IllegalArgumentException when painting image while running out of handles

[ptziegler]

Describe the bug

Trying to paint an image while all available handles have been consumed fails with an IllegalArgumentException instead of an SWTError.

To Reproduce

package gef;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class DrawGC2 {

	public static void main(String[] args) {
		Shell shell = new Shell();
		Display display = shell.getDisplay();

		int width = 310;
		int height = 310;

		List<Image> images = new ArrayList<>();
		for (int i = 0; i < 8000; ++i) {
			Image image = new Image(display, width, height);
			GC gc = new GC(image);
			gc.dispose();
			images.add(image);
		}

		shell.addPaintListener(event -> {
			for (Image image : images) {
				event.gc.drawImage(image, 0, 0, width, height, 0, 0, 100, 100);
			}
		});

		shell.open();

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

		images.forEach(Image::dispose);
	}
}

Stacktrace:

Exception in thread "main" java.lang.IllegalArgumentException: Argument not valid
	at org.eclipse.swt.SWT.error(SWT.java:4915)
	at org.eclipse.swt.SWT.error(SWT.java:4849)
	at org.eclipse.swt.SWT.error(SWT.java:4820)
	at org.eclipse.swt.graphics.ImageData.<init>(ImageData.java:439)
	at org.eclipse.swt.graphics.ImageData.<init>(ImageData.java:287)
	at org.eclipse.swt.graphics.Image$DestroyableImageHandle.getImageData(Image.java:3305)
	at org.eclipse.swt.graphics.Image$AbstractImageProviderWrapper.getClosestAvailableImageData(Image.java:2106)
	at org.eclipse.swt.graphics.Image$PlainImageProviderWrapper.loadImageData(Image.java:2388)
	at org.eclipse.swt.graphics.Image$HandleAtSize.getOrCreateImageHandleAtClosestSize(Image.java:254)
	at org.eclipse.swt.graphics.Image$HandleAtSize.lambda$0(Image.java:225)
	at java.base/java.util.Optional.orElseGet(Optional.java:364)
	at org.eclipse.swt.graphics.Image$HandleAtSize.refresh(Image.java:225)
	at org.eclipse.swt.graphics.Image.executeOnImageHandleAtBestFittingSize(Image.java:968)
	at org.eclipse.swt.graphics.GC$DrawScalingImageToImageOperation.draw(GC.java:1240)
	at org.eclipse.swt.graphics.GC$DrawScalingImageToImageOperation.apply(GC.java:1222)
	at org.eclipse.swt.graphics.GC.storeAndApplyOperationForExistingHandle(GC.java:6136)
	at org.eclipse.swt.graphics.GC.drawImage(GC.java:1152)
	at gef.DrawGC2.lambda$0(DrawGC2.java:30)
	at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:272)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:91)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4363)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1217)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1241)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1226)
	at org.eclipse.swt.widgets.Composite.WM_PAINT(Composite.java:1627)
	at org.eclipse.swt.widgets.Control.windowProc(Control.java:5021)
	at org.eclipse.swt.widgets.Canvas.windowProc(Canvas.java:336)
	at org.eclipse.swt.widgets.Decorations.windowProc(Decorations.java:1490)
	at org.eclipse.swt.widgets.Shell.windowProc(Shell.java:2446)
	at org.eclipse.swt.widgets.Display.windowProc(Display.java:5131)
	at org.eclipse.swt.internal.win32.OS.UpdateWindow(Native Method)
	at org.eclipse.swt.widgets.Decorations.setVisible(Decorations.java:1322)
	at org.eclipse.swt.widgets.Shell.setVisible(Shell.java:2192)
	at org.eclipse.swt.widgets.Shell.open(Shell.java:1334)
	at gef.DrawGC2.main(DrawGC2.java:34)

Expected behavior

SWT should return a proper error message. Ideally an "No more handles" error.

Environment:

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

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

Version since
Only tested on master.

Additional information

I think the problem is that the return value is not validated when calling GetDIBits, for example here:

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/graphics/Image.java

Lines 3254 to 3257 in 725c948

	/* Call with null lpBits to get the image size */
	OS.GetDIBits(hBitmapDC, handle(), 0, height, null, bmi, OS.DIB_RGB_COLORS);
	OS.MoveMemory(bmiHeader, bmi, BITMAPINFOHEADER.sizeof);
	imageSize = bmiHeader.biSizeImage;

From the documentation:

If the function fails, the return value is zero.

Which is the case here, resulting in an "empty" image data, causing the validation error.

[fedejeanne]

cc @HeikoKlare