2020-06-07-Android-滑动冲突

2020-06-15  本文已影响0人  耿望

滑动(平移)的实现方式

首先看一下有几种方式可以实现滑动效果,实际也就是平移。

通过layout实现

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                lastX = x;
                lastY = y;
                break;
            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_MOVE:
                int offsetX = (int) (x - lastX);
                int offsetY = (int) (y - lastY);
                layout(getLeft() + offsetX, getTop() + offsetY,
                        getRight() + offsetX, getBottom() + offsetY);
                break;
        }
        return true;
    }

也可以简单封装成一个方法,实现X轴方向上的平移:

    private void translateWithLayout(int deltaX) {
        layout(getLeft() - deltaX, getTop(),
                getRight() - deltaX, getBottom());
    }

通过offset方法实现

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                lastX = x;
                lastY = y;
                Log.d(TAG, "onTouchDown " + x + " " + y);
                break;
            case MotionEvent.ACTION_MOVE:
                int offsetX = (int) (x - lastX);
                int offsetY = (int) (y - lastY);
                offsetLeftAndRight(offsetX);
                offsetTopAndBottom(offsetY);
                break;
            case MotionEvent.ACTION_UP:
                Log.d(TAG, "onTouchUp " + x + " " + y);
                break;
        }
        return true;
    }

可以封装成一个方法,实现X轴方向的平移:

    private void translateWithOffset(int deltaX) {
        offsetLeftAndRight(deltaX);
    }

通过LayoutParams实现

    private void translateWithParams(int deltaX) {
        MarginLayoutParams layoutParams = (MarginLayoutParams) getLayoutParams();
        layoutParams.leftMargin = getLeft() - deltaX;
        setLayoutParams(layoutParams);
    }

滑动冲突的解决方式

实际上所有的滑动冲突,都是两种解决思路,外部拦截和内部拦截。
下面举了一个实际例子,是在ScrollView的外部添加一个横向滑动效果。
布局文件如下:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <com.one.view.OutsideView
        app:layout_constraintTop_toTopOf="parent"
        android:id="@+id/outside"
        android:layout_marginTop="40dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <ScrollView
            android:layout_gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="100dp">
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:textAlignment="center"
                android:textSize="30sp"
                android:text="HelloWorld1\nHelloWorld2\nHelloWorld3\nHelloWorld4\n"/>
        </ScrollView>
    </com.one.view.OutsideView>

    <com.one.view.InsideView
        app:layout_constraintTop_toBottomOf="@+id/outside"
        android:layout_marginTop="40dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <com.one.view.MyScrollView
            android:layout_gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="100dp">
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:textAlignment="center"
                android:textSize="30sp"
                android:text="HelloWorld1\nHelloWorld2\nHelloWorld3\nHelloWorld4\n"/>
        </com.one.view.MyScrollView>
    </com.one.view.InsideView>

</androidx.constraintlayout.widget.ConstraintLayout>

实现了一个这样的效果:


t1.png

外部拦截

外部拦截是通过重写父容器的onInterceptTouchEvent方法,根据需要返回是否拦截的决定。

    // intercept from outside
    @Override
    public boolean onInterceptTouchEvent(MotionEvent event) {
        int x = (int) event.getX();
        int y = (int) event.getY();
        boolean intercepted = false;
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                lastX = x;
                lastY = y;
                intercepted = false;
                break;
            case MotionEvent.ACTION_MOVE:
                int deltaX = lastX - x;
                int deltaY = lastY - y;
                intercepted = (Math.abs(deltaX) - 10 > 0) && (Math.abs(deltaY) - 10 < 0);
                break;
        }
        Log.d(TAG, "onInterceptTouchEvent " + intercepted
                + " x=" + event.getX() + " y=" + event.getY());
        return intercepted;
    }

接着在onTouchEvent方法中实现横向滑动效果:

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_MOVE) {
            int x = (int) event.getX();
            int y = (int) event.getY();
            int deltaX = lastX - x;
            int deltaY = lastY - y;
            Log.d(TAG, "onTouchEvent x=" + deltaX + " y=" + deltaY);
            layout(getLeft() - deltaX, getTop(),
                    getRight() - deltaX, getBottom());
        }
        return true;
    }

内部拦截

内部拦截方式稍微比较复杂,需要在父容器和子view中都添加逻辑代码。
首先在父容器中,对除了ACTION_DOWN之外的所有事件进行拦截。

    @Override
    public boolean onInterceptTouchEvent(MotionEvent event) {

        int action = event.getAction();
        int x = (int) event.getX();
        int y = (int) event.getY();
        if (action == MotionEvent.ACTION_DOWN) {
            lastX = x;
            lastY = y;
            Log.d(TAG, "onInterceptTouchEvent ACTION_DOWN");
        }

        return (action != MotionEvent.ACTION_DOWN);
    }

接着在onTouchEvent方法中实现一个横向平移。

    @Override
    public boolean onTouchEvent(MotionEvent event) {

        if (event.getAction() == MotionEvent.ACTION_MOVE) {

            int x = (int) event.getX();
            int y = (int) event.getY();
            int deltaX = lastX - x;
            int deltaY = lastY - y;

            Log.d(TAG, "onTouchEvent x=" + deltaX + " y=" + deltaY);

            translateWithParams(deltaX);

        }

        return true;
    }

比较复杂的逻辑是需要在子view中实现一个是否禁止拦截的判断:

    // intercept from inside
    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {

        int x = (int) event.getX();
        int y = (int) event.getY();
        boolean intercepted = false;
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                lastX = x;
                lastY = y;
                intercepted = false;
                getParent().requestDisallowInterceptTouchEvent(true);
                break;
            case MotionEvent.ACTION_MOVE:
                int deltaX = lastX - x;
                int deltaY = lastY - y;
                intercepted = (Math.abs(deltaX) - 10 > 0) && (Math.abs(deltaY) - 10 < 0);
                if (intercepted) {
                    getParent().requestDisallowInterceptTouchEvent(false);
                }
                break;
            default:
                break;

        }
        Log.d(TAG, "dispatchTouchEvent " + intercepted
                + " x=" + event.getX() + " y=" + event.getY());
        return super.dispatchTouchEvent(event);
    }

参考

ViewPager的简单使用
Android View体系(二)实现View滑动的六种方法

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