mpv.net/src/MpvNet.Windows/Native/WinApi.cs

using System.Drawing;
using System.Runtime.InteropServices;

namespace MpvNet.Windows.Native;

public static class WinApi
{
    public static Version WindowsTen1607 { get; } = new Version(10, 0, 14393); // Windows 10 1607

    [DllImport("kernel32.dll")]
    public static extern bool AttachConsole(int dwProcessId);

    [DllImport("kernel32.dll")]
    public static extern bool FreeConsole();

    [DllImport("kernel32.dll")]
    public static extern IntPtr LoadLibrary(string path);

    [DllImport("user32.dll")]
    public static extern uint ActivateKeyboardLayout(IntPtr hkl, uint flags);

    [DllImport("user32.dll")]
    public static extern bool GetWindowRect(IntPtr hwnd, out Rect lpRect);

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    public static extern IntPtr FindWindowEx(
        IntPtr parentHandle, IntPtr childAfter, string lclassName, string? windowTitle);

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    public static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    public static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wParam, ref CopyDataStruct lParam);

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    public static extern IntPtr PostMessage(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
    public static extern int RegisterWindowMessage(string id);

    [DllImport("user32.dll")]
    public static extern bool AllowSetForegroundWindow(int dwProcessId);

    [DllImport("user32.dll")]
    public static extern void ReleaseCapture();

    [DllImport("user32.dll")]
    public static extern int GetDpiForWindow(IntPtr hwnd);

    [DllImport("user32.dll")]
    public static extern bool AdjustWindowRect(ref Rect lpRect, uint dwStyle, bool bMenu);

    [DllImport("user32.dll")]
    public static extern bool AdjustWindowRectExForDpi(
        ref Rect lpRect, uint dwStyle, bool bMenu, uint dwExStyle, uint dpi);

    [DllImport("user32.dll")]
    public static extern bool SetWindowPos(
        IntPtr hWnd, IntPtr hWndInsertAfter, int x, int y, int cx, int cy, uint uFlags);

    [DllImport("user32.dll", EntryPoint = "GetWindowLong")]
    static extern IntPtr GetWindowLong32(IntPtr hWnd, int nIndex);

    [DllImport("user32.dll")]
    static extern IntPtr GetWindowLongPtr(IntPtr hWnd, int nIndex);

    public static IntPtr GetWindowLong(IntPtr hWnd, int nIndex)
    {
        if (IntPtr.Size == 8)
            return GetWindowLongPtr(hWnd, nIndex);
        else
            return GetWindowLong32(hWnd, nIndex);
    }

    [DllImport("user32.dll", EntryPoint = "SetWindowLong")]
    public static extern IntPtr SetWindowLong32(IntPtr hWnd, int nIndex, uint dwNewLong);

    [DllImport("user32.dll")]
    public static extern IntPtr SetWindowLongPtr(IntPtr hWnd, int nIndex, uint dwNewLong);

    public static IntPtr SetWindowLong(IntPtr hWnd, int nIndex, uint dwNewLong)
    {
        if (IntPtr.Size == 8)
            return SetWindowLongPtr(hWnd, nIndex, dwNewLong);
        else
            return SetWindowLong32(hWnd, nIndex, dwNewLong);
    }

    [DllImport("gdi32.dll")]
    public static extern int GetDeviceCaps(IntPtr hdc, int nIndex);

    [DllImport("dwmapi.dll")]
    public static extern int DwmGetWindowAttribute(
        IntPtr hwnd, uint dwAttribute, out Rect pvAttribute, uint cbAttribute);

    public static bool GetDwmWindowRect(IntPtr handle, out Rect rect)
    {
        const uint DWMWA_EXTENDED_FRAME_BOUNDS = 9;

        return 0 == DwmGetWindowAttribute(handle, DWMWA_EXTENDED_FRAME_BOUNDS,
            out rect, (uint)Marshal.SizeOf<Rect>());
    }

    public static Rectangle GetWorkingArea(IntPtr handle, Rectangle workingArea)
    {
        if (handle != IntPtr.Zero && GetDwmWindowRect(handle, out Rect dwmRect) &&
            GetWindowRect(handle, out Rect rect))
        {
            int left = workingArea.Left;
            int top = workingArea.Top;
            int right = workingArea.Right;
            int bottom = workingArea.Bottom;

            left += rect.Left - dwmRect.Left;
            top -= rect.Top - dwmRect.Top;
            right -= dwmRect.Right - rect.Right;
            bottom -= dwmRect.Bottom - rect.Bottom;

            return new Rectangle(left, top, right - left, bottom - top);
        }

        return workingArea;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct Rect
    {
        public int Left;
        public int Top;
        public int Right;
        public int Bottom;

        public Rect(Rectangle r)
        {
            Left = r.Left;
            Top = r.Top;
            Right = r.Right;
            Bottom = r.Bottom;
        }

        public Rect(int left, int top, int right, int bottom)
        {
            Left = left;
            Top = top;
            Right = right;
            Bottom = bottom;
        }

        public Rectangle ToRectangle() => Rectangle.FromLTRB(Left, Top, Right, Bottom);
        public Size Size => new Size(Right - Left, Bottom - Top);
        public int Width => Right - Left;
        public int Height => Bottom - Top;

        public static Rect FromRectangle(Rectangle rect)
        {
            return new Rect(rect.X, rect.Y, rect.X + rect.Width, rect.Y + rect.Height);
        }

        public override string ToString()
        {
            return "{Left=" + Left + ",Top=" + Top + ",Right=" + Right + ",Bottom=" + Bottom + "}";
        }
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct CopyDataStruct
    {
        public IntPtr dwData;
        public int cbData;
        [MarshalAs(UnmanagedType.LPTStr)]
        public string lpData;
    }

    public static int GetResizeBorder(int v)
    {
        switch (v)
        {
            case 1 /* WMSZ_LEFT        */ : return 3;
            case 3 /* WMSZ_TOP         */ : return 2;
            case 2 /* WMSZ_RIGHT       */ : return 3;
            case 6 /* WMSZ_BOTTOM      */ : return 2;
            case 4 /* WMSZ_TOPLEFT     */ : return 1;
            case 5 /* WMSZ_TOPRIGHT    */ : return 1;
            case 7 /* WMSZ_BOTTOMLEFT  */ : return 3;
            case 8 /* WMSZ_BOTTOMRIGHT */ : return 3;
            default: return -1;
        }
    }

    public static void SubtractWindowBorders(IntPtr hwnd, ref Rect rc, int dpi)
    {
        Rect r = new Rect(0, 0, 0, 0);
        AddWindowBorders(hwnd, ref r, dpi);
        rc.Left -= r.Left;
        rc.Top -= r.Top;
        rc.Right -= r.Right;
        rc.Bottom -= r.Bottom;
    }

    public static void AddWindowBorders(IntPtr hwnd, ref Rect rc, int dpi)
    {
        uint windowStyle = (uint)GetWindowLong(hwnd, -16); // GWL_STYLE
        uint windowStyleEx = (uint)GetWindowLong(hwnd, -20); // GWL_EXSTYLE

        if (Environment.OSVersion.Version >= WindowsTen1607)
            AdjustWindowRectExForDpi(ref rc, windowStyle, false, windowStyleEx, (uint)dpi);
        else
            AdjustWindowRect(ref rc, windowStyle, false);
    }
}