Swizzler changes Index8 and 565

src/codec/SkCodec_libbmp.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 "SkCodec_libbmp.h"
 #include "SkCodecPriv.h"
 #include "SkColorPriv.h"
 #include "SkStream.h"
+#include "SkUtils.h"
 
 /*
  *
  * Checks if the conversion between the input image and the requested output
  * image has been implemented
  *
  */
 static bool conversion_possible(const SkImageInfo& dst,
                                 const SkImageInfo& src) {
     // Ensure that the profile type is unchanged
     if (dst.profileType() != src.profileType()) {
         return false;
     }
 
-    // Check for supported color and alpha types
+    // Check for supported alpha types
+    if (src.alphaType() != dst.alphaType()) {
+        if (kOpaque_SkAlphaType == src.alphaType()) {
+            // If the source is opaque, we must decode to opaque
+            return false;
+        }
+
+        // The source is not opaque
+        switch (dst.alphaType()) {
+            case kPremul_SkAlphaType:
+            case kUnpremul_SkAlphaType:
+                // The source is not opaque, so either of these is okay
+                break;
+            default:
+                // We cannot decode a non-opaque image to opaque (or unknown)
+                return false;
+        }
+    }
+
+    // Check for supported color types
     switch (dst.colorType()) {
+        // Allow output to kN32 from any type of input
         case kN32_SkColorType:
-            return src.alphaType() == dst.alphaType() ||
-                    (kPremul_SkAlphaType == dst.alphaType() &&
-                    kUnpremul_SkAlphaType == src.alphaType());
+            return true;
+        // Allow output to kIndex_8 from compatible inputs
+        case kIndex_8_SkColorType:
+            return kIndex_8_SkColorType == src.colorType();
         default:
             return false;
     }
 }
 
 /*
  *
  * Defines the version and type of the second bitmap header
  *
  */
@@ skipping 371 matching lines @@
         // Header types are matched based on size.  If the header is
         // V3+, we are guaranteed to be able to read at least this size.
         SkASSERT(infoBytesRemaining > 52);
         inputMasks.alpha = get_int(iBuffer.get(), 48);
         if (inputMasks.alpha != 0) {
             alphaType = kUnpremul_SkAlphaType;
         }
     }
     iBuffer.free();
 
-    // Additionally, 32 bit bmp-in-icos use the alpha channel
-    if (isIco && 32 == bitsPerPixel) {
+    // Additionally, 32 bit bmp-in-icos use the alpha channel.
+    // And, RLE inputs may skip pixels, leaving them as transparent.  This
+    // is uncommon, but we cannot be certain that an RLE bmp will be opaque.
+    if ((isIco && 32 == bitsPerPixel) || (kRLE_BitmapInputFormat == inputFormat)) {
         alphaType = kUnpremul_SkAlphaType;
     }
 
-    // Check for valid bits per pixel input
+    // Check for valid bits per pixel.
+    // At the same time, use this information to choose a suggested color type
+    // and to set default masks.
+    SkColorType colorType = kN32_SkColorType;
     switch (bitsPerPixel) {
         // In addition to more standard pixel compression formats, bmp supports
         // the use of bit masks to determine pixel components.  The standard
         // format for representing 16-bit colors is 555 (XRRRRRGGGGGBBBBB),
         // which does not map well to any Skia color formats.  For this reason,
         // we will always enable mask mode with 16 bits per pixel.
         case 16:
             if (kBitMask_BitmapInputFormat != inputFormat) {
                 inputMasks.red = 0x7C00;
                 inputMasks.green = 0x03E0;
                 inputMasks.blue = 0x001F;
                 inputFormat = kBitMask_BitmapInputFormat;
             }
             break;
+        // We want to decode to kIndex_8 for input formats that are already
+        // designed in index format.
         case 1:
         case 2:
         case 4:
         case 8:
+            // However, we cannot in RLE format since we may need to leave some
+            // pixels as transparent.  Similarly, we also cannot for ICO images
+            // since we may need to apply a transparent mask.
+            if (kRLE_BitmapInputFormat != inputFormat && !isIco) {
+                colorType = kIndex_8_SkColorType;
+            }
         case 24:
         case 32:
             break;
         default:
             SkCodecPrintf("Error: invalid input value for bits per pixel.\n");
             return false;
     }
 
     // Check that input bit masks are valid and create the masks object
     SkAutoTDelete<SkMasks>
@@ skipping 12 matching lines @@
 
     // Calculate the number of bytes read so far
     const uint32_t bytesRead = kBmpHeaderBytes + infoBytes + maskBytes;
     if (!isIco && offset < bytesRead) {
         SkCodecPrintf("Error: pixel data offset less than header size.\n");
         return false;
     }
 
     if (codecOut) {
         // Return the codec
-        // We will use ImageInfo to store width, height, and alpha type. We
-        // will set color type to kN32_SkColorType because that should be the
-        // default output.
+        // We will use ImageInfo to store width, height, suggested color type, and
+        // suggested alpha type.
         const SkImageInfo& imageInfo = SkImageInfo::Make(width, height,
-                kN32_SkColorType, alphaType);
+                colorType, alphaType);
         *codecOut = SkNEW_ARGS(SkBmpCodec, (imageInfo, stream, bitsPerPixel,
                                             inputFormat, masks.detach(),
                                             numColors, bytesPerColor,
                                             offset - bytesRead, rowOrder,
                                             RLEBytes, isIco));
     }
     return true;
 }
 
 /*
@@ skipping 40 matching lines @@
 
 {}
 
 /*
  *
  * Initiates the bitmap decode
  *
  */
 SkCodec::Result SkBmpCodec::onGetPixels(const SkImageInfo& dstInfo,
                                         void* dst, size_t dstRowBytes,
-                                        const Options&,
-                                        SkPMColor*, int*) {
+                                        const Options& opts,
+                                        SkPMColor* inputColorPtr,
+                                        int* inputColorCount) {
     // Check for proper input and output formats
     SkCodec::RewindState rewindState = this->rewindIfNeeded();
     if (rewindState == kCouldNotRewind_RewindState) {
         return kCouldNotRewind;
     } else if (rewindState == kRewound_RewindState) {
         if (!ReadHeader(this->stream(), fIsIco, NULL)) {
             return kCouldNotRewind;
         }
     }
     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
-    if (!createColorTable(dstInfo.alphaType())) {
+    // Note that if it is non-NULL, inputColorCount will be modified
+    if (!createColorTable(dstInfo.alphaType(), inputColorCount)) {
         SkCodecPrintf("Error: could not create color table.\n");
         return kInvalidInput;
     }
 
+    // Copy the color table to the client if necessary
+    if (kIndex_8_SkColorType == dstInfo.colorType()) {
+        SkASSERT(NULL != inputColorPtr);
+        SkASSERT(NULL != inputColorCount);
+        SkASSERT(NULL != fColorTable.get());
+        sk_memcpy32(inputColorPtr, fColorTable->readColors(), *inputColorCount);
+    }
+
     // Perform the decode
     switch (fInputFormat) {
         case kBitMask_BitmapInputFormat:
             return decodeMask(dstInfo, dst, dstRowBytes);
         case kRLE_BitmapInputFormat:
-            return decodeRLE(dstInfo, dst, dstRowBytes);
+            return decodeRLE(dstInfo, dst, dstRowBytes, opts);
         case kStandard_BitmapInputFormat:
             return decode(dstInfo, dst, dstRowBytes);
         default:
             SkASSERT(false);
             return kInvalidInput;
     }
 }
 
 /*
  *
  * Process the color table for the bmp input
  *
  */
- bool SkBmpCodec::createColorTable(SkAlphaType alphaType) {
+ bool SkBmpCodec::createColorTable(SkAlphaType alphaType, int* numColors) {
     // Allocate memory for color table
     uint32_t colorBytes = 0;
     uint32_t maxColors = 0;
     SkPMColor colorTable[256];
     if (fBitsPerPixel <= 8) {
         // Zero is a default for maxColors
         // Also set fNumColors to maxColors when it is too large
         maxColors = 1 << fBitsPerPixel;
         if (fNumColors == 0 || fNumColors >= maxColors) {
             fNumColors = maxColors;
         }
 
+        // Inform the caller of the number of colors
+        if (NULL != numColors) {
+            SkASSERT(256 == *numColors);
+            // We set the number of colors to maxColors in order to ensure
+            // safe memory accesses.  Otherwise, an invalid pixel could
+            // access memory outside of our color table array.
+            *numColors = maxColors;
+        }
+
         // Read the color table from the stream
         colorBytes = fNumColors * fBytesPerColor;
         SkAutoTDeleteArray<uint8_t> cBuffer(SkNEW_ARRAY(uint8_t, colorBytes));
         if (stream()->read(cBuffer.get(), colorBytes) != colorBytes) {
             SkCodecPrintf("Error: unable to read color table.\n");
             return false;
         }
 
         // Choose the proper packing function
         SkPMColor (*packARGB) (uint32_t, uint32_t, uint32_t, uint32_t);
@@ skipping 13 matching lines @@
                 packARGB = NULL;
                 break;
         }
 
         // Fill in the color table
         uint32_t i = 0;
         for (; i < fNumColors; i++) {
             uint8_t blue = get_byte(cBuffer.get(), i*fBytesPerColor);
             uint8_t green = get_byte(cBuffer.get(), i*fBytesPerColor + 1);
             uint8_t red = get_byte(cBuffer.get(), i*fBytesPerColor + 2);
-            uint8_t alpha = kOpaque_SkAlphaType == alphaType ? 0xFF :
-                    (fMasks->getAlphaMask() >> 24) &
-                    get_byte(cBuffer.get(), i*fBytesPerColor + 3);
+            uint8_t alpha;
+            if (kOpaque_SkAlphaType == alphaType || kRLE_BitmapInputFormat == fInputFormat) {
+                alpha = 0xFF;
+            } else {
+                alpha = (fMasks->getAlphaMask() >> 24) &
+                        get_byte(cBuffer.get(), i*fBytesPerColor + 3);
+            }
             colorTable[i] = packARGB(alpha, red, green, blue);
         }
 
         // To avoid segmentation faults on bad pixel data, fill the end of the
         // color table with black.  This is the same the behavior as the
         // chromium decoder.
         for (; i < maxColors; i++) {
             colorTable[i] = SkPackARGB32NoCheck(0xFF, 0, 0, 0);
         }
     }
@@ skipping 85 matching lines @@
 
     // Finished decoding the entire image
     return kSuccess;
 }
 
 /*
  *
  * Set an RLE pixel using the color table
  *
  */
-void SkBmpCodec::setRLEPixel(SkPMColor* dst, size_t dstRowBytes,
+void SkBmpCodec::setRLEPixel(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 (kBottomUp_RowOrder == fRowOrder) {
         row = height - y - 1;
     } else {
         row = y;
     }
 
     // Set the pixel based on destination color type
     switch (dstInfo.colorType()) {
         case kN32_SkColorType: {
-            SkPMColor* dstRow = SkTAddOffset<SkPMColor>(dst,
+            SkPMColor* dstRow = SkTAddOffset<SkPMColor>((SkPMColor*) dst,
                     row * (int) dstRowBytes);
             dstRow[x] = fColorTable->operator[](index);
             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 SkBmpCodec::setRLE24Pixel(SkPMColor* dst, size_t dstRowBytes,
+void SkBmpCodec::setRLE24Pixel(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 (kBottomUp_RowOrder == fRowOrder) {
         row = height - y - 1;
     } else {
         row = y;
     }
 
     // Set the pixel based on destination color type
     switch (dstInfo.colorType()) {
         case kN32_SkColorType: {
-            SkPMColor* dstRow = SkTAddOffset<SkPMColor>(dst,
+            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;
     }
 }
 
 /*
  *
  * 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 SkBmpCodec::decodeRLE(const SkImageInfo& dstInfo,
-                                      void* dst, size_t dstRowBytes) {
+                                      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 height = dstInfo.height();
 
     // Input buffer parameters
     uint32_t currByte = 0;
     SkAutoTDeleteArray<uint8_t> buffer(SkNEW_ARRAY(uint8_t, fRLEBytes));
     size_t totalBytes = stream()->read(buffer.get(), fRLEBytes);
     if (totalBytes < fRLEBytes) {
         SkCodecPrintf("Warning: incomplete RLE file.\n");
     } else if (totalBytes <= 0) {
         SkCodecPrintf("Error: could not read RLE image data.\n");
         return kInvalidInput;
     }
 
     // Destination parameters
     int x = 0;
     int y = 0;
-    // If the code skips pixels, remaining pixels are transparent or black
-    // TODO: Skip this if memory was already zeroed.
-    memset(dst, 0, dstRowBytes * height);
-    SkPMColor* dstPtr = (SkPMColor*) dst;
+
+    // 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.
+    SkASSERT(kN32_SkColorType == dstInfo.colorType());
+    if (kNo_ZeroInitialized == opts.fZeroInitialized) {
+        SkSwizzler::Fill(dst, dstInfo, dstRowBytes, 0, SK_ColorTRANSPARENT, NULL);
+    }
 
     while (true) {
         // Every entry takes at least two bytes
         if ((int) totalBytes - currByte < 2) {
             SkCodecPrintf("Warning: incomplete RLE input.\n");
             return kIncompleteInput;
         }
 
         // Read the next two bytes.  These bytes have different meanings
         // depending on their values.  In the first interpretation, the first
@@ skipping 50 matching lines @@
                             (int) totalBytes - currByte < SkAlign2(rowBytes)) {
                         SkCodecPrintf("Warning: invalid RLE input.\n");
                         return kIncompleteInput;
                     }
                     // Set numPixels number of pixels
                     while (numPixels > 0) {
                         switch(fBitsPerPixel) {
                             case 4: {
                                 SkASSERT(currByte < totalBytes);
                                 uint8_t val = buffer.get()[currByte++];
-                                setRLEPixel(dstPtr, dstRowBytes, dstInfo, x++,
+                                setRLEPixel(dst, dstRowBytes, dstInfo, x++,
                                         y, val >> 4);
                                 numPixels--;
                                 if (numPixels != 0) {
-                                    setRLEPixel(dstPtr, dstRowBytes, dstInfo,
+                                    setRLEPixel(dst, dstRowBytes, dstInfo,
                                             x++, y, val & 0xF);
                                     numPixels--;
                                 }
                                 break;
                             }
                             case 8:
                                 SkASSERT(currByte < totalBytes);
-                                setRLEPixel(dstPtr, dstRowBytes, dstInfo, x++,
+                                setRLEPixel(dst, dstRowBytes, dstInfo, x++,
                                         y, buffer.get()[currByte++]);
                                 numPixels--;
                                 break;
                             case 24: {
                                 SkASSERT(currByte + 2 < totalBytes);
                                 uint8_t blue = buffer.get()[currByte++];
                                 uint8_t green = buffer.get()[currByte++];
                                 uint8_t red = buffer.get()[currByte++];
-                                setRLE24Pixel(dstPtr, dstRowBytes, dstInfo,
+                                setRLE24Pixel(dst, dstRowBytes, dstInfo,
                                             x++, y, red, green, blue);
                                 numPixels--;
                             }
                             default:
                                 SkASSERT(false);
                                 return kInvalidInput;
                         }
                     }
                     // Skip a byte if necessary to maintain alignment
                     if (!SkIsAlign2(rowBytes)) {
@@ skipping 15 matching lines @@
                 if ((int) totalBytes - currByte < 2) {
                     SkCodecPrintf("Warning: incomplete RLE input\n");
                     return kIncompleteInput;
                 }
 
                 // Fill the pixels up to endX with the specified color
                 uint8_t blue = task;
                 uint8_t green = buffer.get()[currByte++];
                 uint8_t red = buffer.get()[currByte++];
                 while (x < endX) {
-                    setRLE24Pixel(dstPtr, dstRowBytes, dstInfo, x++, y, red,
+                    setRLE24Pixel(dst, dstRowBytes, dstInfo, x++, y, red,
                             green, blue);
                 }
             } else {
                 // In RLE8 or RLE4, the second byte read gives the index in the
                 // color table to look up the pixel color.
                 // RLE8 has one color index that gets repeated
                 // RLE4 has two color indexes in the upper and lower 4 bits of
                 // the bytes, which are alternated
                 uint8_t indices[2] = { task, task };
                 if (4 == fBitsPerPixel) {
                     indices[0] >>= 4;
                     indices[1] &= 0xf;
                 }
 
                 // Set the indicated number of pixels
                 for (int which = 0; x < endX; x++) {
-                    setRLEPixel(dstPtr, dstRowBytes, dstInfo, x, y,
+                    setRLEPixel(dst, dstRowBytes, dstInfo, x, y,
                             indices[which]);
                     which = !which;
                 }
             }
         }
     }
 }
 
 /*
  *
@@ skipping 69 matching lines @@
     }
 
     // FIXME: This code exists to match the behavior in the chromium decoder
     // and to follow the bmp specification as it relates to alpha masks.  It is
     // commented out because we have yet to discover a test image that provides
     // an alpha mask and uses this decode mode.
 
     // Now we adjust the output image with some additional behavior that
     // SkSwizzler does not support.  Firstly, all bmp images that contain
     // alpha are masked by the alpha mask.  Secondly, many fully transparent
-    // bmp images are intended to be opaque.  Here, we make those corrections.
+    // bmp images are intended to be opaque.  Here, we make those corrections
+    // in the kN32 case.
     /*
     SkPMColor* dstRow = (SkPMColor*) dst;
     if (SkSwizzler::kBGRA == config) {
         for (int y = 0; y < height; y++) {
             for (int x = 0; x < width; x++) {
                 if (transparent) {
                     dstRow[x] |= 0xFF000000;
                 } else {
                     dstRow[x] &= alphaMask;
                 }
@@ skipping 34 matching lines @@
                 uint32_t alphaBit =
                         (srcBuffer.get()[quotient] >> shift) & 0x1;
                 dstRow[x] &= alphaBit - 1;
             }
         }
     }
 
     // Finished decoding the entire image
     return kSuccess;
 }