问题
I want to know if it's possible to set the client area of a borderless form. Say for example I define a form like so:
Code
public class MyForm : Form
{
public MyForm()
{
this.FormBorderStyle = FormBorderStyle.None;
}
}
Result
What I want to do is specify the client area, so that the form has a frame (like the standard windows frame, but custom drawn).
Result
Essentially, the blue area would become the non client area, and the gray area would remain as the client area.
I have tried to set the client area, but this just seems to resize the entire form, thus, is does not leave behind a "non-client" area
Is this possible?
回答1:
This is possible, however I don't know how well this works with a Windows Form with the WindowStyle set to Borderless. Using PInvoke (Platform Invoke) Functions, you can remove window themes which will give you a very basic looking Windows Form. You can then use various PInvoke functions to manipulate the Non-client area of the windows form.
I recommend that you read through these topics. They're designed for Win32 Applications using C++, but PInvoke is the process of calling these native APIs using Managed Code (C#)
WM_NCCALCSIZE: https://msdn.microsoft.com/en-us/library/windows/desktop/ms632634(v=vs.85).aspx
WM_NCPAINT: https://msdn.microsoft.com/en-us/library/windows/desktop/dd145212(v=vs.85).aspx
GetDCEx: https://msdn.microsoft.com/en-us/library/windows/desktop/dd144873(v=vs.85).aspx
GetWindowDC: https://msdn.microsoft.com/en-us/library/windows/desktop/dd144947(v=vs.85).aspx
SetWindowTheme: https://msdn.microsoft.com/en-us/library/windows/desktop/bb759827(v=vs.85).aspx
This example is very very crude, but it provides basic functionality. I don't know how SetWindowTheme works on Windows 8 or 8.1, but in Windows 7, it gives windows the "classic" theme.
public partial class MyForm : Form
{
//Window Messages
public const uint WM_NCPAINT = 0x85;
public const uint WM_NCCALCSIZE = 0x83;
public const uint WM_NCHITTEST = 0x84;
//GetDCEx Flags
public const int DCX_WINDOW = 0x00000001;
public const int DCX_CACHE = 0x00000002;
public const int DCX_PARENTCLIP = 0x00000020;
public const int DCX_CLIPSIBLINGS = 0x00000010;
public const int DCX_CLIPCHILDREN = 0x00000008;
public const int DCX_NORESETATTRS = 0x00000004;
public const int DCX_LOCKWINDOWUPDATE = 0x00000400;
public const int DCX_EXCLUDERGN = 0x00000040;
public const int DCX_INTERSECTRGN = 0x00000080;
public const int DCX_INTERSECTUPDATE = 0x00000200;
public const int DCX_VALIDATE = 0x00200000;
//RECT Structure
[System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
public struct RECT
{
public int left, top, right, bottom;
}
//WINDOWPOS Structure
[System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
public struct WINDOWPOS
{
public IntPtr hwnd;
public IntPtr hwndinsertafter;
public int x, y, cx, cy;
public int flags;
}
//NCCALCSIZE_PARAMS Structure
[System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
public struct NCCALCSIZE_PARAMS
{
public RECT rgrc0, rgrc1, rgrc2;
public WINDOWPOS lppos;
}
//SetWindowTheme UXtheme Function
[System.Runtime.InteropServices.DllImport("uxtheme.dll", ExactSpelling = true, CharSet = System.Runtime.InteropServices.CharSet.Unicode)]
public static extern int SetWindowTheme(
IntPtr hWnd,
String pszSubAppName,
String pszSubIdList);
//GetWindowRect User32 Function
[System.Runtime.InteropServices.DllImport("user32.dll", ExactSpelling = true)]
[return: System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.Bool)]
public static extern bool GetWindowRect(
IntPtr hwnd,
out RECT lpRect
);
//GetWindowDC User32 Function
[System.Runtime.InteropServices.DllImport("user32.dll", ExactSpelling = true)]
public static extern IntPtr GetWindowDC(
IntPtr hWnd
);
//GetDCEx User32 Function
[System.Runtime.InteropServices.DllImport("user32.dll", ExactSpelling = true)]
public static extern IntPtr GetDCEx(
IntPtr hWnd,
IntPtr hrgnClip,
int flags
);
//Window Procedure Hook
protected override void WndProc(ref Message m)
{
//Don't style window in designer...
if (DesignMode)
base.WndProc(ref m);
//Handle Message
switch ((uint)m.Msg)
{
case WM_NCCALCSIZE: WmNCCalcSize(ref m); break;
case WM_NCPAINT: WmNCPaint(ref m); break;
default: base.WndProc(ref m); break;
}
}
//Handle Creation
protected override void OnHandleCreated(EventArgs e)
{
//Base Procedure...
base.OnHandleCreated(e);
//Remove Theme
SetWindowTheme(this.Handle, string.Empty, string.Empty);
}
//WM_NCCALCSIZE
private void WmNCCalcSize(ref Message m)
{
//Get Window Rect
RECT formRect = new RECT();
GetWindowRect(m.HWnd, out formRect);
//Check WPARAM
if (m.WParam != IntPtr.Zero) //TRUE
{
//When TRUE, LPARAM Points to a NCCALCSIZE_PARAMS structure
var nccsp = (NCCALCSIZE_PARAMS)System.Runtime.InteropServices.Marshal.PtrToStructure(m.LParam, typeof(NCCALCSIZE_PARAMS));
//We're adjusting the size of the client area here. Right now, the client area is the whole form.
//Adding to the Top, Bottom, Left, and Right will size the client area.
nccsp.rgrc0.top += 30; //30-pixel top border
nccsp.rgrc0.bottom -= 4; //4-pixel bottom (resize) border
nccsp.rgrc0.left += 4; //4-pixel left (resize) border
nccsp.rgrc0.right -= 4; //4-pixel right (resize) border
//Set the structure back into memory
System.Runtime.InteropServices.Marshal.StructureToPtr(nccsp, m.LParam, true);
}
else //FALSE
{
//When FALSE, LPARAM Points to a RECT structure
var clnRect = (RECT)System.Runtime.InteropServices.Marshal.PtrToStructure(m.LParam, typeof(RECT));
//Like before, we're adjusting the rectangle...
//Adding to the Top, Bottom, Left, and Right will size the client area.
clnRect.top += 30; //30-pixel top border
clnRect.bottom -= 4; //4-pixel bottom (resize) border
clnRect.left += 4; //4-pixel left (resize) border
clnRect.right -= 4; //4-pixel right (resize) border
//Set the structure back into memory
System.Runtime.InteropServices.Marshal.StructureToPtr(clnRect, m.LParam, true);
}
//Return Zero
m.Result = IntPtr.Zero;
}
//WM_NCPAINT
private void WmNCPaint(ref Message m)
{
//Store HDC
IntPtr HDC = IntPtr.Zero;
Graphics gfx = null;
//Check the WPARAM
if(m.WParam == (IntPtr)1)
{
//For reasons unknown to me, the update region doesn't contain valid data and calling GetDCEx will do nothing.
//So I call GetWindowDC and exclude the area using System.Drawing.Graphics instead.
//Graphics Object from HDC
HDC = GetWindowDC(m.HWnd);
gfx = Graphics.FromHdc(HDC);
//Exclude Client Area
gfx.ExcludeClip(new Rectangle(4, 30, Width - 8, 34)); //Exclude Client Area (GetWindowDC grabs the WHOLE window's graphics handle)
}
else
{
//Graphics Object from HDC
HDC = GetDCEx(m.HWnd, m.WParam, DCX_WINDOW | DCX_INTERSECTRGN);
gfx = Graphics.FromHdc(HDC);
}
//Call Paint
using (PaintEventArgs ncPaintArgs = new PaintEventArgs(gfx, new Rectangle(0, 0, Width, Height)))
MyForm_NCPaint(this, ncPaintArgs);
//Return Zero
m.Result = IntPtr.Zero;
}
public MyForm()
{
InitializeComponent();
}
private void MyForm_NCPaint(object sender, PaintEventArgs e)
{
//Clear
e.Graphics.Clear(Color.Green);
}
}
来源：https://stackoverflow.com/questions/28277039/how-to-set-the-client-area-clientrectangle-in-a-borderless-form