Add a screen device context method

Add a few device context bits and sort NativeMethods.txt.

src/thirtytwo/DeviceContext.cs

@@ -8,6 +8,10 @@ namespace Windows;
 /// <summary>
 ///  DeviceContext handle (HDC)
 /// </summary>
+/// <devdoc>
+///  <see href="https://devblogs.microsoft.com/oldnewthing/20060601-06/?p=31003">What does the CS_OWNDC class style do?</see>
+///  <see href="https://devblogs.microsoft.com/oldnewthing/20060602-00/?p=30993">What does the CS_CLASSDC class style do?</see>
+/// </devdoc>
 public readonly struct DeviceContext : IDisposable, IHandle<HDC>
 {
     public HDC Handle { get; private init; }
@@ -16,6 +20,16 @@ namespace Windows;
     private readonly HWND HWND { get; init; }
     private readonly CollectionType Type { get; init; }
 
+    /// <summary>
+    ///  Creates a screen device context.
+    /// </summary>
+    public static DeviceContext Create() => new()
+    {
+        HWND = default,
+        Type = CollectionType.Release,
+        Handle = Interop.GetDC(HWND.Null)
+    };
+
     public static DeviceContext Create(
         HDC hdc,
         bool ownsHandle = false)
@@ -47,7 +61,7 @@ public static DeviceContext Create<THdc, THwnd>(
     }
 
     public static DeviceContext Create<THwnd>(
-        ref PAINTSTRUCT paintStruct,
+        ref readonly PAINTSTRUCT paintStruct,
         THwnd hwnd)
         where THwnd : IHandle<HWND>
     {

src/thirtytwo/DeviceContextExtensions.cs

@@ -27,6 +27,18 @@ public static GRAPHICS_MODE SetGraphicsMode<T>(this T deviceContext, GRAPHICS_MO
         return mode;
     }
 
+    /// <inheritdoc cref="Interop.GetWorldTransform(HDC, XFORM*)"/>
+    public static unsafe bool GetWorldTransform<T>(this T deviceContext, ref Matrix3x2 transform)
+        where T : IHandle<HDC>
+    {
+        fixed (Matrix3x2* t = &transform)
+        {
+            bool result = Interop.GetWorldTransform(deviceContext.Handle, (XFORM*)t);
+            GC.KeepAlive(deviceContext.Wrapper);
+            return result;
+        }
+    }
+
     /// <inheritdoc cref="Interop.SetWorldTransform(HDC, XFORM*)"/>
     public static unsafe bool SetWorldTransform<T>(this T deviceContext, ref Matrix3x2 transform)
         where T : IHandle<HDC>
@@ -39,6 +51,15 @@ public static unsafe bool SetWorldTransform<T>(this T deviceContext, ref Matrix3
         }
     }
 
+    /// <inheritdoc cref="Interop.GetDeviceCaps(HDC, GET_DEVICE_CAPS_INDEX)"/>
+    public static int GetDeviceCaps<T>(this T deviceContext, GET_DEVICE_CAPS_INDEX index)
+       where T : IHandle<HDC>
+    {
+        int result = Interop.GetDeviceCaps(deviceContext.Handle, index);
+        GC.KeepAlive(deviceContext.Wrapper);
+        return result;
+    }
+
     /// <summary>
     ///  Converts the requested point size to height based on the DPI of the given device context.
     /// </summary>

src/thirtytwo/NativeMethods.txt

@@ -42,9 +42,9 @@ DefWindowProc
 DeleteDC
 DestroyIcon
 DestroyWindow
+DISP_E_*
 DISPATCH_CONSTRUCT
 DispatchMessage
-DISP_E_*
 DISPID_ACC_*
 DISPID_Delete
 DISPID_Name
@@ -123,6 +123,7 @@ GetWindowRect
 GetWindowRgn
 GetWindowText
 GetWindowTextLength
+GetWorldTransform
 GlobalAlloc
 GlobalFree
 GlobalLock
@@ -161,20 +162,20 @@ InvalidateRect
 IOleClientSite
 IOleContainer
 IOleControlSite
+IOleInPlaceFrame
 IOleInPlaceObject
 IOleInPlaceSite
-IOleInPlaceFrame
 IOleObject
 IOleWindow
 IPropertyNotifySink
 IProvideClassInfo
 IProvideMultipleClassInfo
 IRawElementProviderSimple
 IRecordInfo
+IsClipboardFormatAvailable
 IServiceProvider
 ISimpleFrameSite
 ISupportErrorInfo
-IsClipboardFormatAvailable
 IsWindowEnabled
 IsWindowVisible
 IUIAutomationElement
@@ -189,6 +190,7 @@ LoadLibrary
 LoadRegTypeLib
 LocalFree
 LOGFONTW
+LPtoDP
 LsaNtStatusToWinError
 MapWindowPoints
 MEMBERID_NIL
@@ -201,25 +203,23 @@ MulDiv
 NAVDIR_*
 NtQuerySystemInformation
 NTSTATUS
+OBJ_TYPE
+OBJECT_IDENTIFIER
 OLECONTF
 OLEIVERB*
 OLEIVERB_*
-OBJ_TYPE
-OBJECT_IDENTIFIER
 OpenClipboard
 PARAMDATA
-WIN32_ERROR
-WM_*
 PeekMessage
 POINTS
 PostMessage
 PostQuitMessage
 PROPVARIANT
 PropVariantClear
-RegisterClassEx
-RegisterClipboardFormat
 RegCloseKey
 RegEnumValue
+RegisterClassEx
+RegisterClipboardFormat
 RegOpenKeyEx
 RegQueryInfoKey
 RegQueryValueEx
@@ -233,9 +233,9 @@ SafeArrayGetVartype
 SafeArrayLock
 SafeArrayUnlock
 ScreenToClient
-SendMessage
-SELFLAG_*
 SelectObject
+SELFLAG_*
+SendMessage
 SetActiveWindow
 SetClipboardData
 SetFocus
@@ -250,8 +250,8 @@ SetWorldTransform
 SHCreateShellItem
 SHDefExtractIcon
 SHGetStockIconInfo
-SHParseDisplayName
 ShowWindow
+SHParseDisplayName
 STATE_SYSTEM_*
 STATIC_STYLES
 STATUS_BUFFER_OVERFLOW
@@ -279,7 +279,10 @@ UiaReturnRawElementProvider
 UnregisterClass
 UpdateLayeredWindow
 UpdateWindow
+USER_DEFAULT_SCREEN_DPI
 VARIANT_*
 VIRTUAL_KEY
+WIN32_ERROR
 WINDOWPOS
+WM_*
 XFORMCOORDS

src/thirtytwo/WindowExtensions.cs

@@ -405,7 +405,7 @@ public static unsafe DeviceContext BeginPaint<T>(this T window, out Rectangle pa
     {
         PAINTSTRUCT paintStruct = default;
         Interop.BeginPaint(window.Handle, &paintStruct);
-        DeviceContext context = DeviceContext.Create(ref paintStruct, window);
+        DeviceContext context = DeviceContext.Create(in paintStruct, window);
         paintBounds = paintStruct.rcPaint;
         GC.KeepAlive(window.Wrapper);
         return context;

src/thirtytwo_tests/DeviceContextTests.cs

@@ -0,0 +1,22 @@
+// 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.Drawing;
+using Windows.Win32;
+using Windows.Win32.Graphics.Gdi;
+
+namespace Windows;
+
+public unsafe class DeviceContextTests
+{
+    [Fact]
+    public void DeviceContext_ScreenDeviceContextBehavior()
+    {
+        using DeviceContext context = DeviceContext.Create();
+        int logicalDpi = context.GetDeviceCaps(GET_DEVICE_CAPS_INDEX.LOGPIXELSX);
+
+        Point point = new(0, 8192);
+        Interop.LPtoDP(context, &point, 1);
+        point.Should().Be(new Point(0, (int)(8192 * (logicalDpi / (float)Interop.USER_DEFAULT_SCREEN_DPI))));
+    }
+}