(1)绘制点
利用GDI绘制点的时候不需要画笔和画刷。利用函数SetPixel。
The SetPixel function sets the pixel at the specified coordinates to the specified color.
COLORREF SetPixel( _In_ HDC hdc, _In_ int X, _In_ int Y, _In_ COLORREF crColor );
Parameters
hdc [in] A handle to the device context.
- X [in] The x-coordinate, in logical units, of the point to be set.
- Y [in] The y-coordinate, in logical units, of the point to be set.
- crColor [in] The color to be used to paint the point. To create a COLORREF color value, use the RGB macro.
- Return value
- If the function succeeds, the return value is the RGB value that the function sets the pixel to. This value may differ from the color specified by crColor; that occurs when an exact match for the specified color cannot be found.
If the function fails, the return value is -1.
例子：初始化窗口为400 x 400, 我们在200 x 200的客户区域产生随机的位置和颜色。程序如下：
// INCLUDES /////////////////////////////////////////////// #define WIN32_LEAN_AND_MEAN // just say no to MFC #include <windows.h> // include all the windows headers #include <windowsx.h> // include useful macros #include <mmsystem.h> // very important and include WINMM.LIB too! #include <stdio.h> #include <stdlib.h> #include <math.h> // DEFINES //////////////////////////////////////////////// // defines for windows #define WINDOW_CLASS_NAME "WINCLASS1" #define WINDOW_WIDTH 400 #define WINDOW_HEIGHT 400 // MACROS ///////////////////////////////////////////////// #define KEYDOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0) #define KEYUP(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 0 : 1) // GLOBALS //////////////////////////////////////////////// HWND main_window_handle = NULL; // globally track main window HINSTANCE hinstance_app = NULL; // globally track hinstance char buffer[80]; // general printing buffer // FUNCTIONS ////////////////////////////////////////////// LRESULT CALLBACK WindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) { // this is the main message handler of the system PAINTSTRUCT ps; // used in WM_PAINT HDC hdc; // handle to a device context char buffer[80]; // used to print strings // what is the message switch(msg) { case WM_CREATE: { // do initialization stuff here // return success return(0); } break; case WM_PAINT: { // simply validate the window hdc = BeginPaint(hwnd,&ps); // end painting EndPaint(hwnd,&ps); // return success return(0); } break; case WM_DESTROY: { // kill the application, this sends a WM_QUIT message PostQuitMessage(0); // return success return(0); } break; default:break; } // end switch // process any messages that we didn't take care of return (DefWindowProc(hwnd, msg, wparam, lparam)); } // end WinProc // WINMAIN //////////////////////////////////////////////// int WINAPI WinMain( HINSTANCE hinstance, HINSTANCE hprevinstance, LPSTR lpcmdline, int ncmdshow) { WNDCLASSEX winclass; // this will hold the class we create HWND hwnd; // generic window handle MSG msg; // generic message HDC hdc; // graphics device context // first fill in the window class stucture winclass.cbSize = sizeof(WNDCLASSEX); winclass.style = CS_DBLCLKS | CS_OWNDC | CS_HREDRAW | CS_VREDRAW; winclass.lpfnWndProc = WindowProc; winclass.cbClsExtra = 0; winclass.cbWndExtra = 0; winclass.hInstance = hinstance; winclass.hIcon = LoadIcon(NULL, IDI_APPLICATION); winclass.hCursor = LoadCursor(NULL, IDC_ARROW); winclass.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH); winclass.lpszMenuName = NULL; winclass.lpszClassName = WINDOW_CLASS_NAME; winclass.hIconSm = LoadIcon(NULL, IDI_APPLICATION); // save hinstance in global hinstance_app = hinstance; // register the window class if (!RegisterClassEx(&winclass)) return(0); // create the window if (!(hwnd = CreateWindowEx(NULL, // extended style WINDOW_CLASS_NAME, // class "Pixel Plotting Demo", // title WS_OVERLAPPEDWINDOW | WS_VISIBLE, 0,0, // initial x,y WINDOW_WIDTH, // initial width WINDOW_HEIGHT,// initial height NULL, // handle to parent NULL, // handle to menu hinstance,// instance of this application NULL))) // extra creation parms return(0); // save main window handle main_window_handle = hwnd; // enter main event loop, but this time we use PeekMessage() // instead of GetMessage() to retrieve messages while(TRUE) { // test if there is a message in queue, if so get it if (PeekMessage(&msg,NULL,0,0,PM_REMOVE)) { // test if this is a quit if (msg.message == WM_QUIT) break; // translate any accelerator keys TranslateMessage(&msg); // send the message to the window proc DispatchMessage(&msg); } // end if // draw some pixels each cycle // get the dc for the window hdc = GetDC(hwnd); // draw 1000 pixels for (int index=0; index < 2000; index++) { // get random position int x = rand()%200; int y = rand()%200; COLORREF color = RGB(rand()%255,rand()%255,rand()%255); SetPixel(hdc, x,y, color); } // end for index // release the dc ReleaseDC(hwnd, hdc); // main game processing goes here if (KEYDOWN(VK_ESCAPE)) SendMessage(hwnd, WM_CLOSE, 0,0); } // end while // return to Windows like this return(msg.wParam); } // end WinMain ///////////////////////////////////////////////////////////
所绘制的结果如下，注意代码中400 x 400 是指整个窗口的大小，包括标题区和边框。200 x 200的区域是从左上角的窗口客户区开始计算的。
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