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Diffstat (limited to 'src/3rdparty/libwebp/src/utils/rescaler.c')
| -rw-r--r-- | src/3rdparty/libwebp/src/utils/rescaler.c | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/src/3rdparty/libwebp/src/utils/rescaler.c b/src/3rdparty/libwebp/src/utils/rescaler.c new file mode 100644 index 0000000..7061246 --- /dev/null +++ b/src/3rdparty/libwebp/src/utils/rescaler.c @@ -0,0 +1,152 @@ +// 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) + +#include <assert.h> +#include <stdlib.h> +#include "./rescaler.h" + +//------------------------------------------------------------------------------ + +#define RFIX 30 +#define MULT_FIX(x, y) (((int64_t)(x) * (y) + (1 << (RFIX - 1))) >> RFIX) + +void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height, + uint8_t* const dst, int dst_width, int dst_height, + int dst_stride, int num_channels, int x_add, int x_sub, + int y_add, int y_sub, int32_t* const work) { + wrk->x_expand = (src_width < dst_width); + wrk->src_width = src_width; + wrk->src_height = src_height; + wrk->dst_width = dst_width; + wrk->dst_height = dst_height; + wrk->dst = dst; + wrk->dst_stride = dst_stride; + wrk->num_channels = num_channels; + // for 'x_expand', we use bilinear interpolation + wrk->x_add = wrk->x_expand ? (x_sub - 1) : x_add - x_sub; + wrk->x_sub = wrk->x_expand ? (x_add - 1) : x_sub; + wrk->y_accum = y_add; + wrk->y_add = y_add; + wrk->y_sub = y_sub; + wrk->fx_scale = (1 << RFIX) / x_sub; + wrk->fy_scale = (1 << RFIX) / y_sub; + wrk->fxy_scale = wrk->x_expand ? + ((int64_t)dst_height << RFIX) / (x_sub * src_height) : + ((int64_t)dst_height << RFIX) / (x_add * src_height); + wrk->irow = work; + wrk->frow = work + num_channels * dst_width; +} + +void WebPRescalerImportRow(WebPRescaler* const wrk, + const uint8_t* const src, int channel) { + const int x_stride = wrk->num_channels; + const int x_out_max = wrk->dst_width * wrk->num_channels; + int x_in = channel; + int x_out; + int accum = 0; + if (!wrk->x_expand) { + int sum = 0; + for (x_out = channel; x_out < x_out_max; x_out += x_stride) { + accum += wrk->x_add; + for (; accum > 0; accum -= wrk->x_sub) { + sum += src[x_in]; + x_in += x_stride; + } + { // Emit next horizontal pixel. + const int32_t base = src[x_in]; + const int32_t frac = base * (-accum); + x_in += x_stride; + wrk->frow[x_out] = (sum + base) * wrk->x_sub - frac; + // fresh fractional start for next pixel + sum = (int)MULT_FIX(frac, wrk->fx_scale); + } + } + } else { // simple bilinear interpolation + int left = src[channel], right = src[channel]; + for (x_out = channel; x_out < x_out_max; x_out += x_stride) { + if (accum < 0) { + left = right; + x_in += x_stride; + right = src[x_in]; + accum += wrk->x_add; + } + wrk->frow[x_out] = right * wrk->x_add + (left - right) * accum; + accum -= wrk->x_sub; + } + } + // Accumulate the new row's contribution + for (x_out = channel; x_out < x_out_max; x_out += x_stride) { + wrk->irow[x_out] += wrk->frow[x_out]; + } +} + +uint8_t* WebPRescalerExportRow(WebPRescaler* const wrk) { + if (wrk->y_accum <= 0) { + int x_out; + uint8_t* const dst = wrk->dst; + int32_t* const irow = wrk->irow; + const int32_t* const frow = wrk->frow; + const int yscale = wrk->fy_scale * (-wrk->y_accum); + const int x_out_max = wrk->dst_width * wrk->num_channels; + + for (x_out = 0; x_out < x_out_max; ++x_out) { + const int frac = (int)MULT_FIX(frow[x_out], yscale); + const int v = (int)MULT_FIX(irow[x_out] - frac, wrk->fxy_scale); + dst[x_out] = (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255; + irow[x_out] = frac; // new fractional start + } + wrk->y_accum += wrk->y_add; + wrk->dst += wrk->dst_stride; + return dst; + } else { + return NULL; + } +} + +#undef MULT_FIX +#undef RFIX + +//------------------------------------------------------------------------------ +// all-in-one calls + +int WebPRescaleNeededLines(const WebPRescaler* const wrk, int max_num_lines) { + const int num_lines = (wrk->y_accum + wrk->y_sub - 1) / wrk->y_sub; + return (num_lines > max_num_lines) ? max_num_lines : num_lines; +} + +int WebPRescalerImport(WebPRescaler* const wrk, int num_lines, + const uint8_t* src, int src_stride) { + int total_imported = 0; + while (total_imported < num_lines && wrk->y_accum > 0) { + int channel; + for (channel = 0; channel < wrk->num_channels; ++channel) { + WebPRescalerImportRow(wrk, src, channel); + } + src += src_stride; + ++total_imported; + wrk->y_accum -= wrk->y_sub; + } + return total_imported; +} + +int WebPRescalerExport(WebPRescaler* const rescaler) { + int total_exported = 0; + while (WebPRescalerHasPendingOutput(rescaler)) { + WebPRescalerExportRow(rescaler); + ++total_exported; + } + return total_exported; +} + +//------------------------------------------------------------------------------ + |