Pull to refresh and load more when scroll to bottom

App.xaml.cs

@@ -3,7 +3,11 @@
     public App(NavigatorService navigatorService) {
       InitializeComponent();
 
+#if WINDOWS
+      MainPage = new WindowsAppShell();
+#else
       MainPage = new AppShell();
+#endif
       NavigatorService = navigatorService;
     }
 

Components/Layout/MainLayout.razor

@@ -2,13 +2,83 @@
 @implements IDisposable
 @inject NavigatorService NavigatorService
 @inject NavigationManager NavigationManager
+@inject IJSRuntime JS
 @inject State State
 <NavMenu />
+
 <main class="responsive max">
   @Body
 </main>
 
+<script>
+  class Refresher {
+    constructor(targetEl) {
+      this.lastKnownScrollPosition = 0
+      this.ticking = false
+      this.atTop = true
+      this.atBottom = false
+      this.target = targetEl
+
+      this.target.addEventListener("scroll", this.scrollEvent)
+    }
+
+    scrolledTo = (scrollPos) => {
+      // Do something with the scroll position
+      if (this.atTop && scrollPos > 0) {
+        this.atTop = false
+        CSHARP.invokeMethodAsync("SetAtTop", false)
+      }
+      else if (!this.atTop && scrollPos == 0) {
+        // console.log("AT TOP")
+        this.atTop = true
+        CSHARP.invokeMethodAsync("SetAtTop", true)
+      }
+
+      const bottom = this.target.scrollHeight - Math.ceil(this.target.offsetHeight)
+
+      if (this.atBottom && scrollPos < bottom) {
+        this.atBottom = false
+        CSHARP.invokeMethodAsync("SetAtBottom", false)
+      }
+      else if (!this.atBottom && scrollPos >= bottom) {
+        // console.log("AT BOTTOM")
+        this.atBottom = true
+        CSHARP.invokeMethodAsync("SetAtBottom", true)
+      }
+    }
+
+    scrollEvent = (event) => {
+      this.lastKnownScrollPosition = Math.ceil(event.target.scrollTop)
+
+      if (!this.ticking) {
+        window.requestAnimationFrame(() => {
+          this.scrolledTo(this.lastKnownScrollPosition)
+          this.ticking = false
+        });
+
+        this.ticking = true
+      }
+    }
+
+    Dispose = () => {
+      this.target.removeEventListener("scroll", this.scrollEvent)
+    }
+  }
+  new Refresher(document.querySelector('main'))
+</script>
+
 @code {
+
+  private DotNetObjectReference<State>? DotNetRef { get; set; }
+  protected override void OnAfterRender(bool firstRender) {
+    base.OnAfterRender(firstRender);
+    if (firstRender) {
+      // See warning about memory above in the article
+      DotNetRef = DotNetObjectReference.Create(State);
+      JS.InvokeVoidAsync("injectCSharp", DotNetRef);
+    }
+  }
+
   protected override void OnInitialized() {
     base.OnInitialized();
     NavigatorService.NavigationManager = NavigationManager;
@@ -25,11 +95,12 @@
     }
     else if (!string.IsNullOrEmpty(State.SharePhoto)) {
       NavigationManager.NavigateTo($"/sharepic/{State.SharePhoto}");
-      State.ShareString = null;
+      State.SharePhoto = null;
     }
   }
 
   void IDisposable.Dispose() {
     State.IntentReceived -= IntentRecieved;
+    DotNetRef?.Dispose();
   }
 }

Components/Pages/Person.razor

@@ -3,6 +3,7 @@
 @inject IJSRuntime JS
 @inject NavigationManager Nav
 
+<RefreshButton></RefreshButton>
 
 <div class="row center-align">
   <h3 class="page-heading"><i class="fa-solid fa-fw fa-at"></i>@Address</h3>
@@ -51,7 +52,7 @@
         }
       </article>
     </div>
-    <StatusList @ref="StatusList" StatusFunc="@(async() => await State.GetStatuses(Address))" Editable="@Editable"></StatusList>
+    <StatusList @ref="StatusList" StatusFunc="@(async(forceRefresh) => await State.GetStatuses(Address, forceRefresh))" Editable="@Editable"></StatusList>
     @if(Address == State.SelectedAddressName) {
       <button class="fab circle extra large-elevate" data-ui="#post-modal">
         <i class="fa-solid fa-pen-to-square"></i>
@@ -61,7 +62,7 @@
   </div>
   
   <div id="pics" class="page padding">
-    <PicList @ref="PicList" PicsFunc="@(async() => await State.GetPics(Address))" Editable="@Editable"></PicList>
+    <PicList @ref="PicList" PicsFunc="@(async(forceRefresh) => await State.GetPics(Address, forceRefresh))" Editable="@Editable"></PicList>
     @if (Address == State.SelectedAddressName) {
       <button class="fab circle extra large-elevate" data-ui="#post-modal">
         <i class="fa-solid fa-camera-retro"></i>
@@ -84,8 +85,8 @@
     get => _address;
     set {
       _address = value;
-      if(StatusList != null) StatusList.StatusFunc = async () => await State.GetStatuses(_address);
+      if (StatusList != null) StatusList.StatusFunc = async (forceRefresh) => await State.GetStatuses(_address, forceRefresh);
-      if(PicList != null) PicList.PicsFunc = async () => await State.GetPics(_address);
+      if(PicList != null) PicList.PicsFunc = async (bool forceRefresh) => await State.GetPics(_address, forceRefresh);
     }
   }
   public string ProfileUrl {

Components/Pages/Pics.razor

@@ -15,9 +15,12 @@
 </AuthorizeView>
 
 <div id="pics" class="responsive card-grid">
-  <PicList PicsFunc="@(async() => await State.GetPics())"></PicList>
+  <PicList PicsFunc="@(async(bool forceRefresh) => await State.GetPics(forceRefresh))"></PicList>
 </div>
 
+<RefreshButton></RefreshButton>
+
+
 @code {
 
 }

Components/Pages/StatuslogLatest.razor

@@ -16,10 +16,7 @@
 </AuthorizeView>
 
 <div id="statuses" class="responsive">
-  <StatusList StatusFunc="@(async() => await State.GetStatuses())"></StatusList>
+  <StatusList StatusFunc="@(async(forceRefresh) => await State.GetStatuses(forceRefresh))"></StatusList>
 </div>
 
-@code {
+<RefreshButton></RefreshButton>
-
-}
-

Components/PicList.razor

@@ -1,6 +1,8 @@
 @inject IJSRuntime JS
 @inject State State
 
+@implements IDisposable
+
 @if (Editable) {
   <EditPicDialog @ref="Dialog" id="EditPicModal"></EditPicDialog>
 }
@@ -13,19 +15,60 @@
 
 @code {
   [Parameter]
-  public Func<Task<List<Pic>?>> PicsFunc { get; set; }
+  public Func<bool, Task<List<Pic>?>> PicsFunc { get; set; }
   [Parameter]
   public bool Editable { get; set; } = false;
 
   public EditPicDialog? Dialog { get; set; }
 
   private List<Pic>? pics;
+  private int count { get; set; } = 0;
+  private int pageSize { get; } = 10;
 
   // TODO: There is a noticable rendering delay between the pics loading and the page rendering
   protected override async Task OnInitializedAsync() {
     await base.OnInitializedAsync();
-    if (pics == null || pics.Count == 0) pics = await PicsFunc();
+    State.PropertyChanged += StateChanged;
-    await InvokeAsync(StateHasChanged);
+    State.CanRefresh = true;
+
+    if (pics == null || pics.Count == 0) await LoadNext();
     await JS.InvokeVoidAsync("removeElementById", "pics-loading");
   }
+
+  public async Task<bool> PullUp() {
+    int countBefore = count;
+    await LoadNext();
+    return (count != countBefore);
+  }
+
+  public async Task LoadNext(bool forceRefresh = false) {
+    if (pics == null) pics = new List<Pic>();
+    if (forceRefresh) {
+      count = 0;
+      pics.Clear();
+    }
+
+    var allPics = await PicsFunc(forceRefresh);
+    if(allPics != null && count < allPics.Count) {
+      pics.AddRange(allPics.Skip(count).Take(pageSize));
+      count = pics.Count;
+    }
+    await InvokeAsync(StateHasChanged);
+  }
+
+  private async void StateChanged(object? sender, PropertyChangedEventArgs e) {
+    if (e.PropertyName == nameof(State.IsRefreshing) && State.IsRefreshing) {
+      await LoadNext(true);
+      State.IsRefreshing = false;
+    }
+
+    if (e.PropertyName == nameof(State.AtBottom) && State.AtBottom) {
+      await LoadNext();
+    }
+  }
+
+  public void Dispose() {
+    State.PropertyChanged -= StateChanged;
+    State.CanRefresh = false;
+  }
 }

Components/RefreshButton.razor

@@ -0,0 +1,18 @@
+@inject State State
+
+<button id="refreshButton" class="absolute transparent circle top right margin" @onclick="() => State.IsRefreshing = true">
+  <i class="fa-solid fa-arrow-rotate-right @(State.IsRefreshing ? "fa-spin" : "")"></i>
+</button>
+
+@code {
+  protected override async Task OnInitializedAsync() {
+    await base.OnInitializedAsync();
+    State.PropertyChanged += StateChanged;
+  }
+
+  private async void StateChanged(object? sender, PropertyChangedEventArgs e) {
+    if(e.PropertyName == nameof(State.IsRefreshing)) {
+      await InvokeAsync(StateHasChanged);
+    }
+  }
+}

Components/StatusList.razor

@@ -1,6 +1,8 @@
 @inject IJSRuntime JS
 @inject State State
 
+@implements IDisposable
+
 @if (Editable) {
   <EditStatusDialog @ref="Dialog" id="EditStatusModal"></EditStatusDialog>
 }
@@ -13,18 +15,60 @@
 
 @code {
   [Parameter]
-  public Func<Task<List<Status>?>> StatusFunc { get; set; }
+  public Func<bool,Task<List<Status>?>> StatusFunc { get; set; }
   [Parameter]
   public bool Editable { get; set; } = false;
 
   public EditStatusDialog? Dialog { get; set; }
 
   private List<Status>? statuses;
+  private int count { get; set; } = 0;
+  private int pageSize { get; } = 50;
 
   protected override async Task OnInitializedAsync() {
     await base.OnInitializedAsync();
-    if (statuses == null || statuses.Count == 0) statuses = await StatusFunc();
+    State.PropertyChanged += StateChanged;
+    State.CanRefresh = true;
+
+    if (statuses == null || statuses.Count == 0) await LoadNext();
     await InvokeAsync(StateHasChanged);
     await JS.InvokeVoidAsync("removeElementById", "statusLoading");
   }
+
+  public async Task<bool> PullUp() {
+    int countBefore = count;
+    await LoadNext();
+    return (count != countBefore);
+  }
+
+  public async Task LoadNext(bool forceRefresh = false) {
+    if (statuses == null) statuses = new List<Status>();
+    if (forceRefresh) {
+      count = 0;
+      statuses.Clear();
+    }
+
+    var allStatuses = await StatusFunc(forceRefresh);
+    if (allStatuses != null && count < allStatuses.Count) {
+      statuses.AddRange(allStatuses.Skip(count).Take(pageSize));
+      count = statuses.Count;
+    }
+    await InvokeAsync(StateHasChanged);
+  }
+
+  private async void StateChanged(object? sender, PropertyChangedEventArgs e) {
+    if (e.PropertyName == nameof(State.IsRefreshing) && State.IsRefreshing) {
+      await LoadNext(true);
+      State.IsRefreshing = false;
+    }
+
+    if(e.PropertyName == nameof(State.AtBottom) && State.AtBottom) {
+      await LoadNext();
+    }
+  }
+
+  public void Dispose() {
+    State.PropertyChanged -= StateChanged;
+    State.CanRefresh = false;
+  }
 }

Components/_Imports.razor

@@ -1,4 +1,5 @@
-@using System.Net.Http
+@using System.ComponentModel
+@using System.Net.Http
 @using System.Net.Http.Json
 @using Microsoft.AspNetCore.Components.Forms
 @using Microsoft.AspNetCore.Components.Routing
@@ -11,3 +12,4 @@
 @using Neighbourhood.omg.lol.Components
 @using Neighbourhood.omg.lol.Models
 @using Markdig
+@using BcdLib.Components

MainPage.xaml

@@ -2,13 +2,17 @@
 <ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
              xmlns:local="clr-namespace:Neighbourhood.omg.lol"
+             xmlns:models="clr-namespace:Neighbourhood.omg.lol.Models"
+             x:DataType="models:State"
              x:Class="Neighbourhood.omg.lol.MainPage"
              BackgroundColor="{DynamicResource PageBackgroundColor}">
 
+  <RefreshView x:Name="refreshView" IsRefreshing="{Binding IsRefreshing}" IsEnabled="False">
     <BlazorWebView x:Name="blazorWebView" HostPage="wwwroot/index.html" UrlLoading="BlazorUrlLoading">
       <BlazorWebView.RootComponents>
         <RootComponent Selector="#app" ComponentType="{x:Type local:Components.Routes}" />
       </BlazorWebView.RootComponents>
     </BlazorWebView>
+  </RefreshView>
 
 </ContentPage>

MainPage.xaml.cs

@@ -1,13 +1,26 @@
 using Microsoft.AspNetCore.Components;
 using Microsoft.AspNetCore.Components.WebView;
 using Microsoft.AspNetCore.Components.WebView.Maui;
+using Neighbourhood.omg.lol.Models;
+using System.ComponentModel;
 using System.Diagnostics;
 
 namespace Neighbourhood.omg.lol {
   public partial class MainPage : ContentPage {
 
+    private State State { get; set; }
+
     public MainPage() {
       InitializeComponent();
+      State = IPlatformApplication.Current!.Services.GetService<State>()!;
+      BindingContext = State;
+      State.PropertyChanged += State_PropertyChanged;
+    }
+
+    private void State_PropertyChanged(object? sender, PropertyChangedEventArgs e) {
+      if (e.PropertyName == nameof(State.CanRefresh) || e.PropertyName == nameof(State.AtTop)) {
+        refreshView.IsEnabled = State.CanRefresh && State.AtTop;
+      }
     }
 
     private void BlazorUrlLoading(object? sender, UrlLoadingEventArgs e) {

MauiProgram.cs

@@ -1,4 +1,5 @@
-using Markdig;
+using BcdLib.Components;
+using Markdig;
 using Microsoft.AspNetCore.Components.Authorization;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Logging;
@@ -15,6 +16,7 @@ namespace Neighbourhood.omg.lol {
         });
 
       builder.Services.AddMauiBlazorWebView();
+      builder.Services.AddBcdLibPullComponent();
       builder.Services.AddTransient<LoginWebViewPage>();
       builder.Services.AddTransient<EphemeralWebPage>();
 

Models/State.cs

@@ -1,8 +1,10 @@
 using Microsoft.AspNetCore.Components;
+using Microsoft.JSInterop;
+using System.ComponentModel;
 using System.Text.Json;
 
 namespace Neighbourhood.omg.lol.Models {
-  public class State {
+  public class State : INotifyPropertyChanged {
     // Main data lists
     public List<Status>? Statuses { get; set; }
     public List<Pic>? Pics { get; set; }
@@ -57,7 +59,47 @@ namespace Neighbourhood.omg.lol.Models {
       }
     }
 
+    // refreshing
+    public event PropertyChangedEventHandler? PropertyChanged;
+    private bool _isRefreshing;
+    public bool IsRefreshing {
+      get => _isRefreshing;
+      set {
+        _isRefreshing = value;
+        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(IsRefreshing)));
+      }
+    }
 
+    private bool _canRefresh;
+    public bool CanRefresh {
+      get => _canRefresh;
+      set {
+        _canRefresh = value;
+        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(CanRefresh)));
+      }
+    }
+
+    private bool _atTop;
+    public bool AtTop {
+      get => _atTop;
+      set {
+        if (_atTop != value) {
+          _atTop = value;
+          PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(AtTop)));
+        }
+      }
+    }
+
+    private bool _atBottom;
+    public bool AtBottom {
+      get => _atBottom;
+      set {
+        if (_atBottom != value) {
+          _atBottom = value;
+          PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(AtBottom)));
+        }
+      }
+    }
 
     // api service
     private RestService api { get; set; }
@@ -160,5 +202,18 @@ namespace Neighbourhood.omg.lol.Models {
     public async Task RefreshPics() => await GetPics(forceRefresh: true);
     public async Task RefreshNow() => await GetNowGarden(forceRefresh: true);
 
+
+
+    [JSInvokable("SetAtTop")]
+    public void SetAtTop(bool atTop) {
+      if(AtTop != atTop) AtTop = atTop;
+      //if(CanRefresh != atTop) CanRefresh = atTop;
+    }
+
+    [JSInvokable("SetAtBottom")]
+    public void SetAtBottom(bool atBottom) {
+      if(AtBottom != atBottom) AtBottom = atBottom;
+    }
+
   }
 }

Neighbourhood.omg.lol.csproj

@@ -196,6 +196,7 @@
     </ItemGroup>
 
     <ItemGroup>
+        <PackageReference Include="BcdLib.PullComponent" Version="0.4.0" />
         <PackageReference Include="Humanizer.Core" Version="2.14.1" />
         <PackageReference Include="Markdig" Version="0.37.0" />
         <PackageReference Include="Microsoft.AspNetCore.Authorization" Version="8.0.6" />
@@ -219,6 +220,12 @@
       <MauiXaml Update="LoginWebViewPage.xaml">
         <Generator>MSBuild:Compile</Generator>
       </MauiXaml>
+      <MauiXaml Update="WindowsAppShell.xaml">
+        <Generator>MSBuild:Compile</Generator>
+      </MauiXaml>
+      <MauiXaml Update="WindowsMainPage.xaml">
+        <Generator>MSBuild:Compile</Generator>
+      </MauiXaml>
     </ItemGroup>
 
 </Project>

WindowsAppShell.xaml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<Shell
+    x:Class="Neighbourhood.omg.lol.WindowsAppShell"
+    xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    xmlns:local="clr-namespace:Neighbourhood.omg.lol"
+    Shell.FlyoutBehavior="Disabled"
+    Title="omg.lol Neighbourhood">
+
+  <ShellContent
+        ContentTemplate="{DataTemplate local:WindowsMainPage}"
+        Route="MainPage" />
+
+</Shell>

WindowsAppShell.xaml.cs

@@ -0,0 +1,10 @@
+namespace Neighbourhood.omg.lol;
+
+public partial class WindowsAppShell : Shell {
+  public WindowsAppShell() {
+    InitializeComponent();
+
+    Routing.RegisterRoute(nameof(LoginWebViewPage), typeof(LoginWebViewPage));
+    Routing.RegisterRoute(nameof(EphemeralWebPage), typeof(EphemeralWebPage));
+  }
+}

WindowsMainPage.xaml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:local="clr-namespace:Neighbourhood.omg.lol"
+             x:Class="Neighbourhood.omg.lol.WindowsMainPage"
+             BackgroundColor="{DynamicResource PageBackgroundColor}">
+  <BlazorWebView x:Name="blazorWebView" HostPage="wwwroot/index.html" UrlLoading="BlazorUrlLoading">
+    <BlazorWebView.RootComponents>
+      <RootComponent Selector="#app" ComponentType="{x:Type local:Components.Routes}" />
+    </BlazorWebView.RootComponents>
+  </BlazorWebView>
+</ContentPage>

WindowsMainPage.xaml.cs

@@ -0,0 +1,24 @@
+using Microsoft.AspNetCore.Components;
+using Microsoft.AspNetCore.Components.WebView;
+using Microsoft.AspNetCore.Components.WebView.Maui;
+using Neighbourhood.omg.lol.Models;
+using System.ComponentModel;
+using System.Diagnostics;
+
+namespace Neighbourhood.omg.lol {
+  public partial class WindowsMainPage : ContentPage {
+
+    private State State { get; set; }
+
+    public WindowsMainPage() {
+      InitializeComponent();
+    }
+
+    private void BlazorUrlLoading(object? sender, UrlLoadingEventArgs e) {
+      if (e.Url.Host == "home.omg.lol" && e.Url.AbsolutePath == "/oauth/authorize") {
+        e.UrlLoadingStrategy = UrlLoadingStrategy.CancelLoad;
+        Shell.Current.GoToAsync(nameof(LoginWebViewPage));
+      }
+    }
+  }
+}

wwwroot/css/style.css

@@ -396,3 +396,44 @@ a.row.indent {
     inline-size: 3rem;
   }
 }
+
+[class|="fa"].animated {
+  animation: rotating 1s ease-in-out infinite;
+}
+
+@keyframes rotating {
+  from {
+    transform: rotate(0deg);
+  }
+
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+.pull-container {
+  display: flex;
+  flex-direction: column;
+  flex-grow: 1;
+}
+.pull-container > .pull-wrapper
+{
+  position: relative;
+}
+
+.pull-tip {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0.5rem;
+  height: var(--pull-refresh-head-height, 50px);
+  width: 100%;
+}
+
+.pull-down-tip {
+  position: absolute;
+  transform: translateY(-100%);
+}
+
+.pull-up-tip {
+}

wwwroot/js/csharp.js

@@ -1,5 +1,6 @@
 window.injectCSharp = async function (helper) {
   window.CSHARP = helper
+  console.info("Recieved DotNetReference", window.CSHARP)
 }
 
 
@@ -12,3 +13,7 @@ async function delay(t) {
 async function removeElementById(id) {
   document.getElementById(id)?.remove()
 }
+
+function Dispose(obj) {
+  if (obj && typeof obj.Dispose === "function") obj.Dispose()
+}