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+// 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 <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include "src/dsp/dsp.h"
+#include "src/utils/rescaler_utils.h"
+#include "src/utils/utils.h"
+
+//------------------------------------------------------------------------------
+
+int 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) {
+ const int x_add = src_width, x_sub = dst_width;
+ const int y_add = src_height, y_sub = dst_height;
+ const uint64_t total_size = 2ull * dst_width * num_channels * sizeof(*work);
+ if (!CheckSizeOverflow(total_size)) return 0;
+
+ rescaler->x_expand = (src_width < dst_width);
+ rescaler->y_expand = (src_height < dst_height);
+ rescaler->src_width = src_width;
+ rescaler->src_height = src_height;
+ rescaler->dst_width = dst_width;
+ rescaler->dst_height = dst_height;
+ rescaler->src_y = 0;
+ rescaler->dst_y = 0;
+ rescaler->dst = dst;
+ rescaler->dst_stride = dst_stride;
+ rescaler->num_channels = num_channels;
+
+ // for 'x_expand', we use bilinear interpolation
+ rescaler->x_add = rescaler->x_expand ? (x_sub - 1) : x_add;
+ rescaler->x_sub = rescaler->x_expand ? (x_add - 1) : x_sub;
+ if (!rescaler->x_expand) { // fx_scale is not used otherwise
+ rescaler->fx_scale = WEBP_RESCALER_FRAC(1, rescaler->x_sub);
+ }
+ // vertical scaling parameters
+ rescaler->y_add = rescaler->y_expand ? y_add - 1 : y_add;
+ rescaler->y_sub = rescaler->y_expand ? y_sub - 1 : y_sub;
+ rescaler->y_accum = rescaler->y_expand ? rescaler->y_sub : rescaler->y_add;
+ if (!rescaler->y_expand) {
+ // This is WEBP_RESCALER_FRAC(dst_height, x_add * y_add) without the cast.
+ // Its value is <= WEBP_RESCALER_ONE, because dst_height <= rescaler->y_add
+ // and rescaler->x_add >= 1;
+ const uint64_t num = (uint64_t)dst_height * WEBP_RESCALER_ONE;
+ const uint64_t den = (uint64_t)rescaler->x_add * rescaler->y_add;
+ const uint64_t ratio = num / den;
+ if (ratio != (uint32_t)ratio) {
+ // When ratio == WEBP_RESCALER_ONE, we can't represent the ratio with the
+ // current fixed-point precision. This happens when src_height ==
+ // rescaler->y_add (which == src_height), and rescaler->x_add == 1.
+ // => We special-case fxy_scale = 0, in WebPRescalerExportRow().
+ rescaler->fxy_scale = 0;
+ } else {
+ rescaler->fxy_scale = (uint32_t)ratio;
+ }
+ rescaler->fy_scale = WEBP_RESCALER_FRAC(1, rescaler->y_sub);
+ } else {
+ rescaler->fy_scale = WEBP_RESCALER_FRAC(1, rescaler->x_add);
+ // rescaler->fxy_scale is unused here.
+ }
+ rescaler->irow = work;
+ rescaler->frow = work + num_channels * dst_width;
+ memset(work, 0, (size_t)total_size);
+
+ WebPRescalerDspInit();
+ return 1;
+}
+
+int WebPRescalerGetScaledDimensions(int src_width, int src_height,
+ int* const scaled_width,
+ int* const scaled_height) {
+ assert(scaled_width != NULL);
+ assert(scaled_height != NULL);
+ {
+ int width = *scaled_width;
+ int height = *scaled_height;
+ const int max_size = INT_MAX / 2;
+
+ // if width is unspecified, scale original proportionally to height ratio.
+ if (width == 0 && src_height > 0) {
+ width =
+ (int)(((uint64_t)src_width * height + src_height - 1) / src_height);
+ }
+ // if height is unspecified, scale original proportionally to width ratio.
+ if (height == 0 && src_width > 0) {
+ height =
+ (int)(((uint64_t)src_height * width + src_width - 1) / src_width);
+ }
+ // Check if the overall dimensions still make sense.
+ if (width <= 0 || height <= 0 || width > max_size || height > max_size) {
+ return 0;
+ }
+
+ *scaled_width = width;
+ *scaled_height = height;
+ return 1;
+ }
+}
+
+//------------------------------------------------------------------------------
+// all-in-one calls
+
+int WebPRescaleNeededLines(const WebPRescaler* const rescaler,
+ int max_num_lines) {
+ const int num_lines =
+ (rescaler->y_accum + rescaler->y_sub - 1) / rescaler->y_sub;
+ return (num_lines > max_num_lines) ? max_num_lines : num_lines;
+}
+
+int WebPRescalerImport(WebPRescaler* const rescaler, int num_lines,
+ const uint8_t* src, int src_stride) {
+ int total_imported = 0;
+ while (total_imported < num_lines &&
+ !WebPRescalerHasPendingOutput(rescaler)) {
+ if (rescaler->y_expand) {
+ rescaler_t* const tmp = rescaler->irow;
+ rescaler->irow = rescaler->frow;
+ rescaler->frow = tmp;
+ }
+ WebPRescalerImportRow(rescaler, src);
+ if (!rescaler->y_expand) { // Accumulate the contribution of the new row.
+ int x;
+ for (x = 0; x < rescaler->num_channels * rescaler->dst_width; ++x) {
+ rescaler->irow[x] += rescaler->frow[x];
+ }
+ }
+ ++rescaler->src_y;
+ src += src_stride;
+ ++total_imported;
+ rescaler->y_accum -= rescaler->y_sub;
+ }
+ return total_imported;
+}
+
+int WebPRescalerExport(WebPRescaler* const rescaler) {
+ int total_exported = 0;
+ while (WebPRescalerHasPendingOutput(rescaler)) {
+ WebPRescalerExportRow(rescaler);
+ ++total_exported;
+ }
+ return total_exported;
+}
+
+//------------------------------------------------------------------------------