如何以编程方式将selectableItemBackground添加到ImageButton？

Question

android.R.attr.selectableItemBackground存在,但是如何以编程方式将其添加到ImageButton？

另外,我将如何在文档中找到答案？这里提到了,但我没有看到它是如何实际使用的任何解释.实际上,我似乎很少发现文档有用,但我希望这是我的错,而不是文档的错.

Answer 1

以下是使用答案的示例:如何在代码中获取attr引用？

    // Create an array of the attributes we want to resolve
    // using values from a theme
    // android.R.attr.selectableItemBackground requires API LEVEL 11
    int[] attrs = new int[] { android.R.attr.selectableItemBackground /* index 0 */};

    // Obtain the styled attributes. 'themedContext' is a context with a
    // theme, typically the current Activity (i.e. 'this')
    TypedArray ta = obtainStyledAttributes(attrs);

    // Now get the value of the 'listItemBackground' attribute that was
    // set in the theme used in 'themedContext'. The parameter is the index
    // of the attribute in the 'attrs' array. The returned Drawable
    // is what you are after
    Drawable drawableFromTheme = ta.getDrawable(0 /* index */);

    // Finally free resources used by TypedArray
    ta.recycle();

    // setBackground(Drawable) requires API LEVEL 16, 
    // otherwise you have to use deprecated setBackgroundDrawable(Drawable) method. 
    imageButton.setBackground(drawableFromTheme);
    // imageButton.setBackgroundDrawable(drawableFromTheme);

Answer 2

如果您使用的是AppCompat,则可以使用以下代码:

int[] attrs = new int[]{R.attr.selectableItemBackground};
TypedArray typedArray = context.obtainStyledAttributes(attrs);
int backgroundResource = typedArray.getResourceId(0, 0);
view.setBackgroundResource(backgroundResource);
typedArray.recycle();

Answer 3

这适用于我TextView:

// Get selectable background
TypedValue typedValue = new TypedValue();
getTheme().resolveAttribute(R.attr.selectableItemBackground, typedValue, true);

clickableTextView.setClickable(true);
clickableTextView.setBackgroundResource(typedValue.resourceId);

因为我使用AppCompat库,所以我R.attr.selectableItemBackground没有使用android.R.attr.selectableItemBackground.

我认为typedValue.resourceId拥有所有的drawables selectableItemBackground比使用TypeArray#getResourceId(index, defValue)或者TypeArray#getDrawable(index)只检索给定的drawable index.