[英]How to set transparency of a background image Android xml file
我已經使用以下代碼行將圖像作為我的Android應用程序的背景:
android:background="@drawable/background"
我現在想讓它透明40%但是在xml文件中這怎么可能? 我的exm文件如下所示:
<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>
您可以設置alpha屬性:
android:alpha="0.4"
通過代碼:
yourView.setAlpha(0.5f);
只有背景:
yourView.getBackground().setAlpha(120); // here the value is an integer not float
它可以使用自定義drawable完成。 它是一個非常古老的帖子,但我認為我應該回答,可能對某人有幫助。
資源:
bg.xml
<?xml version="1.0" encoding="utf-8"?>
<bitmap xmlns:android="http://schemas.android.com/apk/res/android"
android:src="@drawable/background" android:alpha="0.4"/>
這就是您的布局現在的樣子:
<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/bg"
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>
如果您已將圖像設置為背景
android:alpha="0.x"
將導致整個屏幕(子視圖)淡出。 相反,你可以利用
android:backgroundTint="#80FFFFFF"
android:backgroundTintMode="src_over"
僅淡化背景圖像而不影響子視圖。
您可以創建圖層列表資源並將其設置為視圖的背景屬性(布局)
background_image_with_alpha.xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<bitmap
android:alpha="0.2"
android:src="@drawable/xxxxxx"
android:gravity="fill">
</bitmap>
</item>
</layer-list >
您可以為View
使用alpha
屬性( http://developer.android.com/reference/android/view/View.html#attr_android:alpha ):
android:alpha="0.4"
嘗試使用Drawable.setAlpha();
View backgroundImage = findViewById(R.id.background_image);
Drawable background = backgroundImage.getBackground();
background.setAlpha(80);
在您的xml文件中設置
android:alpha="0.4"
它將在0到255之間變化。
<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: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:background="@drawable/background"
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>
你可以使用alpha屬性android:alpha =“0.5”; (0到1之間)
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