android學習之螢幕劃線

//建立一個類繼承View

public class Drawl extends View{

 private int mov_x;//聲明起點坐标

 private int mov_y;

 private Paint paint;//聲明畫筆

 private Canvas canvas;//畫布

 private Bitmap bitmap;//位圖

 private int blcolor;

 public Drawl(Context context) {

  super(context);

  paint=new Paint(Paint.DITHER_FLAG);//建立一個畫筆

  bitmap = Bitmap.createBitmap(480, 854, Bitmap.Config.ARGB_8888); //設定位圖的寬高

  canvas=new Canvas();

  canvas.setBitmap(bitmap);

  paint.setStyle(Style.STROKE);//設定非填充

  paint.setStrokeWidth(5);//筆寬5像素

  paint.setColor(Color.RED);//設定為紅筆

  paint.setAntiAlias(true);//鋸齒不顯示

 }

//畫位圖

 @Override

 protected void onDraw(Canvas canvas) {

//  super.onDraw(canvas);

  canvas.drawBitmap(bitmap,0,0,null);

 }

 //觸摸事件

 @Override

 public boolean onTouchEvent(MotionEvent event) {

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

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

   invalidate();

  }

  if (event.getAction()==MotionEvent.ACTION_DOWN) {//如果點選

   mov_x=(int) event.getX();

   mov_y=(int) event.getY();

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

   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視圖放到Activity中顯示

    }