Winforms-如何让对话框显示在 MainForm 的中心？这与基于普通窗口默认设置相反，后者将它们显示在屏幕的中心。在我的例子中，我有一个小的
Winforms-如何使对话框显示在 MainForm 的中心？这与基于普通窗口默认设置（将对话框显示在屏幕中心）相反。
在我的例子中，我有一个小的主窗体，例如，它可能被放置在一个角落里，MessageBox 弹出窗口显示在看似很远的地方。
事实证明，该类还适用于其他两种情况。我有一个 FolderBrowserDialog，我想让它变大，并且让它出现在父对话框的左上角附近（靠近我单击以打开它的按钮）。
我复制了 CenterWinDialog 类并创建了两个新类。一个类更改对话框大小，另一个类将其位置更改为与父窗体的特定偏移量。这是用法：
using (new OffsetWinDialog(this) { PreferredOffset = new Point(75, 75 )})
using (new SizeWinDialog(this) { PreferredSize = new Size(400, 600)})
{
DialogResult result = dlgFolderBrowser.ShowDialog();
if (result == DialogResult.Cancel)
return;
}
这两个类是基于原类的。
class OffsetWinDialog : IDisposable
{
private int mTries = 0;
private Form mOwner;
public OffsetWinDialog(Form owner)
{
mOwner = owner;
owner.BeginInvoke(new MethodInvoker(findDialog));
}
public Point PreferredOffset { get; set; }
private void findDialog()
{
// Enumerate windows to find the message box
if (mTries < 0)
return;
EnumThreadWndProc callback = new EnumThreadWndProc(checkWindow);
if (EnumThreadWindows(GetCurrentThreadId(), callback, IntPtr.Zero))
{
if (++mTries < 10)
mOwner.BeginInvoke(new MethodInvoker(findDialog));
}
}
private bool checkWindow(IntPtr hWnd, IntPtr lp)
{
// Checks if <hWnd> is a dialog
StringBuilder sb = new StringBuilder(260);
GetClassName(hWnd, sb, sb.Capacity);
if (sb.ToString() != "#32770") return true;
// Got it
Rectangle frmRect = new Rectangle(mOwner.Location, mOwner.Size);
RECT dlgRect;
GetWindowRect(hWnd, out dlgRect);
MoveWindow(hWnd,
frmRect.Left + PreferredOffset.X,
frmRect.Top + PreferredOffset.Y,
dlgRect.Right - dlgRect.Left,
dlgRect.Bottom - dlgRect.Top,
true);
return false;
}
public void Dispose()
{
mTries = -1;
}
// P/Invoke declarations
private delegate bool EnumThreadWndProc(IntPtr hWnd, IntPtr lp);
[DllImport("user32.dll")]
private static extern bool EnumThreadWindows(int tid, EnumThreadWndProc callback, IntPtr lp);
[DllImport("kernel32.dll")]
private static extern int GetCurrentThreadId();
[DllImport("user32.dll")]
private static extern int GetClassName(IntPtr hWnd, StringBuilder buffer, int buflen);
[DllImport("user32.dll")]
private static extern bool GetWindowRect(IntPtr hWnd, out RECT rc);
[DllImport("user32.dll")]
private static extern bool MoveWindow(IntPtr hWnd, int x, int y, int w, int h, bool repaint);
private struct RECT { public int Left; public int Top; public int Right; public int Bottom; }
}
和
class SizeWinDialog : IDisposable
{
private int mTries = 0;
private Form mOwner;
public SizeWinDialog(Form owner)
{
mOwner = owner;
mOwner.BeginInvoke(new Action(findDialog));
}
public Size PreferredSize { get; set; }
private void findDialog()
{
// Enumerate windows to find the message box
if (mTries < 0)
return;
EnumThreadWndProc callback = new EnumThreadWndProc(checkWindow);
if (EnumThreadWindows(GetCurrentThreadId(), callback, IntPtr.Zero))
{
if (++mTries < 10)
mOwner.BeginInvoke(new MethodInvoker(findDialog));
}
}
private bool checkWindow(IntPtr hWnd, IntPtr lp)
{
// Checks if <hWnd> is a dialog
StringBuilder sb = new StringBuilder(260);
GetClassName(hWnd, sb, sb.Capacity);
if (sb.ToString() != "#32770")
return true;
// Got it
Rectangle frmRect = new Rectangle(mOwner.Location, mOwner.Size);
RECT dlgRect;
GetWindowRect(hWnd, out dlgRect);
SetWindowPos(new HandleRef(this, hWnd), new HandleRef(), dlgRect.Left, dlgRect.Top, PreferredSize.Width, PreferredSize.Height, 20 | 2);
return false;
}
public void Dispose()
{
mTries = -1;
}
// P/Invoke declarations
private delegate bool EnumThreadWndProc(IntPtr hWnd, IntPtr lp);
[DllImport("user32.dll")]
private static extern bool EnumThreadWindows(int tid, EnumThreadWndProc callback, IntPtr lp);
[DllImport("kernel32.dll")]
private static extern int GetCurrentThreadId();
[DllImport("user32.dll")]
private static extern int GetClassName(IntPtr hWnd, StringBuilder buffer, int buflen);
[DllImport("user32.dll")]
private static extern bool GetWindowRect(IntPtr hWnd, out RECT rc);
[DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
public static extern bool SetWindowPos(HandleRef hWnd, HandleRef hWndInsertAfter, int x, int y, int cx, int cy,
int flags);
private struct RECT { public int Left; public int Top; public int Right; public int Bottom; }
}