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"] or any concrete zoom value e.g. 225

Dependency

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

[github-actions]

Test Results

 3 018 files  ±0   3 018 suites  ±0   2h 14m 33s ⏱️ - 2m 48s
 8 242 tests ±0   7 994 ✅ ±0  248 💤 ±0  0 ❌ ±0 
23 646 runs  ±0  22 855 ✅ ±0  791 💤 ±0  0 ❌ ±0 

Results for commit 939256f. ± Comparison against base commit 2a814c8.

♻️ 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.

[amartya4256]

I have tested the PR and it seems good to me. Approving.

[HeikoKlare]

The many test failures seem to be because actually the DPIUtil#isSetupCompatibleToMonitorSpecificScaling() implementation is currently wrong. It erroneously considers the default autoScale value as incompatible:
https://github.com/eclipse-platform/eclipse.platform.swt/blob/407cb9a1672e429a9ea3272e74bc5588b90e3f12/bundles/org.eclipse.swt/Eclipse%20SWT/common/org/eclipse/swt/internal/DPIUtil.java#L142-L145

That will be implicitly fixed with:

• Limit autoscale mode to quarter and exact only eclipse.platform.swt#2771

For that reason, I propose to process that PR first. I wanted to merge it after this one to avoid that a consumer with a to-be-made-incompatible swt.autoScale value will not see the application start anymore instead of gracefully dealing with the situation as implemented in this PR, but given that's it will be integrated with just one day of delay and hopefully no up-to-date I-Build consumers use such outdated autoscale configurations anyway, it's probably okay to do it like that.

[HeikoKlare]

I have squashed the commits and adapted the commit message to only reflect the changes to Platform UI and not the ones to SWT.