Android 图片手势缩放自定义View

public class Img extends android.support.v7.widget.AppCompatImageView {    float x = 1, y = 1;    double now = 0;    public Img(Context context, AttributeSet attrs) {        super(context, attrs);    }    @Override    protected void onDraw(Canvas canvas) {        canvas.scale(x, y, getWidth() / 2, getHeight() / 2);        canvas.save();        super.onDraw(canvas);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        if (event.getPointerCount() > 1) {            double an = Math.sqrt(Math.pow(event.getX(0) - event.getX(1), 2))                    + Math.sqrt(Math.pow(event.getY(0) - event.getY(1), 2));            if (now != 0) {                if (an > now) {                    if (x < 3) {                        x += 0.05;                        y += 0.05;                        invalidate();                    }                } else {                    if (x > 0.1) {                        x -= 0.05;                        y -= 0.05;                        invalidate();                    }                }            }            now = an;        }        return true;    }}

在布局文件中直接使用就行了

<?xml version="1.0" encoding="utf-8"?>

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