Add dynamic start angle functionality to CircleProgressIndicator

The update made to the CircleProgressIndicator and CircleProgressIndicatorSkin allows the start angle of the progress arc to be dynamically changed. This is done by binding a new startAngle property to the existing progressArc's startAngle property. The start angle of the progress arc can be customized using the setStartAngle method, which will update the visually displayed progress.

gemsfx/src/main/java/com/dlsc/gemsfx/CircleProgressIndicator.java

@@ -1,7 +1,9 @@
 package com.dlsc.gemsfx;
 
 import com.dlsc.gemsfx.skins.CircleProgressIndicatorSkin;
+import javafx.beans.property.DoubleProperty;
 import javafx.beans.property.ObjectProperty;
+import javafx.beans.property.SimpleDoubleProperty;
 import javafx.beans.property.SimpleObjectProperty;
 import javafx.css.CssMetaData;
 import javafx.css.Styleable;
@@ -55,6 +57,7 @@
 public class CircleProgressIndicator extends ProgressIndicator {
 
     private static final String DEFAULT_STYLE_CLASS = "circle-progress-indicator";
+    private static final double DEFAULT_START_ANGLE = 90.0;
     private static final ArcType DEFAULT_ARC_TYPE = ArcType.OPEN;
     private static final StringConverter<Double> DEFAULT_CONVERTER = new StringConverter<>() {
         @Override
@@ -135,6 +138,29 @@ public final void setGraphic(Node graphic) {
         graphicProperty().set(graphic);
     }
 
+    private DoubleProperty startAngle;
+
+    /**
+     * The start angle property defines the starting angle of the arc that is used to display the progress.
+     * The default value is 90 degrees, which corresponds to the top of the circle.
+     *
+     * @return the start angle property
+     */
+    public final DoubleProperty startAngleProperty() {
+        if (startAngle == null) {
+            startAngle = new SimpleDoubleProperty(this, "startAngle", DEFAULT_START_ANGLE);
+        }
+        return startAngle;
+    }
+
+    public final double getStartAngle() {
+        return startAngle == null ? DEFAULT_START_ANGLE : startAngle.get();
+    }
+
+    public final void setStartAngle(double startAngle) {
+        startAngleProperty().set(startAngle);
+    }
+
     private ObjectProperty<ArcType> arcType;
 
     /**

gemsfx/src/main/java/com/dlsc/gemsfx/skins/CircleProgressIndicatorSkin.java

@@ -61,7 +61,7 @@ public CircleProgressIndicatorSkin(CircleProgressIndicator control) {
         // init the progress arc
         progressArc.getStyleClass().add("progress-arc");
         progressArc.setManaged(false);
-        progressArc.setStartAngle(90);
+        progressArc.startAngleProperty().bind(control.startAngleProperty());
         progressArc.setLength(360);
         progressArc.radiusXProperty().bind(radiusBinding);
         progressArc.radiusYProperty().bind(radiusBinding);