Geometry With Float on Scaling #62

This commit introduces FloatAwareRectangle and FloatAwarePoint as an
extension of Rectangle and Point respectively to improve scaling
precision in the DPIUtil by using residuals obtained from rounding.

Contributes to
#62 and
#128

Author: amartya4256

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/widgets/CoordinateSystemMapperTests.java

@@ -137,7 +137,7 @@ void translateRectangleInGapPartiallyInRightBackAndForthInSingleZoomShouldBeTheS
 	void translateRectangleInGapPartiallyInRightBackAndForthInMultiZoomShouldBeInside() {
 		MultiZoomCoordinateSystemMapper mapper = getMultiZoomCoordinateSystemMapper();
 		setupMonitors(mapper);
-		Rectangle rectInPts = new MonitorAwareRectangle(1950, 400, 150, 100, monitors[1]);
+		Rectangle rectInPts = new Rectangle.WithMonitor(1950, 400, 150, 100, monitors[1]);
 		Rectangle rectInPxs = mapper.translateToDisplayCoordinates(rectInPts, monitors[0].getZoom());
 		assertEquals(rectInPts, mapper.translateFromDisplayCoordinates(rectInPxs, monitors[0].getZoom()));
 	}
@@ -223,15 +223,15 @@ private Point createExpectedPoint(CoordinateSystemMapper mapper, int x, int y, M
 		if (mapper instanceof SingleZoomCoordinateSystemMapper) {
 			return new Point(x, y);
 		} else {
-			return new MonitorAwarePoint(x, y, monitor);
+			return new Point.WithMonitor(x, y, monitor);
 		}
 	}
 
 	private Rectangle createExpectedRectangle(CoordinateSystemMapper mapper, int x, int y, int width, int height, Monitor monitor) {
 		if (mapper instanceof SingleZoomCoordinateSystemMapper) {
 			return new Rectangle(x, y, width, height);
 		} else {
-			return new MonitorAwareRectangle(x, y, width, height, monitor);
+			return new Rectangle.WithMonitor(x, y, width, height, monitor);
 		}
 	}
 

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/graphics/MonitorAwarePoint.java

@@ -16,6 +16,8 @@
 
 import java.io.*;
 
+import org.eclipse.swt.widgets.*;
+
 /**
  * Instances of this class represent places on the (x, y)
  * coordinate plane.
@@ -41,7 +43,7 @@
  * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
  */
 
-public sealed class Point implements Serializable permits MonitorAwarePoint {
+public sealed class Point implements Serializable permits Point.OfFloat {
 
 	/**
 	 * the x coordinate of the point
@@ -66,6 +68,8 @@ public Point (int x, int y) {
 	this.y = y;
 }
 
+private Point() {}
+
 /**
  * Compares the argument to the receiver, and returns true
  * if they represent the <em>same</em> object using a class
@@ -116,5 +120,85 @@ public String toString () {
 	return "Point {" + x + ", " + y + "}"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
 }
 
+/**
+ * Instances of this class represent {@link org.eclipse.swt.graphics.Point}
+ * objects with the fields capable of storing more precise value in float.
+ *
+ * @since 3.130
+ * @noreference This class is not intended to be referenced by clients
+ */
+public static sealed class OfFloat extends Point permits Point.WithMonitor {
+
+	private static final long serialVersionUID = -1862062276431597053L;
+
+	public float residualX, residualY;
+
+	public OfFloat(int x, int y) {
+		super(x, y);
+	}
+
+	public OfFloat(float x, float y) {
+		super();
+		this.x = Math.round(x);
+		this.y = Math.round(y);
+		this.residualX = this.x - x;
+		this.residualY = this.y - y;
+	}
+
+	public float getX() {
+		return x + residualX;
+	}
+
+	public float getY() {
+		return y + residualY;
+	}
+
+	public void setX(float x) {
+		this.x = Math.round(x);
+		this.residualX = this.x - x;
+	}
+
+	public void setY(float y) {
+		this.y = Math.round(y);
+		this.residualY = this.y - y;
+	}
+}
+
+/**
+ * Instances of this class represent {@link org.eclipse.swt.graphics.Point.OfFloat}
+ * objects along with the context of the monitor in relation to which they are
+ * placed on the display. The monitor awareness makes it easy to scale and
+ * translate the points between pixels and points.
+ *
+ * @since 3.130
+ * @noreference This class is not intended to be referenced by clients
+ */
+public static final class WithMonitor extends Point.OfFloat {
+
+	private static final long serialVersionUID = 6077427420686999194L;
+
+	private final Monitor monitor;
+
+	/**
+	 * Constructs a new Point.WithMonitor
+	 *
+	 * @param x       the x coordinate of the point
+	 * @param y       the y coordinate of the point
+	 * @param monitor the monitor with whose context the point is created
+	 */
+	public WithMonitor(int x, int y, Monitor monitor) {
+		super(x, y);
+		this.monitor = monitor;
+	}
+
+	/**
+	 * {@return the monitor with whose context the instance is created}
+	 */
+	public Monitor getMonitor() {
+		return monitor;
+	}
+
+}
+
 }