Image loading errors

[fipro78]

When trying to load in image via URLImageDescriptor.createImage() I get a NPE.

java.lang.NullPointerException
        at java.base/java.io.File.<init>(File.java:278)
        at org.eclipse.swt.graphics.GraphicsUtils.getFilename(GraphicsUtils.java:103)
        at org.eclipse.swt.graphics.SwtImage.<init>(SwtImage.java:568)
        at org.eclipse.swt.graphics.Image.<init>(Image.java:423)
        at org.eclipse.jface.resource.URLImageDescriptor.createImage(URLImageDescriptor.java:300)
        at org.eclipse.jface.resource.ImageDescriptor.createImage(ImageDescriptor.java:331)
        at org.eclipse.jface.resource.ImageDescriptor.createImage(ImageDescriptor.java:309)
        at org.eclipse.nebula.widgets.nattable.util.GUIHelper.getImage(GUIHelper.java:512)

My application catches the exception and tries to open an error dialog, which also fails

Caused by: java.lang.IllegalArgumentException: Argument cannot be null
        at org.eclipse.swt.SWT.error(SWT.java:5004)
        at org.eclipse.swt.SWT.error(SWT.java:4937)
        at org.eclipse.swt.SWT.error(SWT.java:4908)
        at org.eclipse.swt.graphics.SwtImage.setBackground(SwtImage.java:1849)
        at org.eclipse.swt.graphics.Image.setBackground(Image.java:755)
        at org.eclipse.jface.dialogs.IconAndMessageDialog.createMessageArea(IconAndMessageDialog.java:92)
        at org.eclipse.jface.dialogs.ErrorDialog.createDialogArea(ErrorDialog.java:242)
        at org.eclipse.jface.util.SafeRunnableDialog.createDialogArea(SafeRunnableDialog.java:94)
        at org.eclipse.jface.dialogs.IconAndMessageDialog.createDialogAndButtonArea(IconAndMessageDialog.java:225)
        at org.eclipse.jface.dialogs.ErrorDialog.createDialogAndButtonArea(ErrorDialog.java:262)
        at org.eclipse.jface.dialogs.IconAndMessageDialog.createContents(IconAndMessageDialog.java:204)

It seems that loading an image always fails somehow.

[fipro78]

I think I located the issue. I started the application on Windows and I have a scaling of 150%. If I get it right, you always return null if the zoom is not 100

swt-evolve/swt_native/src/windows/java/org/eclipse/swt/graphics/SwtImage.java

Lines 527 to 532 in 910666b

	this.imageProvider = new ImageFileNameProviderWrapper(zoom -> {
	if (zoom == 100) {
	return filename;
	}
	return null;
	});

I tried to start the application with -Dswt.autoScale.updateOnRuntime=true which does not solve the issue and actually has a really bad result in the SWT Evolve rendering. It seems that SWT Evolve does not support the autoscale feature of SWT.

[agustinschilling]

Hi @fipro78 !

Thanks for digging into this and sharing your findings.

The scaling behavior is something we still need to review in more detail. We’ll investigate it and keep you updated once we have fixes or improvements available.