sketcharea.java

FIRE (Flexible Interface Rendering Engine)是一个J2ME上的灵活的图形界面引擎

/**
 * 
 */
package gr.fire.ui;

import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;

import gr.fire.core.Component;
import gr.fire.core.FireScreen;

/**
 * @author padeler
 *
 */
public class SketchArea extends Component 
{
	
	private Image area;
	private int POINT_BUF_LENGTH=18; // number of points in buffer
	private int[] pointBuf = new int[POINT_BUF_LENGTH*2]; 
	private int pointsPointer=0;
	
	private void add(int x,int y)
	{
		if(pointsPointer==POINT_BUF_LENGTH)
		{
			flush();
		}
		pointBuf[pointsPointer*2] = x;
		pointBuf[pointsPointer*2 +1 ] = y;
		pointsPointer++;
	}
	
	public void validate()
	{
		int[]ps = getPrefSize();
		if(ps==null) ps = getMinSize();
		if(width<=0 || height<=0)
		{
			width = ps[0];
			height = ps[1];
		}

		area = Image.createImage(width,height);
		clear();
		valid=true;		
	}
	
	public int[] getMinSize()
	{
		FireScreen fs = FireScreen.getScreen();
		return new int[]{fs.getWidth(),fs.getHeight()};
	}
	
	public void clear()
	{
		Graphics g = area.getGraphics();		
		g.setColor(backgroundColor);
		g.fillRect(0,0,width,height);
		pointsPointer=0;
		repaint();
	}
	
	public Image getSketch()
	{
		return area;
	}
	
	
	public void paint(Graphics g)
	{
		g.drawImage(area,0,0,Graphics.TOP|Graphics.LEFT);
	}
	
	public boolean isFocusable()
	{
		return true;
	}
	
	protected void keyReleased(int keyCode)
	{
		setSelected(!isSelected());
	}
	
	protected void pointerDragged(int x, int y)
	{
		pointerEvent(x,y);
	}
	
	protected void pointerReleased(int x, int y)
	{
		flush();
		pointerEvent(x,y);
	}
	
	protected void pointerPressed(int x, int y)
	{
		flush();
		pointerEvent(x,y);
	}
	
	private void flush()
	{	
		if(pointsPointer>=2) // at least two points
		{
			Graphics g = area.getGraphics();
			g.setColor(foregroundColor);
			for(int i=0;i<pointsPointer-2;i++)
			{
				g.drawLine(pointBuf[i*2],pointBuf[i*2+1],pointBuf[i*2+2],pointBuf[i*2+3]);
				g.drawLine(pointBuf[i*2]+1,pointBuf[i*2+1],pointBuf[i*2+2]+1,pointBuf[i*2+3]);
			}
			repaint();	
		}
		pointsPointer=0;
	}
	
	protected void pointerEvent(int x, int y)
	{
		if(isDublicate(x,y)==false)
		{
			add(x,y);
		}
	}
	
	private boolean isDublicate(int x,int y)
	{
		if(pointsPointer>0 && pointBuf[(pointsPointer-1)*2]==x && pointBuf[(pointsPointer-1)*2+1]==y)
		{
			return true;
		}
		return false;
	}
}