Shell 导航栏滚动行为 [英] Shell navigation bar scroll behavior

问题描述

我想问一下是否可以在 Xamarin.Forms Shell 中为导航栏或 TabbedPage (TabLayout) 设置动画滚动它隐藏或发现看到gif.我在 Xamarin 本机 android 中尝试了它，它在添加 layout_scrollFlags 后工作.

解决方案

不确定您是否可以在 XF + Shell 中使用 android 样式实现此行为，但是您可以通过覆盖 CreateToolbarAppearanceTracker().

 公共类 MyShellRenderer : ShellRenderer{公共 MyShellRenderer(上下文上下文):基础(上下文){}受保护的覆盖 IShellToolbarAppearanceTracker CreateToolbarAppearanceTracker(){base.CreateToolbarAppearanceTracker();返回新的 MyShellToolbarAppearanceTracker(this);}}

MyShellToolbarAppearanceTracker(随意命名)

using LP = Android.Views.ViewGroup.LayoutParams;...公共类 MyShellToolbarAppearanceTracker : ShellToolbarAppearanceTracker{公共 MyShellToolbarAppearanceTracker(IShellContext shellContext) : base(shellContext){}public override void SetAppearance(AndroidX.AppCompat.Widget.Toolbar toolbar, IShellToolbarTracker toolbarTracker, ShellAppearance外观){base.SetAppearance(工具栏，toolbarTracker，外观)；toolbar.LayoutParameters = new AppBarLayout.LayoutParams(LP.MatchParent, LP.WrapContent){ScrollFlags = AppBarLayout.LayoutParams.ScrollFlagScroll |AppBarLayout.LayoutParams.ScrollFlagEnterAlways};}}

不要忘记使用 ExportRenderer 正确装饰它，如 文档.

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(如果以下链接的错误/问题已关闭，请忽略此部分)

已知的副作用

这是由 Xamarin.Forms 错误 13338

I would like to ask if it is possible to animate the Navigation Bar or TabbedPage (TabLayout) in the Xamarin.Forms Shell when scrolling it either hides or the discovery see gif. I tried it in Xamarin native android there it works after adding layout_scrollFlags.

http://lomza.totem-soft.com/appbarlayout-scroll-behavior-with-layout_scrollflags

http://karthikraj.net/2016/12/24/scrolling-behavior-for-appbars-in-android

解决方案

Not sure if you can achieve this behavior with an android style in XF + Shell, but you can achieve it using a custom renderer by overriding CreateToolbarAppearanceTracker().

    public class MyShellRenderer : ShellRenderer
    {
        public MyShellRenderer(Context context) : base(context)
        {
        }

        protected override IShellToolbarAppearanceTracker CreateToolbarAppearanceTracker()
        {
            base.CreateToolbarAppearanceTracker();
            return new MyShellToolbarAppearanceTracker(this);
        }
    }

MyShellToolbarAppearanceTracker (name it whatever you want)

using LP = Android.Views.ViewGroup.LayoutParams;
...
public class MyShellToolbarAppearanceTracker : ShellToolbarAppearanceTracker
{
        public MyShellToolbarAppearanceTracker(IShellContext shellContext) : base(shellContext)
        {
        }

        public override void SetAppearance(AndroidX.AppCompat.Widget.Toolbar toolbar, IShellToolbarTracker toolbarTracker, ShellAppearance appearance)
        {
            base.SetAppearance(toolbar, toolbarTracker, appearance);
            toolbar.LayoutParameters = new AppBarLayout.LayoutParams(LP.MatchParent, LP.WrapContent)
            {
                ScrollFlags = AppBarLayout.LayoutParams.ScrollFlagScroll |
                AppBarLayout.LayoutParams.ScrollFlagEnterAlways
            };
        }
}

Don't forget to properly decorate it with ExportRenderer as explained in the documentation.

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(ignore this section if the below linked bug/issue is closed)

Known Side-Effect

This is a trivial undesired side-effect caused by a Xamarin.Forms Bug 13338

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