint32(32); |
| |
| // Windows V4+ can safely read the four bitmasks from 40-56 bytes in, so do |
| // that here. If the bit depth is less than 16, these values will be ignored |
| // by the image data decoders. If the bit depth is at least 16 but the |
| // compression format isn't BITFIELDS, the RGB bitmasks will be ignored and |
| // overwritten in processBitmasks(). (The alpha bitmask will never be |
| // overwritten: images that actually want alpha have to specify a valid |
| // alpha mask. See comments in ProcessBitmasks().) |
| // |
| // For non-Windows V4+, bit_masks_[] et. al will be initialized later |
| // during ProcessBitmasks(). |
| if (IsWindowsV4Plus()) { |
| bit_masks_[0] = ReadUint32(40); |
| bit_masks_[1] = ReadUint32(44); |
| bit_masks_[2] = ReadUint32(48); |
| bit_masks_[3] = ReadUint32(52); |
| } |
| |
| // Detect top-down BMPs. |
| if (info_header_.bi_height < 0) { |
| // We can't negate INT32_MIN below to get a positive int32_t. |
| // IsInfoHeaderValid() will reject heights of 1 << 16 or larger anyway, |
| // so just reject this bitmap now. |
| if (info_header_.bi_height == INT32_MIN) |
| return parent_->SetFailed(); |
| is_top_down_ = true; |
| info_header_.bi_height = -info_header_.bi_height; |
| } |
| |
| return true; |
| } |
| |
| bool BMPImageReader::IsInfoHeaderValid() const { |
| // Non-positive widths/heights are invalid. (We've already flipped the |
| // sign of the height for top-down bitmaps.) |
| if ((info_header_.bi_width <= 0) || !info_header_.bi_height) |
| return false; |
| |
| // Only Windows V3+ has top-down bitmaps. |
| if (is_top_down_ && (is_os21x_ || is_os22x_)) |
| return false; |
| |
| // Only bit depths of 1, 4, 8, or 24 are universally supported. |
| if ((info_header_.bi_bit_count != 1) && (info_header_.bi_bit_count != 4) && |
| (info_header_.bi_bit_count != 8) && (info_header_.bi_bit_count != 24)) { |
| // Windows V3+ additionally supports bit depths of 0 (for embedded |
| // JPEG/PNG images), 16, and 32. |
| if (is_os21x_ || is_os22x_ || |
| (info_header_.bi_bit_count && (info_header_.bi_bit_count != 16) && |
| (info_header_.bi_bit_count != 32))) |
| return false; |
| } |
| |
| // Each compression type is only valid with certain bit depths (except RGB, |
| // which can be used with any bit depth). Also, some formats do not support |
| // some compression types. |
| switch (info_header_.bi_compression) { |
| case RGB: |
| if (!info_header_.bi_bit_count) |
| return false; |
| break; |
| |
| case RLE8: |
| // Supposedly there are undocumented formats like "BitCount = 1, |
| // Compression = RLE4" (which means "4 bit, but with a 2-color table"), |
| // so also allow the paletted RLE compression types to have too low a |
| // bit count; we'll correct this later. |
| if (!info_header_.bi_bit_count || (info_header_.bi_bit_count > 8)) |
| return false; |
| break; |
| |
| case RLE4: |
| // See comments in RLE8. |
| if (!info_header_.bi_bit_count || (info_header_.bi_bit_count > 4)) |
| return false; |
| break; |
| |
| case BITFIELDS: |
| // Only valid for Windows V3+. |
| if (is_os21x_ || is_os22x_ || |
| ((info_header_.bi_bit_count != 16) && |
| (info_header_.bi_bit_count != 32))) |
| return false; |
| break; |
| |
| case JPEG: |
| case PNG: |
| // Only valid for Windows V3+. |
| if (is_os21x_ || is_os22x_ || info_header_.bi_bit_count) |
| return false; |
| break; |
| |
| case HUFFMAN1D: |
| // Only valid for OS/2 2.x. |
| if (!is_os22x_ || (info_header_.bi_bit_count != 1)) |
| return false; |
| break; |
| |
| case RLE24: |
| // Only valid for OS/2 2.x. |
| if (!is_os22x_ || (info_header_.bi_bit_count != 24)) |
| return false; |
| break; |
| |
| default: |
| // Some type we don't understand. This should have been caught in |
| // ReadInfoHeader(). |
| NOTREACHED(); |
| return false; |
| } |
| |
| // Top-down bitmaps cannot be compressed; they must be RGB or BITFIELDS. |
| if (is_top_down_ && (info_header_.bi_compression != RGB) && |
| (info_header_.bi_compression != BITFIELDS)) |
| return false; |
| |
| // Reject the following valid bitmap types that we don't currently bother |
| // decoding. Few other people decode these either, they're unlikely to be |
| // in much use. |
| // TODO(pkasting): Consider supporting these someday. |
| // * Bitmaps larger than 2^16 pixels in either dimension (Windows |
| // probably doesn't draw these well anyway, and the decoded data would |
| // take a lot of memory). |
| if ((info_header_.bi_width >= (1 << 16)) || |
| (info_header_.bi_height >= (1 << 16))) |
| return false; |
| // * Windows V3+ JPEG-in-BMP and PNG-in-BMP bitmaps (supposedly not found |
| // in the wild, only used to send data to printers?). |
| if ((info_header_.bi_compression == JPEG) || |
| (info_header_.bi_compression == PNG)) |
| return false; |
| // * OS/2 2.x Huffman-encoded monochrome bitmaps (see |
| // http://www.fileformat.info/mirror/egff/ch09_05.htm , re: "G31D" |
| // algorithm). |
| if (info_header_.bi_compression == HUFFMAN1D) |
| return false; |
| |
| return true; |
| } |
| |
| bool BMPImageReader::ProcessBitmasks() { |
| // Create bit_masks_[] values for R/G/B. |
| if (info_header_.bi_compression != BITFIELDS) { |
| // The format doesn't actually use bitmasks. To simplify the decode |
| // logic later, create bitmasks for the RGB data. For Windows V4+, |
| // this overwrites the masks we read from the header, which are |
| // supposed to be ignored in non-BITFIELDS cases. |
| // 16 bits: MSB <- xRRRRRGG GGGBBBBB -> LSB |
| // 24/32 bits: MSB <- [AAAAAAAA] RRRRRRRR GGGGGGGG BBBBBBBB -> LSB |
| const int num_bits = (info_header_.bi_bit_count == 16) ? 5 : 8; |
| for (int i = 0; i <= 2; ++i) |
| bit_masks_[i] = ((static_cast<uint32_t>(1) << (num_bits * (3 - i))) - 1) ^ |
| ((static_cast<uint32_t>(1) << (num_bits * (2 - i))) - 1); |
| } else if (!IsWindowsV4Plus()) { |
| // For Windows V4+ BITFIELDS mode bitmaps, this was already done when |
| // we read the info header. |
| |
| // Fail if we don't have enough file space for the bitmasks. |
| const size_t header_end = header_offset_ + info_header_.bi_size; |
| const size_t kBitmasksSize = 12; |
| const size_t bitmasks_end = header_end + kBitmasksSize; |
| if ((bitmasks_end < header_end) || |
| (img_data_offset_ && (img_data_offset_ < bitmasks_end))) |
| return parent_->SetFailed(); |
| |
| // Read bitmasks. |
| if ((data_->size() - decoded_offset_) < kBitmasksSize) |
| return false; |
| bit_masks_[0] = ReadUint32(0); |
| bit_masks_[1] = ReadUint32(4); |
| bit_masks_[2] = ReadUint32(8); |
| |
| decoded_offset_ += kBitmasksSize; |
| } |
| |
| // 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()) |
| bit_masks_[3] = (is_in_ico_ && (info_header_.bi_compression != BITFIELDS) && |
| (info_header_.bi_bit_count == 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 (img_data_offset_) |
| decoded_offset_ = img_data_offset_; |
| need_to_process_bitmasks_ = 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 (info_header_.bi_bit_count < 32) |
| bit_masks_[i] &= |
| ((static_cast<uint32_t>(1) << info_header_.bi_bit_count) - 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 temp_mask = bit_masks_[i]; |
| if (!temp_mask) { |
| bit_shifts_right_[i] = 0; |
| lookup_table_addresses_[i] = nullptr; |
| continue; |
| } |
| |
| // Make sure bitmask does not overlap any other bitmasks. |
| for (int j = 0; j < i; ++j) { |
| if (temp_mask & bit_masks_[j]) |
| return parent_->SetFailed(); |
| } |
| |
| // Count offset into pixel data. |
| for (bit_shifts_right_[i] = 0; !(temp_mask & 1); temp_mask >>= 1) |
| ++bit_shifts_right_[i]; |
| |
| // Count size of mask. |
| size_t num_bits = 0; |
| for (; temp_mask & 1; temp_mask >>= 1) |
| ++num_bits; |
| |
| // Make sure bitmask is contiguous. |
| if (temp_mask) |
| return 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 (num_bits >= 8) { |
| bit_shifts_right_[i] += (num_bits - 8); |
| num_bits = 0; |
| } |
| |
| // Calculate LUT address. |
| lookup_table_addresses_[i] = |
| num_bits ? (nBitTo8BitlookupTable + (1 << num_bits) - 2) : nullptr; |
| } |
| |
| return true; |
| } |
| |
| bool BMPImageReader::ProcessColorTable() { |
| // Fail if we don't have enough file space for the color table. |
| const size_t header_end = header_offset_ + info_header_.bi_size; |
| const size_t table_size_in_bytes = |
| info_header_.bi_clr_used * (is_os21x_ ? 3 : 4); |
| const size_t table_end = header_end + table_size_in_bytes; |
| if ((table_end < header_end) || |
| (img_data_offset_ && (img_data_offset_ < table_end))) |
| return parent_->SetFailed(); |
| |
| // Read color table. |
| if ((decoded_offset_ > data_->size()) || |
| ((data_->size() - decoded_offset_) < table_size_in_bytes)) |
| return false; |
| color_table_.resize(info_header_.bi_clr_used); |
| |
| // On non-OS/2 1.x, an extra padding byte is present, which we need to skip. |
| const size_t bytes_per_color = is_os21x_ ? 3 : 4; |
| for (size_t i = 0; i < info_header_.bi_clr_used; ++i) { |
| color_table_[i].rgb_blue = ReadUint8(0); |
| color_table_[i].rgb_green = ReadUint8(1); |
| color_table_[i].rgb_red = ReadUint8(2); |
| decoded_offset_ += bytes_per_color; |
| } |
| |
| // We've now decoded all the non-image data we care about. Skip anything |
| // else before the actual raster data. |
| if (img_data_offset_) |
| decoded_offset_ = img_data_offset_; |
| need_to_process_color_table_ = false; |
| |
| return true; |
| } |
| |
| BMPImageReader::ProcessingResult BMPImageReader::ProcessRLEData() { |
| if (decoded_offset_ > data_->size()) |
| return kInsufficientData; |
| |
| // 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 ((data_->size() - decoded_offset_) < 2) |
| return kInsufficientData; |
| |
| // For every entry except EOF, we'd better not have reached the end of |
| // the image. |
| const uint8_t count = ReadUint8(0); |
| const uint8_t code = ReadUint8(1); |
| if ((count || (code != 1)) && PastEndOfImage(0)) |
| return kFailure; |
| |
| // Decode. |
| if (!count) { |
| switch (code) { |
| case 0: // Magic token: EOL |
| // Skip any remaining pixels in this row. |
| if (coord_.X() < parent_->Size().Width()) |
| buffer_->SetHasAlpha(true); |
| MoveBufferToNextRow(); |
| |
| decoded_offset_ += 2; |
| break; |
| |
| case 1: // Magic token: EOF |
| // Skip any remaining pixels in the image. |
| if ((coord_.X() < parent_->Size().Width()) || |
| (is_top_down_ ? (coord_.Y() < (parent_->Size().Height() - 1)) |
| : (coord_.Y() > 0))) |
| buffer_->SetHasAlpha(true); |
| // There's no need to move |coord_| here to trigger the caller |
| // to call SetPixelsChanged(). If the only thing that's changed |
| // is the alpha state, that will be properly written into the |
| // underlying SkBitmap when we mark the frame complete. |
| return kSuccess; |
| |
| case 2: { // Magic token: Delta |
| // The next two bytes specify dx and dy. Bail if there isn't |
| // enough data. |
| if ((data_->size() - decoded_offset_) < 4) |
| return kInsufficientData; |
| |
| // Fail if this takes us past the end of the desired row or |
| // past the end of the image. |
| const uint8_t dx = ReadUint8(2); |
| const uint8_t dy = ReadUint8(3); |
| if (dx || dy) |
| buffer_->SetHasAlpha(true); |
| if (((coord_.X() + dx) > parent_->Size().Width()) || |
| PastEndOfImage(dy)) |
| return kFailure; |
| |
| // Skip intervening pixels. |
| coord_.Move(dx, is_top_down_ ? dy : -dy); |
| |
| decoded_offset_ += 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 decoded_offset_ to |
| // point to the beginning of the pixel data, bump it past |
| // the escape bytes and then reset if decoding failed. |
| decoded_offset_ += 2; |
| const ProcessingResult result = ProcessNonRLEData(true, code); |
| if (result != kSuccess) { |
| decoded_offset_ -= 2; |
| return result; |
| } |
| 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 end_x = std::min(coord_.X() + count, parent_->Size().Width()); |
| |
| if (info_header_.bi_compression == RLE24) { |
| // Bail if there isn't enough data. |
| if ((data_->size() - decoded_offset_) < 4) |
| return kInsufficientData; |
| |
| // One BGR triple that we copy |count| times. |
| FillRGBA(end_x, ReadUint8(3), ReadUint8(2), code, 0xff); |
| decoded_offset_ += 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 color_indexes[2] = {code, code}; |
| if (info_header_.bi_compression == RLE4) { |
| color_indexes[0] = (color_indexes[0] >> 4) & 0xf; |
| color_indexes[1] &= 0xf; |
| } |
| for (int which = 0; coord_.X() < end_x;) { |
| // Some images specify color values past the end of the |
| // color table; set these pixels to black. |
| if (color_indexes[which] < info_header_.bi_clr_used) |
| SetI(color_indexes[which]); |
| else |
| SetRGBA(0, 0, 0, 255); |
| which = !which; |
| } |
| |
| decoded_offset_ += 2; |
| } |
| } |
| } |
| } |
| |
| BMPImageReader::ProcessingResult BMPImageReader::ProcessNonRLEData( |
| bool in_rle, |
| int num_pixels) { |
| if (decoded_offset_ > data_->size()) |
| return kInsufficientData; |
| |
| if (!in_rle) |
| num_pixels = parent_->Size().Width(); |
| |
| // Fail if we're being asked to decode more pixels than remain in the row. |
| const int end_x = coord_.X() + num_pixels; |
| if (end_x > parent_->Size().Width()) |
| return kFailure; |
| |
| // Determine how many bytes of data the requested number of pixels |
| // requires. |
| const size_t pixels_per_byte = 8 / info_header_.bi_bit_count; |
| const size_t bytes_per_pixel = info_header_.bi_bit_count / 8; |
| const size_t unpadded_num_bytes = |
| (info_header_.bi_bit_count < 16) |
| ? ((num_pixels + pixels_per_byte - 1) / pixels_per_byte) |
| : (num_pixels * bytes_per_pixel); |
| // 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 align_bits = in_rle ? 1 : 3; |
| const size_t padded_num_bytes = |
| (unpadded_num_bytes + align_bits) & ~align_bits; |
| |
| // 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 ((data_->size() - decoded_offset_) < padded_num_bytes) |
| return kInsufficientData; |
| |
| if (info_header_.bi_bit_count < 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 << info_header_.bi_bit_count) - 1; |
| for (size_t end_offset = decoded_offset_ + unpadded_num_bytes; |
| decoded_offset_ < end_offset; ++decoded_offset_) { |
| uint8_t pixel_data = ReadUint8(0); |
| for (size_t pixel = 0; |
| (pixel < pixels_per_byte) && (coord_.X() < end_x); ++pixel) { |
| const size_t color_index = |
| (pixel_data >> (8 - info_header_.bi_bit_count)) & mask; |
| if (decoding_and_mask_) { |
| // 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 (color_index) { |
| SetRGBA(0, 0, 0, 0); |
| buffer_->SetHasAlpha(true); |
| } else |
| coord_.Move(1, 0); |
| } else { |
| // See comments near the end of ProcessRLEData(). |
| if (color_index < info_header_.bi_clr_used) |
| SetI(color_index); |
| else |
| SetRGBA(0, 0, 0, 255); |
| } |
| pixel_data <<= info_header_.bi_bit_count; |
| } |
| } |
| } else { |
| // RGB data. Decode pixels one at a time, left to right. |
| for (; coord_.X() < end_x; decoded_offset_ += bytes_per_pixel) { |
| const uint32_t pixel = ReadCurrentPixel(bytes_per_pixel); |
| |
| // 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 calling SetHasAlpha(true) for |
| // images where all alpha values are 255; opaque images are |
| // faster to draw. |
| int alpha = GetAlpha(pixel); |
| if (!seen_non_zero_alpha_pixel_ && !alpha) { |
| seen_zero_alpha_pixel_ = true; |
| alpha = 255; |
| } else { |
| seen_non_zero_alpha_pixel_ = true; |
| if (seen_zero_alpha_pixel_) { |
| buffer_->ZeroFillPixelData(); |
| seen_zero_alpha_pixel_ = false; |
| } else if (alpha != 255) |
| buffer_->SetHasAlpha(true); |
| } |
| |
| SetRGBA(GetComponent(pixel, 0), GetComponent(pixel, 1), |
| GetComponent(pixel, 2), alpha); |
| } |
| } |
| |
| // Success, keep going. |
| decoded_offset_ += (padded_num_bytes - unpadded_num_bytes); |
| if (in_rle) |
| return kSuccess; |
| MoveBufferToNextRow(); |
| } |
| |
| // Finished decoding whole image. |
| return kSuccess; |
| } |
| |
| void BMPImageReader::MoveBufferToNextRow() { |
| coord_.Move(-coord_.X(), is_top_down_ ? 1 : -1); |
| } |
| |
| } // namespace blink |
