DFL框架分析(一)

1.框架的意义,一个简单windows程序的要素:
封装了windows窗口,控件,简化windows开发.

声明winProc回调函数;定义窗口属性,绑定回调函数,注册窗口类;创建windows窗口;进入消息处理循环,直到结束.

一个简单的win32程序,D的例子:winsamp
[code]// Compile with: dmd winsamp gdi32.lib winsamp.def
import std.c.windows.windows;
import std.c.stdio;

const int IDC_BTNCLICK = 101;
const int IDC_BTNDONTCLICK = 102;

extern(Windows)
int WindowProc(HWND hWnd, uint uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg)
{
case WM_COMMAND:
{
switch (LOWORD(wParam))
{
case IDC_BTNCLICK:
if (HIWORD(wParam) == BN_CLICKED)
MessageBoxA(hWnd, "Hello, world!", "Greeting",
MB_OK | MB_ICONINFORMATION);
break;
case IDC_BTNDONTCLICK:
if (HIWORD(wParam) == BN_CLICKED)
{
MessageBoxA(hWnd, "You've been warned...", "Prepare to GP fault",
MB_OK | MB_ICONEXCLAMATION);
*(cast(int*) null) = 666;
}
break;
}
break;
}
case WM_PAINT:
{
static char[] text = "D Does Windows";
PAINTSTRUCT ps;
HDC dc = BeginPaint(hWnd, &ps);
RECT r;
GetClientRect(hWnd, &r);
HFONT font = CreateFontA(80, 0, 0, 0, FW_EXTRABOLD, FALSE, FALSE,
FALSE, ANSI_CHARSET, OUT_DEFAULT_PRECIS, CLIP_DEFAULT_PRECIS,
DEFAULT_QUALITY, DEFAULT_PITCH | FF_DONTCARE, "Arial");
HGDIOBJ old = SelectObject(dc, cast(HGDIOBJ) font);
SetTextAlign(dc, TA_CENTER | TA_BASELINE);
TextOutA(dc, r.right / 2, r.bottom / 2, text, text.length);
SelectObject(dc, old);
EndPaint(hWnd, &ps);
break;
}
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
break;
}
return DefWindowProcA(hWnd, uMsg, wParam, lParam); // allow windows process other message
}

int doit()
{
HINSTANCE hInst = GetModuleHandleA(null);

WNDCLASS wc;
wc.lpszClassName = "DWndClass";
wc.style = CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = &WindowProc; //set winProc
wc.hInstance = hInst;
wc.hIcon = LoadIconA(cast(HINSTANCE) null, IDI_APPLICATION);
wc.hCursor = LoadCursorA(cast(HINSTANCE) null, IDC_CROSS);
wc.hbrBackground = cast(HBRUSH) (COLOR_WINDOW + 1);
wc.lpszMenuName = null;
wc.cbClsExtra = wc.cbWndExtra = 0;
RegisterClassA(&wc);

HWND hWnd, btnClick, btnDontClick;
hWnd = CreateWindowA("DWndClass", "Just a window", WS_THICKFRAME |
WS_MAXIMIZEBOX | WS_MINIMIZEBOX | WS_SYSMENU | WS_VISIBLE,
CW_USEDEFAULT, CW_USEDEFAULT, 400, 300, HWND_DESKTOP,
cast(HMENU) null, hInst, null);
assert(hWnd);

btnClick = CreateWindowA("BUTTON", "Click Me", WS_CHILD | WS_VISIBLE,
0, 0, 100, 25, hWnd, cast(HMENU) IDC_BTNCLICK, hInst, null);

btnDontClick = CreateWindowA("BUTTON", "DON'T CLICK!", WS_CHILD | WS_VISIBLE,
110, 0, 100, 25, hWnd, cast(HMENU) IDC_BTNDONTCLICK, hInst, null);

MSG msg;
while (GetMessageA(&msg, cast(HWND) null, 0, 0))
{
TranslateMessage(&msg);
DispatchMessageA(&msg);
}

return 1;
}

extern (C) void gc_init();
extern (C) void gc_term();
extern (C) void _minit();
extern (C) void _moduleCtor();
extern (C) void _moduleUnitTests();

extern (Windows)
int WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow)
{
int result;

gc_init(); // initialize garbage collector
_minit(); // initialize module constructor table

try
{
_moduleCtor(); // call module constructors
_moduleUnitTests(); // run unit tests (optional)
result = doit(); // insert user code here
}
catch (Object o) // catch any uncaught exceptions
{
MessageBoxA(null, cast(char *)o.toString(), "Error", MB_OK | MB_ICONEXCLAMATION);
result = 0; // failed
}
gc_term(); // run finalizers; terminate garbage collector
return result;
}
[/code]

2.DFL的做法

使用面向对象语言的方法,使用继承抽象了窗口组件的层次,封装了消息循环,简化了处理过程.待续...