如何设置背景图片的Andr​​oid xml文件的透明度 [英] How to set transparency of a background image Android xml file

问题描述

我已经把图片作为我的下面一行code的android应用的背景：

I have put an image in as the background of my android application with the following line of code:

 android:background="@drawable/background"

我现在希望把它透明的40％，但是这怎么可能在XML文件中？我EXM文件如下所示：

I now want to make it transparent by 40% but how is this possible within the xml file? My exm file is shown below:

<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:background="@drawable/background"
android:alpha="0.6"
android:orientation="vertical"
android:padding="30dp"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".SecondActivity" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:paddingBottom="5dp"
    android:text="Welcome"
    android:textColor="#292421"
    android:textSize="17sp"
    android:textStyle="bold" />

<TextView
    android:id="@+id/TextView01"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:gravity="center_vertical"
    android:text="This Android application is used to track and record the movements of a person throughout the university of ulster, Magee Campus. The tracking phase of the application can only be initiated whilst within the campus and off campus tracking is unavailable at this moment in time."
    android:textColor="#292421"
    android:textSize="17sp" />

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <Button
        android:id="@+id/button1"
        android:layout_width="fill_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="85dp"
        android:layout_weight="1"
        android:background="#E6E6FA"
        android:onClick="tracking"
        android:text="@string/tracking_service" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:padding="20dp" >

    </LinearLayout>

    <Button
        android:id="@+id/button2"
        android:layout_width="fill_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="85dp"
        android:layout_weight="1"
        android:background="#E6E6FA"
        android:onClick="help"
        android:text="Help" />

</LinearLayout>

推荐答案

您可以设置alpha属性：

You can set the alpha property:

android:alpha="0.4"

通过code：

yourView.setAlpha(0.5f);

只有背景：

yourView.getBackground().setAlpha(120);  // here the value is an integer not float

这篇关于如何设置背景图片的Andr​​oid xml文件的透明度的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！