Android(安卓)利用Matrix实现图片随手指平移、旋转、缩放

一、链接
Android 利用Matrix实现图片随手指平移、旋转、缩放—旋转

Android 利用Matrix实现图片随手指平移、旋转、缩放 —平移

Android 利用Matrix实现图片随手指平移、旋转、缩放—缩放

这篇是用来记录图片随手指缩放的。代码如下：

/** * 使用矩阵（Matrix）来设置图片的属性 * 平移、旋转、放大缩小 *  * 本类的效果：縮放 * Created by lby on 2017/7/24. */public class CropImageViewZoom extends AppCompatImageView {    private Matrix matrix = new Matrix();    private Matrix currentMatrix = new Matrix();    private Bitmap bitmap;    private float oldLength; //  按下時兩個落點的距離    private PointF midPoint = new PointF();    private boolean isMorePoint; // 是否是多根手指    public CropImageViewZoom(Context context) {        this(context, null);    }    public CropImageViewZoom(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public CropImageViewZoom(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        init();    }    private void init() {        bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.aaa);    }    @Override    protected void onDraw(Canvas canvas) {        canvas.save();        canvas.drawBitmap(bitmap, matrix, null);        canvas.restore();    }    @Override    public boolean onTouchEvent(MotionEvent event) {        // 注意：要想监听到ACTION_POINTER_DOWN和ACTION_POINTER_UP，必须有 MotionEvent.ACTION_MASK        switch (event.getAction() & MotionEvent.ACTION_MASK) {            case MotionEvent.ACTION_DOWN:                isMorePoint = false;                break;            case MotionEvent.ACTION_POINTER_DOWN:                isMorePoint = true;                currentMatrix.set(matrix);                oldLength = getLength(event);                getMidPoint(midPoint, event);                break;            case MotionEvent.ACTION_MOVE:                if (isMorePoint) {                    matrix.set(currentMatrix);                    // 计算缩放比例                    float length = getLength(event) / oldLength;                    matrix.postScale(length, length, midPoint.x, midPoint.y);                }                invalidate();                break;            case MotionEvent.ACTION_POINTER_UP:                isMorePoint = false;                break;            case MotionEvent.ACTION_UP:                break;            default:                break;        }        return true;    }    /**     * 取手势中心点     */    private void getMidPoint(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);    }    /**     * 获取两个落点之间的距离     */    private float getLength(MotionEvent event) {        // 获取两个手指的点        float pointX1 = event.getX(0);        float pointX2 = event.getX(1);        float pointY1 = event.getY(0);        float pointY2 = event.getY(1);        return (float) Math.sqrt(Math.pow(pointX1 - pointX2, 2) + Math.pow(pointY1 - pointY2, 2));    }}

更多相关文章

随机推荐