[Peek] Add support for preview handlers

.github/actions/spell-check/expect.txt

@@ -1430,6 +1430,7 @@ ppsi
 ppsid
 ppsrm
 ppsrree
+ppstm
 ppsz
 pptal
 ppv
@@ -1472,6 +1473,8 @@ psfi
 Psr
 psrm
 psrree
+pstatstg
+pstm
 pstr
 pstream
 pstrm
@@ -1826,6 +1829,7 @@ STDMETHODCALLTYPE
 STDMETHODIMP
 stefan
 Stereolithography
+STGC
 STGM
 STGMEDIUM
 sticpl
@@ -2191,6 +2195,7 @@ wnd
 WNDCLASS
 WNDCLASSEX
 WNDCLASSEXW
+WNDCLASSW
 WNDPROC
 wordpad
 workaround

src/modules/peek/Peek.Common/NativeMethods.txt

@@ -2,4 +2,9 @@
 _SHCONTF
 SIGDN
 SHGDNF
-SIATTRIBFLAGS
+SIATTRIBFLAGS
+IInitializeWithFile
+IInitializeWithItem
+IInitializeWithStream
+IPreviewHandler
+IPreviewHandlerVisuals

src/modules/peek/Peek.FilePreviewer/Controls/ShellPreviewHandlerControl.xaml

@@ -0,0 +1,17 @@
+<!-- Copyright (c) Microsoft Corporation. All rights reserved. -->
+<!-- Licensed under the MIT License. See LICENSE in the project root for license information. -->
+
+<UserControl
+    x:Class="Peek.FilePreviewer.Controls.ShellPreviewHandlerControl"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:Peek.FilePreviewer.Controls"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    Loaded="UserControl_Loaded"
+    EffectiveViewportChanged="UserControl_EffectiveViewportChanged"
+    IsEnabled="False" IsTabStop="True" GotFocus="UserControl_GotFocus"
+    ActualThemeChanged="{x:Bind UpdatePreviewerTheme}">
+
+</UserControl>

src/modules/peek/Peek.FilePreviewer/Controls/ShellPreviewHandlerControl.xaml.cs

@@ -0,0 +1,209 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Runtime.CompilerServices;
+using CommunityToolkit.Mvvm.ComponentModel;
+using Microsoft.UI;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Windows.Win32;
+using Windows.Win32.Foundation;
+using Windows.Win32.Graphics.Gdi;
+using Windows.Win32.UI.Shell;
+using Windows.Win32.UI.WindowsAndMessaging;
+
+namespace Peek.FilePreviewer.Controls
+{
+    [INotifyPropertyChanged]
+    public unsafe sealed partial class ShellPreviewHandlerControl : UserControl
+    {
+        // Mica fallback colors
+        private static readonly COLORREF LightThemeBgColor = new(0x00f3f3f3);
+        private static readonly COLORREF DarkThemeBgColor = new(0x00202020);
+
+        private static readonly HBRUSH LightThemeBgBrush = PInvoke.CreateSolidBrush(LightThemeBgColor);
+        private static readonly HBRUSH DarkThemeBgBrush = PInvoke.CreateSolidBrush(DarkThemeBgColor);
+
+        [ObservableProperty]
+        private IPreviewHandler? source;
+
+        private HWND containerHwnd;
+        private WNDPROC containerWndProc;
+        private HBRUSH containerBgBrush;
+        private RECT controlRect;
+
+        public event EventHandler? HandlerLoaded;
+
+        public event EventHandler? HandlerError;
+
+        public static readonly DependencyProperty HandlerVisibilityProperty = DependencyProperty.Register(
+            nameof(HandlerVisibility),
+            typeof(Visibility),
+            typeof(ShellPreviewHandlerControl),
+            new PropertyMetadata(Visibility.Collapsed, new PropertyChangedCallback((d, e) => ((ShellPreviewHandlerControl)d).OnHandlerVisibilityChanged())));
+
+        // Must have its own visibility property so resize events can still fire
+        public Visibility HandlerVisibility
+        {
+            get { return (Visibility)GetValue(HandlerVisibilityProperty); }
+            set { SetValue(HandlerVisibilityProperty, value); }
+        }
+
+        public ShellPreviewHandlerControl()
+        {
+            InitializeComponent();
+
+            containerWndProc = ContainerWndProc;
+        }
+
+        partial void OnSourceChanged(IPreviewHandler? value)
+        {
+            if (Source != null)
+            {
+                UpdatePreviewerTheme();
+
+                try
+                {
+                    // Attach the preview handler to the container window
+                    Source.SetWindow(containerHwnd, (RECT*)Unsafe.AsPointer(ref controlRect));
+                    Source.DoPreview();
+
+                    HandlerLoaded?.Invoke(this, EventArgs.Empty);
+                }
+                catch
+                {
+                    HandlerError?.Invoke(this, EventArgs.Empty);
+                }
+            }
+        }
+
+        private void OnHandlerVisibilityChanged()
+        {
+            if (HandlerVisibility == Visibility.Visible)
+            {
+                PInvoke.ShowWindow(containerHwnd, SHOW_WINDOW_CMD.SW_SHOW);
+                IsEnabled = true;
+
+                // Clears the background from the last previewer
+                // The brush can only be drawn here because flashes will occur during resize
+                PInvoke.SetClassLongPtr(containerHwnd, GET_CLASS_LONG_INDEX.GCLP_HBRBACKGROUND, containerBgBrush);
+                PInvoke.UpdateWindow(containerHwnd);
+                PInvoke.SetClassLongPtr(containerHwnd, GET_CLASS_LONG_INDEX.GCLP_HBRBACKGROUND, IntPtr.Zero);
+                PInvoke.InvalidateRect(containerHwnd, (RECT*)null, true);
+            }
+            else
+            {
+                PInvoke.ShowWindow(containerHwnd, SHOW_WINDOW_CMD.SW_HIDE);
+                IsEnabled = false;
+            }
+        }
+
+        private void UpdatePreviewerTheme()
+        {
+            COLORREF bgColor, fgColor;
+            switch (ActualTheme)
+            {
+                case ElementTheme.Light:
+                    bgColor = LightThemeBgColor;
+                    fgColor = new COLORREF(0x00000000); // Black
+
+                    containerBgBrush = LightThemeBgBrush;
+                    break;
+
+                case ElementTheme.Dark:
+                default:
+                    bgColor = DarkThemeBgColor;
+                    fgColor = new COLORREF(0x00FFFFFF); // White
+
+                    containerBgBrush = DarkThemeBgBrush;
+                    break;
+            }
+
+            if (Source is IPreviewHandlerVisuals visuals)
+            {
+                visuals.SetBackgroundColor(bgColor);
+                visuals.SetTextColor(fgColor);
+
+                // Changing the previewer colors might not always redraw itself
+                PInvoke.InvalidateRect(containerHwnd, (RECT*)null, true);
+            }
+        }
+
+        private LRESULT ContainerWndProc(HWND hWnd, uint msg, WPARAM wParam, LPARAM lParam)
+        {
+            // Here for future use :)
+            return PInvoke.DefWindowProc(hWnd, msg, wParam, lParam);
+        }
+
+        private void UserControl_Loaded(object sender, RoutedEventArgs e)
+        {
+            fixed (char* pContainerClassName = "PeekShellPreviewHandlerContainer")
+            {
+                PInvoke.RegisterClass(new WNDCLASSW()
+                {
+                    lpfnWndProc = containerWndProc,
+                    lpszClassName = pContainerClassName,
+                });
+
+                // Create the container window to host the preview handler
+                containerHwnd = PInvoke.CreateWindowEx(
+                    WINDOW_EX_STYLE.WS_EX_LAYERED,
+                    pContainerClassName,
+                    null,
+                    WINDOW_STYLE.WS_CHILD,
+                    0, // X
+                    0, // Y
+                    0, // Width
+                    0, // Height
+                    (HWND)Win32Interop.GetWindowFromWindowId(XamlRoot.ContentIslandEnvironment.AppWindowId), // Peek UI window
+                    HMENU.Null,
+                    HINSTANCE.Null);
+
+                // Allows the preview handlers to display properly
+                PInvoke.SetLayeredWindowAttributes(containerHwnd, default, byte.MaxValue, LAYERED_WINDOW_ATTRIBUTES_FLAGS.LWA_ALPHA);
+            }
+        }
+
+        private void UserControl_EffectiveViewportChanged(FrameworkElement sender, EffectiveViewportChangedEventArgs args)
+        {
+            var dpi = (float)PInvoke.GetDpiForWindow(containerHwnd) / 96;
+
+            // Resize the container window
+            PInvoke.SetWindowPos(
+                containerHwnd,
+                (HWND)0, // HWND_TOP
+                (int)(Math.Abs(args.EffectiveViewport.X) * dpi),
+                (int)(Math.Abs(args.EffectiveViewport.Y) * dpi),
+                (int)(ActualWidth * dpi),
+                (int)(ActualHeight * dpi),
+                SET_WINDOW_POS_FLAGS.SWP_NOACTIVATE);
+
+            // Resize the preview handler window
+            controlRect.right = (int)(ActualWidth * dpi);
+            controlRect.bottom = (int)(ActualHeight * dpi);
+            try
+            {
+                Source?.SetRect((RECT*)Unsafe.AsPointer(ref controlRect));
+            }
+            catch
+            {
+            }
+
+            // Resizing the previewer might not always redraw itself
+            PInvoke.InvalidateRect(containerHwnd, (RECT*)null, false);
+        }
+
+        private void UserControl_GotFocus(object sender, RoutedEventArgs e)
+        {
+            try
+            {
+                Source?.SetFocus();
+            }
+            catch
+            {
+            }
+        }
+    }
+}

src/modules/peek/Peek.FilePreviewer/FilePreview.xaml

@@ -18,6 +18,13 @@
             VerticalAlignment="Center"
             IsActive="{x:Bind MatchPreviewState(Previewer.State, previewers:PreviewState.Loading), Mode=OneWay}" />
 
+        <controls:ShellPreviewHandlerControl
+            x:Name="ShellPreviewHandlerPreview"
+            Source="{x:Bind ShellPreviewHandlerPreviewer.Preview, Mode=OneWay}"
+            HandlerVisibility="{x:Bind IsPreviewVisible(ShellPreviewHandlerPreviewer, Previewer.State), Mode=OneWay}"
+            HandlerLoaded="ShellPreviewHandlerPreview_HandlerLoaded"
+            HandlerError="ShellPreviewHandlerPreview_HandlerError" />
+
         <Image
             x:Name="ImagePreview"
             MaxWidth="{x:Bind ImagePreviewer.MaxImageSize.Width, Mode=OneWay}"
@@ -59,7 +66,7 @@
             DirectoryCount="{x:Bind ArchivePreviewer.DirectoryCountText, Mode=OneWay}"
             Size="{x:Bind ArchivePreviewer.SizeText, Mode=OneWay}"
             Visibility="{x:Bind IsPreviewVisible(ArchivePreviewer, Previewer.State), Mode=OneWay}" />
-        
+
         <controls:UnsupportedFilePreview
             x:Name="UnsupportedFilePreview"
             LoadingState="{x:Bind UnsupportedFilePreviewer.State, Mode=OneWay}"

src/modules/peek/Peek.FilePreviewer/FilePreview.xaml.cs

@@ -49,6 +49,7 @@ public sealed partial class FilePreview : UserControl, IDisposable
         [NotifyPropertyChangedFor(nameof(VideoPreviewer))]
         [NotifyPropertyChangedFor(nameof(BrowserPreviewer))]
         [NotifyPropertyChangedFor(nameof(ArchivePreviewer))]
+        [NotifyPropertyChangedFor(nameof(ShellPreviewHandlerPreviewer))]
         [NotifyPropertyChangedFor(nameof(UnsupportedFilePreviewer))]
 
         private IPreviewer? previewer;
@@ -96,6 +97,8 @@ private async void Previewer_PropertyChanged(object? sender, System.ComponentMod
 
         public IArchivePreviewer? ArchivePreviewer => Previewer as IArchivePreviewer;
 
+        public IShellPreviewHandlerPreviewer? ShellPreviewHandlerPreviewer => Previewer as IShellPreviewHandlerPreviewer;
+
         public IUnsupportedFilePreviewer? UnsupportedFilePreviewer => Previewer as IUnsupportedFilePreviewer;
 
         public IFileSystemItem Item
@@ -220,6 +223,9 @@ partial void OnPreviewerChanging(IPreviewer? value)
             ArchivePreview.Source = null;
             BrowserPreview.Source = null;
 
+            ShellPreviewHandlerPreviewer?.Clear();
+            ShellPreviewHandlerPreview.Source = null;
+
             if (Previewer != null)
             {
                 Previewer.PropertyChanged -= Previewer_PropertyChanged;
@@ -268,6 +274,22 @@ private void PreviewBrowser_NavigationCompleted(WebView2 sender, CoreWebView2Nav
             }
         }
 
+        private void ShellPreviewHandlerPreview_HandlerLoaded(object sender, EventArgs e)
+        {
+            if (ShellPreviewHandlerPreviewer != null)
+            {
+                ShellPreviewHandlerPreviewer.State = PreviewState.Loaded;
+            }
+        }
+
+        private void ShellPreviewHandlerPreview_HandlerError(object sender, EventArgs e)
+        {
+            if (ShellPreviewHandlerPreviewer != null)
+            {
+                ShellPreviewHandlerPreviewer.State = PreviewState.Error;
+            }
+        }
+
         private async void KeyboardAccelerator_CtrlC_Invoked(KeyboardAccelerator sender, KeyboardAcceleratorInvokedEventArgs args)
         {
             if (Previewer != null)

src/modules/peek/Peek.FilePreviewer/NativeMethods.json

@@ -0,0 +1,4 @@
+{
+    "$schema": "https://aka.ms/CsWin32.schema.json",
+    "public": false
+}

src/modules/peek/Peek.FilePreviewer/NativeMethods.txt

@@ -0,0 +1,14 @@
+IClassFactory
+CoGetClassObject
+CreateSolidBrush
+CreateWindowEx
+DefWindowProc
+GetDpiForWindow
+InvalidateRect
+RegisterClass
+SetClassLongPtr
+SetLayeredWindowAttributes
+SetWindowPos
+ShowWindow
+UpdateWindow
+SHCreateItemFromParsingName