Allow Rulers with a Custom Dots Per Unit Setting (#613)

With this change the API of the RulerProvider class is extended with a
custom dots per unit setting. This allows clients to use our default
Ruler Figure adjusted to application specific resolutions and drawing
scales.

As part of this change the RulerFigure was cleaned by splitting the
paintFigure method in several methods for increased readability and
maintainability.

Bugzilla entry: https://bugs.eclipse.org/bugs/show_bug.cgi?id=105493

Co-authored-by: Patrick Ziegler <[email protected]>

CHANGELOG.md

@@ -9,6 +9,7 @@
  - The look of the palette viewer can be customized via the ColorProvider interface. Supported model elements and properties are:
    - PaletteEntry (hover, selection) 
    - PaletteTemplateEntry (selection)
+ - Rulers can now be created with custom dots per unit settings. The `RulerProvider` interface has now a new unit constant `UNIT_CUSTOM`. When this is used the `RulerProvider` can provide via the new `getCustomRulerDPU()` an application specific dots per unit setting.
 
 ## Zest
  - Integration of Zest 2.0 development branch. See the [wiki](https://github.com/eclipse-gef/gef-classic/wiki/Zest#zest-2x) for more details. In case only default layout algorithms are used, the initial migration should be seamless. Otherwise the algorithms can be adapted to run in legacy mode by extending `AbstractLayoutAlgorithm.Zest1` or have to be re-implemented using the new API by extending `AbstractLayoutAlgorithm`. Note that this legacy mode will be removed in a future release. The following list contains the most significant, deprecated features:

org.eclipse.gef.tests/src/org/eclipse/gef/test/RulerLayoutTests.java

@@ -52,7 +52,12 @@ public void setUp() {
 		constraint = 42;
 		figure = new Figure();
 		dummy = new Figure();
-		container = new RulerFigure(true, RulerProvider.UNIT_CENTIMETERS);
+		container = new RulerFigure(true, new RulerProvider() {
+			@Override
+			public int getUnit() {
+				return RulerProvider.UNIT_CENTIMETERS;
+			}
+		});
 		container.add(figure, (Object) constraint);
 		container.add(dummy);
 		rulerLayout = (RulerLayout) container.getLayoutManager();

org.eclipse.gef/.settings/.api_filters

@@ -16,6 +16,14 @@
             </message_arguments>
         </filter>
     </resource>
+    <resource path="src/org/eclipse/gef/rulers/RulerProvider.java" type="org.eclipse.gef.rulers.RulerProvider">
+        <filter id="336658481">
+            <message_arguments>
+                <message_argument value="org.eclipse.gef.rulers.RulerProvider"/>
+                <message_argument value="UNIT_CUSTOM"/>
+            </message_arguments>
+        </filter>
+    </resource>
     <resource path="src/org/eclipse/gef/ui/actions/AlignmentRetargetAction.java" type="org.eclipse.gef.ui.actions.AlignmentRetargetAction">
         <filter id="571473929">
             <message_arguments>

org.eclipse.gef/src/org/eclipse/gef/internal/ui/rulers/RulerEditPart.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2003, 2023 IBM Corporation and others.
+ * Copyright (c) 2003, 2024 IBM Corporation and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
@@ -96,7 +96,7 @@ protected void createEditPolicies() {
 	 */
 	@Override
 	protected IFigure createFigure() {
-		RulerFigure ruler = new RulerFigure(isHorizontal(), getRulerProvider().getUnit());
+		RulerFigure ruler = new RulerFigure(isHorizontal(), getRulerProvider());
 		if (ruler.getUnit() == RulerProvider.UNIT_PIXELS) {
 			ruler.setInterval(100, 2);
 		}