Copy and paste no longer tries to autoscale the image. The image is always copied and pasted at 100% zoom. Fixes #194

Previously, when copying an image in the clipboard example, the image at
the current zoom level was stored to clipboard using
getImageDataAtCurrentZoom(). However, in normal Windows behavior (e.g.,
Paint), images are always copied at their original size regardless of
the current zoom. When pasting, the image is pasted at 100% zoom, and
the application handles zoom internally when displaying the image.

To match this behavior, copy and paste now always handle images at 100%
scale, ignoring the current zoom and leaving zoom handling to the image
class when it is fetched for display.

Fixes vi-eclipse/Eclipse-Platform#194

Author: arunjose696

bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/win32/org/eclipse/swt/dnd/ImageTransfer.java

@@ -15,7 +15,6 @@
 
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
-import org.eclipse.swt.internal.*;
 import org.eclipse.swt.internal.ole.win32.*;
 import org.eclipse.swt.internal.win32.*;
 
@@ -184,8 +183,9 @@ public Object nativeToJava(TransferData transferData) {
 					pSourceBits -= scanline;
 				}
 			}
-			Image image = Image.win32_new(null, SWT.BITMAP, memDib, DPIUtil.getNativeDeviceZoom());
-			ImageData data = image.getImageData (DPIUtil.getDeviceZoom ());
+			final int DEFAULT_IMAGE_STORAGE_ZOOM = 100;
+			Image image = Image.win32_new(null, SWT.BITMAP, memDib, DEFAULT_IMAGE_STORAGE_ZOOM);
+			ImageData data = image.getImageData ();
 			OS.DeleteObject(memDib);
 			image.dispose();
 			return data;

examples/org.eclipse.swt.examples/src/org/eclipse/swt/examples/clipboard/ClipboardExample.java

@@ -30,7 +30,6 @@
 import org.eclipse.swt.graphics.GC;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.ImageData;
-import org.eclipse.swt.graphics.ImageDataProvider;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.layout.FillLayout;
@@ -62,38 +61,6 @@ public class ClipboardExample {
 	Label status;
 	static final int HSIZE = 100, VSIZE = 60;
 
-static final class AutoScaleImageDataProvider implements ImageDataProvider {
-	ImageData imageData;
-	int currentZoom;
-	public AutoScaleImageDataProvider (ImageData data) {
-		this.imageData = data;
-		this.currentZoom = getDeviceZoom ();
-	}
-
-	@Override
-	public ImageData getImageData (int zoom) {
-		return autoScaleImageData(imageData, zoom, currentZoom);
-	}
-
-	static ImageData autoScaleImageData (ImageData imageData, int targetZoom, int currentZoom) {
-		if (imageData == null || targetZoom == currentZoom) return imageData;
-		float scaleFactor = ((float) targetZoom)/((float) currentZoom);
-		return imageData.scaledTo (Math.round (imageData.width * scaleFactor), Math.round (imageData.height * scaleFactor));
-	}
-
-	static int getDeviceZoom () {
-		int zoom = 100;
-		String value = System.getProperty ("org.eclipse.swt.internal.deviceZoom");
-		if (value != null) {
-			try {
-				zoom = Integer.parseInt(value);
-			} catch (NumberFormatException e) {
-				e.printStackTrace();
-			}
-		}
-		return zoom;
-	}
-}
 
 public static void main( String[] args) {
 	Display display = new Display();
@@ -476,8 +443,8 @@ void createImageTransfer(Composite copyParent, Composite pasteParent){
 	b.addSelectionListener(widgetSelectedAdapter(e -> {
 		if (copyImage[0] != null) {
 			status.setText("");
-			// Fetch ImageData at current zoom and save in the clip-board.
-			clipboard.setContents(new Object[] {copyImage[0].getImageDataAtCurrentZoom()}, new Transfer[] {ImageTransfer.getInstance()});
+			// Fetch ImageData and save in the clip-board.
+			clipboard.setContents(new Object[] {copyImage[0].getImageData()}, new Transfer[] {ImageTransfer.getInstance()});
 		} else {
 			status.setText("No image to copy");
 		}
@@ -540,8 +507,7 @@ void createImageTransfer(Composite copyParent, Composite pasteParent){
 				pasteImage[0].dispose();
 			}
 			status.setText("");
-			// Consume the ImageData at current zoom as-is.
-			pasteImage[0] = new Image(e.display, new AutoScaleImageDataProvider(imageData));
+			pasteImage[0] = new Image(e.display, imageData);
 			pasteVBar.setEnabled(true);
 			pasteHBar.setEnabled(true);
 			pasteOrigin.x = 0; pasteOrigin.y = 0;