Limit monitor-specific scaling to supported autoscale modes

These changes have following affects:

- Upon starting eclipse product when monitor-specific scaling is set
with unsupported autoscale mode, it will show a error dialog and
application won't start.
- User won't be able to enable monitor-specific scaling from appearance
page if unsupported autoscale mode is set from property or ini file.
- User can then either force the unsupported autoscale mode with monitor
specific-scaling by setting swt.autoScale.force to true or switch to
supported autoscale mode.

Author: ShahzaibIbrahim

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/Workbench.java

@@ -148,6 +148,7 @@
 import org.eclipse.osgi.service.runnable.StartupMonitor;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.swt.SWT;
+import org.eclipse.swt.SWTError;
 import org.eclipse.swt.SWTException;
 import org.eclipse.swt.browser.Browser;
 import org.eclipse.swt.custom.BusyIndicator;
@@ -704,6 +705,9 @@ private static void setRescaleAtRuntimePropertyFromPreference() {
 					.getBoolean(IWorkbenchPreferenceConstants.RESCALING_AT_RUNTIME, true);
 			System.setProperty(SWT_RESCALE_AT_RUNTIME_PROPERTY, Boolean.toString(rescaleAtRuntime));
 		}
+		if (Boolean.getBoolean(System.getProperty(SWT_RESCALE_AT_RUNTIME_PROPERTY))) {
+			DPIUtil.setAutoScaleForMonitorSpecificScaling();
+		}
 	}
 
 	private static void setSearchContribution(MApplication app, boolean enabled) {
@@ -773,6 +777,9 @@ public static Display createDisplay() {
 
 		setRescaleAtRuntimePropertyFromPreference();
 
+		if (DPIUtil.isMonitorSpecificScalingActive() && !DPIUtil.isSetupCompatibleToMonitorSpecificScaling()) {
+			showMonitorSpecificIncompambatibilityDialog();
+		}
 		// create the display
 		Display newDisplay = Display.getCurrent();
 		if (newDisplay == null) {
@@ -802,6 +809,15 @@ public static Display createDisplay() {
 		return newDisplay;
 	}
 
+	private static void showMonitorSpecificIncompambatibilityDialog() throws SWTError {
+		MessageDialog.openError(new Shell(Display.getDefault()), WorkbenchMessages.RescaleAtRuntimeIncompatibilityTitle,
+				NLS.bind(WorkbenchMessages.RescaleAtRuntimeIncompatibilityDescription,
+						DPIUtil.getAutoScaleValue()));
+		throw new SWTError(SWT.ERROR_NOT_IMPLEMENTED,
+				"monitor-specific scaling is only implemented for auto-scale values \"quarter\" and \"exact\", but \"" //$NON-NLS-1$
+						+ DPIUtil.getAutoScaleValue() + "\" has been specified"); //$NON-NLS-1$
+	}
+
 	/**
 	 * Create the splash wrapper and set it to work.
 	 *

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/WorkbenchMessages.java

@@ -38,6 +38,12 @@ public class WorkbenchMessages extends NLS {
 
 	public static String RescaleAtRuntimeDescription;
 
+	public static String RescaleAtRuntimeDisabledDescription;
+
+	public static String RescaleAtRuntimeIncompatibilityTitle;
+
+	public static String RescaleAtRuntimeIncompatibilityDescription;
+
 	public static String RescaleAtRuntimeEnabled;
 
 	public static String RescaleAtRuntimeSettingChangeWarningTitle;

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/dialogs/ViewsPreferencePage.java

@@ -53,6 +53,7 @@
 import org.eclipse.jface.dialogs.MessageDialog;
 import org.eclipse.jface.fieldassist.ControlDecoration;
 import org.eclipse.jface.fieldassist.FieldDecorationRegistry;
+import org.eclipse.jface.layout.GridDataFactory;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.jface.preference.PreferencePage;
 import org.eclipse.jface.viewers.ArrayContentProvider;
@@ -65,7 +66,9 @@
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.events.SelectionListener;
+import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.graphics.Image;
+import org.eclipse.swt.internal.DPIUtil;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Button;
@@ -222,7 +225,16 @@ private void createRescaleAtRuntimeCheckButton(Composite parent) {
 				.getBoolean(IWorkbenchPreferenceConstants.RESCALING_AT_RUNTIME, true);
 		rescaleAtRuntime = createCheckButton(parent, WorkbenchMessages.RescaleAtRuntimeEnabled,
 				initialStateRescaleAtRuntime);
-		rescaleAtRuntime.setToolTipText(WorkbenchMessages.RescaleAtRuntimeDescription);
+		if (!DPIUtil.isSetupCompatibleToMonitorSpecificScaling()) {
+			rescaleAtRuntime.setEnabled(false);
+			Font font = parent.getFont();
+			Composite note = createNoteComposite(font, parent, WorkbenchMessages.Preference_note,
+					WorkbenchMessages.RescaleAtRuntimeDisabledDescription);
+			note.setLayoutData(GridDataFactory.swtDefaults().span(2, 1).create());
+		} else {
+			rescaleAtRuntime.setEnabled(true);
+			rescaleAtRuntime.setToolTipText(WorkbenchMessages.RescaleAtRuntimeDescription);
+		}
 	}
 
 	private void createThemeIndependentComposits(Composite comp) {

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/messages.properties

@@ -504,7 +504,10 @@ RescaleAtRuntimeSettingChangeWarningTitle = DPI Setting Changed
 RescaleAtRuntimeSettingChangeWarningText = Restart for the DPI setting changes to take effect
 HiDpiSettingsGroupTitle = HiDPI settings
 RescaleAtRuntimeDescription = Activating this option will dynamically scale all windows according to the monitor they are currently in
+RescaleAtRuntimeDisabledDescription = Incompatible autoscale value was defined via system property or ini
 RescaleAtRuntimeEnabled = Use monitor-specific UI &scaling
+RescaleAtRuntimeIncompatibilityTitle = Scaling Configuration Error
+RescaleAtRuntimeIncompatibilityDescription = Monitor-specific scaling is currently active with the wrong autoscale value (''{0}''). This combination may lead to unexpected UI scaling behavior. Please review your auto-scaling configuration.
 # --- Workbench -----
 WorkbenchPreference_openMode=Open mode
 WorkbenchPreference_doubleClick=D&ouble click