Port the Clover sample from WInterop

src/samples/Petzold/5th/Clover/Clover.csproj

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <AllowUnsafeBlocks>True</AllowUnsafeBlocks>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\..\thirtytwo\thirtytwo.csproj" />
+  </ItemGroup>
+</Project>

src/samples/Petzold/5th/Clover/Program.cs

@@ -0,0 +1,79 @@
+// Copyright (c) Jeremy W. Kuhne. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Windows;
+using Windows.Win32.Foundation;
+using Windows.Win32.Graphics.Gdi;
+
+namespace Clover;
+
+/// <summary>
+///  Sample from Programming Windows, 5th Edition.
+///  Original (c) Charles Petzold, 1998
+///  Figure 5-27, Pages 205-208.
+/// </summary>
+internal static class Program
+{
+    [STAThread]
+    private static void Main() => Application.Run(new Clover(), "Draw a Clover");
+}
+
+internal class Clover : WindowClass
+{
+    private int _cxClient, _cyClient;
+    private HRGN _hrgnClip;
+    private const double TWO_PI = Math.PI * 2;
+
+    public Clover() : base(backgroundBrush: StockBrush.White) { }
+
+    protected override LRESULT WindowProcedure(HWND window, MessageType message, WPARAM wParam, LPARAM lParam)
+    {
+        switch (message)
+        {
+            case MessageType.Size:
+                {
+                    _cxClient = lParam.LOWORD;
+                    _cyClient = lParam.HIWORD;
+
+                    using WaitCursorScope cursorScope = new();
+
+                    _hrgnClip.Dispose();
+
+                    using HRGN region0 = HRGN.FromEllipse(0, _cyClient / 3, _cxClient / 2, 2 * _cyClient / 3);
+                    using HRGN region1 = HRGN.FromEllipse(_cxClient / 2, _cyClient / 3, _cxClient, 2 * _cyClient / 3);
+                    using HRGN region2 = HRGN.FromEllipse(_cxClient / 3, 0, 2 * _cxClient / 3, _cyClient / 2);
+                    using HRGN region3 = HRGN.FromEllipse(_cxClient / 3, _cyClient / 2, 2 * _cxClient / 3, _cyClient);
+                    using HRGN region4 = HRGN.CombineRegion(region0, region1, RegionCombineMode.Or);
+                    using HRGN region5 = HRGN.CombineRegion(region2, region3, RegionCombineMode.Or);
+                    _hrgnClip = HRGN.CombineRegion(region4, region5, RegionCombineMode.Xor);
+
+                    return (LRESULT)0;
+                }
+            case MessageType.Paint:
+                using (DeviceContext dc = window.BeginPaint())
+                {
+                    dc.SetViewportOrigin(new(_cxClient / 2, _cyClient / 2));
+                    dc.SelectClippingRegion(_hrgnClip);
+
+                    double fRadius = Hypotenuse(_cxClient / 2.0, _cyClient / 2.0);
+
+                    for (double fAngle = 0.0; fAngle < TWO_PI; fAngle += TWO_PI / 360)
+                    {
+                        dc.MoveTo(default);
+                        dc.LineTo(
+                            (int)(fRadius * Math.Cos(fAngle) + 0.5),
+                            (int)(-fRadius * Math.Sin(fAngle) + 0.5));
+                    }
+                }
+
+                return (LRESULT)0;
+            case MessageType.Destroy:
+                _hrgnClip.Dispose();
+                break;
+        }
+
+        return base.WindowProcedure(window, message, wParam, lParam);
+    }
+
+    private static double Hypotenuse(double x, double y) => Math.Sqrt(x * x + y * y);
+}

src/thirtytwo/DeviceContextExtensions.cs

@@ -204,8 +204,8 @@ public static DeviceContext CreateCompatibleDeviceContext<TDeviceContext>(this T
         return DeviceContext.Create(hdc, ownsHandle: true);
     }
 
-    public static Bitmap CreateCompatibleBitmap<TDeviceContext>(this TDeviceContext context, Size size)
-        where TDeviceContext : IHandle<HDC>
+    public static Bitmap CreateCompatibleBitmap<T>(this T context, Size size)
+        where T : IHandle<HDC>
     {
         HBITMAP hbitmap = Interop.CreateCompatibleBitmap(context.Handle, size.Width, size.Height);
         if (hbitmap.IsNull)
@@ -216,4 +216,53 @@ public static Bitmap CreateCompatibleBitmap<TDeviceContext>(this TDeviceContext
         GC.KeepAlive(context.Wrapper);
         return Bitmap.Create(hbitmap, ownsHandle: true);
     }
+
+    public static unsafe Point GetViewportOrigin<T>(this T context, out bool success)
+        where T : IHandle<HDC>
+    {
+        Point point;
+        success = Interop.GetViewportOrgEx(context.Handle, &point);
+        GC.KeepAlive(context.Wrapper);
+        return point;
+    }
+
+    public static unsafe bool SetViewportOrigin<T>(this T context, Point point)
+        where T : IHandle<HDC>
+    {
+        bool result = Interop.SetViewportOrgEx(context.Handle, point.X, point.Y, null);
+        GC.KeepAlive(context.Wrapper);
+        return result;
+    }
+
+    public static RegionType SelectClippingRegion<T>(this T context, HRGN region)
+        where T : IHandle<HDC>
+    {
+        RegionType type = (RegionType)Interop.SelectClipRgn(context.Handle, region);
+        GC.KeepAlive(context.Wrapper);
+        return type;
+    }
+
+    public static bool MoveTo<T>(this T context, Point point)
+        where T : IHandle<HDC>
+        => context.MoveTo(point.X, point.Y);
+
+    public static bool MoveTo<T>(this T context, int x, int y)
+        where T : IHandle<HDC>
+    {
+        bool result = Interop.MoveToEx(context.Handle, x, y, null);
+        GC.KeepAlive(context.Wrapper);
+        return result;
+    }
+
+    public static bool LineTo<T>(this T context, Point point)
+        where T : IHandle<HDC>
+        => context.LineTo(point.X, point.Y);
+
+    public static bool LineTo<T>(this T context, int x, int y)
+        where T : IHandle<HDC>
+    {
+        bool success = Interop.LineTo(context.Handle, x, y);
+        GC.KeepAlive(context.Wrapper);
+        return success;
+    }
 }

src/thirtytwo/NativeMethods.txt

@@ -18,6 +18,7 @@ CLIPBOARD_FORMAT
 CloseClipboard
 CoCreateInstance
 CoGetClassObject
+CombineRegion
 CombineRgn
 COMBOBOXINFO_BUTTON_STATE
 CopyImage
@@ -27,6 +28,7 @@ CreateActCtx
 CreateCompatibleBitmap
 CreateCompatibleDC
 CreateDispTypeInfo
+CreateEllipticRgn
 CreateErrorInfo
 CreateFont
 CreateFontIndirect
@@ -93,6 +95,7 @@ GetClientRect
 GetClipboardData
 GetClipboardFormatName
 GetClipboardOwner
+GetClipRgn
 GetCurrentThread
 GetCurrentThreadId
 GetDC
@@ -119,6 +122,7 @@ GetThreadLocale
 GetUpdatedClipboardFormats
 GetUpdateRgn
 GetUserDefaultLCID
+GetViewportOrgEx
 GetWindowRect
 GetWindowRgn
 GetWindowText
@@ -141,6 +145,7 @@ IClassFactory2
 IConnectionPoint
 IConnectionPointContainer
 ICreateErrorInfo
+IDC_*
 IDI_*
 IDispatch
 IDispatchEx
@@ -184,6 +189,7 @@ KEY_INFORMATION_CLASS
 KEY_NAME_INFORMATION
 KF_*
 LIBFLAGS
+LineTo
 LoadCursor
 LoadIcon
 LoadLibrary
@@ -197,6 +203,7 @@ MEMBERID_NIL
 MessageBoxEx
 METHODDATA
 MODIFIERKEYS_FLAGS
+MoveToEx
 MoveWindow
 MSGF_*
 MulDiv
@@ -212,6 +219,7 @@ OpenClipboard
 PARAMDATA
 PeekMessage
 POINTS
+Polygon
 PostMessage
 PostQuitMessage
 PROPVARIANT
@@ -233,23 +241,28 @@ SafeArrayGetVartype
 SafeArrayLock
 SafeArrayUnlock
 ScreenToClient
+SelectClipRgn
 SelectObject
 SELFLAG_*
 SendMessage
 SetActiveWindow
 SetClipboardData
+SetCursor
 SetFocus
 SetGraphicsMode
 SetLayeredWindowAttributes
 SetMapMode
+SetPolyFillMode
 SetThreadDpiAwarenessContext
+SetViewportOrgEx
 SetWindowLong
 SetWindowRgn
 SetWindowText
 SetWorldTransform
 SHCreateShellItem
 SHDefExtractIcon
 SHGetStockIconInfo
+ShowCursor
 ShowWindow
 SHParseDisplayName
 STATE_SYSTEM_*
@@ -285,6 +298,4 @@ VIRTUAL_KEY
 WIN32_ERROR
 WINDOWPOS
 WM_*
-XFORMCOORDS
-SetPolyFillMode
-Polygon
+XFORMCOORDS

src/thirtytwo/WaitCursorScope.cs

@@ -0,0 +1,24 @@
+// Copyright (c) Jeremy W. Kuhne. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace Windows;
+
+/// <summary>
+///  Temporarily sets the cursor to the wait cursor.
+/// </summary>
+public readonly ref struct WaitCursorScope
+{
+    private readonly HCURSOR _cursor;
+
+    public WaitCursorScope()
+    {
+        _cursor = Interop.SetCursor(Interop.LoadCursor(default, Interop.IDC_WAIT));
+        _ = Interop.ShowCursor(true);
+    }
+
+    public void Dispose()
+    {
+        Interop.SetCursor(_cursor);
+        _ = Interop.ShowCursor(false);
+    }
+}

src/thirtytwo/Win32/Graphics/Gdi/HRGN.cs

@@ -18,9 +18,48 @@ public void Dispose()
         Unsafe.AsRef(in this) = default;
     }
 
-    public static HRGN FromRectangle(Rectangle rectangle)
-        => Interop.CreateRectRgn(rectangle.X, rectangle.Y, rectangle.Right, rectangle.Bottom);
+    public static HRGN FromRectangle(Rectangle rectangle) =>
+        Interop.CreateRectRgn(rectangle.X, rectangle.Y, rectangle.Right, rectangle.Bottom);
 
-    public static HRGN CreateEmpty()
-        => Interop.CreateRectRgn(0, 0, 0, 0);
+    public static HRGN FromRectangle(int x1, int y1, int x2, int y2) => Interop.CreateRectRgn(x1, y1, x2, y2);
+
+    public static HRGN FromEllipse(Rectangle bounds) =>
+        Interop.CreateEllipticRgn(bounds.X, bounds.Y, bounds.Right, bounds.Bottom);
+
+    public static HRGN FromEllipse(int x1, int y1, int x2, int y2) => Interop.CreateEllipticRgn(x1, y1, x2, y2);
+
+    public static HRGN CreateEmpty() => Interop.CreateRectRgn(0, 0, 0, 0);
+
+    public static HRGN CombineRegion(HRGN first, HRGN second, RegionCombineMode combineMode) =>
+        CombineRegion(first, second, combineMode, out _);
+
+    public static HRGN CombineRegion(HRGN first, HRGN second, RegionCombineMode combineMode, out RegionType type)
+    {
+        HRGN hrgn = CreateEmpty();
+        type = (RegionType)Interop.CombineRgn(hrgn, first, second, (RGN_COMBINE_MODE)combineMode);
+        if (type == RegionType.Error)
+        {
+            hrgn.Dispose();
+        }
+
+        return hrgn;
+    }
+
+    public static HRGN FromHdc(HDC hdc)
+    {
+        HRGN region = Interop.CreateRectRgn(0, 0, 0, 0);
+        int result = Interop.GetClipRgn(hdc, region);
+        Debug.Assert(result != -1, "GetClipRgn failed");
+
+        if (result == 1)
+        {
+            return region;
+        }
+        else
+        {
+            // No region, delete our temporary region
+            Interop.DeleteObject(region);
+            return default;
+        }
+    }
 }

src/thirtytwo/Win32/UI/WindowsAndMessaging/HCURSOR.SetCursorScope.cs

@@ -0,0 +1,14 @@
+// Copyright (c) Jeremy W. Kuhne. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace Windows.Win32.UI.WindowsAndMessaging;
+
+public unsafe partial struct HCURSOR
+{
+    public readonly struct SetScope : IDisposable
+    {
+        private readonly HCURSOR _previousCursor;
+        public SetScope(HCURSOR cursor) => _previousCursor = Interop.SetCursor(cursor);
+        public readonly void Dispose() => Interop.SetCursor(_previousCursor);
+    }
+}

src/thirtytwo/Win32/UI/WindowsAndMessaging/HCURSOR.cs

@@ -1,11 +1,25 @@
 // Copyright (c) Jeremy W. Kuhne. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using System.Runtime.CompilerServices;
+
 namespace Windows.Win32.UI.WindowsAndMessaging;
 
-public unsafe partial struct HCURSOR
+public unsafe partial struct HCURSOR : IDisposable
 {
     public static HCURSOR Invalid => new(-1);
 
     public static implicit operator HCURSOR(CursorId id) => Interop.LoadCursor(default, (PCWSTR)(char*)(uint)id);
+
+    public SetScope SetCursorScope() => new(this);
+
+    public void Dispose()
+    {
+        if (!IsNull)
+        {
+            Interop.DestroyCursor(this);
+        }
+
+        Unsafe.AsRef(in this) = default;
+    }
 }

src/thirtytwo/WrapperEnums/CursorId.cs

@@ -5,6 +5,8 @@ namespace Windows;
 
 public enum CursorId : uint
 {
+    // Can't use CsWin32 values here as they aren't constant
+
     /// <summary>
     ///  Arrow cursor. (IDC_ARROW)
     /// </summary>