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SWT is an open source widget toolkit for Java designed to provide efficient, portable access to the user-interface facilities of the operating systems on which it is implemented.
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/*******************************************************************************
 * Copyright (c) 2007, 2012 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.dnd;

import org.eclipse.swt.internal.ole.win32.*;
import org.eclipse.swt.internal.win32.*;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.*;

/**
 * The class ImageTransfer provides a platform specific mechanism 
 * for converting an Image represented as a java ImageData to a 
 * platform specific representation of the data and vice versa.  
 * 
 * An example of a java ImageData is shown below:
 * 
 *  *     Image image = new Image(display, "C:\temp\img1.gif");
 *	   ImageData imgData = image.getImageData();
 * 
 *
 * @see Transfer
 * 
 * @since 3.4
 */
public class ImageTransfer extends ByteArrayTransfer {
	
	private static ImageTransfer _instance = new ImageTransfer();
	private static final String CF_DIB = "CF_DIB"; //$NON-NLS-1$
	private static final int CF_DIBID = COM.CF_DIB;
	
private ImageTransfer() {}

/**
 * Returns the singleton instance of the ImageTransfer class.
 *
 * @return the singleton instance of the ImageTransfer class
 */
public static ImageTransfer getInstance () {
	return _instance;
}

/**
 * This implementation of javaToNative converts an ImageData object represented
 * by java ImageData to a platform specific representation.
 * 
 * @param object a java ImageData containing the ImageData to be converted
 * @param transferData an empty TransferData object that will
 *  	be filled in on return with the platform specific format of the data
 * 
 * @see Transfer#nativeToJava
 */
public void javaToNative(Object object, TransferData transferData) {
	if (!checkImage(object) || !isSupportedType(transferData)) {
		DND.error(DND.ERROR_INVALID_DATA);
	}
	ImageData imgData = (ImageData)object;
	if (imgData == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	
	int imageSize = imgData.data.length;
	int imageHeight = imgData.height;
	int bytesPerLine = imgData.bytesPerLine;

	BITMAPINFOHEADER bmiHeader = new BITMAPINFOHEADER();
	bmiHeader.biSize = BITMAPINFOHEADER.sizeof;
	bmiHeader.biSizeImage = imageSize; 
	bmiHeader.biWidth = imgData.width;
	bmiHeader.biHeight = imageHeight;
	bmiHeader.biPlanes = 1;
	bmiHeader.biBitCount = (short)imgData.depth;
	bmiHeader.biCompression = OS.DIB_RGB_COLORS; 

	int colorSize = 0;
	if (bmiHeader.biBitCount <= 8) {
		colorSize += (1 << bmiHeader.biBitCount) * 4;
	}
	byte[] bmi = new byte[BITMAPINFOHEADER.sizeof + colorSize];
	OS.MoveMemory(bmi, bmiHeader, BITMAPINFOHEADER.sizeof);	

	RGB[] rgbs = imgData.palette.getRGBs();	
	if (rgbs != null && colorSize > 0) {
		int offset = BITMAPINFOHEADER.sizeof;
		for (int j = 0; j < rgbs.length; j++) {
			bmi[offset] = (byte)rgbs[j].blue;
			bmi[offset + 1] = (byte)rgbs[j].green;
			bmi[offset + 2] = (byte)rgbs[j].red;
			bmi[offset + 3] = 0;
			offset += 4;
		}
	}
	int /*long*/ newPtr = OS.GlobalAlloc(OS.GMEM_FIXED | OS.GMEM_ZEROINIT, BITMAPINFOHEADER.sizeof + colorSize + imageSize);
	OS.MoveMemory(newPtr, bmi, bmi.length);	
	int /*long*/ pBitDest = newPtr + BITMAPINFOHEADER.sizeof + colorSize;

	if (imageHeight <= 0) {
		OS.MoveMemory(pBitDest, imgData.data, imageSize);
	} else {
		int offset = 0;
		pBitDest += bytesPerLine * (imageHeight - 1);
		byte[] scanline = new byte[bytesPerLine];
		for (int i = 0; i < imageHeight; i++) {
			System.arraycopy(imgData.data, offset, scanline, 0, bytesPerLine);
			OS.MoveMemory(pBitDest, scanline, bytesPerLine);
			offset += bytesPerLine;
			pBitDest -= bytesPerLine;
		}
	}			
	transferData.stgmedium = new STGMEDIUM();
	transferData.stgmedium.tymed = COM.TYMED_HGLOBAL;
	transferData.stgmedium.unionField = newPtr;
	transferData.stgmedium.pUnkForRelease = 0;
	transferData.result = COM.S_OK;
}


/**
 * This implementation of nativeToJava converts a platform specific 
 * representation of an image to java ImageData.  
 * 
 * @param transferData the platform specific representation of the data to be converted
 * @return a java ImageData of the image if the conversion was successful;
 * 		otherwise null
 * 
 * @see Transfer#javaToNative
 */
public Object nativeToJava(TransferData transferData) {
	if (!isSupportedType(transferData) || transferData.pIDataObject == 0) return null;
	IDataObject dataObject = new IDataObject(transferData.pIDataObject);
	dataObject.AddRef();
	FORMATETC formatetc = new FORMATETC();
	formatetc.cfFormat = COM.CF_DIB;
	formatetc.ptd = 0;
	formatetc.dwAspect = COM.DVASPECT_CONTENT;
	formatetc.lindex = -1;
	formatetc.tymed = COM.TYMED_HGLOBAL;
	STGMEDIUM stgmedium = new STGMEDIUM();
	stgmedium.tymed = COM.TYMED_HGLOBAL;
	transferData.result = getData(dataObject, formatetc, stgmedium);

	if (transferData.result != COM.S_OK) return null;
	int /*long*/ hMem = stgmedium.unionField;
	dataObject.Release();
	try {
		int /*long*/ ptr = OS.GlobalLock(hMem);
		if (ptr == 0) return null;
		try {
			BITMAPINFOHEADER bmiHeader = new BITMAPINFOHEADER();				
			OS.MoveMemory(bmiHeader, ptr, BITMAPINFOHEADER.sizeof);
			int /*long*/[] pBits = new int /*long*/[1]; 
			int /*long*/ memDib = OS.CreateDIBSection(0, ptr, OS.DIB_RGB_COLORS, pBits, 0, 0);
			if (memDib == 0) SWT.error(SWT.ERROR_NO_HANDLES);			
			int /*long*/ bits = ptr + bmiHeader.biSize;
			if (bmiHeader.biBitCount <= 8) {
				bits += (bmiHeader.biClrUsed == 0 ? (1 << bmiHeader.biBitCount) : bmiHeader.biClrUsed) * 4;
			} else if (bmiHeader.biCompression == OS.BI_BITFIELDS) {
				bits += 12;
			}
			if (bmiHeader.biHeight < 0) {
				OS.MoveMemory(pBits[0], bits, bmiHeader.biSizeImage);
			} else {
				DIBSECTION dib = new DIBSECTION();
				OS.GetObject(memDib, DIBSECTION.sizeof, dib);
				int biHeight = dib.biHeight;
				int scanline = dib.biSizeImage / biHeight;
				int /*long*/ pDestBits = pBits[0];
				int /*long*/ pSourceBits = bits + scanline * (biHeight - 1);
				for (int i = 0; i < biHeight; i++) {
					OS.MoveMemory(pDestBits, pSourceBits, scanline);
					pDestBits += scanline;
					pSourceBits -= scanline;
				}
			}
			Image image = Image.win32_new(null, SWT.BITMAP, memDib);
			ImageData data = image.getImageData();
			OS.DeleteObject(memDib);
			image.dispose();
			return data;
		} finally {
			OS.GlobalUnlock(hMem);
		}
	} finally {
		OS.GlobalFree(hMem);
	}
}

protected int[] getTypeIds(){
	return new int[] {CF_DIBID};
}

protected String[] getTypeNames(){
	return new String[] {CF_DIB};
}
boolean checkImage(Object object) {
	if (object == null || !(object instanceof ImageData))  return false; 
	return true;
}

protected boolean validate(Object object) {
	return checkImage(object);
}
}