Scanline decoding for bmp

src/codec/SkBmpRLECodec.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBmpRLECodec.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
+#include "SkScaledCodec.h"
 #include "SkScanlineDecoder.h"
 #include "SkStream.h"
 
 /*
  * Creates an instance of the decoder
  * Called only by NewFromStream
  */
 SkBmpRLECodec::SkBmpRLECodec(const SkImageInfo& info, SkStream* stream,
                              uint16_t bitsPerPixel, uint32_t numColors,
                              uint32_t bytesPerColor, uint32_t offset,
@@ skipping 25 matching lines @@
     }
     if (dstInfo.dimensions() != this->getInfo().dimensions()) {
         SkCodecPrintf("Error: scaling not supported.\n");
         return kInvalidScale;
     }
     if (!conversion_possible(dstInfo, this->getInfo())) {
         SkCodecPrintf("Error: cannot convert input type to output type.\n");
         return kInvalidConversion;
     }
 
-    // Create the color table if necessary and prepare the stream for decode
-    // Note that if it is non-NULL, inputColorCount will be modified
-    if (!this->createColorTable(inputColorCount)) {
-        SkCodecPrintf("Error: could not create color table.\n");
-        return kInvalidInput;
-    }
-
-    // Copy the color table to the client if necessary
-    copy_color_table(dstInfo, fColorTable, inputColorPtr, inputColorCount);
-
-    // Initialize a swizzler if necessary
-    if (!this->initializeStreamBuffer()) {
-        SkCodecPrintf("Error: cannot initialize swizzler.\n");
-        return kInvalidConversion;
+    Result result = this->prepareToDecode(dstInfo, opts, inputColorPtr, inputColorCount);
+    if (kSuccess != result) {
+        return result;
     }
 
     // Perform the decode
     return decode(dstInfo, dst, dstRowBytes, opts);
 }
 
 /*
  * Process the color table for the bmp input
  */
  bool SkBmpRLECodec::createColorTable(int* numColors) {
@@ skipping 107 matching lines @@
     fRLEBytes = remainingBytes + additionalBytes;
     return fRLEBytes;
 }
 
 /*
  * Set an RLE pixel using the color table
  */
 void SkBmpRLECodec::setPixel(void* dst, size_t dstRowBytes,
                              const SkImageInfo& dstInfo, uint32_t x, uint32_t y,
                              uint8_t index) {
-    // Set the row
-    int height = dstInfo.height();
-    int row;
-    if (SkBmpCodec::kBottomUp_RowOrder == this->rowOrder()) {
-        row = height - y - 1;
-    } else {
-        row = y;
-    }
+    int sampleX;
+    SkScaledCodec::ComputeSampleSize(dstInfo, this->getInfo(), &sampleX, NULL);
+    if (is_coord_necessary(x, sampleX >> 1, sampleX, dstInfo.width())) {
+        // Set the row
+        uint32_t row = this->getDstRow(y, dstInfo.height());
 
-    // Set the pixel based on destination color type
-    switch (dstInfo.colorType()) {
-        case kN32_SkColorType: {
-            SkPMColor* dstRow = SkTAddOffset<SkPMColor>((SkPMColor*) dst,
-                    row * (int) dstRowBytes);
-            dstRow[x] = fColorTable->operator[](index);
-            break;
+        // Set the pixel based on destination color type
+        switch (dstInfo.colorType()) {
+            case kN32_SkColorType: {
+                SkPMColor* dstRow = SkTAddOffset<SkPMColor>((SkPMColor*) dst,
+                        row * (int) dstRowBytes);
+                dstRow[x / sampleX] = fColorTable->operator[](index);
+                break;
+            }
+            case kRGB_565_SkColorType: {
+                uint16_t* dstRow = SkTAddOffset<uint16_t>(dst, row * (int) dstRowBytes);
+                dstRow[x / sampleX] = SkPixel32ToPixel16(fColorTable->operator[](index));
+                break;
+            }
+            default:
+                // This case should not be reached.  We should catch an invalid
+                // color type when we check that the conversion is possible.
+                SkASSERT(false);
+                break;
         }
-        case kRGB_565_SkColorType: {
-            uint16_t* dstRow = SkTAddOffset<uint16_t>(dst, row * (int) dstRowBytes);
-            dstRow[x] = SkPixel32ToPixel16(fColorTable->operator[](index));
-            break;
-        }
-        default:
-            // This case should not be reached.  We should catch an invalid
-            // color type when we check that the conversion is possible.
-            SkASSERT(false);
-            break;
     }
 }
 
 /*
  * Set an RLE pixel from R, G, B values
  */
 void SkBmpRLECodec::setRGBPixel(void* dst, size_t dstRowBytes,
                                 const SkImageInfo& dstInfo, uint32_t x,
                                 uint32_t y, uint8_t red, uint8_t green,
                                 uint8_t blue) {
-    // Set the row
-    int height = dstInfo.height();
-    int row;
-    if (SkBmpCodec::kBottomUp_RowOrder == this->rowOrder()) {
-        row = height - y - 1;
-    } else {
-        row = y;
-    }
+    int sampleX;
+    SkScaledCodec::ComputeSampleSize(dstInfo, this->getInfo(), &sampleX, NULL);
+    if (is_coord_necessary(x, sampleX >> 1, sampleX, dstInfo.width())) {
+        // Set the row
+        uint32_t row = this->getDstRow(y, dstInfo.height());
 
-    // Set the pixel based on destination color type
-    switch (dstInfo.colorType()) {
-        case kN32_SkColorType: {
-            SkPMColor* dstRow = SkTAddOffset<SkPMColor>((SkPMColor*) dst,
-                    row * (int) dstRowBytes);
-            dstRow[x] = SkPackARGB32NoCheck(0xFF, red, green, blue);
-            break;
+        // Set the pixel based on destination color type
+        switch (dstInfo.colorType()) {
+            case kN32_SkColorType: {
+                SkPMColor* dstRow = SkTAddOffset<SkPMColor>((SkPMColor*) dst,
+                        row * (int) dstRowBytes);
+                dstRow[x] = SkPackARGB32NoCheck(0xFF, red, green, blue);
+                break;
+            }
+            case kRGB_565_SkColorType: {
+                uint16_t* dstRow = SkTAddOffset<uint16_t>(dst, row * (int) dstRowBytes);
+                dstRow[x] = SkPack888ToRGB16(red, green, blue);
+                break;
+            }
+            default:
+                // This case should not be reached.  We should catch an invalid
+                // color type when we check that the conversion is possible.
+                SkASSERT(false);
+                break;
         }
-        case kRGB_565_SkColorType: {
-            uint16_t* dstRow = SkTAddOffset<uint16_t>(dst, row * (int) dstRowBytes);
-            dstRow[x] = SkPack888ToRGB16(red, green, blue);
-            break;
-        }
-        default:
-            // This case should not be reached.  We should catch an invalid
-            // color type when we check that the conversion is possible.
-            SkASSERT(false);
-            break;
     }
 }
 
 /*
  * Performs the bitmap decoding for RLE input format
  * RLE decoding is performed all at once, rather than a one row at a time
  */
 SkCodec::Result SkBmpRLECodec::decode(const SkImageInfo& dstInfo,
                                       void* dst, size_t dstRowBytes,
                                       const Options& opts) {
     // Set RLE flags
     static const uint8_t RLE_ESCAPE = 0;
     static const uint8_t RLE_EOL = 0;
     static const uint8_t RLE_EOF = 1;
     static const uint8_t RLE_DELTA = 2;
 
     // Set constant values
-    const int width = dstInfo.width();
+    const int width = this->getInfo().width();
     const int height = dstInfo.height();
 
     // Destination parameters
     int x = 0;
     int y = 0;
 
     // Set the background as transparent.  Then, if the RLE code skips pixels,
     // the skipped pixels will be transparent.
     // Because of the need for transparent pixels, kN32 is the only color
     // type that makes sense for the destination format.
@@ skipping 160 matching lines @@
                 // Set the indicated number of pixels
                 for (int which = 0; x < endX; x++) {
                     setPixel(dst, dstRowBytes, dstInfo, x, y,
                             indices[which]);
                     which = !which;
                 }
             }
         }
     }
 }
+
+SkCodec::Result SkBmpRLECodec::prepareToDecode(const SkImageInfo& dstInfo,
+        const SkCodec::Options& options, SkPMColor inputColorPtr[], int* inputColorCount) {
+    // Create the color table if necessary and prepare the stream for decode
+    // Note that if it is non-NULL, inputColorCount will be modified
+    if (!this->createColorTable(inputColorCount)) {
+        SkCodecPrintf("Error: could not create color table.\n");
+        return SkCodec::kInvalidInput;
+    }
+
+    // Copy the color table to the client if necessary
+    copy_color_table(dstInfo, this->fColorTable, inputColorPtr, inputColorCount);
+
+    // Initialize a buffer for encoded RLE data
+    if (!this->initializeStreamBuffer()) {
+        SkCodecPrintf("Error: cannot initialize swizzler.\n");
+        return SkCodec::kInvalidConversion;
+    }
+
+    return SkCodec::kSuccess;
+}