android实现简单的画画板实例代码

public class MainActivity extends Activity {

private ImageView iv;

private Bitmap baseBitmap;

private Canvas canvas;

private Paint paint;

@Override

protected void onCreate(Bundle savedInstanceState) {

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 = new Canvas(baseBitmap);

// 画布背景为灰色

canvas.drawColor(Color.GRAY);

// 创建画笔

paint = new Paint();

// 画笔颜色为蓝色

paint.setColor(Color.RED);

// 宽度5个像素

paint.setStrokeWidth(5);

// 先将红色背景画上

canvas.drawBitmap(baseBitmap, new Matrix(), paint);

iv.setImageBitmap(baseBitmap);

iv.setOnTouchListener(new OnTouchListener() {

int startX;

int startY;

@Override

public boolean onTouch(View v, MotionEvent event) {

switch (event.getAction()) {

case MotionEvent.ACTION_DOWN:

// 获取手按下时的坐标

startX = (int) event.getX();

startY = (int) event.getY();

break;

case MotionEvent.ACTION_MOVE:

// 获取手移动后的坐标

int stopX = (int) event.getX();

int stopY = (int) event.getY();

// 在起初跟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;

}

return true;

}

});

}

public void save(View view) {

try {

File file = new File(Environment.getExternalStorageDirectory(),

System.currentTimeMillis() + ".jpg");

OutputStream stream = new FileOutputStream(file);

baseBitmap.compress(CompressFormat.JPEG, 100, stream);

stream.close();

// 模拟一个广播，通知平台sdcard被挂载

Intent intent = new Intent();

intent.setAction(Intent.ACTION_MEDIA_MOUNTED);

intent.setData(Uri.fromFile(Environment

.getExternalStorageDirectory()));

sendBroadcast(intent);

Toast.makeText(this, "保存截图成功", 0).show();

} catch (Exception e) {

Toast.makeText(this, "保存截图失败", 0).show();

e.printStackTrace();

}

}

}

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