Limit monitor-specific scaling to supported autoscale modes

[ShahzaibIbrahim]

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.

Testing

---

Scenario#1: Starting application with -Dswt.autoScale=int200

Result: App should start (if monitor-specific scaling is not checked in Appearance page), but option to turn on monitor-specific scaling in Appearance page should be disabled.

---

Scenario#2: Starting application with -Dswt.autoScale=int200 and -Dswt.autoScale.updateOnRuntime=true

Result: App will start, user will see an error dialog stating the incompatibility of an option and monitor specific-scaling will be disabled.

---

Scenario#3: Starting application with -Dswt.autoScale=int200 and -Dswt.autoScale.updateOnRuntime=true
and -Dswt.autoScale.force=true

Result: makes more sense with swt applications. if user really wants to use other scaling mode with monitor-specific scaling.

import org.eclipse.swt.widgets.*;

public class AutoScaleSnippet {

public static void main (String [] args) {
	System.setProperty("swt.autoScale.updateOnRuntime", "true");
	System.setProperty("swt.autoScale", "int200");
	System.setProperty("swt.autoScale.force", "true");
	Display display = new Display ();
	Shell shell = new Shell(display);
	shell.setText("Autoscale snippet");
	shell.open ();
	while (!shell.isDisposed ()) {
		if (!display.readAndDispatch ()) display.sleep ();
	}
	display.dispose ();
}

---

Scenario#4: Starting application with -Dswt.autoScale=quarter

Result: App should start, and user should be able to turn on/off the monitor-specific scaling in Appearance page.

---

Note: following is the list of allowed autoscale values to be paired with monitor-specific scaling: ["false", "quarter", "exact"]

Dependency

• Requires: [Refactor] Moving methods from Win32DPIUtil to DPIUtil for autoscaling eclipse.platform.swt#2709

[github-actions]

Test Results

0 files   -  3 018  0 suites   - 3 018   0s ⏱️ - 2h 23m 4s
0 tests  -  8 234  0 ✅  -  7 985  0 💤  - 249  0 ❌ ±0 
0 runs   - 23 622  0 ✅  - 22 828  0 💤  - 794  0 ❌ ±0 

Results for commit 938b37b. ± Comparison against base commit 3a441d9.

♻️ This comment has been updated with latest results.

[ShahzaibIbrahim]

Test failures are due to dependent PR: eclipse-platform/eclipse.platform.swt#2709 not being merged yet.