RFR: 8160597: IllegalArgumentException when we initiate drag on Image

[Kevin Rushforth]

On Mon, 15 Nov 2021 11:19:13 GMT, Jose Pereda <jpereda at openjdk.org> wrote:

> This PR fixes an exception that can happen when dragging an image from a WebView on macOS.
> 
> Dragging an image that is directly included like `<img src="some image"/>` works fine, without exception. However, there are (at least) two other cases when the IAE is thrown: 
> 
> - Dragging an image that is part of an hyperlink, like `<a href="some url"><img src="some image"/></a>`.
> - Dragging an image encoded as base64.
> 
> The IAE happens only on macOS, where a native image is created in `GlassPasteboard.m` from an URL, and in those two cases the generated image has 0x0 dimensions:
>  
> `<NSImage 0x... Size={0, 0} ...>`
> 
> which leads to `ByteArrayFromPixels` being called with a null byte array. 
> 
> The included test reproduces the case by directly pushing the `MacPasteboard` content (instead of adding a more complex test with a webView and a drag and drop gesture).

The fix looks good. The test looks good with one minor comment.

tests/system/src/test/java/test/com/sun/glass/ui/mac/MacPasteboardTest.java line 56:

> 54:     public static void setup() throws Exception {
> 55:         Platform.startup(() -> {
> 56:             if (PlatformUtil.isMac()) {

Minor: it might be cleaner to wrap the entire body of the `setup` and `teardown` methods in `if (PlatformUtil.isMac())` so that we don't even start FX on platforms other than macOS.

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PR: https://git.openjdk.java.net/jfx/pull/668