android学习之屏幕划线

//新建一个类继承View

public class Drawl extends View{

 private int mov_x;//声明起点坐标

 private int mov_y;

 private Paint paint;//声明画笔

 private Canvas canvas;//画布

 private Bitmap bitmap;//位图

 private int blcolor;

 public Drawl(Context context) {

  super(context);

  paint=new Paint(Paint.DITHER_FLAG);//创建一个画笔

  bitmap = Bitmap.createBitmap(480, 854, Bitmap.Config.ARGB_8888); //设置位图的宽高

  canvas=new Canvas();

  canvas.setBitmap(bitmap);

  paint.setStyle(Style.STROKE);//设置非填充

  paint.setStrokeWidth(5);//笔宽5像素

  paint.setColor(Color.RED);//设置为红笔

  paint.setAntiAlias(true);//锯齿不显示

 }

//画位图

 @Override

 protected void onDraw(Canvas canvas) {

//  super.onDraw(canvas);

  canvas.drawBitmap(bitmap,0,0,null);

 }

 //触摸事件

 @Override

 public boolean onTouchEvent(MotionEvent event) {

  if (event.getAction()==MotionEvent.ACTION_MOVE) {//如果拖动

   canvas.drawLine(mov_x, mov_y, event.getX(), event.getY(), paint);//画线

   invalidate();

  }

  if (event.getAction()==MotionEvent.ACTION_DOWN) {//如果点击

   mov_x=(int) event.getX();

   mov_y=(int) event.getY();

   canvas.drawPoint(mov_x, mov_y, paint);//画点

   invalidate();

  }

  mov_x=(int) event.getX();

  mov_y=(int) event.getY();

  return true;

 }

}

在Activity中

public class DrawLine extends Activity {

 private Drawl bDrawl;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        bDrawl=new Drawl(this);

       setContentView(bDrawl);//将view视图放到Activity中显示

    }