Tree.
+ *
+ * Classes that wish to provide their own source image for a Tree can
+ * extend TreeDragSourceEffect class and override the TreeDragSourceEffect.dragStart
+ * method and set the field DragSourceEvent.image with their own image.
super method to get the default drag under effect implementation.
+ *
+ * @see DragSourceEffect
+ * @see DragSourceEvent
+ * @see Sample code and further information
+ *
+ * @since 3.3
+ */
+public class TreeDragSourceEffect extends DragSourceEffect {
+ Image dragSourceImage = null;
+
+ /**
+ * Creates a new TreeDragSourceEffect to handle drag effect
+ * from the specified Tree.
+ *
+ * @param tree the Tree that the user clicks on to initiate the drag
+ */
+ public TreeDragSourceEffect(Tree tree) {
+ super(tree);
+ }
+
+ /**
+ * This implementation of dragFinished disposes the image
+ * that was created in TreeDragSourceEffect.dragStart.
+ *
+ * Subclasses that override this method should call super.dragFinished(event)
+ * to dispose the image in the default implementation.
+ *
+ * @param event the information associated with the drag finished event
+ */
+ @Override
+ public void dragFinished(DragSourceEvent event) {
+ if (dragSourceImage != null) dragSourceImage.dispose();
+ dragSourceImage = null;
+ }
+
+ /**
+ * This implementation of dragStart will create a default
+ * image that will be used during the drag. The image should be disposed
+ * when the drag is completed in the TreeDragSourceEffect.dragFinished
+ * method.
+ *
+ * Subclasses that override this method should call super.dragStart(event)
+ * to use the image from the default implementation.
+ *
+ * @param event the information associated with the drag start event
+ */
+ @Override
+ public void dragStart(DragSourceEvent event) {
+ event.image = getDragSourceImage(event);
+ }
+
+ Image getDragSourceImage(DragSourceEvent event) {
+ if (dragSourceImage != null) dragSourceImage.dispose();
+ dragSourceImage = null;
+ SHDRAGIMAGE shdi = new SHDRAGIMAGE();
+ int DI_GETDRAGIMAGE = OS.RegisterWindowMessage (new TCHAR (0, "ShellGetDragImage", true)); //$NON-NLS-1$
+ if (OS.SendMessage (control.handle, DI_GETDRAGIMAGE, 0, shdi) != 0) {
+ if ((control.getStyle() & SWT.MIRRORED) != 0) {
+ event.offsetX = shdi.sizeDragImage.cx - shdi.ptOffset.x;
+ } else {
+ event.offsetX = shdi.ptOffset.x;
+ }
+ event.offsetY = shdi.ptOffset.y;
+ long hImage = shdi.hbmpDragImage;
+ if (hImage != 0) {
+ BITMAP bm = new BITMAP ();
+ OS.GetObject (hImage, BITMAP.sizeof, bm);
+ int srcWidth = bm.bmWidth;
+ int srcHeight = bm.bmHeight;
+
+ /* Create resources */
+ long hdc = OS.GetDC (0);
+ long srcHdc = OS.CreateCompatibleDC (hdc);
+ long oldSrcBitmap = OS.SelectObject (srcHdc, hImage);
+ long memHdc = OS.CreateCompatibleDC (hdc);
+ BITMAPINFOHEADER bmiHeader = new BITMAPINFOHEADER ();
+ bmiHeader.biSize = BITMAPINFOHEADER.sizeof;
+ bmiHeader.biWidth = srcWidth;
+ bmiHeader.biHeight = -srcHeight;
+ bmiHeader.biPlanes = 1;
+ bmiHeader.biBitCount = 32;
+ bmiHeader.biCompression = OS.BI_RGB;
+ byte [] bmi = new byte[BITMAPINFOHEADER.sizeof];
+ OS.MoveMemory (bmi, bmiHeader, BITMAPINFOHEADER.sizeof);
+ long [] pBits = new long [1];
+ long memDib = OS.CreateDIBSection (0, bmi, OS.DIB_RGB_COLORS, pBits, 0, 0);
+ if (memDib == 0) SWT.error (SWT.ERROR_NO_HANDLES);
+ long oldMemBitmap = OS.SelectObject (memHdc, memDib);
+
+ BITMAP dibBM = new BITMAP ();
+ OS.GetObject (memDib, BITMAP.sizeof, dibBM);
+ int sizeInBytes = dibBM.bmWidthBytes * dibBM.bmHeight;
+
+ /* Get the foreground pixels */
+ OS.BitBlt (memHdc, 0, 0, srcWidth, srcHeight, srcHdc, 0, 0, OS.SRCCOPY);
+ byte[] srcData = new byte [sizeInBytes];
+ OS.MoveMemory (srcData, dibBM.bmBits, sizeInBytes);
+
+ PaletteData palette = new PaletteData(0xFF00, 0xFF0000, 0xFF000000);
+ ImageData data = new ImageData(srcWidth, srcHeight, bm.bmBitsPixel, palette, bm.bmWidthBytes, srcData);
+ if (shdi.crColorKey == -1) {
+ byte[] alphaData = new byte[srcWidth * srcHeight];
+ int spinc = dibBM.bmWidthBytes - srcWidth * 4;
+ int ap = 0, sp = 3;
+ for (int y = 0; y < srcHeight; ++y) {
+ for (int x = 0; x < srcWidth; ++x) {
+ alphaData [ap++] = srcData [sp];
+ sp += 4;
+ }
+ sp += spinc;
+ }
+ data.alphaData = alphaData;
+ } else {
+ data.transparentPixel = shdi.crColorKey << 8;
+ }
+ Display display = control.getDisplay ();
+ dragSourceImage = new Image (display, new AutoScaleImageDataProvider(display, data, DPIUtil.getDeviceZoom()));
+ OS.SelectObject (memHdc, oldMemBitmap);
+ OS.DeleteDC (memHdc);
+ OS.DeleteObject (memDib);
+ OS.SelectObject (srcHdc, oldSrcBitmap);
+ OS.DeleteDC (srcHdc);
+ OS.ReleaseDC (0, hdc);
+ OS.DeleteObject (hImage);
+ return dragSourceImage;
+ }
+ }
+ return null;
+ }
+}