android自定义view 旋转 缩放 位移事件处理

说起自定义view一直都很惭愧，一直没有翻开这一张今天简单的写个栗子。

android自定义view

@SuppressLint("AppCompatCustomView")
public class MyImageView extends ImageView {
    /** 按下坐标x */
	float x_down = 0;
    /** 按下坐标y */
	float y_down = 0;
	PointF start = new PointF();
	PointF mid = new PointF();
	float oldDist = 1f;
	float oldRotation = 0;
	/** 图形 Matrix */
	Matrix matrix = new Matrix();
	Matrix matrix1 = new Matrix();
	Matrix savedMatrix = new Matrix();

	private static final int NONE = 0;
	private static final int DRAG = 1;
	private static final int ZOOM = 2;
	int mode = NONE;

	boolean matrixCheck = false;

	int widthScreen;
	int heightScreen;

	Bitmap gintama;

	public MyImageView(Activity activity) {
		super(activity);
		gintama = BitmapFactory.decodeResource(getResources(),
				R.mipmap.mao);

		DisplayMetrics dm = new DisplayMetrics();
		activity.getWindowManager().getDefaultDisplay().getMetrics(dm);
		widthScreen = dm.widthPixels;
		heightScreen = dm.heightPixels;

		matrix = new Matrix();
	}

	@Override
	protected void onDraw(Canvas canvas) {
		// 去除锯齿毛边
		canvas.setDrawFilter(new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG
				| Paint.FILTER_BITMAP_FLAG));
		canvas.save();
		canvas.drawBitmap(gintama, matrix, null);
		canvas.restore();
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		switch (event.getAction() & MotionEvent.ACTION_MASK) {
		case MotionEvent.ACTION_DOWN:
            //第一个手指初次接触屏幕时触发
			mode = DRAG;
			x_down = event.getX();
			y_down = event.getY();
			savedMatrix.set(matrix);
			break;
		case MotionEvent.ACTION_POINTER_DOWN:
            // 有非主要的手指按下(即按下之前已经有手指在屏幕上)
			mode = ZOOM;
			oldDist = spacing(event);
			oldRotation = rotation(event);
			savedMatrix.set(matrix);
			midPoint(mid, event);
			break;
		case MotionEvent.ACTION_MOVE:
            //手指在屏幕滑动时触发
			if (mode == ZOOM) {
				matrix1.set(savedMatrix);
				float rotation = rotation(event) - oldRotation;
				float newDist = spacing(event);
				float scale = newDist / oldDist;
                // 縮放
				matrix1.postScale(scale, scale, mid.x, mid.y);
                // 旋轉
				matrix1.postRotate(rotation, mid.x, mid.y);
				matrixCheck = matrixCheck();
				if (matrixCheck == false) {
					matrix.set(matrix1);
					invalidate();
				}
			} else if (mode == DRAG) {
				matrix1.set(savedMatrix);
				matrix1.postTranslate(event.getX() - x_down, event.getY()
						- y_down);// 平移
				matrixCheck = matrixCheck();
				matrixCheck = matrixCheck();
				if (matrixCheck == false) {
					matrix.set(matrix1);
					invalidate();
				}
			}
			break;
		case MotionEvent.ACTION_UP:
            // 最后一个手指离开屏幕时触发
		case MotionEvent.ACTION_POINTER_UP:
            // 有非主要的手指抬起(即抬起之后仍然有手指在屏幕上)
			mode = NONE;
			break;
            default:
                break;
		}
		return true;
	}

	private boolean matrixCheck() {
		float[] f = new float[9];
		matrix1.getValues(f);
		// 图片4个顶点的坐标
		float x1 = f[0] * 0 + f[1] * 0 + f[2];
		float y1 = f[3] * 0 + f[4] * 0 + f[5];
		float x2 = f[0] * gintama.getWidth() + f[1] * 0 + f[2];
		float y2 = f[3] * gintama.getWidth() + f[4] * 0 + f[5];
		float x3 = f[0] * 0 + f[1] * gintama.getHeight() + f[2];
		float y3 = f[3] * 0 + f[4] * gintama.getHeight() + f[5];
		float x4 = f[0] * gintama.getWidth() + f[1] * gintama.getHeight()
				+ f[2];
		float y4 = f[3] * gintama.getWidth() + f[4] * gintama.getHeight()
				+ f[5];
		// 图片现宽�?
		double width = Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
		// 缩放比率判断
		if (width < widthScreen / 3 || width > widthScreen * 3) {
			return true;
		}
		// 出界判断
		if ((x1 < widthScreen / 3 && x2 < widthScreen / 3
				&& x3 < widthScreen / 3 && x4 < widthScreen / 3)
				|| (x1 > widthScreen * 2 / 3 && x2 > widthScreen * 2 / 3
						&& x3 > widthScreen * 2 / 3 && x4 > widthScreen * 2 / 3)
				|| (y1 < heightScreen / 3 && y2 < heightScreen / 3
						&& y3 < heightScreen / 3 && y4 < heightScreen / 3)
				|| (y1 > heightScreen * 2 / 3 && y2 > heightScreen * 2 / 3
						&& y3 > heightScreen * 2 / 3 && y4 > heightScreen * 2 / 3)) {
			return true;
		}
		return false;
	}

    /**
     *  触碰两点间距
      */
	private float spacing(MotionEvent event) {
		float x = event.getX(0) - event.getX(1);
		float y = event.getY(0) - event.getY(1);
		return  (float)Math.sqrt(x * x + y * y);
	}

    /**
     * 取手势中心点
     */
	private void midPoint(PointF point, MotionEvent event) {
		float x = event.getX(0) + event.getX(1);
		float y = event.getY(0) + event.getY(1);
		point.set(x / 2, y / 2);
	}

    /**
     * 取旋转角
      */
	private float rotation(MotionEvent event) {
		double delta_x = (event.getX(0) - event.getX(1));
		double delta_y = (event.getY(0) - event.getY(1));
		double radians = Math.atan2(delta_y, delta_x);
		
		return (float) Math.toDegrees(radians);
	}

	// 将移动，缩放以及旋转后的图层保存为新图片
	// 本例中沒有用到該方法，需要保存圖片的可以參�?
//	public Bitmap CreatNewPhoto() {
//		Bitmap bitmap = Bitmap.createBitmap(widthScreen, heightScreen,
//				Config.ARGB_8888); // 背景图片
//		Canvas canvas = new Canvas(bitmap); // 新建画布
//		canvas.drawBitmap(gintama, matrix, null); // 画图�?
////		canvas.save(Canvas.ALL_SAVE_FLAG); // 保存画布
//		canvas.save(); // 保存画布
//		canvas.restore();
//		return bitmap;
//	}

}

源码点击下载

上面的代码直接复制就可以测试，有需要的带走，稍后写一篇直接自定义view，通过矩阵操作的，也都是和这个类似的。