org.graphstream.ui.util.swing.ImageCache.scala Maven / Gradle / Ivy

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The GraphStream library. With GraphStream you deal with graphs. Static and Dynamic. You create them from scratch, from a file or any source. You display and render them.
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/*
 * Copyright 2006 - 2015
 *     Stefan Balev     
 *     Julien Baudry    
 *     Antoine Dutot    
 *     Yoann Pigné      
 *     Guilhelm Savin   
 * 
 * This file is part of GraphStream .
 * 
 * GraphStream is a library whose purpose is to handle static or dynamic
 * graph, create them from scratch, file or any source and display them.
 * 
 * This program is free software distributed under the terms of two licenses, the
 * CeCILL-C license that fits European law, and the GNU Lesser General Public
 * License. You can  use, modify and/ or redistribute the software under the terms
 * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
 * URL  or under the terms of the GNU LGPL as published by
 * the Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see .
 * 
 * The fact that you are presently reading this means that you have had
 * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
 */
package org.graphstream.ui.util.swing

import java.awt.{Color, Graphics2D, Image}
import java.awt.image.BufferedImage
import java.io.{File, IOException}
import java.net.URL
import java.util.logging.{Level, Logger}
import scala.collection.mutable.HashMap

import javax.imageio.ImageIO;

/**
 * A simple cache for Java2D images to avoid reloading them constantly and to allow sharing.
 * 
 * TODO have a policy to release images if they have not been used for a given time.
 */
object ImageCache {
// Attribute
  
	/** The image cache. */
	protected val imageCache = new HashMap[String,BufferedImage]

	/** The dummy image used to mark a not found image (and avoid trying to reload it again and again). */
	protected var dummy:BufferedImage = null

// Construction
 
 	init
 
	protected def init() {
		val img = new BufferedImage( 16, 16, BufferedImage.TYPE_INT_RGB )
		val g2  = img.createGraphics
		
		g2.setColor( Color.RED )
		g2.drawRect( 0, 0, img.getWidth()-1, img.getHeight()-1 )
		g2.drawLine( 0, 0, img.getWidth()-1, img.getHeight()-1 )
		g2.drawLine( 0, img.getHeight()-1, img.getWidth()-1, 0 )
		
		dummy = img
	}
	
	/**
	 * Lookup an image based on its name, if found return it, else try to load it. If an image
	 * is not found once, the cache remembers it and will not try to reload it again if the
	 * same image is requested anew.
	 * @param fileNameOrUrl A file name or an URL pointing at the image.
	 * @return An image or null if the image cannot be found.
	 */
	def loadImage(fileNameOrUrl:String):Option[BufferedImage] = loadImage(fileNameOrUrl, false)
	
	/**
	 * The same as {@link #loadImage(String)} but you can force the cache to try to reload
	 * an image that where not found before.
	 * @param fileNameOrUrl A file name or an URL pointing at the image.
	 * @param forceTryReload If true, try to reload an image that where not found before.
	 * @return An image or null if the image cannot be found.
	 */
	def loadImage(fileNameOrUrl:String, forceTryReload:Boolean):Option[BufferedImage] = {
		imageCache.get( fileNameOrUrl ) match {
			case None => {
				val url = getClass().getClassLoader().getResource( fileNameOrUrl )
				var image:BufferedImage = null
				
				if( url != null ) {			// The image is in the class path.
					var i:BufferedImage = null
					try {
						image = ImageIO.read( url )
						imageCache.put( fileNameOrUrl, image )
					} catch { case e:Throwable => e.printStackTrace() }
				} else {					// The image is in a file or on the network.
					try {
						val url = new URL( fileNameOrUrl )
						
						image = ImageIO.read( url )	// Try the network.
						imageCache.put( fileNameOrUrl, image )
					} catch {
						case _:Throwable => {
							try {
								image = ImageIO.read( new File( fileNameOrUrl ) )	// Try the file.
								imageCache.put( fileNameOrUrl, image )
							} catch {
								case e:Throwable => {
									image = dummy
									imageCache.put( fileNameOrUrl, image )
									Logger.getLogger(this.getClass.getSimpleName).log(Level.WARNING, "Cannot read image '%s'.".format(fileNameOrUrl), e)
								}
							}
						}
					}
				}
    
				new Some[BufferedImage]( image )
			} 
			case (x:Some[_]) => {
				if( x.get == dummy && forceTryReload ) {
					imageCache -= fileNameOrUrl
					loadImage( fileNameOrUrl )
				} else x
			}  
		}
	}
	
	/**
	 * A dummy 16x16 image used when an image cannot be loaded or found. 
	 * @return An image.
	 */
	def dummyImage:BufferedImage = dummy
}