Java tutorial
/******************************************************************************* * Copyright (c) 2000, 2017 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.*; import org.eclipse.swt.internal.ole.win32.*; import org.eclipse.swt.internal.win32.*; /** * The class <code>HTMLTransfer</code> provides a platform specific mechanism * for converting text in HTML format represented as a java <code>String</code> * to a platform specific representation of the data and vice versa. * * <p>An example of a java <code>String</code> containing HTML text is shown * below:</p> * * <pre><code> * String htmlData = "<p>This is a paragraph of text.</p>"; * </code></pre> * * @see Transfer */ public class HTMLTransfer extends ByteArrayTransfer { static HTMLTransfer _instance = new HTMLTransfer(); static final String HTML_FORMAT = "HTML Format"; //$NON-NLS-1$ static final int HTML_FORMATID = registerType(HTML_FORMAT); static final String NUMBER = "00000000"; //$NON-NLS-1$ static final String HEADER = "Version:0.9\r\nStartHTML:" + NUMBER + "\r\nEndHTML:" + NUMBER + "\r\nStartFragment:" + NUMBER + "\r\nEndFragment:" + NUMBER + "\r\n"; static final String PREFIX = "<html><body><!--StartFragment-->"; //$NON-NLS-1$ static final String SUFFIX = "<!--EndFragment--></body></html>"; //$NON-NLS-1$ static final String StartFragment = "StartFragment:"; //$NON-NLS-1$ static final String EndFragment = "EndFragment:"; //$NON-NLS-1$ private HTMLTransfer() { } /** * Returns the singleton instance of the HTMLTransfer class. * * @return the singleton instance of the HTMLTransfer class */ public static HTMLTransfer getInstance() { return _instance; } /** * This implementation of <code>javaToNative</code> converts HTML-formatted text * represented by a java <code>String</code> to a platform specific representation. * * @param object a java <code>String</code> containing HTML text * @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 (!checkHTML(object) || !isSupportedType(transferData)) { DND.error(DND.ERROR_INVALID_DATA); } String string = (String) object; int count = string.length(); char[] chars = new char[count + 1]; string.getChars(0, count, chars, 0); /* NOTE: CF_HTML uses UTF-8 encoding. */ int cchMultiByte = OS.WideCharToMultiByte(OS.CP_UTF8, 0, chars, -1, null, 0, null, null); if (cchMultiByte == 0) { transferData.stgmedium = new STGMEDIUM(); transferData.result = COM.DV_E_STGMEDIUM; return; } int startHTML = HEADER.length(); int startFragment = startHTML + PREFIX.length(); int endFragment = startFragment + cchMultiByte - 1; int endHTML = endFragment + SUFFIX.length(); StringBuilder buffer = new StringBuilder(HEADER); int maxLength = NUMBER.length(); //startHTML int start = buffer.toString().indexOf(NUMBER); String temp = Integer.toString(startHTML); buffer.replace(start + maxLength - temp.length(), start + maxLength, temp); //endHTML start = buffer.toString().indexOf(NUMBER, start); temp = Integer.toString(endHTML); buffer.replace(start + maxLength - temp.length(), start + maxLength, temp); //startFragment start = buffer.toString().indexOf(NUMBER, start); temp = Integer.toString(startFragment); buffer.replace(start + maxLength - temp.length(), start + maxLength, temp); //endFragment start = buffer.toString().indexOf(NUMBER, start); temp = Integer.toString(endFragment); buffer.replace(start + maxLength - temp.length(), start + maxLength, temp); buffer.append(PREFIX); buffer.append(string); buffer.append(SUFFIX); count = buffer.length(); chars = new char[count + 1]; buffer.getChars(0, count, chars, 0); cchMultiByte = OS.WideCharToMultiByte(OS.CP_UTF8, 0, chars, -1, null, 0, null, null); long lpMultiByteStr = OS.GlobalAlloc(OS.GMEM_FIXED | OS.GMEM_ZEROINIT, cchMultiByte); OS.WideCharToMultiByte(OS.CP_UTF8, 0, chars, -1, lpMultiByteStr, cchMultiByte, null, null); transferData.stgmedium = new STGMEDIUM(); transferData.stgmedium.tymed = COM.TYMED_HGLOBAL; transferData.stgmedium.unionField = lpMultiByteStr; transferData.stgmedium.pUnkForRelease = 0; transferData.result = COM.S_OK; return; } /** * This implementation of <code>nativeToJava</code> converts a platform specific * representation of HTML text to a java <code>String</code>. * * @param transferData the platform specific representation of the data to be converted * @return a java <code>String</code> containing HTML text if the conversion was successful; * otherwise null * * @see Transfer#javaToNative */ @Override public Object nativeToJava(TransferData transferData) { if (!isSupportedType(transferData) || transferData.pIDataObject == 0) return null; IDataObject data = new IDataObject(transferData.pIDataObject); data.AddRef(); STGMEDIUM stgmedium = new STGMEDIUM(); FORMATETC formatetc = transferData.formatetc; stgmedium.tymed = COM.TYMED_HGLOBAL; transferData.result = getData(data, formatetc, stgmedium); data.Release(); if (transferData.result != COM.S_OK) return null; long hMem = stgmedium.unionField; try { long lpMultiByteStr = OS.GlobalLock(hMem); if (lpMultiByteStr == 0) return null; try { /* NOTE: CF_HTML uses UTF-8 encoding. * The MSDN documentation for MultiByteToWideChar states that dwFlags must be set to 0 for UTF-8. * Otherwise, the function fails with ERROR_INVALID_FLAGS. */ int cchWideChar = OS.MultiByteToWideChar(OS.CP_UTF8, 0, lpMultiByteStr, -1, null, 0); if (cchWideChar == 0) return null; char[] lpWideCharStr = new char[cchWideChar - 1]; OS.MultiByteToWideChar(OS.CP_UTF8, 0, lpMultiByteStr, -1, lpWideCharStr, lpWideCharStr.length); String string = new String(lpWideCharStr); int fragmentStart = 0, fragmentEnd = 0; int start = string.indexOf(StartFragment) + StartFragment.length(); int end = start + 1; while (end < string.length()) { String s = string.substring(start, end); try { fragmentStart = Integer.parseInt(s); end++; } catch (NumberFormatException e) { break; } } start = string.indexOf(EndFragment) + EndFragment.length(); end = start + 1; while (end < string.length()) { String s = string.substring(start, end); try { fragmentEnd = Integer.parseInt(s); end++; } catch (NumberFormatException e) { break; } } if (fragmentEnd <= fragmentStart || fragmentEnd > C.strlen(lpMultiByteStr)) return null; cchWideChar = OS.MultiByteToWideChar(OS.CP_UTF8, 0, lpMultiByteStr + fragmentStart, fragmentEnd - fragmentStart, lpWideCharStr, lpWideCharStr.length); if (cchWideChar == 0) return null; String s = new String(lpWideCharStr, 0, cchWideChar); /* * Firefox includes <!--StartFragment --> in the fragment, so remove it. */ String foxStart = "<!--StartFragment -->\r\n"; //$NON-NLS-1$ int prefix = s.indexOf(foxStart); if (prefix != -1) { prefix += foxStart.length(); s = s.substring(prefix); } return s; } finally { OS.GlobalUnlock(hMem); } } finally { OS.GlobalFree(hMem); } } @Override protected int[] getTypeIds() { return new int[] { HTML_FORMATID }; } @Override protected String[] getTypeNames() { return new String[] { HTML_FORMAT }; } boolean checkHTML(Object object) { return (object != null && object instanceof String && ((String) object).length() > 0); } @Override protected boolean validate(Object object) { return checkHTML(object); } }