Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2012 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * 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.*; /** * The class <code>FileTransfer</code> provides a platform specific mechanism * for converting a list of files represented as a java <code>String[]</code> to a * platform specific representation of the data and vice versa. * Each <code>String</code> in the array contains the absolute path for a single * file or directory. * * <p>An example of a java <code>String[]</code> containing a list of files is shown * below:</p> * * <pre><code> * File file1 = new File("C:\\temp\\file1"); * File file2 = new File("C:\\temp\\file2"); * String[] fileData = new String[2]; * fileData[0] = file1.getAbsolutePath(); * fileData[1] = file2.getAbsolutePath(); * </code></pre> * * @see Transfer */ public class FileTransfer extends ByteArrayTransfer { private static FileTransfer _instance = new FileTransfer(); private static final String CF_HDROP = "CF_HDROP"; //$NON-NLS-1$ private static final int CF_HDROPID = COM.CF_HDROP; private static final String CFSTR_SHELLIDLIST = "Shell IDList Array"; //$NON-NLS-1$ private static final int CFSTR_SHELLIDLISTID = registerType(CFSTR_SHELLIDLIST); private FileTransfer() { } /** * Returns the singleton instance of the FileTransfer class. * * @return the singleton instance of the FileTransfer class */ public static FileTransfer getInstance() { return _instance; } /** * This implementation of <code>javaToNative</code> converts a list of file names * represented by a java <code>String[]</code> to a platform specific representation. * Each <code>String</code> in the array contains the absolute path for a single * file or directory. * * @param object a java <code>String[]</code> containing the file names to be converted * @param transferData an empty <code>TransferData</code> object that will * be filled in on return with the platform specific format of the data * * @see Transfer#nativeToJava */ @Override public void javaToNative(Object object, TransferData transferData) { if (!checkFile(object) || !isSupportedType(transferData)) { DND.error(DND.ERROR_INVALID_DATA); } String[] fileNames = (String[]) object; long newPtr = 0; if (transferData.type == CF_HDROPID) { StringBuilder allFiles = new StringBuilder(); for (int i = 0; i < fileNames.length; i++) { allFiles.append(fileNames[i]); allFiles.append('\0'); // each name is null terminated } allFiles.append('\0'); // there is an extra null terminator at the very end char[] buffer = new char[allFiles.length()]; allFiles.getChars(0, allFiles.length(), buffer, 0); DROPFILES dropfiles = new DROPFILES(); dropfiles.pFiles = DROPFILES.sizeof; dropfiles.pt_x = dropfiles.pt_y = 0; dropfiles.fNC = 0; dropfiles.fWide = 1; // Allocate the memory because the caller (DropTarget) has not handed it in // The caller of this method must release the data when it is done with it. int byteCount = buffer.length * TCHAR.sizeof; newPtr = OS.GlobalAlloc(COM.GMEM_FIXED | COM.GMEM_ZEROINIT, DROPFILES.sizeof + byteCount); if (newPtr != 0) { OS.MoveMemory(newPtr, dropfiles, DROPFILES.sizeof); OS.MoveMemory(newPtr + DROPFILES.sizeof, buffer, byteCount); } } else if (transferData.type == CFSTR_SHELLIDLISTID) { newPtr = generateCidaFromFilepaths(fileNames); } transferData.stgmedium = new STGMEDIUM(); transferData.stgmedium.tymed = COM.TYMED_HGLOBAL; transferData.stgmedium.unionField = newPtr; transferData.stgmedium.pUnkForRelease = 0; transferData.result = newPtr != 0 ? COM.S_OK : COM.E_FAIL; } /** * This implementation of <code>nativeToJava</code> converts a platform specific * representation of a list of file names to a java <code>String[]</code>. * Each String in the array contains the absolute path for a single file or directory. * * @param transferData the platform specific representation of the data to be converted * @return a java <code>String[]</code> containing a list of file names if the conversion * was successful; otherwise null * * @see Transfer#javaToNative */ @Override public Object nativeToJava(TransferData transferData) { if (!isSupportedType(transferData) || transferData.pIDataObject == 0) return null; // get file names from IDataObject IDataObject dataObject = new IDataObject(transferData.pIDataObject); dataObject.AddRef(); FORMATETC formatetc = new FORMATETC(); formatetc.cfFormat = COM.CF_HDROP; 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); dataObject.Release(); if (transferData.result != COM.S_OK) return null; // How many files are there? int count = OS.DragQueryFile(stgmedium.unionField, 0xFFFFFFFF, null, 0); String[] fileNames = new String[count]; for (int i = 0; i < count; i++) { // How long is the name ? int size = OS.DragQueryFile(stgmedium.unionField, i, null, 0); char[] lpszFile = new char[size + 1]; // Get file name and append it to string OS.DragQueryFile(stgmedium.unionField, i, lpszFile, size + 1); fileNames[i] = new String(lpszFile, 0, size); } OS.DragFinish(stgmedium.unionField); // frees data associated with HDROP data return fileNames; } /** * Generate {@link CIDA} structure and trailing data to transfer filenames * as {@link #CFSTR_SHELLIDLIST}. * <p> * For more information on the {@link CIDA} structure see also {@link #resolveCidaToFilepaths(long)}. * </p> * * @param fileNames filenames to pack in {@link CIDA}. * @return pointer to global memory chunk filled with generated data or <code>0</code> on failure */ private long generateCidaFromFilepaths(String[] fileNames) { final int n = fileNames.length; long[] pidls = new long[n]; try { CIDA cida = new CIDA(); cida.cidl = n; int cidaSize = CIDA.sizeof + 4 * n; cida.aoffset = cidaSize; // offsets are from cida begin so the first is equal to cida size int[] pidlOffsets = new int[n]; int[] pidlSizes = new int[n]; int pidlSizeSum = 2; // initialize with 2 for the empty (but double null terminated) parent pidl for (int i = 0; i < n; i++) { TCHAR szfileName = new TCHAR(0, fileNames[i], true); long[] ppv = new long[1]; int hr = COM.PathToPIDL(szfileName.chars, ppv); if (hr != OS.S_OK) { return 0; } pidls[i] = ppv[0]; pidlSizes[i] = OS.ILGetSize(pidls[i]); pidlSizeSum += pidlSizes[i]; if (i == 0) { pidlOffsets[0] = cidaSize + 2; } else { pidlOffsets[i] = pidlOffsets[i - 1] + pidlSizes[i - 1]; } } long newPtr = OS.GlobalAlloc(COM.GMEM_FIXED | COM.GMEM_ZEROINIT, cidaSize + pidlSizeSum); if (newPtr != 0) { OS.MoveMemory(newPtr, cida, CIDA.sizeof); OS.MoveMemory(newPtr + CIDA.sizeof, pidlOffsets, 4 * cida.cidl); for (int i = 0; i < n; i++) { OS.MoveMemory(newPtr + pidlOffsets[i], pidls[i], pidlSizes[i]); } } return newPtr; } finally { for (int i = 0; i < n; i++) { if (pidls[i] != 0) { OS.CoTaskMemFree(pidls[i]); } } } } @Override public boolean isSupportedType(TransferData transferData) { // filter Shell ID List Array transfer only for dropping if (transferData != null && transferData.pIDataObject != 0 && transferData.type == CFSTR_SHELLIDLISTID) { return false; } return super.isSupportedType(transferData); } @Override protected int[] getTypeIds() { // Note: FileTransfer adds Shell ID List as transfer type but later // limit this type for dragging only. return new int[] { CF_HDROPID, CFSTR_SHELLIDLISTID }; } @Override protected String[] getTypeNames() { return new String[] { CF_HDROP, CFSTR_SHELLIDLIST }; } boolean checkFile(Object object) { if (object == null || !(object instanceof String[]) || ((String[]) object).length == 0) return false; String[] strings = (String[]) object; for (int i = 0; i < strings.length; i++) { if (strings[i] == null || strings[i].length() == 0) return false; } return true; } @Override protected boolean validate(Object object) { return checkFile(object); } }