Rewrite the algorithm that sets smallIcon/largeIcon in Decorations class

Don't sort, compare and keep the image that is closest to the desired
dimensions, pixel transparency and pixel depth.

The new method "isCloserThan" is based on the (now deleted) "compare"
method and returns true only if "compare" would have returned -1

Reduce visibility of Decorations::setImages

Author: fedejeanne

bundles/org.eclipse.swt/Eclipse SWT/win32/org/eclipse/swt/widgets/Decorations.java

@@ -274,26 +274,6 @@ void closeWidget () {
 	if (event.doit && !isDisposed ()) dispose ();
 }
 
-int compare (ImageData data1, ImageData data2, int width, int height, int depth) {
-	int value1 = Math.abs (data1.width - width), value2 = Math.abs (data2.width - width);
-	if (value1 == value2) {
-		int transparent1 = data1.getTransparencyType ();
-		int transparent2 = data2.getTransparencyType ();
-		if (transparent1 == transparent2) {
-			if (data1.depth == data2.depth) return 0;
-			return data1.depth > data2.depth && data1.depth <= depth ? -1 : 1;
-		}
-		if (transparent1 == SWT.TRANSPARENCY_ALPHA) return -1;
-		if (transparent2 == SWT.TRANSPARENCY_ALPHA) return 1;
-		if (transparent1 == SWT.TRANSPARENCY_MASK) return -1;
-		if (transparent2 == SWT.TRANSPARENCY_MASK) return 1;
-		if (transparent1 == SWT.TRANSPARENCY_PIXEL) return -1;
-		if (transparent2 == SWT.TRANSPARENCY_PIXEL) return 1;
-		return 0;
-	}
-	return value1 < value2 ? -1 : 1;
-}
-
 @Override
 Widget computeTabGroup () {
 	return this;
@@ -882,7 +862,7 @@ public void setImage (Image image) {
 	setImages (image, null);
 }
 
-void setImages (Image image, Image [] images) {
+private void setImages (Image image, Image [] images) {
 	if (smallImage != null) smallImage.dispose ();
 	if (largeImage != null) largeImage.dispose ();
 	smallImage = largeImage = null;
@@ -893,22 +873,9 @@ void setImages (Image image, Image [] images) {
 	} else {
 		if (images != null && images.length > 0) {
 			int depth = display.getIconDepth ();
-			ImageData [] datas = null;
-			if (images.length > 1) {
-				Image [] bestImages = new Image [images.length];
-				System.arraycopy (images, 0, bestImages, 0, images.length);
-				datas = new ImageData [images.length];
-				for (int i=0; i<datas.length; i++) {
-					datas [i] = images [i].getImageData ();
-				}
-				images = bestImages;
-				sort (images, datas, getSystemMetrics (OS.SM_CXSMICON), getSystemMetrics (OS.SM_CYSMICON), depth);
-			}
-			smallIcon = images [0];
-			if (images.length > 1) {
-				sort (images, datas, getSystemMetrics (OS.SM_CXICON), getSystemMetrics (OS.SM_CYICON), depth);
-			}
-			largeIcon = images [0];
+
+			smallIcon = findClosest(images, getSystemMetrics (OS.SM_CXSMICON), getSystemMetrics (OS.SM_CYSMICON), depth);
+			largeIcon = findClosest(images, getSystemMetrics (OS.SM_CXICON), getSystemMetrics (OS.SM_CYICON), depth);
 		}
 	}
 	if (smallIcon != null) {
@@ -949,6 +916,46 @@ void setImages (Image image, Image [] images) {
 	}
 }
 
+private Image findClosest(Image[] images, int width, int height, int depth) {
+	Image closest = images[0];
+	ImageData closestData = images[0].getImageData();
+	for (int i=1; i<images.length;i++) {
+		ImageData data = images[i].getImageData();
+		if (isCloserThan(data,closestData,  width, height, depth)) {
+			closest = images[i];
+			closestData = data;
+		}
+	}
+
+	return closest;
+}
+
+/**
+ * @return <code>true</code> if <code>data1</code> is closer to the desired width, height and depth than <code>data2</code>.
+ */
+private boolean isCloserThan (ImageData data1, ImageData data2, int width, int height, int depth) {
+	int diffWidth1 = Math.abs (data1.width - width);
+	int diffWidth2 = Math.abs (data2.width - width);
+
+	if (diffWidth1 == diffWidth2) {
+		int transparent1 = data1.getTransparencyType ();
+		int transparent2 = data2.getTransparencyType ();
+		if (transparent1 == transparent2) {
+			if (data1.depth == data2.depth) return false;
+			// TODO: analyze this, it seems broken.
+			return data1.depth > data2.depth && data1.depth <= depth;
+		}
+		if (transparent1 == SWT.TRANSPARENCY_ALPHA) return true;
+		if (transparent2 == SWT.TRANSPARENCY_ALPHA) return false;
+		if (transparent1 == SWT.TRANSPARENCY_MASK) return true;
+		if (transparent2 == SWT.TRANSPARENCY_MASK) return false;
+		if (transparent1 == SWT.TRANSPARENCY_PIXEL) return true;
+		if (transparent2 == SWT.TRANSPARENCY_PIXEL) return false;
+		return false;
+	}
+	return diffWidth1 < diffWidth2;
+}
+
 /**
  * Sets the receiver's images to the argument, which may
  * be an empty array. Images are typically displayed by the
@@ -1313,26 +1320,6 @@ public void setVisible (boolean visible) {
 	}
 }
 
-void sort (Image [] images, ImageData [] datas, int width, int height, int depth) {
-	/* Shell Sort from K&R, pg 108 */
-	int length = images.length;
-	if (length <= 1) return;
-	for (int gap=length/2; gap>0; gap/=2) {
-		for (int i=gap; i<length; i++) {
-			for (int j=i-gap; j>=0; j-=gap) {
-				if (compare (datas [j], datas [j + gap], width, height, depth) >= 0) {
-					Image swap = images [j];
-					images [j] = images [j + gap];
-					images [j + gap] = swap;
-					ImageData swapData = datas [j];
-					datas [j] = datas [j + gap];
-					datas [j + gap] = swapData;
-				}
-			}
-		}
-	}
-}
-
 @Override
 boolean translateAccelerator (MSG msg) {
 	if (!isEnabled () || !isActive ()) return false;