Fix srcBounds computation in SkMatrixConvolutionImageFilter

Note that this does change the behavior of the cropRect for the repeated case. The cropRect now only acts as a hard clip on the output.

BUG= skia:7766

Change-Id: I1d66678bc797cd4835701cd20c36e68b22ac880a
Reviewed-on: https://skia-review.googlesource.com/127338
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/gm/matrixconvolution.cpp b/gm/matrixconvolution.cpp
index 4af12e172d..adb7eceff0 100644
--- a/gm/matrixconvolution.cpp
+++ b/gm/matrixconvolution.cpp
@@ -92,9 +92,14 @@ protected:
                                                                   cropRect));
         canvas->save();
         canvas->translate(SkIntToScalar(x), SkIntToScalar(y));
-        canvas->clipRect(SkRect::MakeWH(SkIntToScalar(fBitmap.width()),
-                                        SkIntToScalar(fBitmap.height())));
-        canvas->drawBitmap(fBitmap, 0, 0, &paint);
+        const SkRect layerBounds = SkRect::MakeIWH(fBitmap.width(), fBitmap.height());
+        canvas->clipRect(layerBounds);
+        // This GM is, in part, intended to display the wrapping behavior of the
+        // matrix image filter. The only (rational) way to achieve that for repeat mode
+        // is to create a tight layer.
+        canvas->saveLayer(layerBounds, &paint);
+            canvas->drawBitmap(fBitmap, 0, 0, nullptr);
+        canvas->restore();
         canvas->restore();
     }