--- a/dwt/internal/image/PngChunkReader.d	Fri Sep 12 13:53:21 2008 +0200
+++ b/dwt/internal/image/PngChunkReader.d	Sun Sep 14 01:45:57 2008 +0200
@@ -1,4 +1,4 @@
-/*******************************************************************************
+/*******************************************************************************
  * 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
@@ -7,18 +7,26 @@
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
+ * Port to the D programming language:
+ *     Frank Benoit <benoit@tionex.de>
  *******************************************************************************/
-module dwt.internal.image;
+module dwt.internal.image.PngChunkReader;
 
 
 import dwt.DWT;
+import dwt.internal.image.LEDataInputStream;
+import dwt.internal.image.PngFileReadState;
+import dwt.internal.image.PngIhdrChunk;
+import dwt.internal.image.PngPlteChunk;
+import dwt.internal.image.PngTrnsChunk;
+import dwt.internal.image.PngChunk;
 
 public class PngChunkReader {
     LEDataInputStream inputStream;
     PngFileReadState readState;
     PngIhdrChunk headerChunk;
     PngPlteChunk paletteChunk;
-    
+
 this(LEDataInputStream inputStream) {
     this.inputStream = inputStream;
     readState = new PngFileReadState();
@@ -27,12 +35,12 @@
 
 PngIhdrChunk getIhdrChunk() {
     if (headerChunk is null) {
-        try { 
-            PngChunk chunk = PngChunk.readNextFromStream(inputStream);
-            if (chunk is null) DWT.error(DWT.ERROR_INVALID_IMAGE);
-            headerChunk = cast(PngIhdrChunk) chunk;
+        PngChunk chunk = PngChunk.readNextFromStream(inputStream);
+        if (chunk is null) DWT.error(DWT.ERROR_INVALID_IMAGE);
+        if(( headerChunk = cast(PngIhdrChunk) chunk ) !is null ){
             headerChunk.validate(readState, null);
-        } catch (ClassCastException e) {
+        }
+        else{
             DWT.error(DWT.ERROR_INVALID_IMAGE);
         }
     }
@@ -41,7 +49,7 @@
 
 PngChunk readNextChunk() {
     if (headerChunk is null) return getIhdrChunk();
-    
+
     PngChunk chunk = PngChunk.readNextFromStream(inputStream);
     if (chunk is null) DWT.error(DWT.ERROR_INVALID_IMAGE);
     switch (chunk.getChunkType()) {