如何在 Android 中为视图设置不透明度(Alpha)

问题描述

我有一个按钮，如下所示:

I have a button as in the following:

<Button
     android:text="Submit"
     android:id="@+id/Button01"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content">
</Button>

在我的 onCreate() 事件中，我像这样调用 Button01:

In my onCreate() event, I am calling Button01 like this:

setContentView(R.layout.main);

View Button01 = this.findViewById(R.id.Button01);
Button01.setOnClickListener(this);

应用中有一个背景，我想在这个提交按钮上设置一个不透明度.如何为此视图设置不透明度?是我可以在java端设置，还是可以在main.xml文件中设置?

There is a background in the application, and I want to set an opacity on this submit button. How can I set an opacity for this view? Is it something that I can set on the java side, or can I set in the main.xml file?

在 Java 方面，我尝试了 Button01.mutate().SetAlpha(100)，但它给了我一个错误.

On the java side I tried Button01.mutate().SetAlpha(100), but it gave me an error.

推荐答案

我刚刚发现了您的问题，同时遇到了与 TextView 类似的问题.我能够通过扩展 TextView 并覆盖 onSetAlpha 来解决它.也许你可以尝试用你的按钮做类似的事情:

I just found your question while having the similar problem with a TextView. I was able to solve it, by extending TextView and overriding onSetAlpha. Maybe you could try something similar with your button:

import android.content.Context;
import android.util.AttributeSet;
import android.widget.TextView;

public class AlphaTextView extends TextView {

  public AlphaTextView(Context context) {
    super(context);
  }

  public AlphaTextView(Context context, AttributeSet attrs) {
    super(context, attrs);
  }

  public AlphaTextView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
  }

  @Override
  public boolean onSetAlpha(int alpha) {
    setTextColor(getTextColors().withAlpha(alpha));
    setHintTextColor(getHintTextColors().withAlpha(alpha));
    setLinkTextColor(getLinkTextColors().withAlpha(alpha));
    return true;
  }
}

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