C # WPF e WinForms Interop - CenterOwner não efetivo

Nov 28 2020

Estou trabalhando em um aplicativo legado que usa WPF e WinForms para sua interface do usuário. O WPF representa a grande maioria, mas a caixa de diálogo principal do aplicativo ainda está no WinForms.

Até agora, consegui fazer com que funcionassem bem em conjunto (graças a System.Windows.Forms.Integration.ElementHost), mas não consigo centralizar as janelas WPF em seu pai WinForms.

Meu código é o seguinte.

Controle WPF (hospedado no ElementHost)

private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
{
    var dialog = new SubWindow();
    WindowOwnershipHelper.SetOwner(dialog, this);
    dialog.ShowDialog();
}

OwnershipHelper (retirado dehttps://stackoverflow.com/a/36606974/13567181)

Esta classe estabelece a relação 'pai-filho' para que os diálogos aninhados abram na mesma tela e minimizem junto com seus pais ...

public static class WindowOwnershipHelper
{
    public static void SetOwner(Window window, Visual parent)
    {
        var source = (HwndSource) PresentationSource.FromVisual(parent);

        if (source == null)
        {
            throw new InvalidOperationException("Could not determine parent from visual.");
        }

        new WindowInteropHelper(window).Owner = source.Handle;
    }
}

O problema que estou enfrentando é que, quando dialog.ShowDialog () é executado, a janela recém-aberta não está centrada em torno de seu proprietário. Está em algum lugar da tela, mas não entendo muito bem como determina sua localização.

Curiosamente, se eu repetir o código ButtonBase_OnClick dentro da classe SubWindow novamente, essa nova janela estará perfeitamente centralizada em torno de seu pai SubWindow .

Do meu ponto de vista, isso tem algo a ver com o ElementHost pai de SubWindow .

Alguém pode me aconselhar sobre como centralizar a SubWindow em torno de seu pai sem calcular manualmente sua posição? (semelhante a estehttps://stackoverflow.com/a/42401001/13567181)

EDIT: Acabei de encontrar isso no MSDN - é de alguma forma semelhante, mas não tenho certeza. https://social.msdn.microsoft.com/Forums/vstudio/en-US/05768951-73cf-4daf-b369-0905ca7e5222/centering-wpf-window-on-winforms-owner-window?forum=wpf

Atenciosamente Norbert

Respostas

2 Loathing Nov 28 2020 at 08:58

Use Application.Run(new MyForm2());e clique no botão para criar um WPF Windowcentralizado no formulário principal.

public class MyForm2 : Form {

    public MyForm2() {
        this.Size = new Size(600,600);
        this.StartPosition = FormStartPosition.CenterScreen;
        Button btn = new Button { Text = "New Window", AutoSize = true, AutoSizeMode = AutoSizeMode.GrowAndShrink };
        btn.Click += btn_Click;
        Controls.Add(btn);
    }

    void btn_Click(object sender, EventArgs e) {
        var w = new System.Windows.Window();
        w.SourceInitialized += w_SourceInitialized;
        w.Width = 400.0; // number of actual pixels might be different
        w.Height = 400.0; // depending on DPI. My laptop is 120 dpi, so 400.0 -> 400 * 120 / 96 = 500 pixels.
        w.Title = "WPF Window";
        w.ShowDialog();
    }

    void w_SourceInitialized(object sender, EventArgs e) {
        var w = (System.Windows.Window) sender;
        WindowInteropHelper helper = new WindowInteropHelper(w);
        //w.WindowStartupLocation = System.Windows.WindowStartupLocation.CenterOwner; does nothing
        int GWL_HWNDPARENT = -8;
        SetWindowLongInternal(helper.Handle, GWL_HWNDPARENT, this.Handle);

        Rectangle r = this.Bounds;
        RECT r2 = new RECT();
        GetWindowRect(helper.Handle, out r2);
        int w2 = r2.Right - r2.Left;
        int h2 = r2.Bottom - r2.Top;

        int x2 = r.X + (r.Width - w2) / 2;
        int y2 = r.Y + (r.Height - h2) / 2;

        uint SWP_NOSIZE        = 0x0001;
        uint SWP_NOZORDER      = 0x0004;
        uint SWP_NOREDRAW      = 0x0008;
        uint SWP_NOACTIVATE    = 0x0010;
        uint SWP_NOCOPYBITS    = 0x0100;
        uint SWP_NOOWNERZORDER = 0x0200;
        uint flags = SWP_NOACTIVATE | SWP_NOCOPYBITS | SWP_NOOWNERZORDER | SWP_NOREDRAW | SWP_NOSIZE | SWP_NOZORDER;

        SetWindowPos(helper.Handle, IntPtr.Zero, x2, y2, 0, 0, flags);
    }

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

    [DllImport("user32.dll")]
    private static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);

    [DllImport("user32.dll", SetLastError=true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int x, int y, int w, int h, uint uFlags);

    [DllImport("user32.dll", SetLastError=true)]
    private static extern int SetWindowLong(IntPtr hWnd, int nIndex, IntPtr dwNewLong);
    [DllImport("user32.dll", SetLastError=true)]
    private static extern int SetWindowLongPtr(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

    private static int SetWindowLongInternal(IntPtr hWnd, int nIndex, IntPtr dwNewLong) {
        if (IntPtr.Size == 4)
            return SetWindowLong(hWnd, nIndex, dwNewLong);

        return SetWindowLongPtr(hWnd, nIndex, dwNewLong);
    }
}
1 Loathing Nov 29 2020 at 05:23

Esta versão adiciona um WPF Buttonque quando clicado exibe os limites do formulário principal.

public class MyForm2 : Form {

    public MyForm2() {
        this.Size = new Size(600,600);
        this.StartPosition = FormStartPosition.CenterScreen;
        Button btn = new Button { Text = "New Window", AutoSize = true, AutoSizeMode = AutoSizeMode.GrowAndShrink };
        btn.Click += btn_Click;
        Controls.Add(btn);
    }

    void btn_Click(object sender, EventArgs e) {
        var w = new System.Windows.Window();
        System.Windows.Controls.Button wpfButton = new System.Windows.Controls.Button { Content = "Button" };
        wpfButton.Click += wpfButton_Click;

        w.SourceInitialized += w_SourceInitialized;
        w.Width = 400.0; // number of actual pixels might be different
        w.Height = 400.0; // depending on DPI. My laptop is 120 dpi, so 400.0 -> 400 * 120 / 96 = 500 pixels.
        w.Title = "WPF Window";
        w.Content = wpfButton;
        w.ShowDialog();
    }

    void wpfButton_Click(object sender, System.Windows.RoutedEventArgs e) {
        var wpfButton = (System.Windows.Controls.Button) sender;
        var wpfWindow = (System.Windows.Window) wpfButton.Parent;
        var helper = new WindowInteropHelper(wpfWindow);
        int GWL_HWNDPARENT = -8;
        IntPtr hwndMainForm = GetWindowLong(helper.Handle, GWL_HWNDPARENT);
        RECT r = new RECT();
        GetWindowRect(hwndMainForm, out r);
        SimpleWindow sw = new SimpleWindow { Handle = helper.Handle };
        MessageBox.Show(sw, "x:" + r.Left + " y:" + r.Top + " w:" + (r.Right - r.Left) + " h:" + (r.Bottom - r.Top), "Main Form Bounds");
    }

    private class SimpleWindow : System.Windows.Forms.IWin32Window {
        public IntPtr Handle { get; set; }
    }

    void w_SourceInitialized(object sender, EventArgs e) {
        var w = (System.Windows.Window) sender;
        WindowInteropHelper helper = new WindowInteropHelper(w);
        //w.WindowStartupLocation = System.Windows.WindowStartupLocation.CenterOwner; does nothing
        int GWL_HWNDPARENT = -8;
        SetWindowLongInternal(helper.Handle, GWL_HWNDPARENT, this.Handle);

        Rectangle r = this.Bounds;
        RECT r2 = new RECT();
        GetWindowRect(helper.Handle, out r2);
        int w2 = r2.Right - r2.Left;
        int h2 = r2.Bottom - r2.Top;

        int x2 = r.X + (r.Width - w2) / 2;
        int y2 = r.Y + (r.Height - h2) / 2;

        uint SWP_NOSIZE        = 0x0001;
        uint SWP_NOZORDER      = 0x0004;
        uint SWP_NOREDRAW      = 0x0008;
        uint SWP_NOACTIVATE    = 0x0010;
        uint SWP_NOCOPYBITS    = 0x0100;
        uint SWP_NOOWNERZORDER = 0x0200;
        uint flags = SWP_NOACTIVATE | SWP_NOCOPYBITS | SWP_NOOWNERZORDER | SWP_NOREDRAW | SWP_NOSIZE | SWP_NOZORDER;

        SetWindowPos(helper.Handle, IntPtr.Zero, x2, y2, 0, 0, flags);
    }

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

    [DllImport("user32.dll")]
    private static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);

    [DllImport("user32.dll", SetLastError=true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int x, int y, int w, int h, uint uFlags);

    [DllImport("user32.dll", SetLastError=true)]
    private static extern int SetWindowLong(IntPtr hWnd, int nIndex, IntPtr dwNewLong);
    [DllImport("user32.dll", SetLastError=true)]
    private static extern int SetWindowLongPtr(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

    private static int SetWindowLongInternal(IntPtr hWnd, int nIndex, IntPtr dwNewLong) {
        if (IntPtr.Size == 4)
            return SetWindowLong(hWnd, nIndex, dwNewLong);

        return SetWindowLongPtr(hWnd, nIndex, dwNewLong);
    }

    [DllImport("user32.dll", SetLastError=true)]
    private static extern IntPtr GetWindowLongPtr(IntPtr hWnd, int nIndex);
    [DllImport("user32.dll", SetLastError=true)]
    private static extern IntPtr GetWindowLong(IntPtr hWnd, int nIndex);

    private static IntPtr GetWindowLongInternal(IntPtr hWnd, int nIndex) {
        if (IntPtr.Size == 4)
            return GetWindowLong(hWnd, (int) nIndex);

        return GetWindowLongPtr(hWnd, (int) nIndex);
    }
}