android - 如何设置 android:layout_marginBottom 程序？

Question

要在屏幕上拖动图像，我创建了自己的类：

private class CustomImageView extends AppCompatImageView

在构造函数中，我想设置参数：

public CustomImageView(Context context) {
    super(context);
    params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
    params.bottomMargin = 50;
    this.setScaleType(ImageView.ScaleType.CENTER_CROP);
    this.setLayoutParams(params);
    this.setWillNotDraw(false);
}

我的activity_main.xml：

<RelativeLayout 
    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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.eleizo.firstapplication.MainActivity">   
</RelativeLayout>

我想实际上是这样：

<RelativeLayout 
    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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.eleizo.firstapplication.MainActivity">

    <ImageView
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop"
        android:layout_marginBottom="50dp"
        />
</RelativeLayout>

为什么字符串"params.bottomMargin = 50"不起作用？我试图设置params = new RelativeLayout.LayoutParams(val1,val2)，但没关系。如何android:layout_marginBottom通过代码在 RelativeLayout 中设置？

Answer 1

尝试使用MarginLayoutParams而不是LayoutParams.

if( params instanceof MarginLayoutParams )
{
    ((MarginLayoutParams) params).bottomMargin = 50;
    ((MarginLayoutParams) params).leftMargin = 10;

}

所以你的代码看起来像

public CustomImageView(Context context) {
    super(context);
    params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);

    if( params instanceof MarginLayoutParams )
    {
    ((MarginLayoutParams) params).bottomMargin = 50;
    }
    this.setScaleType(ImageView.ScaleType.CENTER_CROP);
    this.setLayoutParams(params);
    this.setWillNotDraw(false);

}

Answer 2

在相对布局中添加视图时尝试使用 LayoutParams。ViewGroup.addView(View, LayoutParams)。

像这样的东西。

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.MATCH_PARENT);
params.bottomMargin = 50;

relativeLayout.addView(new CutomImageView(context), params);