<AWT Dev> [9] Review Request: JDK-8029455 JLightweightFrame: support scaled painting

[Sergey Bylokhov]

Hi, Anton.
My expectation was that everything should work automatically, if you get 
correct CGraphicsDevice for the embedded swing window + some tweaks in 
the code related to the peer and CGLSurfaceData/

Why we need all this change in 
CGraphicsDevice,CGLGraphicsConfig,OffScreenImage,CPlatformLWView,JViewport,RepaintManager.Probably 
it will be better to disable doublebuffering and 
SwingPaintEventDispatcher completely(see swing.showFromDoubleBuffer)?
Actually I still do not understand why JViewport works in the standalone 
application.

One unrelated question. Did you try to use CALayer's embedding 
mechanics? Probably it is possible to add CAlayer which is used by the 
swing and awt to the FX CAlayer? In this case all problems related to 
the painting goes away and it will be much faster, only events should be 
generated(The same way our plugin works see CPlatformEmbeddedFrame).

On 10.12.2013 18:22, Anton V. Tarasov wrote:
> Hi Jim, Sergey and All,
>
> Please review the fix that adds support of Retina displays to 
> JLightweightFrame (which javafx SwingNode is based on).
>
> webrev: http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1
> jira: https://bugs.openjdk.java.net/browse/JDK-8029455
>
> (After the fix goes into jdk9 it should be ported to 8u20 as well, 
> because the functionality is essential for SwingNode.)
>
> The general idea of the fix is as follows.
>
> A BufferedImage instance, being created in the context in which the 
> scale factor is determined and is different from one, is automatically 
> created with appropriately extended size. The image itself becomes a 
> scaled image (a "scale" private field is set on it). By the "context" 
> I mean the circumstances where the BufferedImage is related to a  
> JLightweightFrame, a GraphicsConfiguration, a SurfaceData, or a 
> GraphicsDevice which determine the scale factor.
>
> Here are the related changes:
>
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/java/awt/image/BufferedImage.java.udiff.html
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/sun/awt/image/OffScreenImage.java.udiff.html
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/sun/swing/JLightweightFrame.java.udiff.html 
> (the resizeBuffer method)
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/macosx/classes/sun/lwawt/LWLightweightFramePeer.java.udiff.html
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/sun/awt/image/BufferedImageGraphicsConfig.java.udiff.html
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/macosx/classes/sun/java2d/opengl/CGLGraphicsConfig.java.udiff.html
>
> The "scale" value of a BufferedImage is used when 1) 
> BufferedImageGraphicsConfig is created 2) 
> BufImgSurfaceData.getDefaultScale() is called:
>
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/sun/awt/image/BufferedImageGraphicsConfig.java.udiff.html
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/sun/awt/image/BufImgSurfaceData.java.udiff.html
>
> The former is used in the 
> GraphicsConfiguration.createCompatibleImage() calls, and the latter is 
> used in SurfaceManager.getImageScale(Image):
>
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/sun/awt/image/SurfaceManager.java.udiff.html
>
> A scaled BufferedImage is supported by the SunGraphics2D.drawImage() 
> primitives. Here's the pattern of how the image may be created and drawn:
>
> int scale = <get the scale factor from the context>;
> BufferedImage img = new BufferedImage(width * scale, height * scale, 
> ...);
> img.setScale(scale); // an accessor is currently used instead
> <...>
> g2d.drawImage(img, x, y, ...); // 1) draw the image with auto-scale
> g2d.drawImage(img, x, y, dw, dh, ...) // 2) draw the image into a 
> specified rect
>
> In the first case, if the BufferedImage is created with an extended 
> size, the "scale" value of the image matters, it should be drawn as a 
> HiDPI image.
> In the second case, if the BufferedImage is created with an extended 
> size, the "scale" value of the image doesn't matter (it may not be 
> evidently set) as the image will anyway be scaled from its physical 
> bounds into provided logical bounds. This all should (as I suppose) 
> provide backward compatibility for buffered images that were created 
> in their logical bounds or without setting the "scale" field. For 
> instance, the AquaPainter.paintFromSingleCachedImage(...) method 
> creates & draws an image as follows:
>
> int scale = ((SunGraphics2D) g).surfaceData.getDefaultScale();
> int imgW = bounds.width * scale;
> int imgH = bounds.height * scale;
> BufferedImage img = new BufferedImage(imgW, imgH, ...);
> <paint into the img>
> g.drawImage(img, bounds.x, bounds.y, bounds.width, bounds.height, null);
>
> Here, the img.scale value is not set (I didn't modify this code), and 
> SunGraphics2D doesn't treat the image as a HiDPI image, however it is 
> drawn as expected. An alternative way to draw the image would be:
>
> int scale = ((SunGraphics2D) g).surfaceData.getDefaultScale();
> int imgW = bounds.width * scale;
> int imgH = bounds.height * scale;
> BufferedImage img = new BufferedImage(imgW, imgH, ...);
> img.setScale(scale);
> <paint into the img>
> g.drawImage(img, bounds.x, bounds.y, ...);
>
> The result would be the same.
>
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/sun/java2d/SunGraphics2D.java.sdiff.html
>
> The following changes:
>
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/macosx/classes/sun/lwawt/macosx/CPlatformLWView.java.udiff.html
>
> are defined by this logic. Running Swing via JLightweightFrame (JLF) 
> makes it "display agnostic". Swing is painted to an off-screen buffer 
> and it's the host (e.g. SwingNode) that renders the buffer on a 
> particular device. So, the host should detect the scale of the current 
> display and set it on JLF.
Does it mean that all methods related to the 
Component.getLocationOnScreen() does not work?
>
> However, AWT in order to paint to a volatile image requires 
> CGraphicsDevice and CGLSurfaceData to be created. By default AWT 
> creates CGraphicsDevice instances matching all the detected display 
> devices (CGraphicsEnvironment.initDevices()). But, as JLF doesn't have 
> any platform window behind it, AWT can't match JLF to the exact device 
> it's currently displayed on.
Why? You can try to check it youseft via 
CGLGraphicsConfig.getBounds()+Peer.getBounds();
> So, on the one hand, AWT doesn't know which device is current and what 
> is the current scale (the host passes this value), but from the other 
> hand, AWT has a list of all the CGraphicsDevice instances.
>
> I tried to leverage from that fact. The 
> CPlatformLWView.getGraphicsDevice() method takes the current scale 
> from the JLF instance, and then tries to match it to an existent 
> device from the list. In case it can't find a device with the 
> specified scale (which should not actually happen, unless the host 
> passes an arbitrary scale value, which is not the case for SwingNode) 
> it takes a default device and changes its scale forcedly. I'm not sure 
> if I should create a new dummy device instance instead. The scale 
> factor of the device (which is then propagated to CGLSurfaceData on 
> its creation) is the only info that JLF will take from the device to 
> create a scaled volatile image.
>
> The following changes:
>
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/javax/swing/JViewport.java.udiff.html
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/javax/swing/RepaintManager.java.udiff.html
>
> were made to map a backing store image to a scale factor.
>
> The JViewPort.paint(...) method calls SunGraphics2D.copyArea(...) on 
> scrolling. The method was not implemented for a graphics with a scale 
> transform and a BufImgSurfaceData (it threw exceptions). I took that 
> code, copied it to the BufImgSurfaceData.copyArea(...) and added a 
> general translation for the coords:
>
> - 
> http://cr.openjdk.java.net/~ant/JDK-8029455/webrev.1/src/share/classes/sun/awt/image/BufImgSurfaceData.java.udiff.html
>
> It works, but I'm not sure the implementation is eligible (I don't 
> know the details of the Blit class, at least it warns not to use the 
> same source and dest).
>
> The rest of the changes (not covered here) should be clear.
>
> Testing:
>
> - Using jfc/SwingSet2 and jfc/Java2D demos (in a standalone mode & 
> embedded into SwingNode [1]).
> - Testing both Nimbus and Aqua L&F.
> - Setting swing.volatileImageBufferEnabled=false/true for all 
> combinations.
>
> Currently, I see no regressions and no visual issues comparing a 
> standalone mode and a SwingSet mode.
>
> At the end, I suspect there may be some intersection b/w this fix and 
> the fix which introduced MultiResolutionToolkitImage. Unfortunately, I 
> didn't yet read that review saga... Please tell me if I should 
> incorporate anything from that fix.
>
> Thanks,
> Anton.
>
> [1] There's a SwingSet part of the fix which I'm going to post to the 
> jfx alias separately.
>


-- 
Best regards, Sergey.