Android开发仿微信下拉关闭图片11

图片会跟随手指移动，只有是下滑时才会退出查看页面，其他情况会复位，直接当做ImageView使用即可，setViewCall方法是在下滑完成后要执行的操作，上，左，右，可自行扩展

onTouchEvent 监听手指坐标，GestureDetector 监听滑动的惯性，ViewHelper设置图片位移动画

public class FriendCircleView extends android.support.v7.widget.AppCompatImageView implements GestureDetector.OnGestureListener {

public FriendCircleView(Context context) {
    super(context);
    initView(context, null, 0);
}

public FriendCircleView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initView(context, attrs, 0);
}

public FriendCircleView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    initView(context, attrs, defStyleAttr);
}

//设置滑动完成后的回调方法
public void setViewCall(FriendCircleViewCall viewCall) {
    this.viewCall = viewCall;
}

private void initView(Context context, AttributeSet attrs, int defStyleAttr) {
    screenHeight = ScreenUtils.getScreenHeight(context);
    detector = new GestureDetector(context, this);
}

private GestureDetector detector;

private int screenHeight;//设备屏幕高度
private float oldX, oldY;//手机放在屏幕的坐标
private float movY;//移动中在屏幕上的坐标
private float alphaPercent = 1f;//背景颜色透明度
private boolean isFinsh = false;//是否执行关闭页面的操作
private FriendCircleViewCall viewCall = null;

@SuppressLint("ClickableViewAccessibility")
@Override
public boolean onTouchEvent(MotionEvent event) {
    detector.onTouchEvent(event);
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            oldX = event.getRawX();
            oldY = event.getRawY();
            break;
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_CANCEL:
            if (isFinsh) {
                isFinsh = false;
                if (viewCall != null) {
                    viewCall.viewDestry();
                }
                Log.e("ldd------", "页面返回");
            } else {
                setupUping();
                Log.e("ldd------", "手指抬起");
            }
            break;
        case MotionEvent.ACTION_MOVE:
            isFinsh = false;
            float movX = event.getRawX() - oldX;
            movY = event.getRawY() - oldY;
            setupMoving(movX, movY);
            if (Math.abs(movX) > Math.abs(movY)) {
                if (movX < 0) {
                    Log.e("ldd------", "左滑动");
                } else {
                    Log.e("ldd------", "右滑动");
                }
            } else {
                if (movY < 0) {
                    Log.e("ldd------", "上滑动");
                } else {
                    if (movY > (screenHeight / 6)) {
                        isFinsh = true;
                        Log.e("ldd------", "下滑动");
                    }
                }
            }
            return false;
    }
    return true;
}

private void setupUping() {
    animate().setDuration(200)
            .scaleX(1)
            .scaleY(1)
            .translationX(0)
            .translationY(0)
            .setUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    if (alphaPercent < animation.getAnimatedFraction()) {
                        ((ViewGroup) getParent()).setBackgroundColor(convertPercentToBlackAlphaColor(animation.getAnimatedFraction()));
                    }
                }
            })
            .start();
}

private void setupMoving(float deltaX, float deltaY) {
    if (Math.abs(movY) < (screenHeight / 4)) {
        float scale = 1 - Math.abs(movY) / screenHeight;
        alphaPercent = 1 - Math.abs(deltaY) / (screenHeight / 2);
        ViewHelper.setScaleX(this, scale);
        ViewHelper.setScaleY(this, scale);
        ((ViewGroup) getParent()).setBackgroundColor(convertPercentToBlackAlphaColor(alphaPercent));
    }
    ViewHelper.setTranslationX(this, deltaX);
    ViewHelper.setTranslationY(this, deltaY);
}

//设置背景颜色透明度
protected int convertPercentToBlackAlphaColor(float percent) {
    percent = Math.min(1, Math.max(0, percent));
    int intAlpha = (int) (percent * 255);
    String stringAlpha = Integer.toHexString(intAlpha).toLowerCase();
    String color = "#" + (stringAlpha.length() < 2 ? "0" : "") + stringAlpha + "000000";
    return Color.parseColor(color);
}

@Override
public boolean onDown(MotionEvent e) {
    return false;
}

@Override
public void onShowPress(MotionEvent e) {

}

@Override
public boolean onSingleTapUp(MotionEvent e) {
    isFinsh = true;
    return false;
}

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
    return false;
}

@Override
public void onLongPress(MotionEvent e) {

}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
    float movX = e2.getRawX() - e1.getRawX();
    float movY = e2.getRawY() - e1.getRawY();
    Log.e("ldd------2", movX + "---------" + movY);
    if (Math.abs(movX) > Math.abs(movY)) {
        if (movX < 0) {
            Log.e("ldd------2", "左滑动");
        } else {
            Log.e("ldd------2", "右滑动");
        }
    } else {
        if (movY < 0) {
            Log.e("ldd------2", "上滑动");
        } else {
            isFinsh = true;
            Log.e("ldd------2", "下滑动");
        }
    }
    return true;
}

public interface FriendCircleViewCall {
    void viewDestry();
}

}