rebaseline_server: use just skpdiff, not Python Image Library

tools/skpdiff/SkDiffContext.h

Index: tools/skpdiff/SkDiffContext.h
diff --git a/tools/skpdiff/SkDiffContext.h b/tools/skpdiff/SkDiffContext.h
index c036c2ef6cd0c169f1a99a38319af124aff9fdcc..c3e6bbd2cb34da5858f4d2e10bb5a5b26855ecf3 100644
--- a/tools/skpdiff/SkDiffContext.h
+++ b/tools/skpdiff/SkDiffContext.h
@@ -28,10 +28,28 @@ public:
     void setThreadCount(int threadCount) { fThreadCount = threadCount; }
 
     /**
-     * Creates the directory if it does not exist and uses it to store differences
-     * between images.
+     * Sets the directory within which to store alphaMasks (images that
+     * are transparent for each pixel that differs between baseline and test).
+     *
+     * If the directory does not exist yet, it will be created.
+     */
+    void setAlphaMaskDir(const SkString& directory);
+
+    /**
+     * Sets the directory within which to store rgbDiffs (images showing the
+     * per-channel difference between baseline and test at each pixel).
+     *
+     * If the directory does not exist yet, it will be created.
+     */
+    void setRgbDiffDir(const SkString& directory);
+
+    /**
+     * Sets the directory within which to store whiteDiffs (images showing white
+     * for each pixel that differs between baseline and test).
+     *
+     * If the directory does not exist yet, it will be created.
      */
-    void setDifferenceDir(const SkString& directory);
+    void setWhiteDiffDir(const SkString& directory);
 
     /**
      * Sets the differs to be used in each diff. Already started diffs will not retroactively use
@@ -74,6 +92,14 @@ public:
      *    "differencePath" : (optional) string containing the path to an alpha
      *                       mask of the pixel difference between the baseline
      *                       and test images
+     *                       TODO: consider renaming this "alphaMaskPath"
+     *                       to distinguish from other difference types?
+     *    "rgbDiffPath"    : (optional) string containing the path to a bitmap
+     *                       showing per-channel differences between the
+     *                       baseline and test images at each pixel
+     *    "whiteDiffPath"  : (optional) string containing the path to a bitmap

[djsollen, 2014/06/12 13:27:00]

Why do you need a whiteDiffPath?  It stores the exact same info as the alpha
mask in differencePath.  In the UI you should then be able to just draw a white
div the size of the image and then draw the alpha mask image overtop.

[epoger, 2014/06/12 14:02:34]

I'll try that.  A big concern for me is making it as easy as possible for the
client to render the comparison rows.  Do you think the alpha mask will perform
just about as well as a standard single bitmap on constrained platforms,
rendering 50 per page?  (I don't know how expensive the alpha blends are)

+     *                       showing every pixel that differs between the
+     *                       baseline and test images as white
      *
      * They also have an array named "diffs" with each element being one diff record for the two
      * images indicated in the above field.
@@ -118,9 +144,16 @@ private:
 
     struct DiffRecord {
         SkString           fCommonName;
-        SkString           fDifferencePath;
+        SkString           fAlphaMaskPath;
+        SkString           fRgbDiffPath;
+        SkString           fWhiteDiffPath;
         SkString           fBaselinePath;
         SkString               fTestPath;
+        int                       fWidth;
+        int                      fHeight;
+        int                  fMaxRedDiff;
+        int                fMaxGreenDiff;
+        int                 fMaxBlueDiff;
         SkTArray<DiffData>        fDiffs;
     };
 
@@ -137,7 +170,9 @@ private:
     int fDifferCount;
     int fThreadCount;
 
-    SkString fDifferenceDir;
+    SkString fAlphaMaskDir;
+    SkString fRgbDiffDir;
+    SkString fWhiteDiffDir;
 };
 
 #endif