Create window without titlebar, with resizable border and without bogus 6px white stripe
I want a window without title bar but with resizable frames and shadow. This can easily be achieved by removing WS_CAPTION and adding WS_THICKFRAME, however, since Windows 10, there's a 6px white non-client area.
With the following code I create a window and paint all the client area with black, the window gets a left, right and bottom 6px transparent margins, however the top margin is white.
#ifndef UNICODE
#define UNICODE
#endif
#include <windows.h>
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int nCmdShow)
{
// Register the window class.
const wchar_t CLASS_NAME[] = L"Sample Window Class";
WNDCLASS wc = { };
wc.lpfnWndProc = WindowProc;
wc.hInstance = hInstance;
wc.lpszClassName = CLASS_NAME;
RegisterClass(&wc);
// Create the window.
HWND hwnd = CreateWindowEx(
0, // Optional window styles.
CLASS_NAME, // Window class
L"", // Window text
0,
// Size and position
CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
NULL, // Parent window
NULL, // Menu
hInstance, // Instance handle
NULL // Additional application data
);
ShowWindow(hwnd, nCmdShow);
LONG lStyle = GetWindowLong(hwnd, GWL_STYLE);
lStyle |= WS_THICKFRAME;
lStyle = lStyle & ~WS_CAPTION;
SetWindowLong(hwnd, GWL_STYLE, lStyle);
SetWindowPos(hwnd, NULL, 0,0,0,0, SWP_FRAMECHANGED | SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER | SWP_NOOWNERZORDER);
// Run the message loop.
MSG msg = { };
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return 0;
}
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg)
{
case WM_DESTROY:
PostQuitMessage(0);
return 0;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
// Paint everything black
FillRect(hdc, &ps.rcPaint, (HBRUSH) (COLOR_WINDOWTEXT));
EndPaint(hwnd, &ps);
}
return 0;
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
Renders:
How can I remove the white stripe ? I also found this related Qt bug report QTBUG-47543 which was closed as not being a Qt problem, because it can be reproduced with win32 api.
Solution 1:
That's not a bug. In Windows 10 the borders on left/right/bottom are transparent. The top border is not transparent. You should leave it as is. Probably nobody will complain.
To change it, you must modify the non-client area. This is rather difficult in Windows Vista and above. See Custom Window Frame Using DWM for reference.
Find border thickness
Use
DwmExtendFrameIntoClientAreato get access to non-client areaUse
BeginBufferedPaintto draw opaque color over non-client area
Windows 10 example:
(See the next example for compatibility with Windows Vista, 7, 8)
//requires Dwmapi.lib and UxTheme.lib
#include <Windows.h>
#include <Dwmapi.h>
void my_paint(HDC hdc, RECT rc)
{
HBRUSH brush = CreateSolidBrush(RGB(0, 128, 0));
FillRect(hdc, &rc, brush);
DeleteObject(brush);
}
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
static RECT border_thickness;
switch (uMsg)
{
case WM_CREATE:
{
//find border thickness
SetRectEmpty(&border_thickness);
if (GetWindowLongPtr(hwnd, GWL_STYLE) & WS_THICKFRAME)
{
AdjustWindowRectEx(&border_thickness, GetWindowLongPtr(hwnd, GWL_STYLE) & ~WS_CAPTION, FALSE, NULL);
border_thickness.left *= -1;
border_thickness.top *= -1;
}
else if (GetWindowLongPtr(hwnd, GWL_STYLE) & WS_BORDER)
{
SetRect(&border_thickness, 1, 1, 1, 1);
}
MARGINS margins = { 0 };
DwmExtendFrameIntoClientArea(hwnd, &margins);
SetWindowPos(hwnd, NULL, 0, 0, 0, 0, SWP_SHOWWINDOW | SWP_NOMOVE | SWP_NOSIZE | SWP_FRAMECHANGED);
break;
}
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
RECT rc = ps.rcPaint;
BP_PAINTPARAMS params = { sizeof(params), BPPF_NOCLIP | BPPF_ERASE };
HDC memdc;
HPAINTBUFFER hbuffer = BeginBufferedPaint(hdc, &rc, BPBF_TOPDOWNDIB, ¶ms, &memdc);
my_paint(memdc, rc);
BufferedPaintSetAlpha(hbuffer, &rc, 255);
EndBufferedPaint(hbuffer, TRUE);
EndPaint(hwnd, &ps);
return 0;
}
case WM_NCACTIVATE:
return 0;
case WM_NCCALCSIZE:
if (lParam)
{
NCCALCSIZE_PARAMS* sz = (NCCALCSIZE_PARAMS*)lParam;
sz->rgrc[0].left += border_thickness.left;
sz->rgrc[0].right -= border_thickness.right;
sz->rgrc[0].bottom -= border_thickness.bottom;
return 0;
}
break;
case WM_NCHITTEST:
{
//do default processing, but allow resizing from top-border
LRESULT result = DefWindowProc(hwnd, uMsg, wParam, lParam);
if (result == HTCLIENT)
{
POINT pt = { GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam) };
ScreenToClient(hwnd, &pt);
if (pt.y < border_thickness.top) return HTTOP;
}
return result;
}
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR, int)
{
const wchar_t CLASS_NAME[] = L"Sample Window Class";
WNDCLASS wc = {};
wc.lpfnWndProc = WindowProc;
wc.hInstance = hInstance;
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.lpszClassName = CLASS_NAME;
RegisterClass(&wc);
CreateWindowEx(0, CLASS_NAME, NULL,
WS_VISIBLE | WS_THICKFRAME | WS_POPUP,
10, 10, 600, 400, NULL, NULL, hInstance, NULL);
MSG msg = {};
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return 0;
}
For compatibility with Windows Vista/7/8 use this procedure instead. This will paint over left/top/bottom borders as well as top border. This window will appear as a simple rectangle, with resizing borders:
//for Windows Vista, 7, 8, 10
LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
static RECT border_thickness;
switch (uMsg)
{
case WM_CREATE:
{
//find border thickness
SetRectEmpty(&border_thickness);
if (GetWindowLongPtr(hwnd, GWL_STYLE) & WS_THICKFRAME)
{
AdjustWindowRectEx(&border_thickness, GetWindowLongPtr(hwnd, GWL_STYLE) & ~WS_CAPTION, FALSE, NULL);
border_thickness.left *= -1;
border_thickness.top *= -1;
}
else if (GetWindowLongPtr(hwnd, GWL_STYLE) & WS_BORDER)
{
SetRect(&border_thickness, 1, 1, 1, 1);
}
MARGINS margins = { 0 };
DwmExtendFrameIntoClientArea(hwnd, &margins);
SetWindowPos(hwnd, NULL, 0, 0, 0, 0, SWP_SHOWWINDOW | SWP_NOMOVE | SWP_NOSIZE | SWP_FRAMECHANGED);
break;
}
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
RECT rc = ps.rcPaint;
BP_PAINTPARAMS params = { sizeof(params), BPPF_NOCLIP | BPPF_ERASE };
HDC memdc;
HPAINTBUFFER hbuffer = BeginBufferedPaint(hdc, &rc, BPBF_TOPDOWNDIB, ¶ms, &memdc);
my_paint(memdc, rc);
BufferedPaintSetAlpha(hbuffer, &rc, 255);
EndBufferedPaint(hbuffer, TRUE);
EndPaint(hwnd, &ps);
return 0;
}
case WM_NCACTIVATE:
return 0;
case WM_NCCALCSIZE:
if (lParam)
return 0;
case WM_NCHITTEST:
{
POINT pt = { GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam) };
ScreenToClient(hwnd, &pt);
RECT rc;
GetClientRect(hwnd, &rc);
enum {left=1, top=2, right=4, bottom=8};
int hit = 0;
if (pt.x < border_thickness.left) hit |= left;
if (pt.x > rc.right - border_thickness.right) hit |= right;
if (pt.y < border_thickness.top) hit |= top;
if (pt.y > rc.bottom - border_thickness.bottom) hit |= bottom;
if (hit & top && hit & left) return HTTOPLEFT;
if (hit & top && hit & right) return HTTOPRIGHT;
if (hit & bottom && hit & left) return HTBOTTOMLEFT;
if (hit & bottom && hit & right) return HTBOTTOMRIGHT;
if (hit & left) return HTLEFT;
if (hit & top) return HTTOP;
if (hit & right) return HTRIGHT;
if (hit & bottom) return HTBOTTOM;
return HTCLIENT;
}
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
Solution 2:
Just to expand on this a little; in order to remove the white stripe one just has to remove the corresponding value from the first rect in NCCALCSIZE. pywin32 code would be:
if msg == WM_NCCALCSIZE:
if wParam:
res = CallWindowProc(
wndProc, hWnd, msg, wParam, lParam
)
sz = NCCALCSIZE_PARAMS.from_address(lParam)
sz.rgrc[0].top -= 6 # remove 6px top border!
return res
Solution 3:
I think we don't need to work with DWM to remove this border. This white top resize border belongs to the non-client area of a window. So for removing it you should handle window messages related to the resizing and activating of non-client area of a window like below: ( tested only on Win 10 )
LRESULT CALLBACK WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
/* When we have a custom titlebar in the window, we don't need the non-client area of a normal window
* to be painted. In order to achieve this, we handle the "WM_NCCALCSIZE" which is responsible for the
* size of non-client area of a window and set the return value to 0. Also we have to tell the
* application to not paint this area on activate and deactivation events so we also handle
* "WM_NCACTIVATE" message. */
switch( nMsg )
{
case WM_NCACTIVATE:
{
/* Returning 0 from this message disable the window from receiving activate events which is not
desirable. However When a visual style is not active (?) for this window, "lParam" is a handle to an
optional update region for the nonclient area of the window. If this parameter is set to -1,
DefWindowProc does not repaint the nonclient area to reflect the state change. */
lParam = -1;
break;
}
/* To remove the standard window frame, you must handle the WM_NCCALCSIZE message, specifically when
its wParam value is TRUE and the return value is 0 */
case WM_NCCALCSIZE:
if( wParam )
{
/* Detect whether window is maximized or not. We don't need to change the resize border when win is
* maximized because all resize borders are gone automatically */
WINDOWPLACEMENT wPos;
// GetWindowPlacement fail if this member is not set correctly.
wPos.length = sizeof( wPos );
GetWindowPlacement( hWnd, &wPos );
if( wPos.showCmd != SW_SHOWMAXIMIZED )
{
RECT borderThickness;
SetRectEmpty( &borderThickness );
AdjustWindowRectEx( &borderThickness,
GetWindowLongPtr( hWnd, GWL_STYLE ) & ~WS_CAPTION, FALSE, NULL );
borderThickness.left *= -1;
borderThickness.top *= -1;
NCCALCSIZE_PARAMS* sz = reinterpret_cast< NCCALCSIZE_PARAMS* >( lParam );
// Add 1 pixel to the top border to make the window resizable from the top border
sz->rgrc[ 0 ].top += 1;
sz->rgrc[ 0 ].left += borderThickness.left;
sz->rgrc[ 0 ].right -= borderThickness.right;
sz->rgrc[ 0 ].bottom -= borderThickness.bottom;
return 0;
}
}
break;
}
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}