On Sun, 6 Sep 2026 22:27:53 GMT, John Hendrikx <[email protected]> wrote:
>> This PR adds a `getDrawingContext` method to `WritableImage`, which works >> similar to `Canvas::getGraphicsContext` and shares the same signatures. Key >> features include: >> >> - **Shape rendering**: `strokeRect`, `fillRect`, `strokeOval`, `fillOval`, >> `strokeArc`, `fillArc`, `strokePolyline`, `fillPolygon`, etc. >> - **Stroke and fill attributes**: `lineWidth`, `lineCap`, `lineJoin`, >> `miterLimit`, `fillRule`, `stroke` and `fill` paints. >> - **Global graphics settings**: `globalAlpha` and `globalBlendMode`. >> - **Image drawing**: draw other `Image` instances with scaling and >> source/destination rectangles. >> - **Text rendering**: render text >> - **Save/Restore**: store current stroke, font, dashes, etc and restore them >> later >> - **Paths**: begin a path, with lines, curves, etc, then stroke or fill it >> - **Clips**: support rectangular clips in the SW renderer >> >> This feature enables direct software rendering to `WritableImage` without >> requiring a `Canvas` + snapshot. >> >> **Additional notes**: >> >> - The implementation leverages the software stack consisting of the Marlin >> rasterizer and Pisces compositor/painter. >> >> **Example usage**: >> >> >> WritableImage img = new WritableImage(400, 400); >> DrawingContext ctx = img.getDrawingContext(); >> ctx.setFill(Color.RED); >> ctx.fillRect(50, 50, 100, 100); >> >> >> See the sample program `RandomShapesDemo` to see a `WritableImage` and >> `Canvas` side by side performing the same operations: >> >> <img width="1249" height="741" alt="image" >> src="https://github.com/user-attachments/assets/4a0b9dcc-8f96-4faa-99cf-83c66d2c851e"; >> /> >> >> Newer version: >> >> <img width="1249" height="741" alt="image" >> src="https://github.com/user-attachments/assets/c0502620-3d02-4fbd-8c33-43bd5138b42c"; >> /> >> >> --------- >> - [x] I confirm that I make this contribution in accordance with the >> [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). > > John Hendrikx has updated the pull request incrementally with one additional > commit since the last revision: > > Optimized dirty rect handling (benefits more than just SWDraingContext) Regarding performance: I removed the TODO about dirty rect handling in `SWDrawingContext` now. I've added what I think is a sufficient optimization to `Image.Serial` that may also benefit other cases where multiple rects get dirtied in between render operations. The way it works is that the dirty rect is now accumulated until something actually has read it. This means that doing multiple drawing operations in a single frame now just expand the dirty rect instead of invalidating the previous one immediately (which then requires a full image upload). Before just doing two draw ops would require a full upload; now you can do dozens of ops and it will only upload the changed area. I noticed that `PixelWriter` is very poor with this (manipulating a single pixel requires a full upload), but that is a bit out of scope of this PR to fix. ------------- PR Comment: https://git.openjdk.org/jfx/pull/1969#issuecomment-5562655577
