mxBasicCanvas.java

package com.mxgraph.canvas;

import java.awt.Point;
import java.awt.image.BufferedImage;
import java.util.Hashtable;
import java.util.Map;

import com.mxgraph.util.mxConstants;
import com.mxgraph.util.mxUtils;

public abstract class mxBasicCanvas implements mxICanvas
{

	/**
	 * Specifies if image aspect should be preserved in drawImage. Default is true.
	 */
	public static boolean PRESERVE_IMAGE_ASPECT = true;

	/**
	 * Defines the default value for the imageBasePath in all GDI canvases.
	 * Default is an empty string.
	 */
	public static String DEFAULT_IMAGEBASEPATH = "";

	/**
	 * Defines the base path for images with relative paths. Trailing slash
	 * is required. Default value is DEFAULT_IMAGEBASEPATH.
	 */
	protected String imageBasePath = DEFAULT_IMAGEBASEPATH;

	/**
	 * Specifies the current translation. Default is (0,0).
	 */
	protected Point translate = new Point();

	/**
	 * Specifies the current scale. Default is 1.
	 */
	protected double scale = 1;

	/**
	 * Specifies whether labels should be painted. Default is true.
	 */
	protected boolean drawLabels = true;

	/**
	 * Cache for images.
	 */
	protected Hashtable<String, BufferedImage> imageCache = new Hashtable<String, BufferedImage>();

	/**
	 * Sets the current translate.
	 */
	public void setTranslate(int dx, int dy)
	{
		translate = new Point(dx, dy);
	}

	/**
	 * Returns the current translate.
	 */
	public Point getTranslate()
	{
		return translate;
	}

	/**
	 * 
	 */
	public void setScale(double scale)
	{
		this.scale = scale;
	}

	/**
	 * 
	 */
	public double getScale()
	{
		return scale;
	}

	/**
	 * 
	 */
	public void setDrawLabels(boolean drawLabels)
	{
		this.drawLabels = drawLabels;
	}

	/**
	 * 
	 */
	public String getImageBasePath()
	{
		return imageBasePath;
	}

	/**
	 * 
	 */
	public void setImageBasePath(String imageBasePath)
	{
		this.imageBasePath = imageBasePath;
	}

	/**
	 * 
	 */
	public boolean isDrawLabels()
	{
		return drawLabels;
	}

	/**
	 * Returns an image instance for the given URL. If the URL has
	 * been loaded before than an instance of the same instance is
	 * returned as in the previous call.
	 */
	public BufferedImage loadImage(String image)
	{
		BufferedImage img = imageCache.get(image);

		if (img == null)
		{
			img = mxUtils.loadImage(image);

			if (img != null)
			{
				imageCache.put(image, img);
			}
		}

		return img;
	}

	/**
	 * 
	 */
	public void flushImageCache()
	{
		imageCache.clear();
	}

	/**
	 * Gets the image path from the given style. If the path is relative (does
	 * not start with a slash) then it is appended to the imageBasePath.
	 */
	public String getImageForStyle(Map<String, Object> style)
	{
		String filename = mxUtils.getString(style, mxConstants.STYLE_IMAGE);

		if (filename != null && !filename.startsWith("/") && !filename.startsWith("file:/"))
		{
			filename = imageBasePath + filename;
		}

		return filename;
	}

}