dm changes

dm/DMSrcSink.cpp

Index: dm/DMSrcSink.cpp
diff --git a/dm/DMSrcSink.cpp b/dm/DMSrcSink.cpp
index 090a24d86a62590f123881274578b0468e59a01d..f39cb55b51bf4716dae0e8675e83dc3e29d79430 100644
--- a/dm/DMSrcSink.cpp
+++ b/dm/DMSrcSink.cpp
@@ -141,6 +141,7 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
                     // Everything else is considered a failure.
                     return SkStringPrintf("Couldn't getPixels %s.", fPath.c_str());
             }
+            canvas->drawBitmap(bitmap, 0, 0);
             break;
         case kScanline_Mode: {
             SkScanlineDecoder* scanlineDecoder = codec->getScanlineDecoder(decodeInfo, NULL,
@@ -160,10 +161,100 @@ Error CodecSrc::draw(SkCanvas* canvas) const {
                                               fPath.c_str(), y-1, (int) result);
                 }
             }
+            canvas->drawBitmap(bitmap, 0, 0);
+            break;
+        }
+        case kScanline_Subset_Mode: {
+            //this mode decodes the image in divisor*divisor subsets, using a scanline decoder
+            const int divisor = 2;
+            const int w = decodeInfo.width();
+            const int h = decodeInfo.height();
+            if (divisor > w || divisor > h) {
+                return SkStringPrintf("divisor %d is too big for %s with dimensions (%d x %d)",
+                        divisor, fPath.c_str(), w, h);
+            }
+            const int subsetWidth = w/divisor;
+            const int subsetHeight = h/divisor;
+            // One of our subsets will be larger to contain any pixels that do not divide evenly.
+            const int extraX = w % divisor;
+            const int extraY = h % divisor;
+            /*
+            * if w or h are not evenly divided by divisor need to adjust width and height of end
+            * subsets to cover entire image.
+            * Add extraX and extraY to largestSubsetBm's width and height to adjust width
+            * and height of end subsets.
+            * subsetBm is extracted from largestSubsetBm.
+            * subsetBm's size is determined based on the current subset and may be larger for end
+            * subsets.
+            */
+            SkImageInfo largestSubsetDecodeInfo = 
+                    decodeInfo.makeWH(subsetWidth + extraX, subsetHeight + extraY);
+            SkBitmap largestSubsetBm;
+            if (!largestSubsetBm.tryAllocPixels(largestSubsetDecodeInfo, NULL, colorTable.get())) {
+                return SkStringPrintf("Image(%s) is too large (%d x %d)\n", fPath.c_str(),
+                        largestSubsetDecodeInfo.width(), largestSubsetDecodeInfo.height());
+            }
+            char* line = SkNEW_ARRAY(char, decodeInfo.minRowBytes());
+            SkAutoTDeleteArray<char> lineDeleter(line);
+            for (int col = 0; col < divisor; col++) {
+                //currentSubsetWidth may be larger than subsetWidth for rightmost subsets
+                const int currentSubsetWidth = (col + 1 == divisor) ?
+                        subsetWidth + extraX : subsetWidth;
+                const int x = col * subsetWidth;
+                for (int row = 0; row < divisor; row++) {
+                    //currentSubsetHeight may be larger than subsetHeight for bottom subsets
+                    const int currentSubsetHeight = (row + 1 == divisor) ?
+                            subsetHeight + extraY : subsetHeight;
+                    const int y = row * subsetHeight;
+                    //create scanline decoder for each subset
+                    SkScanlineDecoder* subsetScanlineDecoder = codec->getScanlineDecoder(decodeInfo, 

[scroggo, 2015/05/26 19:44:30]

nit: Does this go over 100 columns? reitveld looks strange to me; it looks like
the line wraps but it does not show anything on the second line. (Is there
whitespace at the end that takes it over 100 columns?)

If it's not over 100 characters, just ignore this...

+                            NULL, colorPtr, colorCountPtr);
+                    if (NULL == subsetScanlineDecoder) {
+                        if (x == 0 && y == 0) {
+                            //first try, image may not be compatible
+                            return Error::Nonfatal("Cannot use scanline decoder for all images");
+                        } else {
+                            return "Error scanline decoder is NULL";
+                        }
+                    }
+                    //skip to first line of subset
+                    const SkImageGenerator::Result skipResult = 
+                            subsetScanlineDecoder->skipScanlines(y);
+                    switch (skipResult) {
+                        case SkImageGenerator::kSuccess:
+                        case SkImageGenerator::kIncompleteInput:
+                            break;
+                        default:
+                            return SkStringPrintf("%s failed after attempting to skip %d scanlines"
+                                    "with error message %d", fPath.c_str(), y, (int) skipResult);
+                    }
+                    //create and set size of subsetBm
+                    SkBitmap subsetBm;
+                    SkIRect bounds = SkIRect::MakeWH(subsetWidth, subsetHeight);
+                    bounds.setXYWH(0, 0, currentSubsetWidth, currentSubsetHeight);
+                    SkAssertResult(largestSubsetBm.extractSubset(&subsetBm, bounds));
+                    SkAutoLockPixels autlockSubsetBm(subsetBm, true);
+                    for (int subsetY = 0; subsetY < currentSubsetHeight; ++subsetY) {
+                        const SkImageGenerator::Result subsetResult =
+                                subsetScanlineDecoder->getScanlines(line, 1, 0);
+                        const size_t bpp = decodeInfo.bytesPerPixel();
+                        //copy section of line based on x value
+                        memcpy(subsetBm.getAddr(0, subsetY), line + x*bpp, currentSubsetWidth*bpp);
+                        switch (subsetResult) {
+                            case SkImageGenerator::kSuccess:
+                            case SkImageGenerator::kIncompleteInput:
+                                break;
+                            default:
+                                return SkStringPrintf("%s failed after %d scanlines with error" 
+                                        "message %d", fPath.c_str(), y-1, (int) subsetResult);
+                        }
+                    }
+                    canvas->drawBitmap(subsetBm, x, y);
+                }
+            }
             break;
         }
     }
-    canvas->drawBitmap(bitmap, 0, 0);
     return "";
 }