1 | // Copyright 2012 Google Inc. All Rights Reserved. |
2 | // |
3 | // Use of this source code is governed by a BSD-style license |
4 | // that can be found in the COPYING file in the root of the source |
5 | // tree. An additional intellectual property rights grant can be found |
6 | // in the file PATENTS. All contributing project authors may |
7 | // be found in the AUTHORS file in the root of the source tree. |
8 | // ----------------------------------------------------------------------------- |
9 | // |
10 | // Rescaling functions |
11 | // |
12 | // Author: Skal (pascal.massimino@gmail.com) |
13 | |
14 | #include <assert.h> |
15 | #include <stdlib.h> |
16 | #include <string.h> |
17 | #include "src/dsp/dsp.h" |
18 | #include "src/utils/rescaler_utils.h" |
19 | |
20 | //------------------------------------------------------------------------------ |
21 | |
22 | void WebPRescalerInit(WebPRescaler* const wrk, int src_width, int src_height, |
23 | uint8_t* const dst, |
24 | int dst_width, int dst_height, int dst_stride, |
25 | int num_channels, rescaler_t* const work) { |
26 | const int x_add = src_width, x_sub = dst_width; |
27 | const int y_add = src_height, y_sub = dst_height; |
28 | wrk->x_expand = (src_width < dst_width); |
29 | wrk->y_expand = (src_height < dst_height); |
30 | wrk->src_width = src_width; |
31 | wrk->src_height = src_height; |
32 | wrk->dst_width = dst_width; |
33 | wrk->dst_height = dst_height; |
34 | wrk->src_y = 0; |
35 | wrk->dst_y = 0; |
36 | wrk->dst = dst; |
37 | wrk->dst_stride = dst_stride; |
38 | wrk->num_channels = num_channels; |
39 | |
40 | // for 'x_expand', we use bilinear interpolation |
41 | wrk->x_add = wrk->x_expand ? (x_sub - 1) : x_add; |
42 | wrk->x_sub = wrk->x_expand ? (x_add - 1) : x_sub; |
43 | if (!wrk->x_expand) { // fx_scale is not used otherwise |
44 | wrk->fx_scale = WEBP_RESCALER_FRAC(1, wrk->x_sub); |
45 | } |
46 | // vertical scaling parameters |
47 | wrk->y_add = wrk->y_expand ? y_add - 1 : y_add; |
48 | wrk->y_sub = wrk->y_expand ? y_sub - 1 : y_sub; |
49 | wrk->y_accum = wrk->y_expand ? wrk->y_sub : wrk->y_add; |
50 | if (!wrk->y_expand) { |
51 | // This is WEBP_RESCALER_FRAC(dst_height, x_add * y_add) without the cast. |
52 | // Its value is <= WEBP_RESCALER_ONE, because dst_height <= wrk->y_add, and |
53 | // wrk->x_add >= 1; |
54 | const uint64_t ratio = |
55 | (uint64_t)dst_height * WEBP_RESCALER_ONE / (wrk->x_add * wrk->y_add); |
56 | if (ratio != (uint32_t)ratio) { |
57 | // When ratio == WEBP_RESCALER_ONE, we can't represent the ratio with the |
58 | // current fixed-point precision. This happens when src_height == |
59 | // wrk->y_add (which == src_height), and wrk->x_add == 1. |
60 | // => We special-case fxy_scale = 0, in WebPRescalerExportRow(). |
61 | wrk->fxy_scale = 0; |
62 | } else { |
63 | wrk->fxy_scale = (uint32_t)ratio; |
64 | } |
65 | wrk->fy_scale = WEBP_RESCALER_FRAC(1, wrk->y_sub); |
66 | } else { |
67 | wrk->fy_scale = WEBP_RESCALER_FRAC(1, wrk->x_add); |
68 | // wrk->fxy_scale is unused here. |
69 | } |
70 | wrk->irow = work; |
71 | wrk->frow = work + num_channels * dst_width; |
72 | memset(work, 0, 2 * dst_width * num_channels * sizeof(*work)); |
73 | |
74 | WebPRescalerDspInit(); |
75 | } |
76 | |
77 | int WebPRescalerGetScaledDimensions(int src_width, int src_height, |
78 | int* const scaled_width, |
79 | int* const scaled_height) { |
80 | assert(scaled_width != NULL); |
81 | assert(scaled_height != NULL); |
82 | { |
83 | int width = *scaled_width; |
84 | int height = *scaled_height; |
85 | |
86 | // if width is unspecified, scale original proportionally to height ratio. |
87 | if (width == 0 && src_height > 0) { |
88 | width = |
89 | (int)(((uint64_t)src_width * height + src_height - 1) / src_height); |
90 | } |
91 | // if height is unspecified, scale original proportionally to width ratio. |
92 | if (height == 0 && src_width > 0) { |
93 | height = |
94 | (int)(((uint64_t)src_height * width + src_width - 1) / src_width); |
95 | } |
96 | // Check if the overall dimensions still make sense. |
97 | if (width <= 0 || height <= 0) { |
98 | return 0; |
99 | } |
100 | |
101 | *scaled_width = width; |
102 | *scaled_height = height; |
103 | return 1; |
104 | } |
105 | } |
106 | |
107 | //------------------------------------------------------------------------------ |
108 | // all-in-one calls |
109 | |
110 | int WebPRescaleNeededLines(const WebPRescaler* const wrk, int max_num_lines) { |
111 | const int num_lines = (wrk->y_accum + wrk->y_sub - 1) / wrk->y_sub; |
112 | return (num_lines > max_num_lines) ? max_num_lines : num_lines; |
113 | } |
114 | |
115 | int WebPRescalerImport(WebPRescaler* const wrk, int num_lines, |
116 | const uint8_t* src, int src_stride) { |
117 | int total_imported = 0; |
118 | while (total_imported < num_lines && !WebPRescalerHasPendingOutput(wrk)) { |
119 | if (wrk->y_expand) { |
120 | rescaler_t* const tmp = wrk->irow; |
121 | wrk->irow = wrk->frow; |
122 | wrk->frow = tmp; |
123 | } |
124 | WebPRescalerImportRow(wrk, src); |
125 | if (!wrk->y_expand) { // Accumulate the contribution of the new row. |
126 | int x; |
127 | for (x = 0; x < wrk->num_channels * wrk->dst_width; ++x) { |
128 | wrk->irow[x] += wrk->frow[x]; |
129 | } |
130 | } |
131 | ++wrk->src_y; |
132 | src += src_stride; |
133 | ++total_imported; |
134 | wrk->y_accum -= wrk->y_sub; |
135 | } |
136 | return total_imported; |
137 | } |
138 | |
139 | int WebPRescalerExport(WebPRescaler* const rescaler) { |
140 | int total_exported = 0; |
141 | while (WebPRescalerHasPendingOutput(rescaler)) { |
142 | WebPRescalerExportRow(rescaler); |
143 | ++total_exported; |
144 | } |
145 | return total_exported; |
146 | } |
147 | |
148 | //------------------------------------------------------------------------------ |
149 | |