ViewDragHelper堆棧溢出

Question

我一直在關注這個演練的ViewDragHelper

http://flavienlaurent.com/blog/2013/08/28/each-navigation-drawer-hides-a-viewdraghelper/

目前我正在試圖實現一個自定義的佈局和我有ViewDragHelper問題。我試圖通過從右向左（即水平）打開的拖動手柄來獲得「抽屜」式佈局。我知道SliderDrawer處理這個任務，但我的目標僅僅是瞭解ViewDragHelper。這是我得到的錯誤：

09-24 14:27:21.031: E/AndroidRuntime(24002): FATAL EXCEPTION: main 
09-24 14:27:21.031: E/AndroidRuntime(24002): java.lang.StackOverflowError 
09-24 14:27:21.031: E/AndroidRuntime(24002): at android.widget.TextView.setFrame(TextView.java:4365) 
09-24 14:27:21.031: E/AndroidRuntime(24002): at android.view.View.layout(View.java:14293) 
09-24 14:27:21.031: E/AndroidRuntime(24002): at com.example.vdh.DragLayout.onLayout(DragLayout.java:91) 
09-24 14:27:21.031: E/AndroidRuntime(24002): at android.view.View.layout(View.java:14296) 
09-24 14:27:21.031: E/AndroidRuntime(24002): at android.view.ViewGroup.layout(ViewGroup.java:4562) 
09-24 14:27:21.031: E/AndroidRuntime(24002): at com.example.vdh.DragLayout.onLayout(DragLayout.java:97) 
09-24 14:27:21.031: E/AndroidRuntime(24002): at android.view.View.layout(View.java:14296) 
09-24 14:27:21.031: E/AndroidRuntime(24002): at android.view.ViewGroup.layout(ViewGroup.java:4562) 

請注意，最後3行左右重複。我知道這個onLayout函數負責運行時異常。這裏是源代碼：

package com.example.vdh; 

import android.content.Context; 
import android.support.v4.view.MotionEventCompat; 
import android.support.v4.widget.ViewDragHelper; 
import android.util.AttributeSet; 
import android.util.Log; 
import android.view.MotionEvent; 
import android.view.View; 
import android.widget.LinearLayout; 

public class DragLayout extends LinearLayout { 

private final ViewDragHelper mDragHelper; 
private View mDrawerView; 
private View mHandle; 

private int mDragRange; 
private int mLeft; 

public DragLayout(Context context) { 
    this(context, null); 
} 

public DragLayout(Context context, AttributeSet attrs) { 
    this(context, attrs, 0); 
} 

public DragLayout(Context context, AttributeSet attrs, int defStyle) { 
    super(context, attrs, defStyle); 
    mDragHelper = ViewDragHelper.create(this, 1.0f, new DragHelperCallback()); 
} 

@Override 
protected void onFinishInflate() { 
    mHandle = findViewById(R.id.handle); 
    mDrawerView = findViewById(R.id.drawer); 
} 


@Override 
public boolean onInterceptTouchEvent(MotionEvent ev) { 
    final int action = MotionEventCompat.getActionMasked(ev); 
    if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) { 
     mDragHelper.cancel(); 
     return false; 
    } 
    return mDragHelper.shouldInterceptTouchEvent(ev); 
} 

@Override 
public boolean onTouchEvent(MotionEvent ev) { 
    mDragHelper.processTouchEvent(ev); 
    return true; 
} 

private class DragHelperCallback extends ViewDragHelper.Callback { 

    @Override 
    public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) { 
     mLeft = left; 
     requestLayout(); 
    } 

    @Override 
    public int clampViewPositionHorizontal(View child, int left, int dx) { 
     Log.d("DragLayout", "clampViewPositionHorizontal " + left + "," + dx); 

     final int leftBound = getPaddingLeft(); 
     final int rightBound = getWidth() - mHandle.getWidth(); 

     final int newLeft = Math.min(Math.max(left, leftBound), rightBound); 

     return newLeft; 
    } 

    @Override 
    public boolean tryCaptureView(View child, int pointerId) { 
     return child == mHandle; 
    } 
} 

@Override 
protected void onLayout(boolean changed, int l, int t, int r, int b) { 
    //mDragRange = getHeight() - mHandle.getWidth(); 

    /*Log.d("onLayout", "Handle: " + mHandle.getWidth() + ", " + mHandle.getHeight()); 
    Log.d("onLayout", "Drawer: " + mDrawerView.getWidth() + ", " + mDrawerView.getHeight());*/ 


    mHandle.layout(
     mLeft, 
     0, 
     mLeft + mHandle.getMeasuredWidth(), 
     b); 

    mDrawerView.layout(
     mLeft + mHandle.getMeasuredWidth(), 
     0, 
     mLeft + r, 
     b); 
} 

} 

    mHandle.layout(
     mLeft, 
     0, 
     mLeft + mHandle.getMeasuredWidth(), 
     b); 

    mDrawerView.layout(
     mLeft + mHandle.getMeasuredWidth(), 
     0, 
     mLeft + r, 
     b); 
} 

Answer 1

根據堆棧跟蹤，你有一個遞歸調用你的DragLayout的onLayout。

你DragLayout只要求兩個視圖佈局（...）：mHandle & mDrawerView它似乎是其中之一是導致堆棧溢出（不能由一個日誌告訴）。

請張貼您的意見代碼，以便我可以嘗試並幫助您找到問題。