更改屏幕特定部分相对于 Android 中某些元素的背景颜色

Question

>我有一个ImageView和一个TextView，我想将背景的颜色从底部更改为ImageView高度的一半。我试图用这样的View来做到这一点：

activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.MainActivity">
    <View
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentBottom="true"
        android:background="@color/cyan"
        android:id="@+id/blue_background" />
    <TextView
        android:id="@+id/credits"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:textAlignment="center"
        android:textColor="@color/white"
        android:text="@string/credits"/>
    <ImageView
        android:id="@+id/logo"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_above="@id/credits"
        android:layout_below="@id/resume_button"
        android:layout_centerHorizontal="true"
        android:adjustViewBounds="true"
        android:scaleType="fitCenter"
        android:src="@drawable/logo"/>
</RelativeLayout>

主要活动.java

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ImageView logo = (ImageView) findViewById(R.id.logo);
        TextView credits = (TextView) findViewById(R.id.credits);
        View background_blue = (View) findViewById(R.id.blue_background);
        background_blue.getLayoutParams().height = credits.getLayoutParams().height + (logo.getLayoutParams().height / 2);
    }

但它不起作用，我得到整个背景为蓝色，而不仅仅是我感兴趣的部分。

Answer 1

使用 ViewTreeObserver

final ImageView logo = (ImageView) findViewById(R.id.logo);
ViewTreeObserver vto = logo.getViewTreeObserver(); 
vto.addOnGlobalLayoutListener (new OnGlobalLayoutListener() { 
@Override 
public void onGlobalLayout() {
    logo.getViewTreeObserver().removeOnGlobalLayoutListener(this); 
    int width  = logo.getMeasuredWidth();
    int height = logo.getMeasuredHeight(); 
    background_blue.getLayoutParams().height = credits.getLayoutParams().height + (height / 2);
    } 
});

Answer 2

尝试此解决方法

替换此

 <View
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentBottom="true"
        android:background="@color/cyan"
        android:id="@+id/blue_background" />

有了这个

<LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <View
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1" />
        <View
            android:id="@+id/blue_background"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:background="@color/cyan" />
    </LinearLayout>

并从主活动中删除此行

background_blue.getLayoutParams().height = credits.getLayoutParams().height + (logo.getLayoutParams().height / 2);