Use always advanced mode of GC with GEF

[akoch-yatta]

Description
In GEF rendering of strings is usually tightly coupled to calculating sizes of string, e.g. before tooltips are rendered the required sizes is calculated and the parent Shell is resized to it. Having the advanced mode enabled or disabled in the GC can return in different sizes for the same text - usually the advanced mode will return bigger sizes. If the text size was calculated without the advanced mode and the rendering is done with it, this can result in a cut-off text.

As the advanced mode for the GC can be activated on different ways (e.g. setting anti alias, setting a transform, drawing a path) it is usually impossible to predict whether it will be used when text sizes are calculated, as this is done before the rendering. Therefor always using the advanced mode for the GC in GEF be preferred.

To Do

Two main topics for this issue are:

• Evaluate and decide on the best way to ensure this, e.g. explicitly setting it in GEF with GC#setAdvanced in all places or activating it in Drawable#internal_new_GC. One alternative could be to make the advanced mode the default for GC - at least in windows
• Ensure no test failures for GEF

[arunjose696]

I tried locally by enabling the advanced mode in the GC contructor by default (calling initGdip() in GC(Drawable drawable, int style) the IDE and GEF diagrams seems okay in general observation

I also ran a benchmark where shape, image, and text were drawn 100,000 times using a GC in both normal and advanced modes.

Advanced mode completed in ~5970 ms with ~43743 KB memory.
Normal mode completed in ~6601 ms with ~43511 KB memory.

Memory usage is roughly the same between modes, but advanced mode shows a speed improvement.

Here is the script that was used for benchmarking

package org.eclipse.swt.snippets;
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

public class GCBench {
    private static final int DRAW_OPERATIONS = 100000;

    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("SWT GC Advanced Mode Benchmark");
        shell.setSize(800, 600);

        Image image = new Image(display, "src/org/eclipse/swt/snippets/eclipse16.svg");

        // Run benchmark on open
        shell.addListener(SWT.Paint, e -> {
            System.gc();
            long memBefore = usedMemory();
            long start = System.nanoTime();
            Rectangle area = e.gc.getClipping();

            for (int i = 0; i < DRAW_OPERATIONS; i++) {
                int x = (int) (Math.random() * area.width);
                int y = (int) (Math.random() * area.height);
                int w = 10 + (int) (Math.random() * 40);
                int h = 10 + (int) (Math.random() * 40);


                e.gc.drawRectangle(x, y, w, h);
                e.gc.fillOval(x, y, w, h);
                e.gc.drawString("Test", x, y, true);
                e.gc.drawImage(image, x, y);

            }

            long end = System.nanoTime();
            long memAfter = usedMemory();

            System.out.println(" Time:" +(end - start) / 1_000_000.0+" | Mem: "+ (memAfter - memBefore) / 1024

                   );
        });
        shell.open();
        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) display.sleep();
        }
        display.dispose();
    }



    private static long usedMemory() {
        Runtime r = Runtime.getRuntime();
        return r.totalMemory() - r.freeMemory();
    }
}

[akoch-yatta]

After some discussion we decided, that enabling the advanced mode by default for the GC has too much risk in it.

We will reshape the scope of the ticket to analyze the enabling of the advanced mode in GC to eventually propose enabling it programmatically in GEF by default. Therefor we should investigate where the advanced mode is currently activated in common diagrams like the logic or the flow editor.