Workaround for HiDPI line number rulers on macOS retina

Oxygen (platform.text 3.12) introduces a work-around for blurry line
numbers in rulers on Retina displays. Basically GC drawing must scale
according to the zoom factor. C.f. bug 516293.
 
Bug: 516322
Change-Id: I6978a80e912b64323e1bc7ee7ad0e461ca8723c8
Signed-off-by: Markus Keller <markus_keller@ch.ibm.com>

2 files changed, 32 insertions, 1 deletions

diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/commit/LogicalLineNumberRulerColumn.java b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/commit/LogicalLineNumberRulerColumn.java
index deccdfafdd..68266c320a 100644
--- a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/commit/LogicalLineNumberRulerColumn.java
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/commit/LogicalLineNumberRulerColumn.java
@@ -25,6 +25,13 @@ public class LogicalLineNumberRulerColumn extends LineNumberRulerColumn {
 	private final @NonNull DiffEntry.Side side;
 
 	/**
+	 * Zoom level for workaround for HiDPI line number rulers on macOS retina.
+	 *
+	 * @see <a href="https://bugs.eclipse.org/516322">Bug 516322</a>
+	 */
+	int zoom = 100;
+
+	/**
 	 * @param side
 	 */
 	public LogicalLineNumberRulerColumn(@NonNull DiffEntry.Side side) {
@@ -69,4 +76,27 @@ public class LogicalLineNumberRulerColumn extends LineNumberRulerColumn {
 		}
 		return digits;
 	}
+
+	/**
+	 * Enable workaround for HiDPI line number rulers on macOS retina. This
+	 * method will override an internal method in Oxygen (4.7).
+	 *
+	 * @return true
+	 * @see <a href="https://bugs.eclipse.org/516322">Bug 516322</a>
+	 */
+	protected boolean internalSupportsZoomedPaint() {
+		return true;
+	}
+
+	/**
+	 * Store zoom level for workaround for HiDPI line number rulers on macOS
+	 * retina. This method will override an internal method in Oxygen (4.7).
+	 *
+	 * @param zoomLevel
+	 *            the zoom level to use for drawing operations
+	 * @see <a href="https://bugs.eclipse.org/516322">Bug 516322</a>
+	 */
+	protected void internalSetZoom(int zoomLevel) {
+		this.zoom = zoomLevel;
+	}
 }
diff --git a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/commit/OldNewLogicalLineNumberRulerColumn.java b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/commit/OldNewLogicalLineNumberRulerColumn.java
index dc56fd12e5..6b57391461 100644
--- a/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/commit/OldNewLogicalLineNumberRulerColumn.java
+++ b/org.eclipse.egit.ui/src/org/eclipse/egit/ui/internal/commit/OldNewLogicalLineNumberRulerColumn.java
@@ -105,7 +105,8 @@ public class OldNewLogicalLineNumberRulerColumn extends LineNumberRulerColumn {
 			// drawn.
 			Rectangle bounds = super.getControl().getBounds();
 			gc.setForeground(lineColor);
-			gc.drawLine(x, 0, x, bounds.height);
+			gc.drawLine(x * zoom / 100, 0, x * zoom / 100,
+					bounds.height * zoom / 100);
 			gc.setForeground(foreground);
 		}