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Diffstat (limited to 'media/libwebp/utils/rescaler_utils.h')
| -rw-r--r-- | media/libwebp/utils/rescaler_utils.h | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/media/libwebp/utils/rescaler_utils.h b/media/libwebp/utils/rescaler_utils.h new file mode 100644 index 000000000..98b01a76d --- /dev/null +++ b/media/libwebp/utils/rescaler_utils.h @@ -0,0 +1,101 @@ +// Copyright 2012 Google Inc. All Rights Reserved. +// +// Use of this source code is governed by a BSD-style license +// that can be found in the COPYING file in the root of the source +// tree. An additional intellectual property rights grant can be found +// in the file PATENTS. All contributing project authors may +// be found in the AUTHORS file in the root of the source tree. +// ----------------------------------------------------------------------------- +// +// Rescaling functions +// +// Author: Skal (pascal.massimino@gmail.com) + +#ifndef WEBP_UTILS_RESCALER_H_ +#define WEBP_UTILS_RESCALER_H_ + +#ifdef __cplusplus +extern "C" { +#endif + +#include "../webp/types.h" + +#define WEBP_RESCALER_RFIX 32 // fixed-point precision for multiplies +#define WEBP_RESCALER_ONE (1ull << WEBP_RESCALER_RFIX) +#define WEBP_RESCALER_FRAC(x, y) \ + ((uint32_t)(((uint64_t)(x) << WEBP_RESCALER_RFIX) / (y))) + +// Structure used for on-the-fly rescaling +typedef uint32_t rescaler_t; // type for side-buffer +typedef struct WebPRescaler WebPRescaler; +struct WebPRescaler { + int x_expand; // true if we're expanding in the x direction + int y_expand; // true if we're expanding in the y direction + int num_channels; // bytes to jump between pixels + uint32_t fx_scale; // fixed-point scaling factors + uint32_t fy_scale; // '' + uint32_t fxy_scale; // '' + int y_accum; // vertical accumulator + int y_add, y_sub; // vertical increments + int x_add, x_sub; // horizontal increments + int src_width, src_height; // source dimensions + int dst_width, dst_height; // destination dimensions + int src_y, dst_y; // row counters for input and output + uint8_t* dst; + int dst_stride; + rescaler_t* irow, *frow; // work buffer +}; + +// Initialize a rescaler given scratch area 'work' and dimensions of src & dst. +void WebPRescalerInit(WebPRescaler* const rescaler, + int src_width, int src_height, + uint8_t* const dst, + int dst_width, int dst_height, int dst_stride, + int num_channels, + rescaler_t* const work); + +// If either 'scaled_width' or 'scaled_height' (but not both) is 0 the value +// will be calculated preserving the aspect ratio, otherwise the values are +// left unmodified. Returns true on success, false if either value is 0 after +// performing the scaling calculation. +int WebPRescalerGetScaledDimensions(int src_width, int src_height, + int* const scaled_width, + int* const scaled_height); + +// Returns the number of input lines needed next to produce one output line, +// considering that the maximum available input lines are 'max_num_lines'. +int WebPRescaleNeededLines(const WebPRescaler* const rescaler, + int max_num_lines); + +// Import multiple rows over all channels, until at least one row is ready to +// be exported. Returns the actual number of lines that were imported. +int WebPRescalerImport(WebPRescaler* const rescaler, int num_rows, + const uint8_t* src, int src_stride); + +// Export as many rows as possible. Return the numbers of rows written. +int WebPRescalerExport(WebPRescaler* const rescaler); + +// Return true if input is finished +static WEBP_INLINE +int WebPRescalerInputDone(const WebPRescaler* const rescaler) { + return (rescaler->src_y >= rescaler->src_height); +} +// Return true if output is finished +static WEBP_INLINE +int WebPRescalerOutputDone(const WebPRescaler* const rescaler) { + return (rescaler->dst_y >= rescaler->dst_height); +} + +// Return true if there are pending output rows ready. +static WEBP_INLINE +int WebPRescalerHasPendingOutput(const WebPRescaler* const rescaler) { + return !WebPRescalerOutputDone(rescaler) && (rescaler->y_accum <= 0); +} + +//------------------------------------------------------------------------------ + +#ifdef __cplusplus +} // extern "C" +#endif + +#endif /* WEBP_UTILS_RESCALER_H_ */ |