SVG rasterization mac is low-resolution

[nedtwigg]

Describe the bug
The new SVG rasterization seems to not be HiDPI on macOS.

To Reproduce

• Before: ImageDescriptor.createFromFile("foo.png") (with a @2x.png available also)
• After: ImageDescriptor.createFromFile("foo.svg") with the new (org.eclipse.swt.svg applied)

Expected behavior
I expected the SVG to render at high-resolution for the mac.

Screenshots

Top row is @2x.png, bottom row is .svg

Environment:

1. Select the platform(s) on which the behavior is seen:

• • All OS
• • Windows
• • Linux
• • macOS

2. Additional OS info (e.g. OS version, Linux Desktop, etc)
   macOS Sequoia 15.5

3. JRE/JDK version
   21

Version since
Eclipse 4.36

[fedejeanne]

cc @HeikoKlare , @Michael5601 .

Is there anything that can be done here? How much influence do we have over the scaling algorithm?

[tmssngr]

I reckon, it needs to be rasterized with doubled (= pixel) scaling.

[HeikoKlare]

I can see the issue also in, e.g., toolbars, of Eclipse products on MacOS. The icons look as if they are upscaled from their 100% version. SVGs are of course rendered in whatever zoom they are needed. I have not seen any issues withthat behavior on Windows so far. So there seems to be a specific bug in how this is handled on MacOS, which means that it's probably an issue of the Image class.

[Phillipus]

Most Macs these days have "retina" displays so hi-dpi x2 is the norm. However, it is possible to have an external x1 dpi display so don't assume it will always be x2.

[HeikoKlare]

I can see the issue also in, e.g., toolbars, of Eclipse products on MacOS. The icons look as if they are upscaled from their 100% version. SVGs are of course rendered in whatever zoom they are needed. I have not seen any issues withthat behavior on Windows so far. So there seems to be a specific bug in how this is handled on MacOS, which means that it's probably an issue of the Image class.

I have to revoke my statement: I took a look at how the icons look in dark theme and they appeared more blurry because of the interpolation with the background. Everything looks fine for me in Eclipse products with a 200% display.

@nedtwigg can you please give us a reproducer? The method ImageDescriptor.createFromFile(String) does not exist, so having a small snippet would be nice.

[nedtwigg]

I'm on an M4 Macbook Air, no external display:

Here is the code that produced the screenshot above

// two-column grid
Layouts.setGrid(parent).numColumns(2);

// “.svg” label + image
Label svgLabel = new Label(parent, SWT.NONE);
svgLabel.setText(".svg");

Label svgImage = new Label(parent, SWT.NONE);
ImageDescriptor svgDesc = ImageDescriptor.createFromFile(
		Issue_2228.class, "/issue_2228/strikethrough.svg");
svgImage.setImage(svgDesc.createImage());

// “.png” label + image
Label pngLabel = new Label(parent, SWT.NONE);
pngLabel.setText(".png");

Label pngImage = new Label(parent, SWT.NONE);
ImageDescriptor pngDesc = ImageDescriptor.createFromFile(
		Issue_2228.class, "/issue_2228/strikethrough.png");
pngImage.setImage(pngDesc.createImage());

And if it's helpful here's that code in an easy-to run test:

• Demonstrate that SVG rasterization on mac is low-resolution  diffplug/durian-swt#33