Hi! This is my desperate fix for what I believe to be a critical bug. Since my knowledge of the codebase is minimal, and the class structure is a bit controversial, my fix is mostly based on historical excavation.
# What is the problem? VM started to crash after webkit 620.1 update when running simple [CanvasTest](https://github.com/openjdk/jfx/blob/1c3cfcb8bb4e8874406d3a5b507f38859f4c1d9b/modules/javafx.web/src/test/java/test/javafx/scene/web/CanvasTest.java#L125). Running with `-Xcheck:jni ` reveals invalid object is passed to JNI [call](https://github.com/openjdk/jfx/blob/0555fb25a16b6b6705a42c6d8592cf1c6ddccc67/modules/javafx.web/src/main/native/Source/WebCore/platform/graphics/java/NativeImageJava.cpp#L56): expected is`WCImageFrame` but provided is `RTImage` (an descendant of `WCImage`). The latter has no `getSize` method. Stack trace frame #4: 0x0000000101a36094 libjvm.dylib`checked_jni_CallObjectMethodV(env=0x0000000124a89cb0, obj=0x000000012310f9e8, methodID=0x00006000019abde8, args="\xa0\U00000012\U0000001ev\U00000001") at jniCheck.cpp:1012:1 [opt] frame #5: 0x000000033e88ea60 libjfxwebkit.dylib`JNIEnv_::CallObjectMethod(this=0x0000000124a89cb0, obj=0x000000012310f9e8, methodID=0x00006000019abde8) at jni.h:906:18 frame #6: 0x00000003426fcda0 libjfxwebkit.dylib`WebCore::PlatformImageNativeImageBackend::size(this=0x0000600000e12790) const at NativeImageJava.cpp:55:48 frame #7: 0x000000034258d76c libjfxwebkit.dylib`WebCore::NativeImage::size(this=0x00000001761c2c00) const at NativeImage.cpp:89:23 frame #8: 0x00000003425723c0 libjfxwebkit.dylib`WebCore::ImageFrame::ImageFrame(this=0x00000001761e1270, nativeImage=0x000000016fdf7090) at ImageFrame.cpp:40:29 frame #9: 0x0000000342572420 libjfxwebkit.dylib`WebCore::ImageFrame::ImageFrame(this=0x00000001761e1270, nativeImage=0x000000016fdf7090) at ImageFrame.cpp:39:1 frame #10: 0x00000003425a4d7c libjfxwebkit.dylib`WebCore::NativeImageSource::NativeImageSource(this=0x00000001761e1260, nativeImage=0x000000016fdf7090) at NativeImageSource.cpp:37:7 frame #11: 0x00000003425a4d24 libjfxwebkit.dylib`WebCore::NativeImageSource::NativeImageSource(this=0x00000001761e1260, nativeImage=0x000000016fdf7090) at NativeImageSource.cpp:38:1 frame #12: 0x00000003425a4cac libjfxwebkit.dylib`WebCore::NativeImageSource::create(nativeImage=0x000000016fdf7090) at NativeImageSource.cpp:33:26 frame #13: 0x00000003423a6f18 libjfxwebkit.dylib`WebCore::BitmapImage::BitmapImage(this=0x00000001761e1200, image=0x000000016fdf7090) at BitmapImage.cpp:67:16 frame #14: 0x00000003423a6b60 libjfxwebkit.dylib`WebCore::BitmapImage::BitmapImage(this=0x00000001761e1200, image=0x000000016fdf7090) at BitmapImage.cpp:68:1 frame #15: 0x00000003423a6bd0 libjfxwebkit.dylib`WebCore::BitmapImage::create(nativeImage=0x000000016fdf70e0) at BitmapImage.cpp:52:26 frame #16: 0x00000003416abcf0 libjfxwebkit.dylib`WebCore::HTMLCanvasElement::copiedImage(this=0x0000000321008640) const at HTMLCanvasElement.cpp:903:29 frame #17: 0x0000000341899e70 libjfxwebkit.dylib`WebCore::CanvasRenderingContext2DBase::createPattern(this=0x0000000321008b00, canvas=0x0000000321008640, repeatX=true, repeatY=true) at CanvasRenderingContext2DBase.cpp:2232:32 # Historical excavation There was a similar problem in the [past](https://hg.openjdk.org/openjfx/10-dev/rt/rev/542116615e59). The predecessor of `PlatformImageNativeImageBackend::size` knew that there is an `Image` (like gif with multiple frames, or still image) and ImageFrame. But then it assumes "NativeImage" is always backed by `WCImageFrame` # The fix The fix restores original idea and checks the backend class. The method returns zero size if the `m_platformImage` is not `WCImageFrame` # The alternative I believe there is a more straightforward and correct way to fix this. Don't hesitate to reject the PR if you know a better solution. ------------- Commit messages: - 8347937: Canvas pattern test fails on WebKit 620.1 Changes: https://git.openjdk.org/jfx/pull/1734/files Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1734&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8347937 Stats: 19 lines in 3 files changed: 12 ins; 1 del; 6 mod Patch: https://git.openjdk.org/jfx/pull/1734.diff Fetch: git fetch https://git.openjdk.org/jfx.git pull/1734/head:pull/1734 PR: https://git.openjdk.org/jfx/pull/1734
