Question

我正在尝试构建一个组件，可以在所有方向上刷卡，并可以将其带回。其转换如下：

从左到右：带回前一张卡
从右到左：将新卡带到
从上到下：带回前一张卡
从下到上：将新卡带到

我决定，如果我扩展Viewpager并结合垂直和水平Viewpager实现，那么前进的最佳方式就是。它将解决所有与动画相关的问题以及片段管理工作。

最终，我能够创造出我想要的东西，但现在却陷入了最后的问题。当Viewpager垂直滑动时，它具有标记的区域，其行为流畅，但暗区不能正确滑动（下图）。对于垂直滑动实现，我使用了触摸坐标交换方法并映射了坐标。我试图查看交换映射，但看不出我错在哪里。

如果有人能指出我正确的方向，那将是一个很大的帮助：

以下是代码：

AllDirectionViewPager.java

import android.content.Context;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;

public class AllDirectionViewPager extends ViewPager {
    public static String TAG = "AllDirectionViewPager";
    private float startX, startY, mHeight, mWidth;
    int DIRECTION_LOCKING_THRESHOLD_X=5, DIRECTION_LOCKING_THRESHOLD_Y=5, mDirection=-1;
    boolean directionLocked=false;
    VDepthPageTransformer mVerticalTransformer;
    HDepthPageTransformer mHorizontalTransformer;

    public AllDirectionViewPager(Context context) {
        super(context);
        init();
    }

    public AllDirectionViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        setOverScrollMode(OVER_SCROLL_NEVER);
        mVerticalTransformer = new VDepthPageTransformer();
        mHorizontalTransformer = new HDepthPageTransformer();
    }

    /**
     * Swaps the X and Y coordinates of touch event.
     */
    private MotionEvent swapXY(MotionEvent ev) {
        float width = getWidth();
        float height = getHeight();

        float newX = (ev.getY() / height) * width;
        float newY = (ev.getX() / width) * height;

        Log.i(TAG, "swap xy called. init: "+ev.getX()+","+ev.getY()+" final: "+newX+","+newY+" with height: "+height);
        ev.setLocation(newX, newY);

        return ev;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev){
        boolean intercepted = false;
        int direction;
        direction = getDirection(ev);
        Log.i(TAG, "viewpager intercepted: "+mDirection);
        if(mDirection==0) {
            intercepted = super.onInterceptTouchEvent(swapXY(ev));
            swapXY(ev); // return touch coordinates to original reference frame for any child views
        } else if (mDirection==1) {
            intercepted = super.onInterceptTouchEvent(ev);
        }

        return intercepted;
    }

    //1: Left-Right; 0: UP-DOWN; -1: continuing
    int getDirection(MotionEvent ev) {
        float dirX=0, dirY=0;
        boolean continuing = false;
        switch (ev.getAction()) {
            case MotionEvent.ACTION_DOWN:
                startX = ev.getX();
                startY = ev.getY();
                mDirection = -1;
                directionLocked = false;
                Log.d(TAG, "swipe start");
                break;
            case MotionEvent.ACTION_MOVE:
                float endX = ev.getX();
                float endY = ev.getY();
                Log.d(TAG, "direction locked: "+directionLocked+" diffY: "+(endY - startY)+ " diffX: "+(endX - startX));
                if (!directionLocked && ((Math.abs(endX - startX)>DIRECTION_LOCKING_THRESHOLD_X)||(Math.abs(endY - startY) > DIRECTION_LOCKING_THRESHOLD_Y))) {
                    dirX = (endX - startX) / getHeight();
                    dirY = (endY - startY) / getWidth();
                    directionLocked = true;
                    if (Math.abs(dirX) < Math.abs(dirY)) {
                        mDirection = 0;
                        this.setPageTransformer(true, mVerticalTransformer);
                        Log.d(TAG, "Vertical set");
                    }
                    else if (Math.abs(dirX) > Math.abs(dirY)) {
                        mDirection = 1;
                        this.setPageTransformer(true, mHorizontalTransformer);
                        Log.d(TAG, "Horizontal set");
                    }
                    else {
                        mDirection = -1;
                        directionLocked = false;
                        Log.d(TAG, "nothing found");
                    }
                }
                break;
            case MotionEvent.ACTION_UP:
                Log.d(TAG, "swipe done");
                directionLocked = false;
                break;
            default:
                continuing = true;
        }
        if(continuing)
            return -1;

        return -1;
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        int direction = getDirection(ev);
        Log.i(TAG, "viewpager touch: "+mDirection);
        Log.i(TAG, "Touch coords: "+ev.getX()+","+ev.getY());
        if(mDirection==0) {
            return super.onTouchEvent(swapXY(ev));
        }else/* if(mDirection==1) */{
            return super.onTouchEvent(ev);
        }
//        return false;
    }
}

HDepthPageTransformer.java

import android.support.v4.view.ViewPager;
import android.view.View;

public class HDepthPageTransformer implements ViewPager.PageTransformer {
    private static final float MIN_SCALE = 0.85f;

    public void transformPage(View view, float position) {
        int pageWidth = view.getWidth();

        if (position < -1) { // [-Infinity,-1)
            // This page is way off-screen to the left.
            view.setAlpha(0);

        } else if (position <= 0) { // [-1,0]
            // Use the default slide transition when moving to the left page
            view.setAlpha(1);
            view.setTranslationX(0);
            view.setScaleX(1);
            view.setScaleY(1);

        } else if (position <= 1) { // (0,1]
            // Fade the page out.
            view.setAlpha(1);

            // Counteract the default slide transition
            view.setTranslationX(pageWidth * -position);

            // Scale the page down (between MIN_SCALE and 1)
            float scaleFactor = MIN_SCALE
                    + (1 - MIN_SCALE) * (1 - Math.abs(position));
            view.setScaleX(scaleFactor);
            view.setScaleY(scaleFactor);

        } else { // (1,+Infinity]
            // This page is way off-screen to the right.
            view.setAlpha(0);
        }
    }
}

VDepthPageTransformer.java

import android.support.v4.view.ViewPager;
import android.view.View;

public class VDepthPageTransformer implements ViewPager.PageTransformer {
    private static final float MIN_SCALE = 0.85f;

    public void transformPage(View view, float position) {
        int pageWidth = view.getWidth();

        if (position < -1) { // [-Infinity,-1)
            // This page is way off-screen to the left.
            view.setAlpha(0);

        } else if (position <= 0) { // [-1,0]
            // Use the default slide transition when moving to the top page
            view.setAlpha(1);
            // Counteract the default slide transition
            view.setTranslationX(view.getWidth() * -position);

            //set Y position to swipe in from top
            float yPosition = position * view.getHeight();
            view.setTranslationY(yPosition);
            view.setScaleX(1);
            view.setScaleY(1);

        } else if (position <= 1) { // (0,1]
            // Fade the page out.
            view.setAlpha(1 - position);

            // Counteract the default slide transition
            view.setTranslationX(pageWidth * -position);

            // Scale the page down (between MIN_SCALE and 1)
            float scaleFactor = MIN_SCALE
                    + (1 - MIN_SCALE) * (1 - Math.abs(position));
            view.setScaleX(scaleFactor);
            view.setScaleY(scaleFactor);

        } else { // (1,+Infinity]
            // This page is way off-screen to the right.
            view.setAlpha(0);
        }
    }
}

图片无法缩放以显示问题区域（对不起的艺术品抱歉）：

深度页面变换器来自android开发者网站。使用此处的某些部分进行垂直滚动：Android: Vertical ViewPager

Answer 1

由于没有人回答这个问题，我潜入了viewpager的android源代码，并意识到虽然观察结果很奇怪，但原因是初始化不正确。

因为onInterceptTouchEvent在实际发生任何拖动之前被触发（即在onTouchEvent之前）。在将控制权交给onTouchEvent之前，正确初始化过程非常重要。这就是上面代码中需要做的所有事情。希望很快我会在这里发布相同的库:)但如果有人在此之前需要它，请发表评论。

Android全方位视图寻呼机滑动问题

1 个答案: