我的应用程序必须使用 GridLayout。 GridLayout 的问题是权重的限制，因此我必须在运行时缩放其子项的大小。我在 OnGlobalLayoutListener 的帮助下完成了这项工作。

我的 GridLayout 的子级是两个 Button，它们具有父级的宽度和父级高度的一半。上面有一个 Button，下面有一个 Button。 如果单击上方的 Button，我想将 GridLayout 的大小切换为 500(宽度和高度)以及 700(宽度和高度)。 单击上方的 Button 后，Button 应该会正确缩放，但它们不会那样做。

public class HauptAktivitaet extends Activity implements OnLayoutChangeListener, OnClickListener{

  /** ContentView its sizes I will change on a click later */

  private GridLayout mGridLayout;

  /** LayoutParams of the above child */

  private GridLayout.LayoutParams mGridLayout_LayoutParams_Above;

  /** LayoutParams of the below child */

  private GridLayout.LayoutParams mGridLayout_LayoutParams_Below;

  /** Children of the ContentView */

  private Button mButtonAbove;
  private Button mButtonBelow;


  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    inline();

    setContentView(mGridLayout);

  }

  private void inline(){

    /* instantiation of ContentView which is named mGridLayout */

    mGridLayout = new GridLayout(this);

    /* set the count of rows and columns of ContentView */

    mGridLayout.setRowCount(2);
    mGridLayout.setColumnCount(1);

      /* set OnGlobalLayoutListener for observe a change of its layout */

    mGridLayout.addOnLayoutChangeListener(this);

    /* instantiation of the LayoutParams for the children */

    mGridLayout_LayoutParams_Above = new GridLayout.LayoutParams(GridLayout.spec(0), GridLayout.spec(0));
    mGridLayout_LayoutParams_Below = new GridLayout.LayoutParams(GridLayout.spec(1), GridLayout.spec(0));

    /* instantiation of the children and setting of their LayoutParams */

    mButtonAbove = new Button(this);
    mButtonAbove.setLayoutParams(mGridLayout_LayoutParams_Above);
    mButtonAbove.setOnClickListener(this); // A click on this Button changes the Size of its parent ViewGroup.

    /* instantiation of ContentView */

    mButtonBelow = new Button(this);
    mButtonBelow.setLayoutParams(mGridLayout_LayoutParams_Below);

    /* add children to the ContentView */

    mGridLayout.addView(mButtonAbove);
    mGridLayout.addView(mButtonBelow);

  }

  @Override
  public void onLayoutChange(View v, int left, int top, int right, int bottom,
      int oldLeft, int oldTop, int oldRight, int oldBottom) {

    /* Width and height on this time are known */

    int width = mGridLayout.getWidth();
    int height = mGridLayout.getHeight();

    /* Changes the LayoutParams of ContentViews children dynamicly*/

    mGridLayout_LayoutParams_Above.width = width;
    mGridLayout_LayoutParams_Above.height = height / 2;

    mGridLayout_LayoutParams_Below.width = width;
    mGridLayout_LayoutParams_Below.height = height / 2;

    /* ISSUE:
     * should update the rendering of the buttons but it doesn't work correctly */

    mButtonAbove.requestLayout();
    mButtonBelow.requestLayout();

    /* A little debug info for knowing of the ContentViews size */

    mButtonBelow.setText("Own Width = " + mButtonBelow.getWidth() + "\n" + 
                         "Own Height = " + mButtonBelow.getHeight() + "\n" +
                         "Perents Width = " + width + "\n" +
                         "Perents Height = " + height);


  }

  private boolean switcher = true;

  /** 
   * Works correctly
   * */

  @Override
  public void onClick(View v) {

    int width = 0;
    int height = 0;

    if(switcher){
      width = 500;
      height = 500;
      switcher = false;
    }else{
      width = 700;
      height = 700;
      switcher = true;
    }

    mGridLayout.getLayoutParams().width = width;
    mGridLayout.getLayoutParams().height = height;

    mGridLayout.requestLayout();

  }

}

谁能告诉我该怎么做？

如何让 ContentView 刷新自身及其子级？我正在寻找一个优雅的解决方案。

非常感谢您的回答!

问候! :-)

最佳答案

我遇到了同样的问题。我猜当 onLayoutChanges() 被调用时 Android 还没有完成新布局的计算，并且无法从该方法中触发重新计算。 解决方案是使用 Handler将布局更改发布到 UI 线程的末尾。

我不太确定 requestLayout()，也许用 setLayoutParams() 的另一个调用替换它。它可能具有相同的效果。

因此，在实现 Runnable 的类中实现重新布局，在 onCreate() 和 onLayoutChanges( ) 实例化 Runnable 类并将其提交给 Handler:

public class HauptAktivitaet extends Activity implements OnLayoutChangeListener, OnClickListener{

  // this class updates the layout
  private class LayoutUpdater implements Runnable {
    private final int width;
    private final int height;

    private LayoutUpdater(int width, int height) {
      this.width = width;
      this.height = height;
    }

    public void run() {
      mGridLayout_LayoutParams_Above.width = width;
      mGridLayout_LayoutParams_Above.height = height;

      mGridLayout_LayoutParams_Below.width = width;
      mGridLayout_LayoutParams_Below.height = height;

      // might be necessary or not: set layout parameters to trigger update
      mButtonAbove.setLayoutParams(mGridLayout_LayoutParams_Above);   
      mButtonBelow.setLayoutParams(mGridLayout_LayoutParams_Below);
    }
  }

  /* snip */

  // add handler running in UI thread
  private Handler uiHandler;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // instantiate handler
    uiHandler = new Handler();

    inline();

    setContentView(mGridLayout);

  }

  /* snip */

  @Override
  public void onLayoutChange(View v, int left, int top, int right, int bottom,
      int oldLeft, int oldTop, int oldRight, int oldBottom) {

    /* Width and height on this time are known */

    int width = mGridLayout.getWidth();
    int height = mGridLayout.getHeight();

    // post layout update to the end of queue
    uiHandler.post(new LayoutUpdater(width, height / 2);
  }
}

关于java - Android - View.requestLayout 在 OnLayoutChangeListener 中不起作用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/25329934/