本文主要讲述了Android 实现图片画画板

设计项目布局：

首先实现画图功能：

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);        iv = (ImageView) findViewById(R.id.iv);        paint = new Paint();        paint.setStrokeWidth(5);        paint.setColor(Color.GREEN);                // 创建一个可以被修改的bitmap        baseBitmap = Bitmap.createBitmap(320, 360,                Bitmap.Config.ARGB_8888);        System.out.println("图宽度："+iv.getWidth());        System.out.println("图高度："+iv.getHeight());        canvas = new Canvas(baseBitmap);        canvas.drawColor(Color.WHITE);        // 知道用户手指在屏幕上移动的轨迹        iv.setOnTouchListener(new OnTouchListener() {            // 设置手指开始的坐标            int startX;            int startY;            @Override            public boolean onTouch(View v, MotionEvent event) {                switch (event.getAction()) {                case MotionEvent.ACTION_DOWN: // 手指第一次接触屏幕                    startX = (int) event.getX();                    startY = (int) event.getY();                    break;                case MotionEvent.ACTION_MOVE:// 手指在屏幕上滑动                    int newX = (int) event.getX();                    int newY = (int) event.getY();                    canvas.drawLine(startX, startY, newX, newY, paint);                    // 重新更新画笔的开始位置                    startX = (int) event.getX();                    startY = (int) event.getY();                    iv.setImageBitmap(baseBitmap);                    break;                case MotionEvent.ACTION_UP: // 手指离开屏幕                    break;                default:                    break;                }                return true;            }        });    }    public void save(View view) {    }}

接下来完成保存图片的功能：

public void save(View view) {        try {            File file = new File(Environment.getExternalStorageDirectory(),                    System.currentTimeMillis() + ".jpg");            FileOutputStream stream = new FileOutputStream(file);            baseBitmap.compress(CompressFormat.JPEG, 100, stream);            stream.close();            Toast.makeText(this, "保存图片成功", 1).show();                        //模拟一个消息通知系统sd卡被重新挂载了            Intent intent = new Intent();            intent.setAction(intent.ACTION_MEDIA_MOUNTED);            intent.setData(Uri.fromFile(Environment                    .getExternalStorageDirectory()));            sendBroadcast(intent);        } catch (Exception e) {            Toast.makeText(this, "保存图片失败", 1).show();            e.printStackTrace();        }    }