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[Win32] TextLayout.getBounds() calculates incorrect width on monitors with non 100% scaling

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#3,461 5 comentarios 0 reacciones 0 asignados Ver en GitHub

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Evaluación

Dificultad
4/5
Tiempo estimado
3-5 días
Aptitud para principiantes
48/100
Tipo de issue
Error
Claridad
Bastante claro
Estado de actividad
Tranquilo
Stack tecnológico
java
Área
desktop

Línea de trabajo

Start by tracing TextLayout.getBounds() and TextLayout.setWidth() in SWT's Windows implementation, using the supplied standalone snippet to reproduce the issue at different monitor scaling levels. Compare the returned bounds and wrapping behavior under disabled and enabled autoscaling, including after moving the window between monitors. Done means the width from getBounds() keeps the text unwrapped in the reported Windows scenarios without breaking autoscaling behavior.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

Describe the bug
TextLayout.getBounds() method returns bad width on monitors with non 100% scaling. The code that I expect to work correctly is the following:

textLayout.setWidth(textLayout.getBounds().width)

When doing this I expect the text of the TextLayout to not wrap. But with certain font sizes and on monitors with non 100% scaling the text wraps. I've initially suspected fractional scaling values like 125%, but testing with 200% shows that the problem is present there too. I've tried to adjust the width by 1px and even by 2px, but it looks like this is not just an off by 1 error.

Note that I am testing this with 2 autoscale modes for the control:

  • AutoscaleMode.DISABLED - the text is wrapped incorrectly
  • AutoscaleMode.ENABLED - the text is correct initially, but broken when window is moved from to another monitor, for example from one with 125% to one with 100% scaling

To Reproduce
A standalone SWT snippet to reproduce the behavior:

package org.eclipse.swt.snippets;

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.AutoscalingMode;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontData;
import org.eclipse.swt.graphics.TextLayout;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class TextLayoutBoundsBug {
	public static void main(String[] args) {
		Display display = new Display();
		final Shell shell = new Shell(display, SWT.SHELL_TRIM | SWT.DOUBLE_BUFFERED);
		shell.setText("TextLayoutBoundsBug");
		shell.setAutoscalingMode(AutoscalingMode.DISABLED);
		shell.setSize(1000, 1000);

		Font font = shell.getFont();
		FontData fontData = font.getFontData()[0];

		createTextLayoutAt(shell, 10, 10, fontData, 42, "Reset", 0);
		createTextLayoutAt(shell, 10, 80, fontData, 41, "Reset", 0);

		createTextLayoutAt(shell, 210, 10, fontData, 42, "Download", 1);
		createTextLayoutAt(shell, 210, 80, fontData, 41, "Download", 1);

		createTextLayoutAt(shell, 510, 10, fontData, 42, "Download & Reset", 2);
		createTextLayoutAt(shell, 510, 80, fontData, 41, "Download & Reset", 2);

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

	private static TextLayout createTextLayoutAt(Control parent, int x, int y, FontData fontData, int fontHeight,
			String text,
			int widthCorrection) {
		Font derivedFont = new Font(parent.getDisplay(),
				new FontData(fontData.getName(), fontHeight, fontData.getStyle()));

		TextLayout textLayout = new TextLayout(parent.getDisplay());
		textLayout.setFont(derivedFont);
		textLayout.setText(text);
		textLayout.setWidth(textLayout.getBounds().width + widthCorrection);
		parent.addListener(SWT.Paint, event -> {
			textLayout.draw(event.gc, x, y);
		});

		return textLayout;
	}
}

Screenshots

  1. AutoscalingMode.DISABLED, 125% scaling. Text is wrapping:
Image
  1. AutoscalingMode.ENABLED, 125% scaling. Text looks correct:
Image

Then moved to monitor with 100% scaling. Text is wrapping again:

Image

Exactly the same problem can be seen with 200% scaling so I am not including additional screenshots.

Environment:

  1. Select the platform(s) on which the behavior is seen:
    • All OS
    • Windows
    • Linux
    • macOS

I've tested this also on Linux with 200% scaling and it worked correctly. Didn't test macOS.

Lenguaje dominante
Java
Estrellas
202
Forks
206
Merge medio
20 h 20 min
PR fusionados (30 d)
113

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