Osheep

时光不回头,当下最重要。

android 右滑返回

类似于微信的右滑返回,在BaseActivity里利用dispatchTouchEvent()拦截右滑动作,利用setTranslationX()实现动画,在DecorView里添加View作为滑动时的左侧阴影。

《android 右滑返回》

image.png

渐进步骤:

  1. 设置activity背景透明
  2. 重写finish()等方法设置activity的跳转动画
  3. 重写dispatchTouchEvent()拦截 所需要 右滑动作
  4. 重写onTouchEvent()给根布局设置偏移量
  5. 添加滑动时上层activity的左侧阴影
  6. 滑动时关联下层activity滑动

注意:步骤中的代码为了不关联到后面的步骤,会与最终的有点不同

背景透明

    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:windowIsTranslucent">true</item>

activity的跳转动画

根据项目需要,重写用到的startActivity(Intent intent),startActivityForResult(Intent intent, int requestCode),finish()等activity跳转和销毁方法

@Override
public void startActivity(Intent intent) {
    super.startActivity(intent);
    overridePendingTransition(R.anim.slide_right_in, 0);
}

@Override
public void startActivityForResult(Intent intent, int requestCode) {
    super.startActivityForResult(intent, requestCode);
    overridePendingTransition(R.anim.slide_right_in, 0);
}

@Override
public void finish() {
    super.finish();
    overridePendingTransition(0, R.anim.slide_right_out);
}

//R.anim.slide_right_in
<set xmlns:android="http://schemas.android.com/apk/res/android">
  <translate
      android:duration="300"
      android:fromXDelta="100%"
      android:toXDelta="0"
      android:fromYDelta="0"
      android:toYDelta="0"/>
</set>

//R.anim.slide_right_out
<set xmlns:android="http://schemas.android.com/apk/res/android">
  <translate
      android:duration="300"
      android:fromXDelta="0"
      android:toXDelta="100%"
      android:fromYDelta="0"
      android:toYDelta="0" />
</set>

拦截右滑动作

所有的触摸事件通过activity.dispatchTouchEvent(MotionEvent ev)向view分发。
手指在X轴方向右滑动50~100px时,判断是否为(产品经理要)右滑动作

  • 手指落点为全屏幕,X方向滑动距离要比Y方向的大一些;
  • 手指落点为左侧边,X方向滑动距离有一些就行
private float downX = 0;
private float downY = 0;
private boolean shouldIntercept = false;
private boolean hadJudge = false;

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    if (shouldIntercept) {
        return onTouchEvent(ev);
    }
    switch (ev.getAction()) {
        case MotionEvent.ACTION_DOWN: {
            downX = ev.getRawX();
            downY = ev.getRawY();
            hadJudge = false;
            break;
        }
        case MotionEvent.ACTION_MOVE: {
            if (hadJudge) break;
            if (ev.getRawX() == downX) break;
            if (ev.getRawX() < downX) {
                //左滑
                hadJudge = true;
                break;
            }
            if (ev.getRawX() - downX >=100){
                //超出判断距离
                hadJudge = true;
                break;
            }
            if (ev.getRawX() - downX > 50) {
                //x轴右滑50~100px
                float rate = (ev.getRawX() - downX) / (Math.abs(ev.getRawY() - downY));
                if ((downX < 50 && rate > 0.5f) || rate > 2) {
                    shouldIntercept = true;
                }
            }
            break;
        }
        case MotionEvent.ACTION_UP: {
            downX =0;
            downY = 0;
            shouldIntercept = false;
            hadJudge=false;
            break;
        }
    }
    //Activity的默认分发
    if (ev.getAction() == MotionEvent.ACTION_DOWN) {
        onUserInteraction();
    }
    if (getWindow().superDispatchTouchEvent(ev)) {
        return true;
    }
    return true;
}

根布局位移动画

根据手指滑动距离设置根布局偏移距离,用滑动距离和手指抬起时的速度判断是否返回

private View rootView = null;
private float lastX = -1;    
private VelocityTracker velocityTracker = null;
private int maxFlingVelocity;


@Override
public boolean onTouchEvent(MotionEvent event) {
    if (rootView == null) {
        ViewGroup rootGroup = (ViewGroup) (getWindow().getDecorView());
        rootView = rootGroup.getChildAt(0);
    }
    //测量手指抬起时的速度
    if (velocityTracker == null) {
        velocityTracker = VelocityTracker.obtain();
        maxFlingVelocity = ViewConfiguration.get(this).getScaledMaximumFlingVelocity();
    }
    velocityTracker.addMovement(event);


    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN: {
            lastX = event.getRawX();
            break;
        }
        case MotionEvent.ACTION_MOVE: {
            if (lastX == -1) {
                lastX = event.getRawX();
                break;
            }
            //根据手指滑动距离设置根布局偏移距离
            rootView.setTranslationX(rootView.getTranslationX() + event.getRawX() - lastX);
            if (rootView.getTranslationX() < 0) rootView.setTranslationX(0);
            lastX = event.getRawX();
            break;
        }
        case MotionEvent.ACTION_UP: {
            //测量手指抬起时的速度
            velocityTracker.computeCurrentVelocity(1000, maxFlingVelocity);
            float velocityX = velocityTracker.getXVelocity();
            if (velocityTracker != null) {
                velocityTracker.recycle();
                velocityTracker = null;
            }

            //判断是否返回
            if (downX < 50 && velocityX > 1000) {
                //手指在左侧边落下,返回
                onBack();
            } else if (velocityX > 3600) {
                //手指快速滑动,返回
                onBack();
            } else if (rootView.getTranslationX() > ConvertUtil.getWidthInPx() * 0.3) {
                //滑动距离超过30%屏幕宽度,返回
                onBack();
            } else {
                //不返回,根布局偏移归零
                rootView.animate().translationX(0).setDuration(200).start();
            }
            
            lastX = -1;
            shouldIntercept = false;
            hadJudge=false;
            downX = 0;
            downY = 0;
            break;
        }
    }
    return super.onTouchEvent(event);
}

添加左侧阴影

Activity的最顶层View为DecorView,DecorView是一个FrameLayout,里面只有一个Linearlayout,Linearlayout包含着标题栏和自定义布局(setContentView)。
上一步跟随手指滑动进行偏移的就是Linearlayout,现在要在DecorView里添加一个View,设置背景作为阴影,并跟随Linearlayout进行移动

private View shadowView = null;
@Override
public boolean onTouchEvent(MotionEvent event) {
    if (rootView == null) {
        //添加阴影
        
        ViewGroup rootGroup = (ViewGroup) (getWindow().getDecorView());

        shadowView = new View(this);
        rootGroup.addView(shadowView, 0);
        ViewGroup.LayoutParams params = shadowView.getLayoutParams();
        //阴影宽度
        params.width = (int) ((float) ConvertUtil.getWidthInPx() * 0.05f);
        params.height = ConvertUtil.getHeightInPx();
        shadowView.setLayoutParams(params);
        shadowView.setBackgroundResource(R.drawable.shadow_grey_h);
        shadowView.setTranslationX(params.width);

        rootView = rootGroup.getChildAt(1);
    }

    ...

    switch (event.getAction()) {
        ...
        case MotionEvent.ACTION_MOVE: {
            if (lastX == -1) {
                lastX = event.getRawX();
                break;
            }
            //根据手指滑动距离设置根布局偏移距离
            rootView.setTranslationX(rootView.getTranslationX() + event.getRawX() - lastX);
            if (rootView.getTranslationX() < 0) rootView.setTranslationX(0);
            //阴影跟随根布局移动
            shadowView.setTranslationX(-shadowView.getWidth()+rootView.getTranslationX());
            lastX = event.getRawX();
            break;
        }
        case MotionEvent.ACTION_UP: {
            ...
            } else {
                //不返回,根布局偏移归零
                rootView.animate().translationX(0).setDuration(200).start();
                //阴影偏移归零
                shadowView.animate().translationX(-shadowView.getWidth()).setDuration(200).start();
            }
            ...
        }
    }
    ...
}

关联下层activity滑动

  • 保存所有的activity以获取下层activity
  • 给下层activity添加退出和进入的动画
  • 在上层activity滑动时调用下层滑动

获取下层activity

private static ArrayList<Activity> Activity_Stack = new ArrayList<>();
private BaseSwipeBackActivity lastActivity = null;

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    maxFlingVelocity = ViewConfiguration.get(this).getScaledMaximumFlingVelocity();

    if (!Activity_Stack.contains(this)) Activity_Stack.add(this);
    if (Activity_Stack.size() >= 2) {
        Activity last = Activity_Stack.get(Activity_Stack.size() - 2);
        if (last instanceof BaseSwipeBackActivity) {
            lastActivity = (BaseSwipeBackActivity) last;
        }
    }
}

@Override
protected void onDestroy() {
    super.onDestroy();
    Activity_Stack.remove(this);
}

下层activity的退出、进入动画

private void lowerActivityExitAnim() {
    if (rootView == null) return;
    //只移动30%
    rootView.animate().translationX(-ConvertUtil.getWidthInPx() * 0.3f).setDuration(300).start();
}

private void lowerActivityEnterAnim(float upperTranslationX) {
    if (rootView == null) return;
    //保证滑动退出时,上下层时间同步
    float r = 1-upperTranslationX/ (float) ConvertUtil.getWidthInPx();
    rootView.animate().translationX(0).setDuration((long) (300f * r)).start();
}

在跳转时,调用下层activity的退出、进入动画

@Override
public void startActivity(Intent intent) {
    super.startActivity(intent);
    overridePendingTransition(R.anim.slide_right_in, 0);
    lowerActivityExitAnim();
}

@Override
public void startActivityForResult(Intent intent, int requestCode) {
    super.startActivityForResult(intent, requestCode);
    overridePendingTransition(R.anim.slide_right_in, 0);
    lowerActivityExitAnim();
}

@Override
public void finish() {
    super.finish();
    overridePendingTransition(0, R.anim.slide_right_out);
    if (lastActivity != null) lastActivity.lowerActivityEnterAnim(rootView.getTranslationX());
    Activity_Stack.remove(this);
}

上层activity滑动时关联下层滑动

@Override
public boolean onTouchEvent(MotionEvent event) {
    ...
    switch (event.getAction()) {
        ...
        case MotionEvent.ACTION_MOVE: {
            ...
            //根据手指滑动距离设置根布局偏移距离
            rootView.setTranslationX(rootView.getTranslationX() + event.getRawX() - lastX);
            if (rootView.getTranslationX() < 0) rootView.setTranslationX(0);
            //阴影跟随根布局移动
            shadowView.setTranslationX(-shadowView.getWidth() + rootView.getTranslationX());
            //下层activity跟随移动
            if (lastActivity != null && lastActivity.rootView != null)
                //-ConvertUtil.getWidthInPx() * 0.3f初始的偏移
                lastActivity.rootView.setTranslationX(-ConvertUtil.getWidthInPx() * 0.3f + rootView.getTranslationX() * 0.3f);
            ...
        }
        case MotionEvent.ACTION_UP: {
            ...
            } else {
                //不返回,根布局偏移归零
                rootView.animate().translationX(0).setDuration(200).start();
                //阴影偏移归零
                shadowView.animate().translationX(-shadowView.getWidth()).setDuration(200).start();
                //下层activity偏移复原
                if (lastActivity != null)
                    lastActivity.lowerActivityExitAnim();
            }
            ...
        }
    }

    return super.onTouchEvent(event);
}

完整的

public abstract class BaseSwipeBackActivity extends AppCompatActivity {

    private static ArrayList<Activity> Activity_Stack = new ArrayList<>();
    private BaseSwipeBackActivity lastActivity = null;

    private View rootView = null;
    private View shadowView = null;

    private float downX = 0;
    private float downY = 0;
    private boolean shouldIntercept = false;
    private boolean hadJudge = false;

    private float lastX = -1;
    private VelocityTracker velocityTracker = null;
    private int maxFlingVelocity;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        maxFlingVelocity = ViewConfiguration.get(this).getScaledMaximumFlingVelocity();

        if (!Activity_Stack.contains(this)) Activity_Stack.add(this);
        if (Activity_Stack.size() >= 2) {
            Activity last = Activity_Stack.get(Activity_Stack.size() - 2);
            if (last instanceof BaseSwipeBackActivity) {
                lastActivity = (BaseSwipeBackActivity) last;
            }
        }
    }

    @Override
    protected void onResume() {
        initShadow();
        super.onResume();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Activity_Stack.remove(this);
    }

    @Override
    public void startActivity(Intent intent) {
        super.startActivity(intent);
        overridePendingTransition(R.anim.slide_right_in, 0);
        lowerActivityExitAnim();
    }

    @Override
    public void startActivityForResult(Intent intent, int requestCode) {
        super.startActivityForResult(intent, requestCode);
        overridePendingTransition(R.anim.slide_right_in, 0);
        lowerActivityExitAnim();
    }

    @Override
    public void finish() {
        super.finish();
        overridePendingTransition(0, R.anim.slide_right_out);
        if (lastActivity != null) lastActivity.lowerActivityEnterAnim(rootView.getTranslationX());
        Activity_Stack.remove(this);
    }

    private void initShadow() {
        if (shadowView == null) {
            ViewGroup rootGroup = (ViewGroup) (getWindow().getDecorView());

            shadowView = new View(this);
            rootGroup.addView(shadowView, 0);
            ViewGroup.LayoutParams params = shadowView.getLayoutParams();
            //阴影宽度
            params.width = (int) ((float) ConvertUtil.getWidthInPx() * 0.05f);
            params.height = ConvertUtil.getHeightInPx();
            shadowView.setLayoutParams(params);
            //渐变背景作为阴影
            shadowView.setBackgroundResource(R.drawable.shadow_grey_h);
            shadowView.setTranslationX(-params.width);

            rootView = rootGroup.getChildAt(1);
        }
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent ev) {
        if (shouldIntercept) {
            return onTouchEvent(ev);
        }
        switch (ev.getAction()) {
            case MotionEvent.ACTION_DOWN: {
                downX = ev.getRawX();
                downY = ev.getRawY();
                hadJudge = false;
                break;
            }
            case MotionEvent.ACTION_MOVE: {
                if (hadJudge) break;
                if (ev.getRawX() == downX) break;
                if (ev.getRawX() < downX) {
                    //左滑
                    hadJudge = true;
                    break;
                }
                if (ev.getRawX() - downX >= 100) {
                    //超出判断距离
                    hadJudge = true;
                    break;
                }
                if (ev.getRawX() - downX > 50) {
                    //x轴右滑50~100px
                    float rate = (ev.getRawX() - downX) / (Math.abs(ev.getRawY() - downY));
                    if ((downX < 50 && rate > 0.5f) || rate > 2) {
                        shouldIntercept = true;
                    }
                }
                break;
            }
            case MotionEvent.ACTION_UP: {
                downX = 0;
                downY = 0;
                shouldIntercept = false;
                hadJudge = false;
                break;
            }
        }
        //Activity的默认分发
        if (ev.getAction() == MotionEvent.ACTION_DOWN) {
            onUserInteraction();
        }
        if (getWindow().superDispatchTouchEvent(ev)) {
            return true;
        }
        return true;
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        initShadow();

        //测量手指抬起时的速度
        if (velocityTracker == null) {
            velocityTracker = VelocityTracker.obtain();
            maxFlingVelocity = ViewConfiguration.get(this).getScaledMaximumFlingVelocity();
        }
        velocityTracker.addMovement(event);


        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN: {
                lastX = event.getRawX();
                break;
            }
            case MotionEvent.ACTION_MOVE: {
                if (lastX == -1) {
                    lastX = event.getRawX();
                    break;
                }
                //根据手指滑动距离设置根布局偏移距离
                rootView.setTranslationX(rootView.getTranslationX() + event.getRawX() - lastX);
                if (rootView.getTranslationX() < 0) rootView.setTranslationX(0);
                //阴影跟随根布局移动
                shadowView.setTranslationX(-shadowView.getWidth() + rootView.getTranslationX());
                //下层activity跟随移动
                if (lastActivity != null && lastActivity.rootView != null)
                    lastActivity.rootView.setTranslationX(-ConvertUtil.getWidthInPx() * 0.3f + rootView.getTranslationX() * 0.3f);

                lastX = event.getRawX();
                break;
            }
            case MotionEvent.ACTION_UP: {
                //测量手指抬起时的速度
                velocityTracker.computeCurrentVelocity(1000, maxFlingVelocity);
                float velocityX = velocityTracker.getXVelocity();
                if (velocityTracker != null) {
                    velocityTracker.recycle();
                    velocityTracker = null;
                }

                //判断是否返回
                if (downX < 50 && velocityX > 1000) {
                    //手指在左侧边落下,返回
                    onBack();
                } else if (velocityX > 3600) {
                    //手指快速滑动,返回
                    onBack();
                } else if (rootView.getTranslationX() > ConvertUtil.getWidthInPx() * 0.3) {
                    //滑动距离超过30%屏幕宽度,返回
                    onBack();
                } else {
                    //不返回,根布局偏移归零
                    rootView.animate().translationX(0).setDuration(200).start();
                    //阴影偏移归零
                    shadowView.animate().translationX(-shadowView.getWidth()).setDuration(200).start();
                    //下层activity偏移复原
                    if (lastActivity != null) lastActivity.lowerActivityExitAnim();
                }

                lastX = -1;
                shouldIntercept = false;
                hadJudge = false;
                downX = 0;
                downY = 0;
                break;
            }
        }

        return super.onTouchEvent(event);
    }
    

    private void lowerActivityExitAnim() {
        if (rootView == null) return;
        rootView.animate().translationX(-ConvertUtil.getWidthInPx() * 0.3f).setDuration(300).start();
    }

    private void lowerActivityEnterAnim(float upperTranslationX) {
        if (rootView == null) return;
        float r = 1-upperTranslationX/ (float) ConvertUtil.getWidthInPx();
        rootView.animate().translationX(0).setDuration(r == 0.0f ? 10 : (long) (300f * r)).start();
    }

    //退出
    abstract public void onBack();
}
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