55414bc573
Note that there are two Godot-specific changes made to libwebp
for the javascript/HTML5 platform. They are documented in the
README.md.
(cherry picked from commit ee3cf211c6)
102 lines
4.0 KiB
C++
102 lines
4.0 KiB
C++
// Copyright 2012 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// Rescaling functions
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//
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// Author: Skal (pascal.massimino@gmail.com)
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#ifndef WEBP_UTILS_RESCALER_H_
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#define WEBP_UTILS_RESCALER_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "../webp/types.h"
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#define WEBP_RESCALER_RFIX 32 // fixed-point precision for multiplies
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#define WEBP_RESCALER_ONE (1ull << WEBP_RESCALER_RFIX)
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#define WEBP_RESCALER_FRAC(x, y) \
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((uint32_t)(((uint64_t)(x) << WEBP_RESCALER_RFIX) / (y)))
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// Structure used for on-the-fly rescaling
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typedef uint32_t rescaler_t; // type for side-buffer
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typedef struct WebPRescaler WebPRescaler;
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struct WebPRescaler {
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int x_expand; // true if we're expanding in the x direction
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int y_expand; // true if we're expanding in the y direction
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int num_channels; // bytes to jump between pixels
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uint32_t fx_scale; // fixed-point scaling factors
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uint32_t fy_scale; // ''
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uint32_t fxy_scale; // ''
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int y_accum; // vertical accumulator
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int y_add, y_sub; // vertical increments
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int x_add, x_sub; // horizontal increments
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int src_width, src_height; // source dimensions
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int dst_width, dst_height; // destination dimensions
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int src_y, dst_y; // row counters for input and output
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uint8_t* dst;
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int dst_stride;
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rescaler_t* irow, *frow; // work buffer
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};
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// Initialize a rescaler given scratch area 'work' and dimensions of src & dst.
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void WebPRescalerInit(WebPRescaler* const rescaler,
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int src_width, int src_height,
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uint8_t* const dst,
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int dst_width, int dst_height, int dst_stride,
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int num_channels,
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rescaler_t* const work);
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// If either 'scaled_width' or 'scaled_height' (but not both) is 0 the value
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// will be calculated preserving the aspect ratio, otherwise the values are
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// left unmodified. Returns true on success, false if either value is 0 after
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// performing the scaling calculation.
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int WebPRescalerGetScaledDimensions(int src_width, int src_height,
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int* const scaled_width,
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int* const scaled_height);
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// Returns the number of input lines needed next to produce one output line,
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// considering that the maximum available input lines are 'max_num_lines'.
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int WebPRescaleNeededLines(const WebPRescaler* const rescaler,
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int max_num_lines);
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// Import multiple rows over all channels, until at least one row is ready to
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// be exported. Returns the actual number of lines that were imported.
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int WebPRescalerImport(WebPRescaler* const rescaler, int num_rows,
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const uint8_t* src, int src_stride);
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// Export as many rows as possible. Return the numbers of rows written.
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int WebPRescalerExport(WebPRescaler* const rescaler);
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// Return true if input is finished
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static WEBP_INLINE
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int WebPRescalerInputDone(const WebPRescaler* const rescaler) {
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return (rescaler->src_y >= rescaler->src_height);
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}
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// Return true if output is finished
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static WEBP_INLINE
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int WebPRescalerOutputDone(const WebPRescaler* const rescaler) {
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return (rescaler->dst_y >= rescaler->dst_height);
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}
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// Return true if there are pending output rows ready.
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static WEBP_INLINE
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int WebPRescalerHasPendingOutput(const WebPRescaler* const rescaler) {
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return !WebPRescalerOutputDone(rescaler) && (rescaler->y_accum <= 0);
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}
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//------------------------------------------------------------------------------
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif /* WEBP_UTILS_RESCALER_H_ */
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