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理解为什么onClick()在onDispatchTouchEvent()返回True后仍被调用

ontouch onclick user-interface android java

Nerdy Bunz · 技术社区 · 6 年前

比方说,在Android应用程序中,我们希望能够在任何时刻暂时可靠地忽略所有用户触摸。

根据我对堆栈溢出和 here here ,和 here ,商定的解决方案似乎是这样的:

// returning true should mean touches are ignored/blocked
@Override
public boolean dispatchTouchEvent(MotionEvent pEvent) {

    if (disableTouches) {
        return true;
    } else {
        return super.dispatchTouchEvent(pEvent);
    }

}

Android Monkey Exerciser Tool 并且以快速的速度向应用程序发送触摸事件,很明显,猪开始在量子层次上飞翔——我们可以接到呼叫 onClick() 即使在“blocktouchs”设置为true之后/期间。

我的问题是:为什么会这样?——这是Android的正常行为,还是我的代码出错了?:)

我已经排除了由用户输入而不是触摸调用(因此不受 onDispatchTouchEvent()

下面是我用于此测试的代码:

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    View rootView; // turns black when "touch rejection" is in progress

    View allowedButton;
    View notAllowedButton;

    // Used to decide whether to process touch events.
    // Set true temporarily when notAllowedButton is clicked.
    boolean touchRejectionAnimationInProgress = false;

    int errorCount = 0; // counting "unexpected/impossible" click calls

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        rootView = findViewById(R.id.rootView);

        allowedButton = findViewById(R.id.allowedButton);
        notAllowedButton = findViewById(R.id.notAllowedButton);

        allowedButton.setOnClickListener(this);
        notAllowedButton.setOnClickListener(this);

        allowedButton.setBackgroundColor(Color.GREEN);
        notAllowedButton.setBackgroundColor(Color.RED);

    }

    // returning true should mean touches are ignored/blocked
    @Override
    public boolean dispatchTouchEvent(MotionEvent pEvent) {

        if (touchRejectionAnimationInProgress) {
            Log.i("XXX", "touch rejected in dispatchTouchevent()");
            return true;
        } else {
            return super.dispatchTouchEvent(pEvent);
        }

    }

    @Override
    public void onClick(View viewThatWasClicked){

        Log.i("XXX", "onClick() called.  View clicked: " + viewThatWasClicked.getTag());

        //checking for unexpected/"impossible"(?) calls to this method
        if (touchRejectionAnimationInProgress) {
            Log.i("XXX!", "IMPOSSIBLE(?) call to onClick() detected.");
            errorCount ++;
            Log.i("XXX!", "Number of unexpected clicks: " + errorCount);
            return;
        } // else proceed...

        if (viewThatWasClicked == allowedButton) {
            // Irrelevant
        } else if (viewThatWasClicked == notAllowedButton) {
            // user did something that is not allowed.
            touchRejectionAnimation();
        }

    }

    // When the user clicks on something "illegal,"
    // all user input is ignored temporarily for 200 ms.
    // (arbitrary choice of duration, but smaller is better for testing)
    private void touchRejectionAnimation() {

        Log.i("XXX", "touchRejectionAnimation() called.");

        touchRejectionAnimationInProgress = true;
        rootView.setBackgroundColor(Color.BLACK);

        // for logging/debugging purposes...
        final String rejectionID = (new Random().nextInt() % 9999999) + "";
        Log.i("XXX", "rejection : " + rejectionID + " started.");

        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                try { Thread.sleep(200); } catch (Exception e) {
                    Log.e("XXX", "exception in touchRejection() BG thread!");
                }
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Log.i("XXX", "rejection " + rejectionID + " ending");
                        rootView.setBackgroundColor(Color.WHITE);
                        touchRejectionAnimationInProgress = false;
                    }
                });
            }
        });

        thread.start();

    }

}

layout.xml格式:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:id="@+id/rootView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <View
        android:id="@+id/allowedButton"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="32dp"
        android:layout_marginBottom="32dp"
        android:tag="allowedButton"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/notAllowedButton"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <View
        android:id="@+id/notAllowedButton"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="32dp"
        android:layout_marginBottom="32dp"
        android:tag="view2"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/allowedButton"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

1 回复 | 直到 6 年前

-1

Jitesh Mohite 6 年前

如果不想在任何视图上触发onClick(),请单击。

创建自定义视图组例如:MyConstraintLayout并添加所有子视图

重写onInterceptTouchEvent(MotionEvent ev)并返回true。

public class MyConstraintLayout extends ConstraintLayout {

    private boolean mIsViewsTouchable;

    public ParentView(Context context) {
        super(context);
    }

    public ParentView(Context context, AttributeSet attrs) {
        super(context, attrs);
        inflate(context, R.layout.custom_view, this);
    }

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

    public void setViewsTouchable(boolean isViewTouchable) {
        mIsViewsTouchable = isViewTouchable;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return mIsViewsTouchable;
    }
 }