Bir Windows API programında, bir butonun içinde yer aldığı pencere fonksiyonu içinde WM_NOTIFY mesajının NM_CUSTOMDRAW kodunu kullanarak, Button kontrolünü kendi belirlediğimiz görünümlere göre çizebiliriz.
Bu işlemi normal koşullarda sadece butonun içinde yer aldığı pencere fonksiyonu içinde yapabiliriz. Subclassing işlemi yapılmış bir buton için oluşturulan subclassing fonksiyonu içinde yapamayız. Çünkü, WM_NOTIFY mesajı buton penceresi tarafından sadece içinde bulunduğu ana pencereye gönderilir.
Ancak, bu işlemi mutlaka gerçekleştirmek istersek, butonun içinde bulunduğu pencereye gönderilen WM_NOTIFY mesajının parametrelerini yeni tanımladığımız bir mesaja aktararak, bu mesaja subclassing fonksiyonu içinde işlem yapabiliriz.
Programda yer alacak main.c, resource.rc ve manifest.xml dosyalarının içeriği aşağıdaki şekilde olacaktır:
main.c
#if defined(UNICODE) && !defined(_UNICODE)
#define _UNICODE
#elif defined(_UNICODE) && !defined(UNICODE)
#define UNICODE
#endif
#define _WIN32_WINNT 0x0501
#define _WIN32_IE 0x0501
/* Yeni oluşturulan mesaj */
#define MY_NOTIFY (WM_APP+1)
#include <tchar.h>
#include <windows.h>
#include <commctrl.h>
#define IDC_BUTTON01 1001
#define IDC_BUTTON02 1002
/* Declare Windows procedure */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);
LRESULT CALLBACK ButtonProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData);
/* Make the class name into a global variable */
TCHAR szClassName[ ] = _T("CodeBlocksWindowsApp");
HWND hwndButton01, hwndButton02;
int WINAPI WinMain (HINSTANCE hThisInstance,
HINSTANCE hPrevInstance,
LPSTR lpszArgument,
int nCmdShow)
{
HWND hwnd; /* This is the handle for our window */
MSG messages; /* Here messages to the application are saved */
WNDCLASSEX wincl; /* Data structure for the windowclass */
/* The Window structure */
wincl.hInstance = hThisInstance;
wincl.lpszClassName = szClassName;
wincl.lpfnWndProc = WindowProcedure; /* This function is called by windows */
wincl.style = CS_DBLCLKS; /* Catch double-clicks */
wincl.cbSize = sizeof (WNDCLASSEX);
/* Use default icon and mouse-pointer */
wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
wincl.lpszMenuName = NULL; /* No menu */
wincl.cbClsExtra = 0; /* No extra bytes after the window class */
wincl.cbWndExtra = 0; /* structure or the window instance */
/* Use Windows's default colour as the background of the window */
wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;
/* Register the window class, and if it fails quit the program */
if (!RegisterClassEx (&wincl))
return 0;
/* The class is registered, let's create the program*/
hwnd = CreateWindowEx (
0, /* Extended possibilites for variation */
szClassName, /* Classname */
_T("Subclassing ile Custom Draw Button"), /* Title Text */
WS_OVERLAPPEDWINDOW, /* default window */
CW_USEDEFAULT, /* Windows decides the position */
CW_USEDEFAULT, /* where the window ends up on the screen */
400, /* The programs width */
300, /* and height in pixels */
HWND_DESKTOP, /* The window is a child-window to desktop */
NULL, /* No menu */
hThisInstance, /* Program Instance handler */
NULL /* No Window Creation data */
);
/* Make the window visible on the screen */
ShowWindow (hwnd, nCmdShow);
/* Run the message loop. It will run until GetMessage() returns 0 */
while (GetMessage (&messages, NULL, 0, 0))
{
/* Translate virtual-key messages into character messages */
TranslateMessage(&messages);
/* Send message to WindowProcedure */
DispatchMessage(&messages);
}
/* The program return-value is 0 - The value that PostQuitMessage() gave */
return messages.wParam;
}
/* This function is called by the Windows function DispatchMessage() */
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message) /* handle the messages */
{
case WM_CREATE:
{
// Subclassing ile Custom Draw button (ButtonProc)
hwndButton01 = CreateWindowEx(0, "BUTTON", "Button01",
WS_CHILD | WS_VISIBLE, 20, 20, 120, 25,
hwnd, (HMENU) IDC_BUTTON01, NULL, NULL);
SetWindowSubclass(hwndButton01, ButtonProc, 0, 0);
hwndButton02 = CreateWindowEx(0, "BUTTON", "Button02",
WS_CHILD | WS_VISIBLE, 20, 60, 120, 25,
hwnd, (HMENU) IDC_BUTTON02, NULL, NULL);
SetWindowSubclass(hwndButton02, ButtonProc, 0, 0);
}
break;
case WM_COMMAND:
{
if (HIWORD(wParam) == BN_CLICKED) {
switch(LOWORD(wParam)) {
case IDC_BUTTON01:
MessageBox(NULL, "Button01 tıklandı.", "Buton tıklama", MB_OK);
break;
case IDC_BUTTON02:
MessageBox(NULL, "Button02 tıklandı.", "Buton tıklama", MB_OK);
break;
}
}
}
break;
case WM_NOTIFY:
{
LPNMHDR lpnmhdr = (LPNMHDR)lParam;
if ((lpnmhdr->hwndFrom == hwndButton01) || (lpnmhdr->hwndFrom == hwndButton02)) {
/* Mesajı yeni oluşturulan mesaj ile ButtonProc() fonksiyonuna yönlendirme */
return SendMessage(lpnmhdr->hwndFrom, MY_NOTIFY, wParam, lParam);
}
}
break;
case WM_DESTROY:
PostQuitMessage (0); /* send a WM_QUIT to the message queue */
break;
default: /* for messages that we don't deal with */
return DefWindowProc (hwnd, message, wParam, lParam);
}
return 0;
}
LRESULT CALLBACK ButtonProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
{
switch (message) {
case MY_NOTIFY:
{
LPNMHDR lpnmhdr = (LPNMHDR)lParam;
HBRUSH hBrushBack;
char cdizi[40];
switch(lpnmhdr->code) {
case NM_CUSTOMDRAW:
LPNMCUSTOMDRAW lpnmcd = (LPNMCUSTOMDRAW)lpnmhdr;
if (lpnmcd->uItemState & CDIS_SELECTED) { // Butona tıklayınca
hBrushBack = CreateSolidBrush(RGB(170, 170, 50));
SetTextColor(lpnmcd->hdc, RGB(236, 236, 236));
}
else {
if (lpnmcd->uItemState & CDIS_HOT) { // Mouse buton üzerinde
hBrushBack = CreateSolidBrush(RGB(240, 230, 140));
SetTextColor(lpnmcd->hdc, RGB(180, 180, 180));
}
else {
hBrushBack = CreateSolidBrush(RGB(255, 219, 88));
SetTextColor(lpnmcd->hdc, RGB(150, 150, 150));
}
}
SetBkMode(lpnmcd->hdc, TRANSPARENT);
FillRect(lpnmcd->hdc, &lpnmcd->rc, hBrushBack);
DeleteObject(hBrushBack);
GetWindowText(lpnmhdr->hwndFrom, cdizi, sizeof(cdizi));
DrawText(lpnmcd->hdc, cdizi, strlen(cdizi), &lpnmcd->rc, DT_CENTER | DT_VCENTER | DT_SINGLELINE);
return CDRF_SKIPDEFAULT;
}
}
break;
}
return DefSubclassProc(hwnd, message, wParam, lParam);
}
resource.rc
1 24 "manifest.xml"
manifest.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
<assemblyIdentity version="1.0.0.0" processorArchitecture="*" name="CompanyName.ProductName.YourApplication" type="win32" />
<description>Your application description here.</description>
<dependency>
<dependentAssembly>
<assemblyIdentity type="win32" name="Microsoft.Windows.Common-Controls" version="6.0.0.0" processorArchitecture="*" publicKeyToken="6595b64144ccf1df" language="*" />
</dependentAssembly>
</dependency>
</assembly>
Program derleyip çalıştırdığımızda aşağıdakine benzer bir ekran görüntüsü karşımıza gelecektir: