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46 lines
1.4 KiB
C
46 lines
1.4 KiB
C
// Copyright 2011 Google Inc. All Rights Reserved.
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//
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// This code is licensed under the same terms as WebM:
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// Software License Agreement: http://www.webmproject.org/license/software/
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// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
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// -----------------------------------------------------------------------------
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//
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// Alpha-plane decompression.
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#include <stdlib.h>
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#include "./vp8i.h"
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#include "../utils/alpha.h"
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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//------------------------------------------------------------------------------
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const uint8_t* VP8DecompressAlphaRows(VP8Decoder* const dec,
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int row, int num_rows) {
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const int stride = dec->pic_hdr_.width_;
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if (row < 0 || num_rows < 0 || row + num_rows > dec->pic_hdr_.height_) {
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return NULL; // sanity check.
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}
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if (row == 0) {
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// Decode everything during the first call.
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if (!DecodeAlpha(dec->alpha_data_, (size_t)dec->alpha_data_size_,
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dec->pic_hdr_.width_, dec->pic_hdr_.height_, stride,
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dec->alpha_plane_)) {
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return NULL; // Error.
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}
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}
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// Return a pointer to the current decoded row.
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return dec->alpha_plane_ + row * stride;
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}
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#if defined(__cplusplus) || defined(c_plusplus)
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} // extern "C"
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#endif
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