1 2 /* 3 * Copyright 2006 The Android Open Source Project 4 * 5 * Use of this source code is governed by a BSD-style license that can be 6 * found in the LICENSE file. 7 */ 8 9 10 #include "SkImageDecoder.h" 11 #include "SkColor.h" 12 #include "SkColorPriv.h" 13 #include "SkMath.h" 14 #include "SkStream.h" 15 #include "SkTemplates.h" 16 #include "SkUtils.h" 17 18 class SkWBMPImageDecoder : public SkImageDecoder { 19 public: 20 virtual Format getFormat() const SK_OVERRIDE { 21 return kWBMP_Format; 22 } 23 24 protected: 25 virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE; 26 27 private: 28 typedef SkImageDecoder INHERITED; 29 }; 30 31 static bool read_byte(SkStream* stream, uint8_t* data) 32 { 33 return stream->read(data, 1) == 1; 34 } 35 36 static bool read_mbf(SkStream* stream, int* value) 37 { 38 int n = 0; 39 uint8_t data; 40 do { 41 if (!read_byte(stream, &data)) { 42 return false; 43 } 44 n = (n << 7) | (data & 0x7F); 45 } while (data & 0x80); 46 47 *value = n; 48 return true; 49 } 50 51 struct wbmp_head { 52 int fWidth; 53 int fHeight; 54 55 bool init(SkStream* stream) 56 { 57 uint8_t data; 58 59 if (!read_byte(stream, &data) || data != 0) { // unknown type 60 return false; 61 } 62 if (!read_byte(stream, &data) || (data & 0x9F)) { // skip fixed header 63 return false; 64 } 65 if (!read_mbf(stream, &fWidth) || (unsigned)fWidth > 0xFFFF) { 66 return false; 67 } 68 if (!read_mbf(stream, &fHeight) || (unsigned)fHeight > 0xFFFF) { 69 return false; 70 } 71 return fWidth != 0 && fHeight != 0; 72 } 73 }; 74 75 static void expand_bits_to_bytes(uint8_t dst[], const uint8_t src[], int bits) 76 { 77 int bytes = bits >> 3; 78 79 for (int i = 0; i < bytes; i++) { 80 unsigned mask = *src++; 81 dst[0] = (mask >> 7) & 1; 82 dst[1] = (mask >> 6) & 1; 83 dst[2] = (mask >> 5) & 1; 84 dst[3] = (mask >> 4) & 1; 85 dst[4] = (mask >> 3) & 1; 86 dst[5] = (mask >> 2) & 1; 87 dst[6] = (mask >> 1) & 1; 88 dst[7] = (mask >> 0) & 1; 89 dst += 8; 90 } 91 92 bits &= 7; 93 if (bits > 0) { 94 unsigned mask = *src; 95 do { 96 *dst++ = (mask >> 7) & 1;; 97 mask <<= 1; 98 } while (--bits != 0); 99 } 100 } 101 102 bool SkWBMPImageDecoder::onDecode(SkStream* stream, SkBitmap* decodedBitmap, 103 Mode mode) 104 { 105 wbmp_head head; 106 107 if (!head.init(stream)) { 108 return false; 109 } 110 111 int width = head.fWidth; 112 int height = head.fHeight; 113 114 decodedBitmap->setInfo(SkImageInfo::Make(width, height, 115 kIndex_8_SkColorType, kOpaque_SkAlphaType)); 116 117 if (SkImageDecoder::kDecodeBounds_Mode == mode) { 118 return true; 119 } 120 121 const SkPMColor colors[] = { SK_ColorBLACK, SK_ColorWHITE }; 122 SkColorTable* ct = SkNEW_ARGS(SkColorTable, (colors, 2)); 123 SkAutoUnref aur(ct); 124 125 if (!this->allocPixelRef(decodedBitmap, ct)) { 126 return false; 127 } 128 129 SkAutoLockPixels alp(*decodedBitmap); 130 131 uint8_t* dst = decodedBitmap->getAddr8(0, 0); 132 // store the 1-bit valuess at the end of our pixels, so we won't stomp 133 // on them before we're read them. Just trying to avoid a temp allocation 134 size_t srcRB = SkAlign8(width) >> 3; 135 size_t srcSize = height * srcRB; 136 uint8_t* src = dst + decodedBitmap->getSize() - srcSize; 137 if (stream->read(src, srcSize) != srcSize) { 138 return false; 139 } 140 141 for (int y = 0; y < height; y++) 142 { 143 expand_bits_to_bytes(dst, src, width); 144 dst += decodedBitmap->rowBytes(); 145 src += srcRB; 146 } 147 148 return true; 149 } 150 151 /////////////////////////////////////////////////////////////////////////////// 152 DEFINE_DECODER_CREATOR(WBMPImageDecoder); 153 /////////////////////////////////////////////////////////////////////////////// 154 155 static SkImageDecoder* sk_wbmp_dfactory(SkStreamRewindable* stream) { 156 wbmp_head head; 157 158 if (head.init(stream)) { 159 return SkNEW(SkWBMPImageDecoder); 160 } 161 return NULL; 162 } 163 164 static SkImageDecoder::Format get_format_wbmp(SkStreamRewindable* stream) { 165 wbmp_head head; 166 if (head.init(stream)) { 167 return SkImageDecoder::kWBMP_Format; 168 } 169 return SkImageDecoder::kUnknown_Format; 170 } 171 172 static SkImageDecoder_DecodeReg gDReg(sk_wbmp_dfactory); 173 static SkImageDecoder_FormatReg gFormatReg(get_format_wbmp); 174