reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame^] | 1 | /** |
| 2 | ** Copyright 2006, The Android Open Source Project |
| 3 | ** |
| 4 | ** Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | ** you may not use this file except in compliance with the License. |
| 6 | ** You may obtain a copy of the License at |
| 7 | ** |
| 8 | ** http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | ** |
| 10 | ** Unless required by applicable law or agreed to in writing, software |
| 11 | ** distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | ** See the License for the specific language governing permissions and |
| 14 | ** limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #include "SkImageDecoder.h" |
| 18 | #include "SkColor.h" |
| 19 | #include "SkColorPriv.h" |
| 20 | #include "SkMath.h" |
| 21 | #include "SkStream.h" |
| 22 | #include "SkTemplates.h" |
| 23 | #include "SkUtils.h" |
| 24 | |
| 25 | class SkWBMPImageDecoder : public SkImageDecoder { |
| 26 | public: |
| 27 | virtual Format getFormat() const { |
| 28 | return kWBMP_Format; |
| 29 | } |
| 30 | |
| 31 | protected: |
| 32 | virtual bool onDecode(SkStream* stream, SkBitmap* bm, |
| 33 | SkBitmap::Config pref, Mode); |
| 34 | }; |
| 35 | |
| 36 | static bool read_byte(SkStream* stream, uint8_t* data) |
| 37 | { |
| 38 | return stream->read(data, 1) == 1; |
| 39 | } |
| 40 | |
| 41 | static bool read_mbf(SkStream* stream, int* value) |
| 42 | { |
| 43 | int n = 0; |
| 44 | uint8_t data; |
| 45 | do { |
| 46 | if (!read_byte(stream, &data)) { |
| 47 | return false; |
| 48 | } |
| 49 | n = (n << 7) | (data & 0x7F); |
| 50 | } while (data & 0x80); |
| 51 | |
| 52 | *value = n; |
| 53 | return true; |
| 54 | } |
| 55 | |
| 56 | struct wbmp_head { |
| 57 | int fWidth; |
| 58 | int fHeight; |
| 59 | |
| 60 | bool init(SkStream* stream) |
| 61 | { |
| 62 | uint8_t data; |
| 63 | |
| 64 | if (!read_byte(stream, &data) || data != 0) { // unknown type |
| 65 | return false; |
| 66 | } |
| 67 | if (!read_byte(stream, &data) || (data & 0x9F)) { // skip fixed header |
| 68 | return false; |
| 69 | } |
| 70 | if (!read_mbf(stream, &fWidth) || (unsigned)fWidth > 0xFFFF) { |
| 71 | return false; |
| 72 | } |
| 73 | if (!read_mbf(stream, &fHeight) || (unsigned)fHeight > 0xFFFF) { |
| 74 | return false; |
| 75 | } |
| 76 | return fWidth != 0 && fHeight != 0; |
| 77 | } |
| 78 | }; |
| 79 | |
| 80 | SkImageDecoder* SkImageDecoder_WBMP_Factory(SkStream* stream) |
| 81 | { |
| 82 | wbmp_head head; |
| 83 | |
| 84 | if (head.init(stream)) { |
| 85 | return SkNEW(SkWBMPImageDecoder); |
| 86 | } |
| 87 | return NULL; |
| 88 | } |
| 89 | |
| 90 | static void expand_bits_to_bytes(uint8_t dst[], const uint8_t src[], int bits) |
| 91 | { |
| 92 | int bytes = bits >> 3; |
| 93 | |
| 94 | for (int i = 0; i < bytes; i++) { |
| 95 | unsigned mask = *src++; |
| 96 | dst[0] = (mask >> 7) & 1; |
| 97 | dst[1] = (mask >> 6) & 1; |
| 98 | dst[2] = (mask >> 5) & 1; |
| 99 | dst[3] = (mask >> 4) & 1; |
| 100 | dst[4] = (mask >> 3) & 1; |
| 101 | dst[5] = (mask >> 2) & 1; |
| 102 | dst[6] = (mask >> 1) & 1; |
| 103 | dst[7] = (mask >> 0) & 1; |
| 104 | dst += 8; |
| 105 | } |
| 106 | |
| 107 | bits &= 7; |
| 108 | if (bits > 0) { |
| 109 | unsigned mask = *src; |
| 110 | do { |
| 111 | *dst++ = (mask >> 7) & 1;; |
| 112 | mask <<= 1; |
| 113 | } while (--bits != 0); |
| 114 | } |
| 115 | } |
| 116 | |
| 117 | #define SkAlign8(x) (((x) + 7) & ~7) |
| 118 | |
| 119 | bool SkWBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* decodedBitmap, |
| 120 | SkBitmap::Config prefConfig, Mode mode) |
| 121 | { |
| 122 | wbmp_head head; |
| 123 | |
| 124 | if (!head.init(stream)) { |
| 125 | return false; |
| 126 | } |
| 127 | |
| 128 | int width = head.fWidth; |
| 129 | int height = head.fHeight; |
| 130 | |
| 131 | // assign these directly, in case we return kDimensions_Result |
| 132 | decodedBitmap->setConfig(SkBitmap::kIndex8_Config, width, height); |
| 133 | decodedBitmap->setIsOpaque(true); |
| 134 | |
| 135 | if (SkImageDecoder::kDecodeBounds_Mode == mode) |
| 136 | return true; |
| 137 | |
| 138 | const SkPMColor colors[] = { SK_ColorBLACK, SK_ColorWHITE }; |
| 139 | SkColorTable* ct = SkNEW_ARGS(SkColorTable, (colors, 2)); |
| 140 | SkAutoUnref aur(ct); |
| 141 | |
| 142 | if (!this->allocPixelRef(decodedBitmap, ct)) { |
| 143 | return false; |
| 144 | } |
| 145 | |
| 146 | SkAutoLockPixels alp(*decodedBitmap); |
| 147 | |
| 148 | uint8_t* dst = decodedBitmap->getAddr8(0, 0); |
| 149 | // store the 1-bit valuess at the end of our pixels, so we won't stomp |
| 150 | // on them before we're read them. Just trying to avoid a temp allocation |
| 151 | size_t srcRB = SkAlign8(width) >> 3; |
| 152 | size_t srcSize = height * srcRB; |
| 153 | uint8_t* src = dst + decodedBitmap->getSize() - srcSize; |
| 154 | if (stream->read(src, srcSize) != srcSize) { |
| 155 | return false; |
| 156 | } |
| 157 | |
| 158 | for (int y = 0; y < height; y++) |
| 159 | { |
| 160 | expand_bits_to_bytes(dst, src, width); |
| 161 | dst += decodedBitmap->rowBytes(); |
| 162 | src += srcRB; |
| 163 | } |
| 164 | |
| 165 | return true; |
| 166 | } |
| 167 | |