How to extract a CSS property from CSS file.

[ethanyhou]

Hi team, is there a way to extract a CSS property from a CSS file?

We want to apply a color to the GC of a Canvas. However, the GC doesn't support the setData API, and we can only use setBackground to apply color changes. To avoid hardcoding the color, we’d like to extract the color property directly from the CSS file.
Is there a way to achieve this?

Simple code snippet:

cardCanvas.addPaintListener(new PaintListener() {
      @Override
      public void paintControl(PaintEvent e) {
        GC gc = e.gc;
        // Get background color from stored data, fallback to canvas background
        // Color bgColor = null; // How to get a color from CSS file?
        gc.setBackground(bgColor);
        Rectangle bounds = cardCanvas.getBounds();
        gc.fillRoundRectangle(2, 2, bounds.width - 5, bounds.height - 5, 15, 15);
      }
    });

Appreciate it.

[vogella]

You can use CSS to set a color preference value and use it in your code. Example: https://www.vogella.com/tutorials/EclipseEditors/article.html#adding-colors-and-fonts-preferences

[ethanyhou]

Appreciate it @vogella , this works!

[ethanyhou]

Hi @vogella ,

Thank you for your response.

One more quick question, we noticed that in this way the color will be exposed to the client and the colors will also be configurable:

Is there any way to hide the color configurations or block color editing?

Thanks.

[mickaelistria]

Is there any way to hide the color configurations or block color editing?

I think you usually don't want that. Users will never complain for being able to replace a color (it can even be an important accessibility feature for colorblind people who usually need a more contrasted palette), and having code that hides or disable this page is just more work for you. So the return on investment seems rather negative.

But if you really want it, there are probably some ways to achieve that with a bunch of listeners: a listener on the workbench or the root Shell to detect when the Preference wizard is open, then add a listener on the Preference wizard to listen to page change, and when the colors page is open, call setEnabled(false) and place a pop-up on the page to explicit you've disabled this feature intentionally.

[vogella]

You can use any preference in CSS, so if you want just use another preference without the color and fonts extension point.