4729 buffering implementation in the SWT implementation of the canvas.

org.mwc.cmap.core/src/org/mwc/cmap/core/ui_support/swt/SWTCanvasAdapter.java

@@ -278,6 +278,10 @@ static synchronized public java.awt.BasicStroke getStrokeFor(final int style) {
 		return _myLineStyles.get(new Integer(style));
 	}
 
+	private GC buffer;
+
+	private Image bufferImage;
+
 	/**
 	 * remember the background color - SWT has trouble remembering it
 	 */
@@ -293,6 +297,10 @@ static synchronized public java.awt.BasicStroke getStrokeFor(final int style) {
 	 */
 	private GC _theDest = null;
 
+	private GC _destBuffered = null;
+
+	private boolean bufferEnabled = false;
+
 	/**
 	 * the list of registered painters for this canvas.
 	 */
@@ -793,6 +801,7 @@ public void emptyShape(final Shape shape) {
 
 	@Override
 	public final void endDraw(final Object theVal) {
+		flushBuffer();
 		// _theDest = null;
 
 		// and forget the line width
@@ -889,6 +898,20 @@ public void fillShape(final Shape shape) {
 		}
 	}
 
+	public void flushBuffer() {
+		if (bufferEnabled) {
+			_theDest.dispose();
+			_theDest = _destBuffered;
+			this.drawImage(bufferImage, 0, 1, getSize().width, getSize().height);
+
+			buffer = null;
+
+			bufferImage.dispose();
+
+			bufferEnabled = false;
+		}
+	}
+
 	/**
 	 * get the current background colour
 	 */
@@ -1076,6 +1099,24 @@ public final boolean hasEditor() {
 		return true;
 	}
 
+	public void initializeBuffer() {
+		final String operSys = System.getProperty("os.name").toLowerCase();
+		final boolean isMacOs = operSys.contains("mac");
+		if (_theDest != null && !bufferEnabled && !isMacOs) {
+			final Color foregroundColor = _theDest.getForeground();
+
+			bufferEnabled = true;
+			final ImageData imageData = new ImageData(getSize().width, getSize().height, 24, new PaletteData(0, 0, 0));
+			bufferImage = new Image(_theDest.getDevice(), imageData);
+			buffer = new GC(bufferImage);
+			_destBuffered = _theDest;
+			_theDest = buffer;
+			setBackgroundColor(_backgroundColor);
+
+			_theDest.setForeground(foregroundColor);
+		}
+	}
+
 	@Override
 	public final void removePainter(final CanvasType.PaintListener listener) {
 		_thePainters.removeElement(listener);

org.mwc.debrief.core/src/org/mwc/debrief/core/actions/DragFeature.java

@@ -24,7 +24,6 @@
 import org.eclipse.swt.events.PaintListener;
 import org.eclipse.swt.graphics.Cursor;
 import org.eclipse.swt.graphics.GC;
-import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.ui.IEditorPart;
 import org.eclipse.ui.IViewPart;
@@ -439,11 +438,6 @@ private void drawHere(final GC graphics, final WorldVector newVector) {
 				final SWTCanvasAdapter ca = new SWTCanvasAdapter(_myCanvas.getProjection()) {
 					private static final long serialVersionUID = 1L;
 
-					@Override
-					public void drawImage(final Image image, final int x, final int y, final int width,
-							final int height) {
-					}
-
 					@Override
 					public void drawText(final Font theFont, final String theStr, final int x, final int y) {
 					}
@@ -472,6 +466,7 @@ protected void switchAntiAliasOn(final boolean val) {
 				graphics.setBackground(fc);
 				graphics.setLineWidth(2);
 				ca.startDraw(graphics);
+				ca.initializeBuffer();
 
 				// see if it's a painter that also wants to know the error score
 
@@ -486,6 +481,8 @@ protected void switchAntiAliasOn(final boolean val) {
 						if (errorProvider != null) {
 							final CoreTMASegment coreSeg = (CoreTMASegment) segment;
 							coreSeg.paint(ca, errorProvider);
+							ca.flushBuffer();
+							coreSeg.writeMessage(ca);
 							painted = true;
 						}
 					}

org.mwc.debrief.legacy/src/Debrief/Wrappers/Track/CoreTMASegment.java

@@ -73,6 +73,11 @@ abstract public class CoreTMASegment extends TrackSegment implements CanBePlotte
 	 */
 	protected String _dragMsg;
 
+	/**
+	 * Position of the Draw
+	 */
+	protected WorldLocation _dragPosition;
+
 	/**
 	 * base constructor - sorts out the obvious
 	 *
@@ -160,7 +165,7 @@ public void paint(final CanvasType dest, final ITimeVariableProvider errorProvid
 			// ok, is this our first location?
 			if (tmaLastLoc == null) {
 				tmaLastLoc = new WorldLocation(getTrackStart());
-				firstEnd = new WorldLocation(tmaLastLoc);
+				_dragPosition = firstEnd = new WorldLocation(tmaLastLoc);
 			} else {
 				// calculate a new vector
 				final long timeDelta = thisTime - tmaLastDTG;
@@ -204,7 +209,7 @@ public void paint(final CanvasType dest, final ITimeVariableProvider errorProvid
 
 		// ok, plot the 1/2 way message
 		if (_dragMsg != null) {
-			writeMessage(dest, firstEnd);
+			// writeMessage(dest, firstEnd);
 		}
 	}
 
@@ -295,6 +300,12 @@ public void setSpeed(final WorldSpeed speed) {
 	 */
 	abstract public void stretch(double rngDegs, final WorldLocation origin);
 
+	public void writeMessage(final CanvasType dest) {
+		if (_dragMsg != null && _dragPosition != null) {
+			writeMessage(dest, _dragPosition);
+		}
+	}
+
 	private void writeMessage(final CanvasType dest, final WorldLocation firstEnd) {
 		final Point pt = dest.toScreen(firstEnd);