父中心不适用于自定义相对布局

Question

我正在尝试创建基于相对布局的自定义布局 "SquareBox" 以将 ImageView 居中。并且此自定义布局将始终为正方形大小（取决于 ImageView 的高度和宽度）。

protected void onMeasure(int width, int height) {
    super.onMeasure(width, height);
    int measuredWidth = getMeasuredWidth();
    int measuredHeight = getMeasuredHeight();
    int size;
    if (measuredWidth > measuredHeight) {
        size = measuredWidth;
    } else {
        size = measuredHeight;
    }
    setMeasuredDimension(size, size);
}

这是我的布局代码：

  <com.example.tools.SquareBox
        android:id="@+id/square_box"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:background="@android:color/darker_gray">

    <ImageView
        android:id="@+id/canvas_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="0dp"
        android:layout_centerInParent="true"
        android:adjustViewBounds="true"
        android:scaleType="fitCenter"
        tools:src="@drawable/demo_image" />
</com.example.tools.SquareBox>

它工作正常，但图像视图不在该自定义视图的中心。我试过以下： ->android:layout_centerInParent="true" 对于 ImageView。

->android:gravity="center" for "SquareBox".

->在 SquareBox 的 onMeasure 方法中以编程方式将 CENTER_IN_PARENT 添加到 ImageView。

但没有任何效果。我在这里错过了什么？

Answer 1

试试这个：-android:layout_gravity="center_horizontal"

Answer 2

将布局更改为此（将 layout_width 更改为 match_parent）：

<com.example.tools.SquareBox
        android:id="@+id/square_box"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:background="@android:color/darker_gray">

    <ImageView
        android:id="@+id/canvas_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="0dp"
        android:layout_centerInParent="true"
        android:adjustViewBounds="true"
        android:scaleType="fitCenter"
        tools:src="@drawable/demo_image" />
</com.example.tools.SquareBox>

并将您的自定义布局更改为：

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    int widthSize = MeasureSpec.getSize(widthMeasureSpec);
    int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    int heightSize = MeasureSpec.getSize(heightMeasureSpec);

    int size;
    if(widthMode == MeasureSpec.EXACTLY && widthSize > 0){
      size = widthSize;
    }
    else if(heightMode == MeasureSpec.EXACTLY && heightSize > 0){
      size = heightSize;
    }
    else{
      size = widthSize < heightSize ? widthSize : heightSize;
    }

    int finalMeasureSpec = MeasureSpec.makeMeasureSpec(size, MeasureSpec.EXACTLY);
    super.onMeasure(finalMeasureSpec, finalMeasureSpec);
  }

Answer 3

我用另一种方式模拟了方框的行为。我认为这是一种解决方法，它可能不是最好的解决方案，但它确实有效。我想知道更好更干净的解决方案。

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <RelativeLayout
        android:id="@+id/square_box_holder"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_margin="0dp"
        android:layout_weight="3">

        <View
            android:id="@+id/square_box"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_centerInParent="true"
            android:background="@android:color/darker_gray" />


        <ImageView
            android:id="@+id/canvas_image"
            style="@style/CanvasImageStyle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:layout_margin="0dp"
            android:adjustViewBounds="true"
            tools:src="@drawable/demo_image2" />

    </RelativeLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">

    </LinearLayout>
</LinearLayout>

调整视图大小的代码：

 squareImageView.setImageBitmap(getResultBitmap());
            squareBoxHolder.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
                @Override
                public boolean onPreDraw() {
                    squareBoxHolder.getViewTreeObserver().removeOnPreDrawListener(this);
                    Log.i(TAG, "onPreDraw: squareBoxHolder");
                    squareBoxHolderSize = new Point(squareBoxHolder.getMeasuredWidth(), squareBoxHolder.getMeasuredHeight());
                    return true;
                }
            });
            squareImageView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
                @Override
                public boolean onPreDraw() {
                    squareImageView.getViewTreeObserver().removeOnPreDrawListener(this);
                    Log.i(TAG, "onPreDraw: squareImageView");
                    int imageWidth = squareImageView.getMeasuredWidth();
                    int imageHeight = squareImageView.getMeasuredHeight();
                    int size;
                    ViewGroup.LayoutParams layoutParams = squareImageView.getLayoutParams();
                    if (imageWidth > imageHeight) {
                        if (imageWidth > squareBoxHolderSize.y) {
                            size = squareBoxHolderSize.y;
                            layoutParams.width = size;
                            squareImageView.setLayoutParams(layoutParams);
                        } else {
                            size = imageWidth;
                        }
                    } else {
                        if (imageHeight > squareBoxHolderSize.x) {
                            size = squareBoxHolderSize.x;
                            layoutParams.height = size;
                            squareImageView.setLayoutParams(layoutParams);
                        } else {
                            size = imageHeight;
                        }
                    }

                    layoutParams = squareBox.getLayoutParams();
                    layoutParams.height = size;
                    layoutParams.width = size;
                    squareBox.setLayoutParams(layoutParams);
                    return true;
                }
            });

父中心不适用于自定义相对布局

Center in parent is not working for custom relative layout

android

android-layout

android-relativelayout