Why is my DwmExtendFrameIntoClientArea()'d window not drawing the DWM borders?

Question

I've been following MSDN's guide to using the DWM API to extend the frame into the client area, but redone so I can experiment with it once I have something working.

However, when I build it, using cl wincompositiontest.cpp in the Visual Studio 2013 x64 Native Tools Command Line, the program does not draw the window borders. The standard window buttons do work: I can see the Windows 7 button glow and tooltips, and clicking on the buttons does their respective action (so I can close this window). But nothing else works: I can't move or resize the window with the edges, and the borders don't draw, instead drawing white:

Window

DwmExtendFrameIntoClientArea() returns S_OK.

What's going on? This is on Windows 7 x64 running in VirtualBox; I gave the code to a friend also running Windows 7 on real hardware and they get the same results. Thanks.

// 12 december 2016
#define UNICODE
#define _UNICODE
#define STRICT
#define STRICT_TYPED_ITEMIDS
// get Windows version right; right now Windows Vista
// unless otherwise stated, all values from Microsoft's sdkddkver.h
// TODO is all of this necessary? how is NTDDI_VERSION used?
// TODO plaform update sp2
#define WINVER          0x0600  /* from Microsoft's winnls.h */
#define _WIN32_WINNT        0x0600
#define _WIN32_WINDOWS  0x0600  /* from Microsoft's pdh.h */
#define _WIN32_IE           0x0700
#define NTDDI_VERSION       0x06000000
#include <windows.h>
#include <commctrl.h>
#include <uxtheme.h>
#include <windowsx.h>
#include <shobjidl.h>
#include <d2d1.h>
#include <d2d1helper.h>
#include <dwrite.h>
#include <usp10.h>
#include <msctf.h>
#include <textstor.h>
#include <olectl.h>
#include <shlwapi.h>
#include <dwmapi.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <wchar.h>
#include <stdarg.h>
#include <stdio.h>
#include <math.h>
#include <float.h>
#include <inttypes.h>
#include <vector>
#include <map>
#include <string>

#pragma comment(linker, \
    "\"/manifestdependency:type='Win32' " \
    "name='Microsoft.Windows.Common-Controls' " \
    "version='6.0.0.0' " \
    "processorArchitecture='*' " \
    "publicKeyToken='6595b64144ccf1df' " \
    "language='*'\"")
#pragma comment(lib, "user32.lib")
#pragma comment(lib, "kernel32.lib")
#pragma comment(lib, "gdi32.lib")
#pragma comment(lib, "comctl32.lib")
#pragma comment(lib, "uxtheme.lib")
#pragma comment(lib, "dwmapi.lib")

#define HR(call) printf("%s -> 0x%I32X\n", #call, call)

LRESULT CALLBACK wndproc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    RECT r;
    MARGINS margins;
    BOOL dwmHandled;
    LRESULT lResult;

    dwmHandled = DwmDefWindowProc(hwnd, uMsg, wParam, lParam, &lResult);
    switch (uMsg) {
    case WM_CREATE:
        GetWindowRect(hwnd, &r);
        SetWindowPos(hwnd, NULL,
            r.left, r.top,
            r.right - r.left, r.bottom - r.top,
            SWP_FRAMECHANGED);
        // TODO if we pass SWP_NOOWNERZORDER || SWP_NOZORDER, the default frame is not correctly inhibited
        break;
    case WM_ACTIVATE:
        margins.cxLeftWidth = 8;
        margins.cxRightWidth = 8;
        margins.cyBottomHeight = 20;
        margins.cyTopHeight = 27;
        HR(DwmExtendFrameIntoClientArea(hwnd, &margins));
        break;
    case WM_NCCALCSIZE:
        if (wParam != (WPARAM) FALSE)
            return 0;
        break;
    case WM_CLOSE:
        PostQuitMessage(0);
        break;
    }
    if (dwmHandled)
        return lResult;
    return DefWindowProcW(hwnd, uMsg, wParam, lParam);
}

int main(void)
{
    WNDCLASSW wc;
    HWND mainwin;
    MSG msg;

    ZeroMemory(&wc, sizeof (WNDCLASSW));
    wc.lpszClassName = L"mainwin";
    wc.lpfnWndProc = wndproc;
    wc.hInstance = GetModuleHandle(NULL);
    wc.hIcon = LoadIconW(NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursorW(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH) (COLOR_BTNFACE + 1);
    RegisterClassW(&wc);

    mainwin = CreateWindowExW(0,
        L"mainwin", L"Main Window",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,
        400, 400,
        NULL, NULL, GetModuleHandle(NULL), NULL);

    ShowWindow(mainwin, SW_SHOWDEFAULT);
    UpdateWindow(mainwin);

    while (GetMessageW(&msg, NULL, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessageW(&msg);
    }
    return 0;
}

For WM_NCCALCSIZE MSDN: When wParam is TRUE, simply returning 0 without processing the NCCALCSIZE_PARAMS rectangles will cause the client area to resize to the size of the window, including the window frame. This will remove the window frame and caption items from your window, leaving only the client area displayed. — γηράσκω δ' αεί πολλά διδασκόμε
@γηράσκωδ'αείπολλάδιδασκόμε yes, but take a look at the MSDN page I linked: it simply sets pncsp->rgrc[0] to itself without changing it, then instructs WndProc() to return 0 without calling DefWIndowProc(). Unless there's something subtle I'm missing (setting pncsp->rgrc[0] to itself is not the same as doing nothing?)? — andlabs
@γηράσκωδ'αείπολλάδιδασκόμε okay, that fixed everything except the border dragging, and now I'm not sure why. Would you know? (For hit testing, it appears DwmDefWindowProc() is not doing the hit testing for some reason, but the page I linked tells me how to do it in this case, which is not a problem.) — andlabs
I used the black brush some years ago when i wanted to draw tranparently with directx. The idea is the same. Extend the frame to the whole form set the brush to black. I believe setting the brush to black is also setting the alpha value of the extended area to 0 and thus you can see the transparent borders — γηράσκω δ' αεί πολλά διδασκόμε

Barmak Shemirani Barmak Shemirani · Accepted Answer · 2016-12-12T23:38:22

For compatibility with Windows 10, the left/right/bottom margins should be zero.

Usually you need to change the title bar area only. Therefore, only change the value for margins.cyTopHeight

Calculate the default border widths for the given window style using AdjustWindowRectEx and pass these values to WM_NCCALCSIZE, this will show the default borders.

DwmDefWindowProc is required in response to WM_NCHITTEST and WM_NCMOUSELEAVE only (but maybe the way you have set it up is better for future compatibility)

You also have to handle WM_PAINT for system buttons to display correctly. It's probably easier to hide the system buttons and draw your own buttons, so the title-bar is completely custom with its own background color.

Below is example for Windows 10, it should work for Windows 7. Application should be DPI aware otherwise there will be small display problems with borders.

void paint_caption(HWND hWnd, HDC hdc, int caption_height)
{
    RECT rc;
    GetClientRect(hWnd, &rc);
    rc.bottom = caption_height;

    HDC memdc = CreateCompatibleDC(hdc);
    BITMAPINFOHEADER bmpInfoHdr = 
        { sizeof(BITMAPINFOHEADER), rc.right, -rc.bottom, 1, 32 };
    HBITMAP hbitmap = 
        CreateDIBSection(memdc, (BITMAPINFO*)(&bmpInfoHdr), DIB_RGB_COLORS, 0, 0, 0);
    HGDIOBJ oldbitmap = SelectObject(memdc, hbitmap);

    //Note, GDI functions don't support alpha channel, they can't be used here
    //Use GDI+, BufferedPaint, or DrawThemeXXX functions

    BitBlt(hdc, 0, 0, rc.right, caption_height, memdc, 0, 0, SRCCOPY);
    SelectObject(memdc, oldbitmap);
    DeleteObject(hbitmap);
    DeleteDC(memdc);
}

LRESULT CALLBACK wndproc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    //static MARGINS margins = { -1,-1,100,-1 };
    static MARGINS margins = { 0,0,100,0 };
    static RECT border_thickness = { 0 };

    switch(uMsg) 
    {
    case WM_CREATE:
        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)
        {
            border_thickness = { 1,1,1,1 };
        }

        DwmExtendFrameIntoClientArea(hwnd, &margins);
        SetWindowPos(hwnd, NULL, 0, 0, 0, 0,
            SWP_SHOWWINDOW | SWP_NOMOVE | SWP_NOSIZE | SWP_FRAMECHANGED);

        break;

    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_PAINT:
    {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hwnd, &ps);

        //paint caption area
        paint_caption(hwnd, hdc, margins.cyTopHeight);

        EndPaint(hwnd, &ps);
        return 0;
    }

    case WM_NCHITTEST:
    {
        //handle close/minimize/maximize/help button
        LRESULT lResult;
        if (DwmDefWindowProc(hwnd, uMsg, wParam, lParam, &lResult))
            return lResult;

        //do default processing, except change the result for caption area
        lResult = DefWindowProc(hwnd, uMsg, wParam, lParam);
        if(lResult == HTCLIENT)
        {
            POINT pt = { LOWORD(lParam), HIWORD(lParam) };
            ScreenToClient(hwnd, &pt);
            if(pt.y < border_thickness.top) return HTTOP;
            if(pt.y < margins.cyTopHeight)  return HTCAPTION;
        }

        return lResult;
    }

    case WM_NCMOUSELEAVE:
    {
        LRESULT lResult;
        if(DwmDefWindowProc(hwnd, uMsg, wParam, lParam, &lResult))
            return lResult;
        break;
    }

    case WM_CLOSE:
        PostQuitMessage(0);
        break;
    }

    return DefWindowProcW(hwnd, uMsg, wParam, lParam);
}

Result in Windows 10:

Win 7:

Why is my DwmExtendFrameIntoClientArea()'d window not drawing the DWM borders?

2 Answers