Android编程实现画板功能的方法总结【附源码下载】

public class MySurfaceView extends SurfaceView implements
    SurfaceHolder.Callback, Runnable {
  // SurfaceHolder实例
  private SurfaceHolder mSurfaceHolder;
  // Canvas对象
  private Canvas mCanvas;
  // 控制子线程是否运行
  private boolean startDraw;
  // Path实例
  private Path mPath = new Path();
  // Paint实例
  private Paint mpaint = new Paint();
  public MySurfaceView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initView(); // 初始化
  }
  private void initView() {
    mSurfaceHolder = getHolder();
    mSurfaceHolder.addCallback(this);
    // 设置可获得焦点
    setFocusable(true);
    setFocusableInTouchMode(true);
    // 设置常亮
    this.setKeepScreenOn(true);
  }
  @Override
  public void run() {
    // 如果不停止就一直绘制
    while (startDraw) {
      // 绘制
      draw();
    }
  }
  /*
   * 创建
   */
  @Override
  public void surfaceCreated(SurfaceHolder holder) {
    startDraw = true;
    new Thread(this).start();
  }
  /*
   * 改变
   */
  @Override
  public void surfaceChanged(SurfaceHolder holder, int format, int width,
      int height) {
  }
  /*
   * 销毁
   */
  @Override
  public void surfaceDestroyed(SurfaceHolder holder) {
    startDraw = false;
  }
  private void draw() {
    try {
      mCanvas = mSurfaceHolder.lockCanvas();
      mCanvas.drawColor(Color.WHITE);
      mpaint.setStyle(Paint.Style.STROKE);
      mpaint.setStrokeWidth(DensityUtil.px2dip(getContext(), 30));
      mpaint.setColor(Color.BLACK);
      mCanvas.drawPath(mPath, mpaint);
    } catch (Exception e) {
    } finally {
      // 对画布内容进行提交
      if (mCanvas != null) {
        mSurfaceHolder.unlockCanvasAndPost(mCanvas);
      }
    }
  }
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    int x = (int) event.getX();  //获取手指移动的x坐标
    int y = (int) event.getY();  //获取手指移动的y坐标
    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
      mPath.moveTo(x, y);
      break;
    case MotionEvent.ACTION_MOVE:
      mPath.lineTo(x, y);
      break;
    case MotionEvent.ACTION_UP:
      break;
    }
    return true;
  }
  // 重置画布
  public void reset() {
    mPath.reset();
  }
}

private Button reset_btn;
private MySurfaceView mview;
@Override
protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  cOntext= this;
  mview = (MySurfaceView) findViewById(R.id.MySurfaceView);
  reset_btn = (Button) findViewById(R.id.reset_btn);
  reset_btn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
      //清除
      mview.reset();
    }
  });

public class SecondActivity extends Activity {
  private ImageView img;
  private Bitmap mBitmap;
  private Canvas canvas;
  private Paint paint;
  // 重置按钮
  private Button reset_btn;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_second);
    img = (ImageView) findViewById(R.id.img);
    reset_btn = (Button) findViewById(R.id.reset_btn);
    reset_btn.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        img.setImageBitmap(null);
        showImage();
      }
    });
    // 绘图
    showImage();
  }
  private void showImage() {
    // 创建一张空白图片
    mBitmap = Bitmap.createBitmap(720, 1280, Bitmap.Config.ARGB_8888);
    // 创建一张画布
    canvas = new Canvas(mBitmap);
    // 画布背景为白色
    canvas.drawColor(Color.WHITE);
    // 创建画笔
    paint = new Paint();
    // 画笔颜色为蓝色
    paint.setColor(Color.BLUE);
    // 宽度5个像素
    paint.setStrokeWidth(5);
    // 先将白色背景画上
    canvas.drawBitmap(mBitmap, new Matrix(), paint);
    img.setImageBitmap(mBitmap);
    img.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 endX = (int) event.getX();
          int endY = (int) event.getY();
          // 在开始和结束坐标间画一条线
          canvas.drawLine(startX, startY, endX, endY, paint);
          // 刷新开始坐标
          startX = (int) event.getX();
          startY = (int) event.getY();
          img.setImageBitmap(mBitmap);
          break;
        }
        return true;
      }
    });
  }
}

File file = new File(Environment.getExternalStorageDirectory(),
    System.currentTimeMillis() + ".jpg");
OutputStream stream;
try {
   stream = new FileOutputStream(file);
   mBitmap.compress(CompressFormat.JPEG, 200, stream);
   stream.close();
} catch (IOException e) {
  e.printStackTrace();
}