[fiddle] Clear the canvas to white before calling draw().

Bug: skia:
Change-Id: I17f1d47c3d04f09ca613e2d3f98d4c73e4bad02c
Reviewed-on: https://skia-review.googlesource.com/19847
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Joe Gregorio <jcgregorio@google.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/tools/fiddle/fiddle_main.cpp b/tools/fiddle/fiddle_main.cpp
index dbc0141ca0..74aefb8bbb 100644
--- a/tools/fiddle/fiddle_main.cpp
+++ b/tools/fiddle/fiddle_main.cpp
@@ -93,6 +93,11 @@ static SkData* encode_snapshot(const sk_sp<SkSurface>& surface) {
     return img ? img->encode() : nullptr;
 }
 
+static SkCanvas* prepare_canvas(SkCanvas * canvas) {
+    canvas->clear(SK_ColorWHITE);
+    return canvas;
+}
+
 int main(int argc, char** argv) {
     SkCommandLineFlags::Parse(argc, argv);
     duration = FLAGS_duration;
@@ -136,7 +141,7 @@ int main(int argc, char** argv) {
     if (options.raster) {
         auto rasterSurface = SkSurface::MakeRaster(info);
         srand(0);
-        draw(rasterSurface->getCanvas());
+        draw(prepare_canvas(rasterSurface->getCanvas()));
         rasterData.reset(encode_snapshot(rasterSurface));
     }
     if (options.gpu) {
@@ -150,7 +155,7 @@ int main(int argc, char** argv) {
                 exit(1);
             }
             srand(0);
-            draw(surface->getCanvas());
+            draw(prepare_canvas(surface->getCanvas()));
             gpuData.reset(encode_snapshot(surface));
         }
     }
@@ -159,7 +164,7 @@ int main(int argc, char** argv) {
         sk_sp<SkDocument> document(SkDocument::MakePDF(&pdfStream));
         if (document) {
             srand(0);
-            draw(document->beginPage(options.size.width(), options.size.height()));
+            draw(prepare_canvas(document->beginPage(options.size.width(), options.size.height())));
             document->close();
             pdfData = pdfStream.detachAsData();
         }
@@ -169,7 +174,7 @@ int main(int argc, char** argv) {
         size = options.size;
         SkPictureRecorder recorder;
         srand(0);
-        draw(recorder.beginRecording(size.width(), size.height()));
+        draw(prepare_canvas(recorder.beginRecording(size.width(), size.height())));
         auto picture = recorder.finishRecordingAsPicture();
         SkDynamicMemoryWStream skpStream;
         picture->serialize(&skpStream);