1 files changed, 376 insertions, 0 deletions
diff --git a/src/images/bmpdecoderhelper.cpp b/src/images/bmpdecoderhelper.cpp
new file mode 100644
index 0000000..acabf44
--- /dev/null
+++ b/src/images/bmpdecoderhelper.cpp
@@ -0,0 +1,376 @@
+/*
+ * Copyright 2007, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); 
+ * you may not use this file except in compliance with the License. 
+ * You may obtain a copy of the License at 
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0 
+ *
+ * Unless required by applicable law or agreed to in writing, software 
+ * distributed under the License is distributed on an "AS IS" BASIS, 
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
+ * See the License for the specific language governing permissions and 
+ * limitations under the License.
+ */
+// Author: cevans@google.com (Chris Evans)
+
+#include "bmpdecoderhelper.h"
+
+namespace image_codec {
+
+static const int kBmpHeaderSize = 14;
+static const int kBmpInfoSize = 40;
+static const int kBmpOS2InfoSize = 12;
+static const int kMaxDim = SHRT_MAX / 2;
+
+bool BmpDecoderHelper::DecodeImage(const char* p,
+                                   int len,
+                                   int max_pixels,
+                                   BmpDecoderCallback* callback) {
+  data_ = reinterpret_cast<const uint8*>(p);
+  pos_ = 0;
+  len_ = len;
+  inverted_ = true;
+  // Parse the header structure.
+  if (len < kBmpHeaderSize + 4) {
+    return false;
+  }
+  GetShort();  // Signature.
+  GetInt();  // Size.
+  GetInt();  // Reserved.
+  int offset = GetInt();
+  // Parse the info structure.
+  int infoSize = GetInt();
+  if (infoSize != kBmpOS2InfoSize && infoSize < kBmpInfoSize) {
+    return false;
+  }
+  int cols = 0;
+  int comp = 0;
+  int colLen = 4;
+  if (infoSize >= kBmpInfoSize) {
+    if (len < kBmpHeaderSize + kBmpInfoSize) {
+      return false;
+    }
+    width_ = GetInt();
+    height_ = GetInt();
+    GetShort();  // Planes.
+    bpp_ = GetShort();
+    comp = GetInt();
+    GetInt();  // Size.
+    GetInt();  // XPPM.
+    GetInt();  // YPPM.
+    cols = GetInt();
+    GetInt();  // Important colours.
+  } else {
+    if (len < kBmpHeaderSize + kBmpOS2InfoSize) {
+      return false;
+    }
+    colLen = 3;
+    width_ = GetShort();
+    height_ = GetShort();
+    GetShort();  // Planes.
+    bpp_ = GetShort();
+  }
+  if (height_ < 0) {
+    height_ = -height_;
+    inverted_ = false;
+  }
+  if (width_ <= 0 || width_ > kMaxDim || height_ <= 0 || height_ > kMaxDim) {
+    return false;
+  }
+  if (width_ * height_ > max_pixels) {
+    return false;
+  }
+  if (cols < 0 || cols > 256) {
+    return false;
+  }
+  // Allocate then read in the colour map.
+  if (cols == 0 && bpp_ <= 8) {
+    cols = 1 << bpp_;
+  }
+  if (bpp_ <= 8 || cols > 0) {
+    uint8* colBuf = new uint8[256 * 3];
+    memset(colBuf, '\0', 256 * 3);
+    colTab_.reset(colBuf);
+  }
+  if (cols > 0) {
+    if (pos_ + (cols * colLen) > len_) {
+      return false;
+    }
+    for (int i = 0; i < cols; ++i) {
+      int base = i * 3;
+      colTab_[base + 2] = GetByte();
+      colTab_[base + 1] = GetByte();
+      colTab_[base] = GetByte();
+      if (colLen == 4) {
+        GetByte();
+      }
+    }
+  }
+  // Read in the compression data if necessary.
+  redBits_ = 0x7c00;
+  greenBits_ = 0x03e0;
+  blueBits_ = 0x001f;
+  bool rle = false;
+  if (comp == 1 || comp == 2) {
+    rle = true;
+  } else if (comp == 3) {
+    if (pos_ + 12 > len_) {
+      return false;
+    }
+    redBits_ = GetInt() & 0xffff;
+    greenBits_ = GetInt() & 0xffff;
+    blueBits_ = GetInt() & 0xffff;
+  }
+  redShiftRight_ = CalcShiftRight(redBits_);
+  greenShiftRight_ = CalcShiftRight(greenBits_);
+  blueShiftRight_ = CalcShiftRight(blueBits_);
+  redShiftLeft_ = CalcShiftLeft(redBits_);
+  greenShiftLeft_ = CalcShiftLeft(greenBits_);
+  blueShiftLeft_ = CalcShiftLeft(blueBits_);
+  rowPad_ = 0;
+  pixelPad_ = 0;
+  int rowLen;
+  if (bpp_ == 32) {
+    rowLen = width_ * 4;
+    pixelPad_ = 1;
+  } else if (bpp_ == 24) {
+    rowLen = width_ * 3;
+  } else if (bpp_ == 16) {
+    rowLen = width_ * 2;
+  } else if (bpp_ == 8) {
+    rowLen = width_;
+  } else if (bpp_ == 4) {
+    rowLen = width_ / 2;
+    if (width_ & 1) {
+      rowLen++;
+    }
+  } else if (bpp_ == 1) {
+    rowLen = width_ / 8;
+    if (width_ & 7) {
+      rowLen++;
+    }
+  } else {
+    return false;
+  }
+  // Round the rowLen up to a multiple of 4.
+  if (rowLen % 4 != 0) {
+    rowPad_ = 4 - (rowLen % 4);
+    rowLen += rowPad_;
+  }
+
+  if (offset > 0 && offset > pos_ && offset < len_) {
+    pos_ = offset;
+  }
+  // Deliberately off-by-one; a load of BMPs seem to have their last byte
+  // missing.
+  if (!rle && (pos_ + (rowLen * height_) > len_ + 1)) {
+    return false;
+  }
+
+  output_ = callback->SetSize(width_, height_);
+  if (NULL == output_) {
+    return true;  // meaning we succeeded, but they want us to stop now
+  }
+
+  if (rle && (bpp_ == 4 || bpp_ == 8)) {
+    DoRLEDecode();
+  } else {
+    DoStandardDecode();
+  }
+  return true;
+}
+
+void BmpDecoderHelper::DoRLEDecode() {
+  static const uint8 RLE_ESCAPE = 0;
+  static const uint8 RLE_EOL = 0;
+  static const uint8 RLE_EOF = 1;
+  static const uint8 RLE_DELTA = 2;
+  int x = 0;
+  int y = height_ - 1;
+  while (pos_ < len_ - 1) {
+    uint8 cmd = GetByte();
+    if (cmd != RLE_ESCAPE) {
+      uint8 pixels = GetByte();
+      int num = 0;
+      uint8 col = pixels;
+      while (cmd-- && x < width_) {
+        if (bpp_ == 4) {
+          if (num & 1) {
+            col = pixels & 0xf;
+          } else {
+            col = pixels >> 4;
+          }
+        }
+        PutPixel(x++, y, col);
+        num++;
+      }
+    } else {
+      cmd = GetByte();
+      if (cmd == RLE_EOF) {
+        return;
+      } else if (cmd == RLE_EOL) {
+        x = 0;
+        y--;
+        if (y < 0) {
+          return;
+        }
+      } else if (cmd == RLE_DELTA) {
+        if (pos_ < len_ - 1) {
+          uint8 dx = GetByte();
+          uint8 dy = GetByte();
+          x += dx;
+          if (x > width_) {
+            x = width_;
+          }
+          y -= dy;
+          if (y < 0) {
+            return;
+          }
+        }
+      } else {
+        int num = 0;
+        int bytesRead = 0;
+        uint8 val = 0;
+        while (cmd-- && pos_ < len_) {
+          if (bpp_ == 8 || !(num & 1)) {
+            val = GetByte();
+            bytesRead++;
+          }
+          uint8 col = val;
+          if (bpp_ == 4) {
+            if (num & 1) {
+              col = col & 0xf;
+            } else {
+              col >>= 4;
+            }
+          }
+          if (x < width_) {
+            PutPixel(x++, y, col);
+          }
+          num++;
+        }
+        // All pixel runs must be an even number of bytes - skip a byte if we
+        // read an odd number.
+        if ((bytesRead & 1) && pos_ < len_) {
+          GetByte();
+        }
+      }
+    }
+  }
+}
+
+void BmpDecoderHelper::PutPixel(int x, int y, uint8 col) {
+  CHECK(x >= 0 && x < width_);
+  CHECK(y >= 0 && y < height_);
+  if (!inverted_) {
+    y = height_ - (y + 1);
+  }
+
+  int base = ((y * width_) + x) * 3;
+  int colBase = col * 3;
+  output_[base] = colTab_[colBase];
+  output_[base + 1] = colTab_[colBase + 1];
+  output_[base + 2] = colTab_[colBase + 2];
+}
+
+void BmpDecoderHelper::DoStandardDecode() {
+  int row = 0;
+  uint8 currVal = 0;
+  for (int h = height_ - 1; h >= 0; h--, row++) {
+    int realH = h;
+    if (!inverted_) {
+      realH = height_ - (h + 1);
+    }
+    uint8* line = output_ + (3 * width_ * realH);
+    for (int w = 0; w < width_; w++) {
+      if (bpp_ >= 24) {
+        line[2] = GetByte();
+        line[1] = GetByte();
+        line[0] = GetByte();
+      } else if (bpp_ == 16) {
+        uint32 val = GetShort();
+        line[0] = ((val & redBits_) >> redShiftRight_) << redShiftLeft_;
+        line[1] = ((val & greenBits_) >> greenShiftRight_) << greenShiftLeft_;
+        line[2] = ((val & blueBits_) >> blueShiftRight_) << blueShiftLeft_;
+      } else if (bpp_ <= 8) {
+        uint8 col;
+        if (bpp_ == 8) {
+          col = GetByte();
+        } else if (bpp_ == 4) {
+          if ((w % 2) == 0) {
+            currVal = GetByte();
+            col = currVal >> 4;
+          } else {
+            col = currVal & 0xf;
+          }
+        } else {
+          if ((w % 8) == 0) {
+            currVal = GetByte();
+          }
+          int bit = w & 7;
+          col = ((currVal >> (7 - bit)) & 1);
+        }
+        int base = col * 3;
+        line[0] = colTab_[base];
+        line[1] = colTab_[base + 1];
+        line[2] = colTab_[base + 2];
+      }
+      line += 3;
+      for (int i = 0; i < pixelPad_; ++i) {
+        GetByte();
+      }
+    }
+    for (int i = 0; i < rowPad_; ++i) {
+      GetByte();
+    }
+  }
+}
+
+int BmpDecoderHelper::GetInt() {
+  uint8 b1 = GetByte();
+  uint8 b2 = GetByte();
+  uint8 b3 = GetByte();
+  uint8 b4 = GetByte();
+  return b1 | (b2 << 8) | (b3 << 16) | (b4 << 24);
+}
+
+int BmpDecoderHelper::GetShort() {
+  uint8 b1 = GetByte();
+  uint8 b2 = GetByte();
+  return b1 | (b2 << 8);
+}
+
+uint8 BmpDecoderHelper::GetByte() {
+  CHECK(pos_ >= 0 && pos_ <= len_);
+  // We deliberately allow this off-by-one access to cater for BMPs with their
+  // last byte missing.
+  if (pos_ == len_) {
+    return 0;
+  }
+  return data_[pos_++];
+}
+
+int BmpDecoderHelper::CalcShiftRight(uint32 mask) {
+  int ret = 0;
+  while (mask != 0 && !(mask & 1)) {
+    mask >>= 1;
+    ret++;
+  }
+  return ret;
+}
+
+int BmpDecoderHelper::CalcShiftLeft(uint32 mask) {
+  int ret = 0;
+  while (mask != 0 && !(mask & 1)) {
+    mask >>= 1;
+  }
+  while (mask != 0 && !(mask & 0x80)) {
+    mask <<= 1;
+    ret++;
+  }
+  return ret;
+}
+
+}  // namespace image_codec