Ensure playing back a picture always balances saves and restores

tests/PictureTest.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapDevice.h"
 #include "SkBlurImageFilter.h"
 #include "SkCanvas.h"
@@ skipping 957 matching lines @@
     {
         SkCanvas* canvas = recorder.beginRecording(100, 100, NULL, 0);
         canvas->translate(10, 10);
         canvas->drawRect(rect, paint);
         SkAutoTUnref<SkPicture> noSavePicture(recorder.endRecording());
 
         testCanvas.drawPicture(*noSavePicture);
         REPORTER_ASSERT(reporter, 4 == testCanvas.getSaveCount());
         REPORTER_ASSERT(reporter, testCanvas.getTotalMatrix().isIdentity());
     }
+
+#if defined(SK_SUPPORT_LEGACY_PICTURE_CAN_RECORD) && defined(SK_SUPPORT_LEGACY_DERIVED_PICTURE_CLASSES)

[scroggo, 2014/05/16 18:20:53]

Aren't we going to change Android to use the newer version of SkPicture and
remove SK_SUPPORT_LEGACY_PICTURE_CAN_RECORD? Maybe this test belongs in Android.

Also:
nit: 100 chars.

[scroggo, 2014/05/16 18:37:57]

Also, it appears we only define SK_SUPPORT_LEGACY_PICTURE_CAN_RECORD for the
Android framework, so this test won't be run anywhere (yet; eventually we'll run
our test suite within the Android framework).

[robertphillips, 2014/05/16 19:18:15]

I'm trying to separate the fix for this SkPicture behavior from the switch to
the new recording interface. I think combining them in one (Android-side) CL
will obscure what is going on. I intend to add a unit test to Android that
verifies the new behavior of their Java Picture copy constructor.

The path I was envisioning was:
  Land something like this in Skia
  Update Android docs & add unit test
  Move Android to new recording API
  Delete legacy recording API in Skia
Done.
Right. This was more so I could be confident I actually fixed it here. This will
be deleted once Android is moved to the new API.

+    set_canvas_to_save_count_4(&testCanvas);
+
+    // Due to "fake" endRecording, the old SkPicture recording interface
+    // allowed unbalanced saves/restores to leak out. This sub-test checks
+    // that the situation has been remedied.
+    {
+        SkPicture p;
+
+        SkCanvas* canvas = p.beginRecording(100, 100);
+        for (int i = 0; i < 4; ++i) {
+           canvas->save();
+        }
+        SkRect r = SkRect::MakeWH(50, 50);
+        SkPaint paint;
+        canvas->drawRect(r, paint);
+
+        // Copying a mid-recording picture could result in unbalanced saves/restores
+        SkPicture p2(p);
+
+        testCanvas.drawPicture(p2);
+        REPORTER_ASSERT(reporter, 4 == testCanvas.getSaveCount());
+        set_canvas_to_save_count_4(&testCanvas);
+
+        // Cloning a mid-recording picture could result in unbalanced saves/restores
+        SkAutoTUnref<SkPicture> p3(p.clone());
+        testCanvas.drawPicture(*p3);
+        REPORTER_ASSERT(reporter, 4 == testCanvas.getSaveCount());
+        set_canvas_to_save_count_4(&testCanvas);
+
+        // Serializing a mid-recording picture could result in unbalanced saves/restores
+        SkDynamicMemoryWStream wStream;
+        p.serialize(&wStream);
+        SkAutoDataUnref data(wStream.copyToData());
+        SkMemoryStream stream(data);
+        SkAutoTUnref<SkPicture> p4(SkPicture::CreateFromStream(&stream, NULL));
+        testCanvas.drawPicture(*p4);
+        REPORTER_ASSERT(reporter, 4 == testCanvas.getSaveCount());
+    }
+#endif
 }
 
 static void test_peephole() {
     SkRandom rand;
 
     SkPictureRecorder recorder;
 
     for (int j = 0; j < 100; j++) {
         SkRandom rand2(rand); // remember the seed
 
@@ skipping 470 matching lines @@
     SkAutoTUnref<SkPicture> picture(recorder.endRecording());
 }
 
 DEF_TEST(Canvas_EmptyBitmap, r) {
     SkBitmap dst;
     dst.allocN32Pixels(10, 10);
     SkCanvas canvas(dst);
 
     test_draw_bitmaps(&canvas);
 }