1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
//
// Copyright 2022 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// loadimage_paletted.cpp: Decodes GL_PALETTE_* textures.
#include "image_util/loadimage.h"
#include <type_traits>
#include "common/mathutil.h"
#include "image_util/imageformats.h"
namespace angle
{
namespace
{
template <typename T>
R8G8B8A8 ReadColor(const T *src)
{
gl::ColorF tmp;
T::readColor(&tmp, src);
R8G8B8A8 rgba;
R8G8B8A8::writeColor(&rgba, &tmp);
return rgba;
}
size_t DecodeIndexIntoPalette(const uint8_t *row, size_t i, uint32_t indexBits)
{
switch (indexBits)
{
case 4:
{
// From OES_compressed_paletted_texture, section Additions to
// Chapter 3 of the OpenGL 1.3 Specification (Rasterization):
//
// Texel Data Formats for compressed paletted textures
//
// PALETTE4_xxx:
//
// 7 6 5 4 3 2 1 0
// ---------------
// | 1st | 2nd |
// | texel | texel |
// ---------------
bool even = i % 2 == 0;
return (row[i / 2] >> (even ? 4 : 0)) & 0x0f;
}
case 8:
return row[i];
default:
UNREACHABLE();
return 0;
}
}
R8G8B8A8 DecodeColor(const uint8_t *src,
uint32_t redBlueBits,
uint32_t greenBits,
uint32_t alphaBits)
{
switch (redBlueBits)
{
case 8:
ASSERT(greenBits == 8);
switch (alphaBits)
{
case 0:
return ReadColor<>(reinterpret_cast<const R8G8B8 *>(src));
case 8:
return ReadColor<>(reinterpret_cast<const R8G8B8A8 *>(src));
default:
UNREACHABLE();
break;
}
break;
case 5:
switch (greenBits)
{
case 6:
ASSERT(alphaBits == 0);
return ReadColor<>(reinterpret_cast<const R5G6B5 *>(src));
case 5:
ASSERT(alphaBits == 1);
return ReadColor<>(reinterpret_cast<const R5G5B5A1 *>(src));
default:
UNREACHABLE();
break;
}
break;
case 4:
ASSERT(greenBits == 4 && alphaBits == 4);
return ReadColor<>(reinterpret_cast<const R4G4B4A4 *>(src));
default:
UNREACHABLE();
break;
}
UNREACHABLE();
return R8G8B8A8{0, 0, 0, 255};
}
} // namespace
// See LoadPalettedToRGBA8.
void LoadPalettedToRGBA8Impl(size_t width,
size_t height,
size_t depth,
uint32_t indexBits,
uint32_t redBlueBits,
uint32_t greenBits,
uint32_t alphaBits,
const uint8_t *input,
size_t inputRowPitch,
size_t inputDepthPitch,
uint8_t *output,
size_t outputRowPitch,
size_t outputDepthPitch)
{
size_t colorBytes = (redBlueBits + greenBits + redBlueBits + alphaBits) / 8;
size_t paletteSize = 1 << indexBits;
size_t paletteBytes = paletteSize * colorBytes;
const uint8_t *palette = input;
const uint8_t *texels = input + paletteBytes; // + TODO(http://anglebug.com/7688): mip levels
for (size_t z = 0; z < depth; z++)
{
for (size_t y = 0; y < height; y++)
{
const uint8_t *srcRow =
priv::OffsetDataPointer<uint8_t>(texels, y, z, inputRowPitch, inputDepthPitch);
R8G8B8A8 *dstRow =
priv::OffsetDataPointer<R8G8B8A8>(output, y, z, outputRowPitch, outputDepthPitch);
for (size_t x = 0; x < width; x++)
{
size_t indexIntoPalette = DecodeIndexIntoPalette(srcRow, x, indexBits);
dstRow[x] = DecodeColor(palette + indexIntoPalette * colorBytes, redBlueBits,
greenBits, alphaBits);
}
}
}
}
} // namespace angle
|
