--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dwt/internal/image/PngIdatChunk.d	Sat Aug 09 17:00:02 2008 +0200
@@ -0,0 +1,62 @@
+/*******************************************************************************
+ * Copyright (c) 2000, 2006 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
+ *******************************************************************************/
+module dwt.internal.image;
+
+
+import dwt.DWT;
+
+class PngIdatChunk : PngChunk {
+
+    static final int HEADER_BYTES_LENGTH = 2;
+    static final int ADLER_FIELD_LENGTH = 4;
+    static final int HEADER_BYTE1_DATA_OFFSET = DATA_OFFSET + 0;
+    static final int HEADER_BYTE2_DATA_OFFSET = DATA_OFFSET + 1;
+    static final int ADLER_DATA_OFFSET = DATA_OFFSET + 2; // plus variable compressed data length
+
+PngIdatChunk(byte headerByte1, byte headerByte2, byte[] data, int adler) {
+    super(data.length + HEADER_BYTES_LENGTH + ADLER_FIELD_LENGTH);
+    setType(TYPE_IDAT);
+    reference[HEADER_BYTE1_DATA_OFFSET] = headerByte1;
+    reference[HEADER_BYTE2_DATA_OFFSET] = headerByte2;
+    System.arraycopy(data, 0, reference, DATA_OFFSET, data.length);
+    setInt32(ADLER_DATA_OFFSET, adler);
+    setCRC(computeCRC());
+}
+        
+PngIdatChunk(byte[] reference) {
+    super(reference);
+}
+
+int getChunkType() {
+    return CHUNK_IDAT;
+}
+
+/**
+ * Answer whether the chunk is a valid IDAT chunk.
+ */
+void validate(PngFileReadState readState, PngIhdrChunk headerChunk) {
+    if (!readState.readIHDR
+        || (headerChunk.getMustHavePalette() && !readState.readPLTE)
+        || readState.readIEND) 
+    {
+        DWT.error(DWT.ERROR_INVALID_IMAGE);
+    } else {
+        readState.readIDAT = true;
+    }
+    
+    super.validate(readState, headerChunk);
+}
+
+byte getDataByteAtOffset(int offset) {
+    return reference[DATA_OFFSET + offset];
+}
+
+}