ImageView使用tint属性

Android

Android中颜色值对应的也是一个Drawable,其实现类是ColorDrawable,ColorDrawable中对应的了多状态的颜色ColorStateList即color目录下的selector.

API 21+,使用的是ColorStateList存储状态颜色,在Drawable不同状态下使用对应的颜色更新ColorFilter去着色

public ImageView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes){
    if (a.hasValue(R.styleable.ImageView_tint)) {
        mDrawableTintList = a.getColorStateList(R.styleable.ImageView_tint);
        mHasDrawableTint = true;
        // Prior to L, this attribute would always set a color filter with
        // blending mode SRC_ATOP. Preserve that default behavior.
        mDrawableTintMode = PorterDuff.Mode.SRC_ATOP;
        mHasDrawableTintMode = true;
    }
    if (a.hasValue(R.styleable.ImageView_tintMode)) {
        mDrawableTintMode = Drawable.parseTintMode(a.getInt(
            R.styleable.ImageView_tintMode, -1), mDrawableTintMode);
        mHasDrawableTintMode = true;
    }
    applyImageTint();                
}
// 更新着色 -> BitmapDrawable.setTintList -> Drawable.updateTintFilter
private void applyImageTint() {
    if (mDrawable != null && (mHasDrawableTint || mHasDrawableTintMode)) {
        mDrawable = mDrawable.mutate();
        if (mHasDrawableTint) {
            mDrawable.setTintList(mDrawableTintList);
        }
        if (mHasDrawableTintMode) {
            mDrawable.setTintMode(mDrawableTintMode);
        }
        // The drawable (or one of its children) may not have been
        // stateful before applying the tint, so let's try again.
        if (mDrawable.isStateful()) {
            mDrawable.setState(getDrawableState());
        }
    }
}

API 19,使用的是单一的颜色值,直接通过设置ColorFilter直接着色

// ImageView构造函数
int tint = a.getInt(com.android.internal.R.styleable.ImageView_tint, 0);
if (tint != 0) {
    setColorFilter(tint);
}
//...
// 相当于设置tint
public final void setColorFilter(int color, PorterDuff.Mode mode) {
    setColorFilter(new PorterDuffColorFilter(color, mode));
}

所以API21以前不能在xml中使用ColorStateList的颜色,只能指定单一的颜色值.
res/color/text_color

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="#d2b978" android:state_pressed="true" />
    <item android:color="#b4b9c3" />
</selector>

ImageView布局:

<!-- API 21 以下只支持单色 -->
<ImageView 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:tint="#f00"
    android:src="@mipmap/ic_search" />
<!-- tint 使用多状态颜色(ColorStateList),API<21 不支持,会Crash -->
<ImageView 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:tint="@color/text_color"
    android:src="@mipmap/ic_search" />    

为了兼容版本可以使用java代码动态设置

// 不同状态下着色的颜色color
ColorStateList colorStateList = ContextCompat.getColorStateList(getContext(), R.color.text_color);
// 对应color state
int[][] states = new int[][]{new int[]{android.R.attr.state_pressed}, new int[]{}};
StateListDrawable stateListDrawable = new StateListDrawable();
Drawable drawable = ContextCompat.getDrawable(getContext(), R.mipmap.ic_search);
stateListDrawable.addState(states[0], drawable);
stateListDrawable.addState(states[1], drawable);
Drawable wrap = DrawableCompat.wrap(stateListDrawable);
DrawableCompat.setTintList(wrap, colorStateList);
ImageView imageView = (ImageView) view.findViewById(R.id.image);
imageView.setImageDrawable(wrap);