android实现简单的画画板实例代码

 @Override
 protectedvoidonCreate(BundlesavedInstanceState){
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  this.iv=(ImageView)this.findViewById(R.id.iv);
  //创建一张空白图片
  baseBitmap=Bitmap.createBitmap(480,640,Bitmap.Config.ARGB_8888);
  //创建一张画布
  canvas=newCanvas(baseBitmap);
  //画布背景为灰色
  canvas.drawColor(Color.GRAY);
  //创建画笔
  paint=newPaint();
  //画笔颜色为红色
  paint.setColor(Color.RED);
  //宽度5个像素
  paint.setStrokeWidth(5);
  //先将灰色背景画上
  canvas.drawBitmap(baseBitmap,newMatrix(),paint);
  iv.setImageBitmap(baseBitmap);

  iv.setOnTouchListener(newOnTouchListener(){
   intstartX;
   intstartY;

   @Override
   publicbooleanonTouch(Viewv,MotionEventevent){
    switch(event.getAction()){
    caseMotionEvent.ACTION_DOWN:
     //获取手按下时的坐标
     startX=(int)event.getX();
     startY=(int)event.getY();
     break;
    caseMotionEvent.ACTION_MOVE:
     //获取手移动后的坐标
     intstopX=(int)event.getX();
     intstopY=(int)event.getY();
     //在开始和结束坐标间画一条线
     canvas.drawLine(startX,startY,stopX,stopY,paint);
     //实时更新开始坐标
     startX=(int)event.getX();
     startY=(int)event.getY();
     iv.setImageBitmap(baseBitmap);
     break;
    }
    returntrue;
   }
  });
 }

 publicvoidsave(Viewview){
  try{
   Filefile=newFile(Environment.getExternalStorageDirectory(),
     System.currentTimeMillis()+".jpg");
   OutputStreamstream=newFileOutputStream(file);
   baseBitmap.compress(CompressFormat.JPEG,100,stream);
   stream.close();
   //模拟一个广播，通知系统sdcard被挂载
   Intentintent=newIntent();
   intent.setAction(Intent.ACTION_MEDIA_MOUNTED);
   intent.setData(Uri.fromFile(Environment
     .getExternalStorageDirectory()));
   sendBroadcast(intent);

   Toast.makeText(this,"保存图片成功",0).show();
  }catch(Exceptione){
   Toast.makeText(this,"保存图片失败",0).show();
   e.printStackTrace();
  }
 }

}