CoordinatorLayout.java 文件源码

public void setStatusBarBackground(@Nullable Drawable bg) {
    Drawable drawable = null;
    if (this.mStatusBarBackground != bg) {
        if (this.mStatusBarBackground != null) {
            this.mStatusBarBackground.setCallback(null);
        }
        if (bg != null) {
            drawable = bg.mutate();
        }
        this.mStatusBarBackground = drawable;
        if (this.mStatusBarBackground != null) {
            if (this.mStatusBarBackground.isStateful()) {
                this.mStatusBarBackground.setState(getDrawableState());
            }
            DrawableCompat.setLayoutDirection(this.mStatusBarBackground, ViewCompat.getLayoutDirection(this));
            this.mStatusBarBackground.setVisible(getVisibility() == 0, false);
            this.mStatusBarBackground.setCallback(this);
        }
        ViewCompat.postInvalidateOnAnimation(this);
    }
}