RFR: 8187759: Background not refreshed when painting over a transparent JFrame

[Abhishek Kumar]

On Tue, 12 Dec 2023 13:04:26 GMT, Tejesh R <tr at openjdk.org> wrote:

> This is happening in linux where `BuffereStrategyPaintManager` is used to paint to offscreen. Here `bsg` bufferStrategy SunGraphics2D is used to paint to offscreen where the background is not refreshed, which does only clipping and then paints to offscreen. In order to handle the screen updated/clear the buffer, `setBackground` to component background color and `clearRect` against the clip area is used which solves the issue without causing any regression. 
> CI is green for the fix and manual test is provided.

test/jdk/javax/swing/JFrame/JFrameBackgroundRefreshTest.java line 89:

> 87:         frame.addMouseMotionListener(new MouseDragListener());
> 88:         frame.setVisible(true);
> 89: 

May not require.

test/jdk/javax/swing/JFrame/JFrameBackgroundRefreshTest.java line 90:

> 88:         frame.setVisible(true);
> 89: 
> 90:     }

Blank line before method.

test/jdk/javax/swing/JFrame/JFrameBackgroundRefreshTest.java line 101:

> 99:     /** Capture an image of any component **/
> 100:     private static BufferedImage getImage(Component c) {
> 101:         if(c==null) return null;

Suggestion:

        if (c == null) {
            return null;
        }

test/jdk/javax/swing/JFrame/JFrameBackgroundRefreshTest.java line 122:

> 120:         public TranslucentPane() {
> 121:             setOpaque(false);
> 122:         }

Blank line after this.

test/jdk/javax/swing/JFrame/JFrameBackgroundRefreshTest.java line 129:

> 127:             g2d.setColor(new Color(0,0,0,0));
> 128:             g2d.fillRect(0, 0, getWidth(), getHeight());
> 129:             g2d.drawImage(test, p.x, p.y, this);

should we dispose `Graphics2D` object?

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PR Review Comment: https://git.openjdk.org/jdk/pull/17081#discussion_r1449902105
PR Review Comment: https://git.openjdk.org/jdk/pull/17081#discussion_r1449901861
PR Review Comment: https://git.openjdk.org/jdk/pull/17081#discussion_r1449902602
PR Review Comment: https://git.openjdk.org/jdk/pull/17081#discussion_r1449903249
PR Review Comment: https://git.openjdk.org/jdk/pull/17081#discussion_r1449904073