我如何使一个Textview的背景大约20%透明(不完全透明),在哪里有一个颜色的背景(即白色)?
当前回答
我已经接受了三个观点。在第一个视图中,我设置了全颜色(无alpha),在第二个视图中,我设置了半颜色(0.5 alpha),在第三个视图中,我设置了浅色(0.2 alpha)。
你可以使用下面的代码设置任何颜色并使用alpha获取颜色:
文件activity_main.xml
<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:gravity = "center"
android:orientation = "vertical"
tools:context = "com.example.temp.MainActivity" >
<View
android:id = "@+id/fullColorView"
android:layout_width = "100dip"
android:layout_height = "100dip" />
<View
android:id = "@+id/halfalphaColorView"
android:layout_width = "100dip"
android:layout_height = "100dip"
android:layout_marginTop = "20dip" />
<View
android:id = "@+id/alphaColorView"
android:layout_width = "100dip"
android:layout_height = "100dip"
android:layout_marginTop = "20dip" />
</LinearLayout>
文件MainActivity.java
public class MainActivity extends Activity {
private View fullColorView, halfalphaColorView, alphaColorView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fullColorView = (View)findViewById(R.id.fullColorView);
halfalphaColorView = (View)findViewById(R.id.halfalphaColorView);
alphaColorView = (View)findViewById(R.id.alphaColorView);
fullColorView.setBackgroundColor(Color.BLUE);
halfalphaColorView.setBackgroundColor(getColorWithAlpha(Color.BLUE, 0.5f));
alphaColorView.setBackgroundColor(getColorWithAlpha(Color.BLUE, 0.2f));
}
private int getColorWithAlpha(int color, float ratio) {
int newColor = 0;
int alpha = Math.round(Color.alpha(color) * ratio);
int r = Color.red(color);
int g = Color.green(color);
int b = Color.blue(color);
newColor = Color.argb(alpha, r, g, b);
return newColor;
}
}
芬兰湾的科特林版:
private fun getColorWithAlpha(color: Int, ratio: Float): Int {
return Color.argb(Math.round(Color.alpha(color) * ratio), Color.red(color), Color.green(color), Color.blue(color))
}
Done
其他回答
我已经接受了三个观点。在第一个视图中,我设置了全颜色(无alpha),在第二个视图中,我设置了半颜色(0.5 alpha),在第三个视图中,我设置了浅色(0.2 alpha)。
你可以使用下面的代码设置任何颜色并使用alpha获取颜色:
文件activity_main.xml
<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:gravity = "center"
android:orientation = "vertical"
tools:context = "com.example.temp.MainActivity" >
<View
android:id = "@+id/fullColorView"
android:layout_width = "100dip"
android:layout_height = "100dip" />
<View
android:id = "@+id/halfalphaColorView"
android:layout_width = "100dip"
android:layout_height = "100dip"
android:layout_marginTop = "20dip" />
<View
android:id = "@+id/alphaColorView"
android:layout_width = "100dip"
android:layout_height = "100dip"
android:layout_marginTop = "20dip" />
</LinearLayout>
文件MainActivity.java
public class MainActivity extends Activity {
private View fullColorView, halfalphaColorView, alphaColorView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fullColorView = (View)findViewById(R.id.fullColorView);
halfalphaColorView = (View)findViewById(R.id.halfalphaColorView);
alphaColorView = (View)findViewById(R.id.alphaColorView);
fullColorView.setBackgroundColor(Color.BLUE);
halfalphaColorView.setBackgroundColor(getColorWithAlpha(Color.BLUE, 0.5f));
alphaColorView.setBackgroundColor(getColorWithAlpha(Color.BLUE, 0.2f));
}
private int getColorWithAlpha(int color, float ratio) {
int newColor = 0;
int alpha = Math.round(Color.alpha(color) * ratio);
int r = Color.red(color);
int g = Color.green(color);
int b = Color.blue(color);
newColor = Color.argb(alpha, r, g, b);
return newColor;
}
}
芬兰湾的科特林版:
private fun getColorWithAlpha(color: Int, ratio: Float): Int {
return Color.argb(Math.round(Color.alpha(color) * ratio), Color.red(color), Color.green(color), Color.blue(color))
}
Done
下面是来自@Aromero的答案的编程解决方案,用于计算alpha通道的十六进制值。:)
public static void main(String[] args) throws Exception {
final Scanner scanner = new Scanner(System.in);
int transPerc;
float fPerc;
System.out.println("Enter the transparency percentage without % symbol:");
while((transPerc=scanner.nextInt())>=0 && transPerc <=100){
fPerc = (float) transPerc / 100;
transPerc = Math.round(255 * fPerc);
System.out.println("= " + Integer.toHexString(transPerc));
System.out.print("another one please : ");
}
scanner.close();
}
有一个XML值alpha,它接受双重值。
从API 11+开始,范围从0f到1f(包括),0f是透明的,1f是不透明的:
Android:alpha="0.0"这是不可见的 android:α= " 0.5 "透明 Android:alpha="1.0"完全可见
它就是这样运作的。
我建议使用alpha属性。
<TextView
android:alpha="0.8" />
或者现在你可以使用选择器。在colors包中创建background_color_25.xml。
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:alpha="0.8" android:color="@color/background_color" />
</selector>
用法如下:
<TextView
android:background="@color/background_color_25" />
查看下面的流行textView使用这个
android:alpha="0.38"
XML
android:color="#3983BE00" // Partially transparent sky blue
动态
btn.getBackground () .setAlpha (128);// 50%透明
tv_name.getBackground () .setAlpha (128);// 50%透明
Where the INT ranges from 0 (fully transparent) to 255 (fully opaque).
<TextView
style="@style/TextAppearance.AppCompat.Caption"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:alpha="0.38"
android:gravity="start"
android:textStyle="bold"
tools:text="1994|EN" />
android:α= " 0.38 "
Text View alpha property set 0.38 to your textView visibility is faid
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