如何为我的相对布局设置Alpha值?

您好我试图为我的相对布局设置阿尔法值,但是,我越来越错误如何解决这个帮助我…..

我有我的xml布局的三个布局第一个布局使用的背景第二个布局使用的第三个布局使用页脚。 我希望设置阿尔法值2和第三布局,所以我尝试了很多方法,仍然我不知道请告诉如何设置阿尔法值

xml代码:

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="wrap_content" android:layout_height="fill_parent" android:layout_alignParentLeft="true" android:orientation="vertical" android:background="@drawable/blue"> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="60px" android:orientation="horizontal" android:layout_alignParentTop="true" android:background="@drawable/gradient_black" android:id="@+id/ttest"> <ImageView android:id="@+id/imageView1" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <TextView android:id="@+id/header_text" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerVertical="true" android:layout_marginLeft="6dp" android:layout_toRightOf="@+id/imageView1" android:text="settings" android:textColor="@color/white" android:textSize="20sp" /> </RelativeLayout> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="55px" android:background="@drawable/gradient_black" android:gravity="bottom" android:orientation="horizontal" android:layout_alignParentBottom="true" > <ImageView android:id="@+id/imageView2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="ssss" /> </RelativeLayout> </RelativeLayout> 

码:

 public class DesignActivity extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); int width = getWindowManager().getDefaultDisplay().getWidth(); int height = getWindowManager().getDefaultDisplay().getHeight(); ImageView imgHead = (ImageView)findViewById(R.id.imageView1); ImageView imgbottom = (ImageView)findViewById(R.id.imageView2); imgbottom.setImageResource(R.drawable.back); imgbottom.setLayoutParams(new RelativeLayout.LayoutParams(width/8, height/8)); imgHead.setImageResource(R.drawable.b); imgHead.setLayoutParams(new RelativeLayout.LayoutParams(width/8, height/8)); // RelativeLayout relative = (RelativeLayout)findViewById(R.id.ttest); } } 

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尝试这个

 AlphaAnimation alpha = new AlphaAnimation(0.5F, 0.5F); alpha.setDuration(0); // Make animation instant alpha.setFillAfter(true); // Tell it to persist after the animation ends // And then on your layout yourLayout.startAnimation(alpha); 

RelativeLayout rl; …
rl.setAlpha(0.5F);

 <RelativeLayout android:id="@+id/rl" android:layout_width="200dp" android:layout_height="200dp" android:background="@drawable/bg" android:alpha="0.5"> 

在这些情况下,我通常倾向于同时设置颜色和alpha,所以我只是使用rl.setBackgroundColor(0xAACCCCCC); 其中A是阿尔法值,C是hex格式的颜色。

例如: rl.setBackgroundColor(0x88000000); 为0.5透明的黑色背景。

或XML: android:background="#88000000"