/* ******************************************************************************
* Copyright (c) 2006-2013 XMind Ltd. and others.
*
* This file is a part of XMind 3. XMind releases 3 and
* above are dual-licensed under the Eclipse Public License (EPL),
* which is available at http://www.eclipse.org/legal/epl-v10.html
* and the GNU Lesser General Public License (LGPL),
* which is available at http://www.gnu.org/licenses/lgpl.html
* See http://www.xmind.net/license.html for details.
*
* Contributors:
* XMind Ltd. - initial API and implementation
*******************************************************************************/
package org.xmind.de.erichseifert.vectorgraphics2d.util;
import java.awt.Graphics;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.HeadlessException;
import java.awt.Image;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.DataBuffer;
import java.awt.image.PixelGrabber;
import java.awt.image.Raster;
import java.awt.image.RenderedImage;
import java.awt.image.WritableRaster;
import java.util.Hashtable;
import javax.swing.ImageIcon;
/**
* Abstract class that contains utility functions for working with graphics. For
* example, this includes font handling.
*
* @author Jason Wong
*/
public abstract class GraphicsUtils {
/**
* Default constructor that prevents creation of class.
*/
protected GraphicsUtils() {
throw new UnsupportedOperationException();
}
/**
* This method returns {@code true} if the specified image has the
* possibility to store transparent pixels. Inspired by
* http://www.exampledepot.com/egs/java.awt.image/HasAlpha.html
*
* @param image
* Image that should be checked for alpha channel.
* @return {@code true} if the specified image can have transparent pixels,
* {@code false} otherwise
*/
public static boolean hasAlpha(Image image) {
ColorModel cm;
// If buffered image, the color model is readily available
if (image instanceof BufferedImage) {
BufferedImage bimage = (BufferedImage) image;
cm = bimage.getColorModel();
} else {
// Use a pixel grabber to retrieve the image's color model;
// grabbing a single pixel is usually sufficient
PixelGrabber pg = new PixelGrabber(image, 0, 0, 1, 1, false);
try {
pg.grabPixels();
} catch (InterruptedException e) {
return false;
}
// Get the image's color model
cm = pg.getColorModel();
}
return cm.hasAlpha();
}
/**
* This method returns {@code true} if the specified image has at least one
* pixel that is not fully opaque.
*
* @param image
* Image that should be checked for non-opaque pixels.
* @return {@code true} if the specified image has transparent pixels,
* {@code false} otherwise
*/
public static boolean usesAlpha(Image image) {
if (image == null) {
return false;
}
BufferedImage bimage = toBufferedImage(image);
Raster alphaRaster = bimage.getAlphaRaster();
if (alphaRaster == null) {
return false;
}
DataBuffer dataBuffer = alphaRaster.getDataBuffer();
for (int i = 0; i < dataBuffer.getSize(); i++) {
int alpha = dataBuffer.getElem(i);
if (alpha < 255) {
return true;
}
}
return false;
}
/**
* Converts an arbitrary image to a {@code BufferedImage}.
*
* @param image
* Image that should be converted.
* @return a buffered image containing the image pixels, or the original
* instance if the image already was of type {@code BufferedImage}.
*/
public static BufferedImage toBufferedImage(RenderedImage image) {
if (image instanceof BufferedImage) {
return (BufferedImage) image;
}
ColorModel cm = image.getColorModel();
WritableRaster raster = cm.createCompatibleWritableRaster(
image.getWidth(), image.getHeight());
boolean isRasterPremultiplied = cm.isAlphaPremultiplied();
Hashtable<String, Object> properties = null;
if (image.getPropertyNames() != null) {
properties = new Hashtable<String, Object>();
for (String key : image.getPropertyNames()) {
properties.put(key, image.getProperty(key));
}
}
BufferedImage bimage = new BufferedImage(cm, raster,
isRasterPremultiplied, properties);
image.copyData(raster);
return bimage;
}
/**
* This method returns a buffered image with the contents of an image. Taken
* from http://www.exampledepot.com/egs/java.awt.image/Image2Buf.html
*
* @param image
* Image to be converted
* @return a buffered image with the contents of the specified image
*/
public static BufferedImage toBufferedImage(Image image) {
if (image instanceof BufferedImage) {
return (BufferedImage) image;
}
// This code ensures that all the pixels in the image are loaded
image = new ImageIcon(image).getImage();
// Determine if the image has transparent pixels
boolean hasAlpha = hasAlpha(image);
// Create a buffered image with a format that's compatible with the
// screen
BufferedImage bimage = null;
GraphicsEnvironment ge = GraphicsEnvironment
.getLocalGraphicsEnvironment();
try {
// Determine the type of transparency of the new buffered image
int transparency = Transparency.OPAQUE;
if (hasAlpha) {
transparency = Transparency.TRANSLUCENT;
}
// Create the buffered image
GraphicsDevice gs = ge.getDefaultScreenDevice();
GraphicsConfiguration gc = gs.getDefaultConfiguration();
bimage = gc.createCompatibleImage(image.getWidth(null),
image.getHeight(null), transparency);
} catch (HeadlessException e) {
// The system does not have a screen
bimage = null;
}
if (bimage == null) {
// Create a buffered image using the default color model
int type = BufferedImage.TYPE_INT_RGB;
if (hasAlpha) {
type = BufferedImage.TYPE_INT_ARGB;
}
bimage = new BufferedImage(image.getWidth(null),
image.getHeight(null), type);
}
// Copy image to buffered image
Graphics g = bimage.createGraphics();
// Paint the image onto the buffered image
g.drawImage(image, 0, 0, null);
g.dispose();
return bimage;
}
}
