Windows程序设计 HELLOBIT.C -- SKETCH.C 范例分析笔记

/*-----------------------------------------
HELLOBIT.C – 在内存设备内容中的位图上输出
文字
-----------------------------------------*/

#include <windows.h>
#include "resource.h"

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName [] = TEXT ("HelloBit") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;

wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
wndclass.lpszMenuName = szAppName ;
wndclass.lpszClassName = szAppName ;

if (!RegisterClass (&wndclass))
{
MessageBox (NULL, TEXT ("This program requires Windows NT!"),
szAppName, MB_ICONERROR) ;
return 0 ;
}

hwnd = CreateWindow (szAppName, TEXT ("HelloBit"),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL, hInstance, NULL) ;

ShowWindow (hwnd, iCmdShow) ;
UpdateWindow (hwnd) ;

while (GetMessage (&msg, NULL, 0, 0))
{
TranslateMessage (&msg) ;
DispatchMessage (&msg) ;
}
return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static HBITMAP hBitmap ;
static HDC hdcMem ;
static int cxBitmap, cyBitmap, cxClient, cyClient, iSize = IDM_BIG ;
static TCHAR * szText = TEXT (" Hello, world! ") ;
HDC hdc ;
HMENU hMenu ;
int x, y ;
PAINTSTRUCT ps ;
SIZE size ;

switch (message)
{
case WM_CREATE:
hdc = GetDC (hwnd) ; //取整个窗体的设备内容句柄
hdcMem = CreateCompatibleDC (hdc) ; //建立与视讯显示器兼容的内存设备内容

//计算字符串的高度和宽度的图素尺寸
//lstrlen (szText) 计算字符串的字符数
GetTextExtentPoint32 (hdc, szText, lstrlen (szText), &size) ;
cxBitmap = size.cx ;
cyBitmap = size.cy ; //以字符串的宽度和高度来设定位图大小

//建立与设备内容兼容的位图，大小为上面计算的字符串宽高
hBitmap = CreateCompatibleBitmap (hdc, cxBitmap, cyBitmap) ;

ReleaseDC (hwnd, hdc) ; //释放设备内容句柄

SelectObject (hdcMem, hBitmap) ; //将建立的位图选进内存设备内容

//在内存设备内容上输出字符串
TextOut (hdcMem, 0, 0, szText, lstrlen (szText)) ;
return 0 ;

case WM_SIZE:
cxClient = LOWORD (lParam) ;
cyClient = HIWORD (lParam) ;
return 0 ;

case WM_COMMAND:
hMenu = GetMenu (hwnd) ; //取得窗体的菜单句柄

switch (LOWORD (wParam))
{
case IDM_BIG:
case IDM_SMALL:
//删除iSize所对应的菜单的选取标记
CheckMenuItem (hMenu, iSize, MF_UNCHECKED) ;
iSize = LOWORD (wParam) ; //读取当前选择的菜单项
CheckMenuItem (hMenu, iSize, MF_CHECKED) ; //标记当前选择的菜单项
InvalidateRect (hwnd, NULL, TRUE) ; //要求系统重绘整个窗体
break ;
}
return 0 ;

case WM_PAINT:
hdc = BeginPaint (hwnd, &ps) ;

switch (iSize)
{
case IDM_BIG: //拉伸位图到整个窗体
StretchBlt (hdc, 0, 0, cxClient, cyClient,
hdcMem, 0, 0, cxBitmap, cyBitmap, SRCCOPY) ;
break ;

case IDM_SMALL: //平铺位图到窗体
for (y = 0 ; y < cyClient ; y += cyBitmap)
for (x = 0 ; x < cxClient ; x += cxBitmap)
{
BitBlt (hdc, x, y, cxBitmap, cyBitmap,
hdcMem, 0, 0, SRCCOPY) ;
}
break ;
}

EndPaint (hwnd, &ps) ;
return 0 ;

case WM_DESTROY:
DeleteDC (hdcMem) ; //删除内存设备内容
DeleteObject (hBitmap) ; //删除建立的位图
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}

/*-----------------------------------------
HelloBit.rc – HELLOBIT.C资源文件
-----------------------------------------*/
//Microsoft Developer Studio generated resource script.
//
#include "resource.h"

#define APSTUDIO_READONLY_SYMBOLS
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 2 resource.
//
#include "afxres.h"

/////////////////////////////////////////////////////////////////////////////
#undef APSTUDIO_READONLY_SYMBOLS

/////////////////////////////////////////////////////////////////////////////
// English (U.S.) resources

#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_ENU)
#ifdef _WIN32
LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
#pragma code_page(1252)
#endif //_WIN32

#ifdef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// TEXTINCLUDE
//

1 TEXTINCLUDE DISCARDABLE
BEGIN
"resource.h/0"
END

2 TEXTINCLUDE DISCARDABLE
BEGIN
"#include ""afxres.h""/r/n"
"/0"
END

3 TEXTINCLUDE DISCARDABLE
BEGIN
"/r/n"
"/0"
END

#endif // APSTUDIO_INVOKED

/////////////////////////////////////////////////////////////////////////////
//
// Menu
//

HELLOBIT MENU DISCARDABLE
BEGIN
POPUP "&Size"
BEGIN
MENUITEM "&Big", IDM_BIG, CHECKED
MENUITEM "&Small", IDM_SMALL
END
END

#endif // English (U.S.) resources
/////////////////////////////////////////////////////////////////////////////

#ifndef APSTUDIO_INVOKED
/////////////////////////////////////////////////////////////////////////////
//
// Generated from the TEXTINCLUDE 3 resource.
//

/////////////////////////////////////////////////////////////////////////////
#endif // not APSTUDIO_INVOKED

/*-----------------------------------------
RESOURCE.H – HELLOBIT.C资源头文件
-----------------------------------------*/
//{{NO_DEPENDENCIES}}
// Microsoft Developer Studio generated include file.
// Used by HelloBit.rc
//
#define IDM_BIG 40001
#define IDM_SMALL 40002

// Next default values for new objects
//
#ifdef APSTUDIO_INVOKED
#ifndef APSTUDIO_READONLY_SYMBOLS
#define _APS_NEXT_RESOURCE_VALUE 102
#define _APS_NEXT_COMMAND_VALUE 40003
#define _APS_NEXT_CONTROL_VALUE 1000
#define _APS_NEXT_SYMED_VALUE 101
#endif
#endif

/*-----------------------------------------
SKETCH.C – 在显示设备内容和内存设备内容
上绘画
-----------------------------------------*/

#include <windows.h>

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName [] = TEXT ("Sketch") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;

wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
wndclass.lpszMenuName = NULL ;
wndclass.lpszClassName = szAppName ;

if (!RegisterClass (&wndclass))
{
MessageBox (NULL, TEXT ("This program requires Windows NT!"),
szAppName, MB_ICONERROR) ;
return 0 ;
}

hwnd = CreateWindow (szAppName, TEXT ("Sketch"),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL, hInstance, NULL) ;

if (hwnd == NULL)
{
MessageBox (NULL, TEXT ("Not enough memory to create bitmap!"),
szAppName, MB_ICONERROR) ;
return 0 ;
}

ShowWindow (hwnd, iCmdShow) ;
UpdateWindow (hwnd) ;

while (GetMessage (&msg, NULL, 0, 0))
{
TranslateMessage (&msg) ;
DispatchMessage (&msg) ;
}
return msg.wParam ;
}

void GetLargestDisplayMode (int * pcxBitmap, int * pcyBitmap)
{
DEVMODE devmode ;
int iModeNum = 0 ;

* pcxBitmap = * pcyBitmap = 0 ;

//用0来填充devmode内存区域
ZeroMemory (&devmode, sizeof (DEVMODE)) ;

devmode.dmSize = sizeof (DEVMODE) ;
//获取调用线程正运行在计算机的当前显示设备所有的图形模式信息，记录在devmode结构中
//枚举调用，使其能获得当前显示设备的最大显示尺寸
while (EnumDisplaySettings (NULL, iModeNum++, &devmode))
{
//取当前显示设备宽和高来设置位图尺寸，以像素为单位。MAX宏限制了该数不可为负数
* pcxBitmap = max (* pcxBitmap, (int) devmode.dmPelsWidth) ;
* pcyBitmap = max (* pcyBitmap, (int) devmode.dmPelsHeight) ;
}
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static BOOL fLeftButtonDown, fRightButtonDown ;
static HBITMAP hBitmap ;
static HDC hdcMem ;
static int cxBitmap, cyBitmap, cxClient, cyClient, xMouse, yMouse ;
HDC hdc ;
PAINTSTRUCT ps ;

switch (message)
{
case WM_CREATE:
//调用自定义函数，取当前显示设备的最大尺寸来设定位图尺寸
GetLargestDisplayMode (&cxBitmap, &cyBitmap) ;

hdc = GetDC (hwnd) ; //取整个程序窗体的句柄
//建立与显示设备兼容的位图
hBitmap = CreateCompatibleBitmap (hdc, cxBitmap, cyBitmap) ;
//建立与显示设备兼容的内存设备内容
hdcMem = CreateCompatibleDC (hdc) ;
ReleaseDC (hwnd, hdc) ;//删除窗体句柄

//判断位图是否成功建立，如果CreateCompatibleBitmap调用失败，hBitmap值为NULL
if (!hBitmap)
{
//删除内存设备内容，并返回-1的错误消息
DeleteDC (hdcMem) ;
return -1 ;
}
//将建立的位图选进内存设备内容，等于是扩充内存设备内容
SelectObject (hdcMem, hBitmap) ;
//将内存设备内容中的位图刷成白色
PatBlt (hdcMem, 0, 0, cxBitmap, cyBitmap,WHITENESS) ;
return 0 ;

case WM_SIZE:
cxClient = LOWORD (lParam) ;
cyClient = HIWORD (lParam) ;
return 0 ;

case WM_LBUTTONDOWN: //鼠标左键按下
//如果鼠标右键已经释放，则为当前窗口捕获鼠标
if (!fRightButtonDown)
SetCapture (hwnd) ;

//获取鼠标光标相对于客户区域左上角的坐标
xMouse = LOWORD (lParam) ;
yMouse = HIWORD (lParam) ;
//设置鼠标左键按下标记
fLeftButtonDown = TRUE ;
return 0 ;

case WM_LBUTTONUP: //鼠标左键释放
//如果鼠标左键按下标记被设置，则释放先前的鼠标捕获
if (fLeftButtonDown)
SetCapture (NULL) ;
//设置鼠标左键释放标记
fLeftButtonDown = FALSE ;
return 0 ;

case WM_RBUTTONDOWN: //鼠标右键按下
//如果鼠标左键已经释放，则为当前窗口捕获鼠标
if (!fLeftButtonDown)
SetCapture (hwnd) ;

//获取鼠标光标相对于客户区域左上角的坐标
xMouse = LOWORD (lParam) ;
yMouse = HIWORD (lParam) ;
//设置鼠标右键按下标记
fRightButtonDown = TRUE ;
return 0 ;

case WM_RBUTTONUP: //鼠标右键释放
//如果鼠标右键按下标记被设置，则释放先前的鼠标捕获
if (fRightButtonDown)
SetCapture (NULL) ;
//设置鼠标右键释放标记
fRightButtonDown = FALSE ;
return 0 ;

case WM_MOUSEMOVE:
//如果鼠标左右键均已释放，则直接返回
if (!fLeftButtonDown && !fRightButtonDown)
return 0 ;

hdc = GetDC (hwnd) ; //取得程序的整个窗体句柄

//将相应的钢笔句柄选进设备内容中
SelectObject (hdc,
//鼠标左键按下则获取黑色钢笔句柄，否则取白色钢笔句柄
GetStockObject (fLeftButtonDown ? BLACK_PEN : WHITE_PEN)) ;

//在内存设备内容中做相同操作
SelectObject (hdcMem,
GetStockObject (fLeftButtonDown ? BLACK_PEN : WHITE_PEN)) ;

//移动画线起始点到鼠标按下时所保存的位置
MoveToEx (hdc, xMouse, yMouse, NULL) ;
MoveToEx (hdcMem, xMouse, yMouse, NULL) ;

//获取当前鼠标移动到的位置
xMouse = (short) LOWORD (lParam) ;
yMouse = (short) HIWORD (lParam) ;

//在窗口和内存设备内容中的位图上划线
LineTo (hdc, xMouse, yMouse) ;
LineTo (hdcMem, xMouse, yMouse) ;

ReleaseDC (hwnd, hdc) ; //删除窗体设备内容句柄
return 0 ;

case WM_PAINT:
hdc = BeginPaint (hwnd, &ps) ;
//当显示区域重绘时，用内存设备内容中的位图来更新
//这一设置与鼠标捕获结合时，可以在窗口以外屏幕之内作画，通过拉伸窗口来显示隐藏的数据
BitBlt (hdc, 0, 0, cxClient, cyClient, hdcMem, 0, 0, SRCCOPY) ;

EndPaint (hwnd, &ps) ;
return 0 ;

case WM_DESTROY:
//释放内存设备内容和建立的位图
DeleteDC (hdcMem) ;
DeleteObject (hBitmap) ;
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}