如何将现有的`Blazor`项目的主题切换写的更好看?

在现有的系统当中，我们的主题切换会比较生硬，下面我们将基于Masa Blazor实现好看的扩散主题切换的样式效果。

安装MASA.Template

dotnet new install MASA.Template

创建Masa Blazor项目

打开vs2022

选择server app模板

打开wwwroot/CSS/site.css

添加一下代码，这个代码是核心样式实现。 animation: clip .5s ease-in;的.5s则是扩散时间。


::view-transition-old(root) {
    animation: none;
}
::view-transition-new(root) {
    mix-blend-mode: normal;
    animation: clip .5s ease-in;
}

@keyframes clip {
    from {
        clip-path: circle(0% at var(--x) var(--y));
    }
    to{
        clip-path: circle(100% at var(--x) var(--y));
    }
}

打开Pages/_Host.cshtml

添加以下代码，请添加到body的内部的最尾部的位置。

    <script>
        window.switchTheme = function (dotNetHelper, x, y) {
            document.documentElement.style.setProperty('--x', x + 'px')
            document.documentElement.style.setProperty('--y', y + 'px')
            document.startViewTransition(() => {
                dotNetHelper.invokeMethodAsync('SwitchTheme');
            });
            
        }
    </script>

这个方法向window添加一个switchTheme的js方法，需要传递调用的实例，x,y则是扩散的开始位置，

然后会创建一个css的变量，这个变量对应到上面的clip里面的var(–x)和var(–y)

打开SharedMainLayout.razor，修改成以下代码

@inherits LayoutComponentBase
@inject GlobalConfig GlobalConfig
@inject IJSRuntime JsRuntime
@inject MasaBlazor MasaBlazor

<MApp >
    <PPageTabsProvider>
        <CascadingValue Value="GlobalConfig.Culture.Name" Name="CultureName">
            <MAppBar  Elevation=0 App Height="100" Class="default-app-bar mx-6">
                 <div class="default-app-bar__actions @PageModeClass">
                     <Favorite />
                     <MSpacer />
                     <Search />
                     <MIcon Size=20 Class="ml-5" Color="neutral-lighten-3">mdi-message-processing-outline</MIcon>
                     <MIcon Size=20 Class="ml-5" Color="neutral-lighten-3" OnClick="() => _showSetting = true">mdi-cog-outline</MIcon>
                     <Language OnLanguageChanged="OnLanguageChanged" />
                     <MButton OnClick="ClickSwitchTheme">切换</MButton>
                     <Login />
                 </div>
                 <div class="default-app-bar__nav @PageModeClass">
                     @if (_pageTab == PageModes.PageTab)
                    {
                        <PageTabs @ref="_pageTabs" SelfPatterns="@s_selfPatterns" />
                    }
                    else
                    {
                        <Breadcrumb />
                    }
                </div>
            </MAppBar>

            <Navigation />

            <MMain Class="fill-lighten-1">
                <div class="pa-6">
                    @if (_pageTab == PageModes.PageTab)
                    {
                        <PPageContainer PageTabs="@_pageTabs?.PPageTabs" SelfPatterns="@s_selfPatterns">
                            @Body
                        </PPageContainer>
                    }
                    else
                    {
                        @Body
                    }
                </div>
            </MMain>
            <Settings @bind-PageModel="_pageTab" @bind-Show=_showSetting />
        </CascadingValue>
    </PPageTabsProvider>
</MApp>

@code {

    private DotNetObjectReference<MainLayout>? objRef;

    private bool dark = false;

    private static readonly string[] s_selfPatterns =
    {
        "/app/todo"
    };

    private bool? _showSetting;

    private string? _pageTab;

    private PageTabs? _pageTabs;

    private string PageModeClass => _pageTab == PageModes.PageTab ? "page-mode--tab" : "page-mode--breadcrumb";

    protected override void OnInitialized()
    {
        objRef = DotNetObjectReference.Create(this);
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        await base.OnAfterRenderAsync(firstRender);

        if (firstRender)
        {
            await GlobalConfig.InitFromStorage();
        }
    }

    void OnLanguageChanged(CultureInfo culture)
    {
        GlobalConfig.Culture = culture;
    }

    private void ClickSwitchTheme(MouseEventArgs args)
    {
        _ = JsRuntime.InvokeVoidAsync("switchTheme", objRef, args.ClientX, args.ClientY);
    }

    [JSInvokable]
    public void SwitchTheme()
    {
        dark = !dark;
        MasaBlazor.ToggleTheme();
    }

}