Prepare the implementation of dynamically sized image file-formats

bundles/org.eclipse.swt/Eclipse SWT/cocoa/org/eclipse/swt/graphics/InternalImageLoader.java

@@ -14,13 +14,15 @@
 package org.eclipse.swt.graphics;
 
 import java.io.*;
+import java.util.*;
 
+import org.eclipse.swt.internal.DPIUtil.*;
 import org.eclipse.swt.internal.image.*;
 
 class InternalImageLoader {
 
-	static ImageData[] load(InputStream stream, ImageLoader imageLoader) {
-		return FileFormat.load(stream, imageLoader);
+	static List<ElementAtZoom<ImageData>> load(InputStream stream, ImageLoader imageLoader, int fileZoom, int targetZoom) {
+		return FileFormat.load(stream, imageLoader, fileZoom, targetZoom);
 	}
 
 	static void save(OutputStream stream, int format, ImageLoader imageLoader) {

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/graphics/ImageLoader.java

@@ -18,6 +18,8 @@
 import java.util.*;
 
 import org.eclipse.swt.*;
+import org.eclipse.swt.internal.DPIUtil.*;
+import org.eclipse.swt.internal.image.*;
 
 /**
  * Instances of this class are used to load images from,
@@ -148,10 +150,16 @@ void reset() {
  * </ul>
  */
 public ImageData[] load(InputStream stream) {
+	load(stream, FileFormat.DEFAULT_ZOOM, FileFormat.DEFAULT_ZOOM);
+	return data;
+}
+
+List<ElementAtZoom<ImageData>> load(InputStream stream, int fileZoom, int targetZoom) {
 	if (stream == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
 	reset();
-	data = InternalImageLoader.load(stream, this);
-	return data;
+	List<ElementAtZoom<ImageData>> images = InternalImageLoader.load(stream, this, fileZoom, targetZoom);
+	data = images.stream().map(ElementAtZoom::element).toArray(ImageData[]::new);
+	return images;
 }
 
 /**
@@ -173,9 +181,14 @@ public ImageData[] load(InputStream stream) {
  * </ul>
  */
 public ImageData[] load(String filename) {
+	load(filename, FileFormat.DEFAULT_ZOOM, FileFormat.DEFAULT_ZOOM);
+	return data;
+}
+
+List<ElementAtZoom<ImageData>> load(String filename, int fileZoom, int targetZoom) {
 	if (filename == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
 	try (InputStream stream = new FileInputStream(filename)) {
-		return load(stream);
+		return load(stream, fileZoom, targetZoom);
 	} catch (IOException e) {
 		SWT.error(SWT.ERROR_IO, e);
 	}

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/image/FileFormat.java

@@ -20,6 +20,7 @@
 
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
+import org.eclipse.swt.internal.DPIUtil.*;
 
 /**
  * Abstract factory class for loading/unloading images from files or streams
@@ -54,27 +55,60 @@ public abstract class FileFormat {
 		} catch (NoClassDefFoundError e) { } // ignore format
 	}
 
+	public static final int DEFAULT_ZOOM = 100;
+
+	private static Optional<FileFormat> determineFileFormat(LEDataInputStream stream) {
+		return FORMAT_FACTORIES.stream().skip(1).map(Supplier::get).filter(f -> {
+			try {
+				return f.isFileFormat(stream);
+			} catch (IOException e) {
+				return false;
+			}
+		}).findFirst();
+	}
+
+	private static final int MAX_SIGNATURE_BYTES = 18 + 2; // e.g. Win-BMP or OS2-BMP plus a safety-margin
+
+	public static boolean isDynamicallySizableFormat(InputStream is) {
+		Optional<FileFormat> format = determineFileFormat(new LEDataInputStream(is, MAX_SIGNATURE_BYTES));
+		return format.isPresent() && !(format.get() instanceof StaticImageFileFormat);
+	}
+
+	static abstract class StaticImageFileFormat extends FileFormat {
+
+		abstract ImageData[] loadFromByteStream();
+
+		@Override
+		List<ElementAtZoom<ImageData>> loadFromByteStream(int fileZoom, int targetZoom) {
+			return Arrays.stream(loadFromByteStream()).map(d -> new ElementAtZoom<>(d, fileZoom)).toList();
+		}
+	}
+
 	LEDataInputStream inputStream;
 	LEDataOutputStream outputStream;
 	ImageLoader loader;
 	int compression;
 
-/**
- * Return whether or not the specified input stream
- * represents a supported file format.
- */
-abstract boolean isFileFormat(LEDataInputStream stream);
+	/**
+	 * Return whether or not the specified input stream represents a supported file
+	 * format.
+	 */
+	abstract boolean isFileFormat(LEDataInputStream stream) throws IOException;
 
-abstract ImageData[] loadFromByteStream();
+	/**
+	 * Format that do not implement {@link StaticImageFileFormat} MUST return
+	 * {@link ImageData} with the specified {@code targetZoom}.
+	 */
+	abstract List<ElementAtZoom<ImageData>> loadFromByteStream(int fileZoom, int targetZoom);
 
 /**
  * Read the specified input stream, and return the
  * device independent image array represented by the stream.
  */
-public ImageData[] loadFromStream(LEDataInputStream stream) {
+public List<ElementAtZoom<ImageData>> loadFromStream(LEDataInputStream stream, int fileZoom, int targetZoom) {
 	try {
 		inputStream = stream;
-		return loadFromByteStream();
+		return loadFromByteStream(fileZoom, targetZoom);
 	} catch (Exception e) {
 		if (e instanceof IOException) {
 			SWT.error(SWT.ERROR_IO, e);
@@ -89,14 +123,14 @@ public ImageData[] loadFromStream(LEDataInputStream stream) {
  * Read the specified input stream using the specified loader, and
  * return the device independent image array represented by the stream.
  */
-public static ImageData[] load(InputStream is, ImageLoader loader) {
+public static List<ElementAtZoom<ImageData>> load(InputStream is, ImageLoader loader, int fileZoom, int targetZoom) {
 	LEDataInputStream stream = new LEDataInputStream(is);
-	FileFormat fileFormat = FORMAT_FACTORIES.stream().skip(1) //
-			.map(Supplier::get).filter(f -> f.isFileFormat(stream)) //
-			.findFirst().orElse(null);
- 	if (fileFormat == null) SWT.error(SWT.ERROR_UNSUPPORTED_FORMAT);
+	FileFormat fileFormat = determineFileFormat(stream).orElseGet(() -> {
+		SWT.error(SWT.ERROR_UNSUPPORTED_FORMAT);
+		return null;
+	});
 	fileFormat.loader = loader;
-	return fileFormat.loadFromStream(stream);
+	return fileFormat.loadFromStream(stream, fileZoom, targetZoom);
 }
 
 /**

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/image/GIFFileFormat.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2012 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -14,11 +14,13 @@
 package org.eclipse.swt.internal.image;
 
 
+import java.io.*;
+
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
-import java.io.*;
+import org.eclipse.swt.internal.image.FileFormat.*;
 
-public final class GIFFileFormat extends FileFormat {
+public final class GIFFileFormat extends StaticImageFileFormat {
 	String signature;
 	int screenWidth, screenHeight, backgroundPixel, bitsPerPixel, defaultDepth;
 	int disposalMethod = 0;
@@ -51,15 +53,11 @@ static PaletteData grayRamp(int numGrays) {
 	}
 
 	@Override
-	boolean isFileFormat(LEDataInputStream stream) {
-		try {
-			byte[] signature = new byte[3];
-			stream.read(signature);
-			stream.unread(signature);
-			return signature[0] == 'G' && signature[1] == 'I' && signature[2] == 'F';
-		} catch (Exception e) {
-			return false;
-		}
+	boolean isFileFormat(LEDataInputStream stream) throws IOException {
+		byte[] signature = new byte[3];
+		stream.read(signature);
+		stream.unread(signature);
+		return signature[0] == 'G' && signature[1] == 'I' && signature[2] == 'F';
 	}
 
 	/**

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/image/JPEGFileFormat.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2014 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -18,11 +18,13 @@
 package org.eclipse.swt.internal.image;
 
 
+import java.io.*;
+
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
-import java.io.*;
+import org.eclipse.swt.internal.image.FileFormat.*;
 
-public final class JPEGFileFormat extends FileFormat {
+public final class JPEGFileFormat extends StaticImageFileFormat {
 	int restartInterval;
 	JPEGFrameHeader frameHeader;
 	int imageWidth, imageHeight;
@@ -1362,16 +1364,14 @@ void inverseDCT(int[] dataUnit) {
 		}
 	}
 }
-@Override
-boolean isFileFormat(LEDataInputStream stream) {
-	try {
+
+	@Override
+	boolean isFileFormat(LEDataInputStream stream) throws IOException {
 		JPEGStartOfImage soi = new JPEGStartOfImage(stream);
 		stream.unread(soi.reference);
-		return soi.verify();  // we no longer check for appN
-	} catch (Exception e) {
-		return false;
+		return soi.verify(); // we no longer check for appN
 	}
-}
+
 boolean isZeroInColumn(int[] dataUnit, int col) {
 	return dataUnit[col + 8] == 0 && dataUnit[col + 16] == 0
 			&& dataUnit[col + 24] == 0 && dataUnit[col + 32] == 0

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/image/OS2BMPFileFormat.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2008 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -14,27 +14,26 @@
 package org.eclipse.swt.internal.image;
 
 
+import java.io.*;
+
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
-import java.io.*;
+import org.eclipse.swt.internal.image.FileFormat.*;
 
-public final class OS2BMPFileFormat extends FileFormat {
+public final class OS2BMPFileFormat extends StaticImageFileFormat {
 	static final int BMPFileHeaderSize = 14;
 	static final int BMPHeaderFixedSize = 12;
 	int width, height, bitCount;
 
-@Override
-boolean isFileFormat(LEDataInputStream stream) {
-	try {
+	@Override
+	boolean isFileFormat(LEDataInputStream stream) throws IOException {
 		byte[] header = new byte[18];
 		stream.read(header);
 		stream.unread(header);
 		int infoHeaderSize = (header[14] & 0xFF) | ((header[15] & 0xFF) << 8) | ((header[16] & 0xFF) << 16) | ((header[17] & 0xFF) << 24);
 		return header[0] == 0x42 && header[1] == 0x4D && infoHeaderSize == BMPHeaderFixedSize;
-	} catch (Exception e) {
-		return false;
 	}
-}
+
 byte[] loadData(byte[] infoHeader) {
 	int stride = (width * bitCount + 7) / 8;
 	stride = (stride + 3) / 4 * 4; // Round up to 4 byte multiple

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/image/PNGFileFormat.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2011 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -19,8 +19,9 @@
 
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
+import org.eclipse.swt.internal.image.FileFormat.*;
 
-public final class PNGFileFormat extends FileFormat {
+public final class PNGFileFormat extends StaticImageFileFormat {
 	static final int SIGNATURE_LENGTH = 8;
 	static final int PRIME = 65521;
 	PngIhdrChunk headerChunk;
@@ -151,9 +152,9 @@ void unloadIntoByteStream(ImageLoader loader) {
 	PngEncoder encoder = new PngEncoder(loader);
 	encoder.encode(outputStream);
 }
-@Override
-boolean isFileFormat(LEDataInputStream stream) {
-	try {
+
+	@Override
+	boolean isFileFormat(LEDataInputStream stream) throws IOException {
 		byte[] signature = new byte[SIGNATURE_LENGTH];
 		stream.read(signature);
 		stream.unread(signature);
@@ -166,10 +167,8 @@ boolean isFileFormat(LEDataInputStream stream) {
 		if ((signature[6] & 0xFF) != 26) return false; //<CTRL/Z>
 		if ((signature[7] & 0xFF) != 10) return false; //<LINEFEED>
 		return true;
-	} catch (Exception e) {
-		return false;
 	}
-}
+
 /**
  * SWT does not support 16-bit depths. If this image uses
  * 16-bit depths, convert the data to an 8-bit depth.

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/internal/image/TIFFFileFormat.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2009 IBM Corporation and others.
+ * Copyright (c) 2000, 2025 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -14,19 +14,20 @@
 package org.eclipse.swt.internal.image;
 
 
+import java.io.*;
+
 import org.eclipse.swt.*;
 import org.eclipse.swt.graphics.*;
-import java.io.*;
+import org.eclipse.swt.internal.image.FileFormat.*;
 
 /**
  * Baseline TIFF decoder revision 6.0
  * Extension T4-encoding CCITT T.4 1D
  */
-public final class TIFFFileFormat extends FileFormat {
+public final class TIFFFileFormat extends StaticImageFileFormat {
 
-@Override
-boolean isFileFormat(LEDataInputStream stream) {
-	try {
+	@Override
+	boolean isFileFormat(LEDataInputStream stream) throws IOException {
 		byte[] header = new byte[4];
 		stream.read(header);
 		stream.unread(header);
@@ -36,10 +37,7 @@ boolean isFileFormat(LEDataInputStream stream) {
 			return false;
 		}
 		return true;
-	} catch (Exception e) {
-		return false;
 	}
-}
 
 @Override
 ImageData[] loadFromByteStream() {