codec: introduce experimental methods PNGImage.toBufferedImage() an…

…d `PNGImageDecoder.decodeAsBufferedImage(int)`

The produced `BufferedImage` contains the properties that were obtained during decoding.

Package visibility for now.

echosvg-codec/src/main/java/io/sf/carte/echosvg/ext/awt/image/codec/png/PNGImage.java

@@ -1929,4 +1929,30 @@ private void decodeImage(boolean useInterlacing) {
 		}
 	}
 
+	/**
+	 * Convert to a {@code BufferedImage}.
+	 * <p>
+	 * This method is experimental and could be removed without warning.
+	 * </p>
+	 * 
+	 * @return the {@code BufferedImage}.
+	 */
+	BufferedImage toBufferedImage() {
+		ColorModel cm = getColorModel();
+		SampleModel sm = getSampleModel();
+
+		Point loc = new Point(getMinX(), getMinY());
+
+		WritableRaster raster = Raster.createWritableRaster(sm, loc);
+		Hashtable<String, Object> props = new Hashtable<>(properties);
+
+		BufferedImage img = new BufferedImage(cm, raster, cm.isAlphaPremultiplied(), props);
+
+		Graphics2D ig = img.createGraphics();
+		ig.drawRenderedImage(this, new AffineTransform());
+		ig.dispose();
+
+		return img;
+	}
+
 }

echosvg-codec/src/main/java/io/sf/carte/echosvg/ext/awt/image/codec/png/PNGImageDecoder.java

@@ -59,4 +59,27 @@ public RenderedImage decodeAsRenderedImage(int page) throws IOException {
 		return new PNGImage(input, (PNGDecodeParam) param);
 	}
 
+	/**
+	 * Returns a <code>BufferedImage</code> that contains the decoded contents of
+	 * the <code>SeekableStream</code> associated with this
+	 * <code>ImageDecoder</code>. The given page of a multi-page image is decoded.
+	 * Page numbering begins at zero.
+	 * <p>
+	 * This method is experimental and could be removed in the future.
+	 * </p>
+	 *
+	 * @param page The page to be decoded.
+	 * @throws IOException if the page does not exist.
+	 */
+	BufferedImage decodeAsBufferedImage(int page) throws IOException {
+		if (page != 0) {
+			throw new IOException(PropertyUtil.formatMessage("PNGImageDecoder.unknown.page",
+					new Object[] { page }));
+		}
+
+		PNGImage png = new PNGImage(input, (PNGDecodeParam) param);
+
+		return png.toBufferedImage();
+	}
+
 }