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comparison dwt/dnd/ByteArrayTransfer.d @ 0:380af2bdd8e5

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author Jacob Carlborg <doob@me.com> <jacob.carlborg@gmail.com>
date Sat, 09 Aug 2008 17:00:02 +0200
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1 /*******************************************************************************
2 * Copyright (c) 2000, 2006 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * IBM Corporation - initial API and implementation
10 *******************************************************************************/
11 module dwt.dnd;
12
13
14 /**
15 * The class <code>ByteArrayTransfer</code> provides a platform specific
16 * mechanism for converting a java <code>byte[]</code> to a platform
17 * specific representation of the byte array and vice versa. See
18 * <code>Transfer</code> for additional information.
19 *
20 * <p><code>ByteArrayTransfer</code> is never used directly but is sub-classed
21 * by transfer agents that convert between data in a java format such as a
22 * <code>String</code> and a platform specific byte array.
23 *
24 * <p>If the data you are converting <b>does not</b> map to a
25 * <code>byte[]</code>, you should sub-class <code>Transfer</code> directly
26 * and do your own mapping to a platform data type.</p>
27 *
28 * <p>The following snippet shows a subclass of ByteArrayTransfer that transfers
29 * data defined by the class <code>MyType</code>.</p>
30 *
31 * <pre><code>
32 * public class MyType {
33 * public String fileName;
34 * public long fileLength;
35 * public long lastModified;
36 * }
37 * </code></pre>
38 *
39 * <pre><code>
40 * public class MyTypeTransfer : ByteArrayTransfer {
41 *
42 * private static final String MYTYPENAME = "my_type_name";
43 * private static final int MYTYPEID = registerType(MYTYPENAME);
44 * private static MyTypeTransfer _instance = new MyTypeTransfer();
45 *
46 * private MyTypeTransfer() {}
47 *
48 * public static MyTypeTransfer getInstance () {
49 * return _instance;
50 * }
51 * public void javaToNative (Object object, TransferData transferData) {
52 * if (object is null || !(object instanceof MyType[])) return;
53 *
54 * if (isSupportedType(transferData)) {
55 * MyType[] myTypes = (MyType[]) object;
56 * try {
57 * // write data to a byte array and then ask super to convert to pMedium
58 * ByteArrayOutputStream out = new ByteArrayOutputStream();
59 * DataOutputStream writeOut = new DataOutputStream(out);
60 * for (int i = 0, length = myTypes.length; i &lt; length; i++){
61 * byte[] buffer = myTypes[i].fileName.getBytes();
62 * writeOut.writeInt(buffer.length);
63 * writeOut.write(buffer);
64 * writeOut.writeLong(myTypes[i].fileLength);
65 * writeOut.writeLong(myTypes[i].lastModified);
66 * }
67 * byte[] buffer = out.toByteArray();
68 * writeOut.close();
69 *
70 * super.javaToNative(buffer, transferData);
71 *
72 * } catch (IOException e) {
73 * }
74 * }
75 * }
76 * public Object nativeToJava(TransferData transferData){
77 *
78 * if (isSupportedType(transferData)) {
79 *
80 * byte[] buffer = (byte[])super.nativeToJava(transferData);
81 * if (buffer is null) return null;
82 *
83 * MyType[] myData = new MyType[0];
84 * try {
85 * ByteArrayInputStream in = new ByteArrayInputStream(buffer);
86 * DataInputStream readIn = new DataInputStream(in);
87 * while(readIn.available() > 20) {
88 * MyType datum = new MyType();
89 * int size = readIn.readInt();
90 * byte[] name = new byte[size];
91 * readIn.read(name);
92 * datum.fileName = new String(name);
93 * datum.fileLength = readIn.readLong();
94 * datum.lastModified = readIn.readLong();
95 * MyType[] newMyData = new MyType[myData.length + 1];
96 * System.arraycopy(myData, 0, newMyData, 0, myData.length);
97 * newMyData[myData.length] = datum;
98 * myData = newMyData;
99 * }
100 * readIn.close();
101 * } catch (IOException ex) {
102 * return null;
103 * }
104 * return myData;
105 * }
106 *
107 * return null;
108 * }
109 * protected String[] getTypeNames(){
110 * return new String[]{MYTYPENAME};
111 * }
112 * protected int[] getTypeIds(){
113 * return new int[] {MYTYPEID};
114 * }
115 * }
116 * </code></pre>
117 */
118 public abstract class ByteArrayTransfer : Transfer {
119
120 public TransferData[] getSupportedTypes() {
121 int[] types = getTypeIds();
122 TransferData[] data = new TransferData[types.length];
123 for (int i = 0; i < types.length; i++) {
124 data[i] = new TransferData();
125 data[i].type = types[i];
126 }
127 return data;
128 }
129
130 public bool isSupportedType(TransferData transferData){
131 if (transferData is null) return false;
132 int[] types = getTypeIds();
133 for (int i = 0; i < types.length; i++) {
134 if (transferData.type is types[i]) return true;
135 }
136 return false;
137 }
138
139 /**
140 * This implementation of <code>javaToNative</code> converts a java
141 * <code>byte[]</code> to a platform specific representation. For additional
142 * information see <code>Transfer#javaToNative</code>.
143 *
144 * @see Transfer#javaToNative
145 *
146 * @param object a java <code>byte[]</code> containing the data to be converted
147 * @param transferData an empty <code>TransferData</code> object; this
148 * object will be filled in on return with the platform specific format of the data
149 */
150 protected void javaToNative (Object object, TransferData transferData) {
151 if (!checkByteArray(object) && !isSupportedType(transferData)) {
152 DND.error(DND.ERROR_INVALID_DATA);
153 }
154 byte[] orig = (byte[])object;
155 byte[] buffer = new byte[orig.length];
156 System.arraycopy(orig, 0, buffer, 0, orig.length);
157 transferData.data = new byte[1][];
158 transferData.data[0] = buffer;
159 transferData.result = 0;
160 }
161
162 /**
163 * This implementation of <code>nativeToJava</code> converts a platform specific
164 * representation of a byte array to a java <code>byte[]</code>.
165 * For additional information see <code>Transfer#nativeToJava</code>.
166 *
167 * @see Transfer#nativeToJava
168 *
169 * @param transferData the platform specific representation of the data to be
170 * been converted
171 * @return a java <code>byte[]</code> containing the converted data if the
172 * conversion was successful; otherwise null
173 */
174 protected Object nativeToJava(TransferData transferData) {
175 if (!isSupportedType(transferData) || transferData.data is null) return null;
176 if (transferData.data.length is 0 || transferData.data[0].length is 0) return null;
177 return transferData.data[0];
178 }
179 bool checkByteArray(Object object) {
180 return (object !is null && object instanceof byte[] && ((byte[])object).length > 0);
181 }
182 }