* Deprecating Display#getDPI

Having the scale factor being based on the screen DPI leads to
unexpected result e.g. Image too big/small. Having a screen dpi
independent factor leads to consistent results

Author: ShahzaibIbrahim

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Display.java

@@ -2037,6 +2037,31 @@ public int getIconDepth () {
 	};
 }
 
+/**
+ * Returns the DPI (dots per inch) for the display.
+ * <p>
+ * <strong>Deprecated:</strong> This method returns a single global DPI value
+ * that does not reflect per-monitor DPI settings on modern operating systems.
+ * In environments with different scaling factors across monitors, this method
+ * provides a misleading or meaningless result, as it does not correspond to
+ * the actual DPI of any specific monitor.
+ * </p>
+ * <p>
+ * In most cases, callers should not rely on this method. If a fallback is
+ * needed, a value of 96 DPI (the default baseline for 100% scaling) may be
+ * used.
+ * </p>
+ *
+ * @return the DPI of the display device
+ *
+ * @deprecated Use per-monitor DPI or scaling APIs instead. This method is unreliable in multi-monitor setups with varying DPI.
+ */
+@Deprecated
+@Override
+public Point getDPI () {
+	return super.getDPI();
+}
+
 ImageList getImageList (int style, int width, int height, int zoom) {
 	if (imageList == null) imageList = new ImageList [4];
 

examples/org.eclipse.swt.examples/src/org/eclipse/swt/examples/imageanalyzer/ImageAnalyzer.java

@@ -1165,16 +1165,16 @@ void menuPrint() {
 		if (image == null) return;
 
 		try {
+			final int DOTS_PER_INCH = 96;
 			// Ask the user to specify the printer.
 			PrintDialog dialog = new PrintDialog(shell, SWT.NONE);
 			if (printerData != null) dialog.setPrinterData(printerData);
 			printerData = dialog.open();
 			if (printerData == null) return;
 
 			Printer printer = new Printer(printerData);
-			Point screenDPI = display.getDPI();
 			Point printerDPI = printer.getDPI();
-			int scaleFactor = printerDPI.x / screenDPI.x;
+			int scaleFactor = printerDPI.x / DOTS_PER_INCH;
 			Rectangle trim = printer.computeTrim(0, 0, 0, 0);
 			if (printer.startJob(currentName)) {
 				if (printer.startPage()) {

examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet361.java

@@ -146,6 +146,7 @@ public void getName(AccessibleEvent e) {
 	}
 
 	private static void performPrintAction(final Display display, final Shell shell) {
+		final int DOTS_PER_INCH = 96;
 		Rectangle r = composite.getBounds();
 		Point p = shell.toDisplay(r.x, r.y);
 		org.eclipse.swt.graphics.Image snapshotImage
@@ -159,9 +160,8 @@ private static void performPrintAction(final Display display, final Shell shell)
 		data = dialog.open();
 		if (data != null) {
 			Printer printer = new Printer(data);
-			Point screenDPI = display.getDPI();
 			Point printerDPI = printer.getDPI();
-			int scaleFactor = printerDPI.x / screenDPI.x;
+			int scaleFactor = printerDPI.x / DOTS_PER_INCH;
 			Rectangle trim = printer.computeTrim(0, 0, 0, 0);
 			if (printer.startJob("Print Image")) {
 				ImageData imageData = snapshotImage.getImageData();

examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet367.java

@@ -185,7 +185,7 @@ public int getGcStyle() {
 
 		createSeparator(shell);
 
-		new Label (shell, SWT.NONE).setText ("5. 50x50 box\n(Display#getDPI(): " + display.getDPI().x + ")");
+		new Label (shell, SWT.NONE).setText ("5. 50x50 box");
 		Label box= new Label (shell, SWT.NONE);
 		box.setBackground(display.getSystemColor(SWT.COLOR_WIDGET_DARK_SHADOW));
 		box.setLayoutData (new GridData (50, 50));

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Display.java

@@ -1573,6 +1573,7 @@ public void test_wake() {
 /* custom */
 boolean disposeExecRan;
 
+@SuppressWarnings("deprecation")
 @Test
 public void test_getDPI() {
 	Display display = new Display();