RFR: 8258754: Gracefully fallback to the OpenGL rendering pipeline if Metal rendering pipeline initialization fails

[Sergey Bylokhov]

On Thu, 7 Jan 2021 07:22:56 GMT, Ajit Ghaisas <aghaisas at openjdk.org> wrote:

>> src/java.desktop/macosx/classes/sun/awt/CGraphicsDevice.java line 71:
>> 
>>> 69: 
>>> 70:         // Check whether -Dsun.java2d.metal=true has been specified
>>> 71:         if (MacOSFlags.isMetalEnabled()) {
>> 
>> Is it possible to use metal and OGL at the same time on different devices? I think it is better to move these checks to the CGraphicsEnvironment.makeScreenDevice(), similar Win32GraphicsEnvironment.makeScreenDevice()
>
> I am not sure why someone wants to use different pipelines on different devices? and should we support it?
> On Windows we do that as a fallback to overcome a limitation of WGL - that's what I could infer from code in W32GraphicsDevice.getDefaultConfiguration()
> 
> I doubt whether we can add these checks in CGraphicsEnvironment.makeScreenDevice() - as we do not have specific MTLGraphicsDevice and CGLGraphicsDevice classes. That's the reason this method is currently unsupported.
> 
> Win32GraphicsEnvironment.makeScreenDevice() - creates either D3DGraphicsDevice or Win32GraphicsDevice based on whether isD3DEnabled. 
> Win32GraphicsDevice in turn uses either WGLGraphicsConfig or Win32GraphicsConfig based on whether OGL is enabled.
> 
> I felt CGraphicsDevice (similar to Win32GraphicsDevice) can differentiate between metal or OGL. Hence, I have added checks here.

If it is unsupported then why you should check that for every device creation? What happens if one device was created using metal and then another device will use OGL?

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PR: https://git.openjdk.java.net/lanai/pull/147