drawshapecommand.java

自己写的一个Java画图板程序 支持鼠标拖动图形 选中图形 改变颜色等 推荐使用Eclipse来运行

package project;

//具体命令，实现了Command接口，负责绘制图形以及undo,redo操作
public class DrawShapeCommand implements Command{

	private DrawShapePanel drawShapePanel;
	
	private DrawShapeFrame drawShapeFrame;
	
	private Shape shape;
	
	
	public DrawShapeCommand(DrawShapePanel drawShapePanel)
	{
		this.drawShapePanel = drawShapePanel;
	}
	
	//必要参数，指定绘制图形所需要的DrawShapeFrame
	public void setDrawShapeFrame(DrawShapeFrame drawShapeFrame)
	{
		this.drawShapeFrame = drawShapeFrame;
	}
	
	//必要参数，指定需要绘制的图形的具体类型
	public void setShape(Shape shape)
	{
		this.shape = shape;
	}
	
	
	
	
	//执行绘制命令
	public void execute() {
			
		drawShapePanel.addShape(shape);	
		
		drawShapePanel.repaint();
		
		
		
		checkEmptyArrayList();
		
		
		//控制redo菜单与redo按钮是否可使用
		if((drawShapePanel.preservedShapeArrayList).size() > 0)
		{
			(drawShapePanel.preservedShapeArrayList).clear();
			
			(drawShapeFrame.redo).setEnabled(false);
			(drawShapeFrame.redoButton).setEnabled(false);
		}
		
		
	}

	//undo操作
	public void undo() {
		
		
		
		int lastIndex = (drawShapePanel.shapeArrayList).size() - 1;
		
		Shape shape = (drawShapePanel.shapeArrayList).get(lastIndex);
		
		(drawShapePanel.preservedShapeArrayList).add(shape);
		
		(drawShapePanel.shapeArrayList).remove(lastIndex);
		
		drawShapePanel.repaint();
		
		
		checkEmptyArrayList();
		
		
		
		
	}
	
	//redo操作
	public void redo() {
		
		
		
		int lastIndex = (drawShapePanel.preservedShapeArrayList).size() - 1;
		
		Shape shape = (drawShapePanel.preservedShapeArrayList).get(lastIndex);
		
		(drawShapePanel.shapeArrayList).add(shape);
		
		(drawShapePanel.preservedShapeArrayList).remove(lastIndex);
		
		
		
		
		drawShapePanel.repaint();
		
		
		checkEmptyArrayList();
		
		
	
	}

	//检查drawShapePanel的两个ArrayList
	//其中shapeArrayList负责记录当前存在的图形
	//preservedShapeArrayList负责记录当前不存在，但是在undo,redo时需要恢复的图形
	//根据检查的结果，控制undo菜单与undo按钮，redo菜单与redo按钮的可用与不可用
	public void checkEmptyArrayList()
	{
		if((drawShapePanel.shapeArrayList).size() <= 0)
		{
			(drawShapeFrame.undo).setEnabled(false);
			(drawShapeFrame.undoButton).setEnabled(false);
			
			
		}
		else
		{
			(drawShapeFrame.undo).setEnabled(true);
			(drawShapeFrame.undoButton).setEnabled(true);
		}
		
		if((drawShapePanel.preservedShapeArrayList).size() <= 0)
		{
			
			(drawShapeFrame.redo).setEnabled(false);
			(drawShapeFrame.redoButton).setEnabled(false);
			
			
		}
		
		else
		{
			(drawShapeFrame.redo).setEnabled(true);
			(drawShapeFrame.redoButton).setEnabled(true);
		}
	}
	

}