Vẽ Marker

[anbinhtrong]

Bài marker nguyên mẫu:

// Ve Marker.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include "resource.h"

#define MAX_LOADSTRING 100
#define MARKER_SIZE 5
#define MARKER_MAX 100

// Global Variables:
HINSTANCE hInst;                                // current instance
TCHAR szTitle[MAX_LOADSTRING];                                // The title bar text
TCHAR szWindowClass[MAX_LOADSTRING];                                // The title bar text

// Foward declarations of functions included in this code module:
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
LRESULT CALLBACK    About(HWND, UINT, WPARAM, LPARAM);

//---------Dinh nghia cac ham--------------
void DrawMarker(HDC hdc, POINT pt, int size);

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
     // TODO: Place code here.
    MSG msg;
    HACCEL hAccelTable;

    // Initialize global strings
    LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadString(hInstance, IDC_VEMARKER, szWindowClass, MAX_LOADSTRING);
    MyRegisterClass(hInstance);

    // Perform application initialization:
    if (!InitInstance (hInstance, nCmdShow)) 
    {
        return FALSE;
    }

    hAccelTable = LoadAccelerators(hInstance, (LPCTSTR)IDC_VEMARKER);

    // Main message loop:
    while (GetMessage(&msg, NULL, 0, 0)) 
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg)) 
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

    return msg.wParam;
}



//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
//  COMMENTS:
//
//    This function and its usage is only necessary if you want this code
//    to be compatible with Win32 systems prior to the 'RegisterClassEx'
//    function that was added to Windows 95. It is important to call this function
//    so that the application will get 'well formed' small icons associated
//    with it.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEX wcex;

    wcex.cbSize = sizeof(WNDCLASSEX); 

    wcex.style            = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = (WNDPROC)WndProc;
    wcex.cbClsExtra        = 0;
    wcex.cbWndExtra        = 0;
    wcex.hInstance        = hInstance;
    wcex.hIcon            = LoadIcon(hInstance, (LPCTSTR)IDI_VEMARKER);
    wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground    = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName    = (LPCSTR)IDC_VEMARKER;
    wcex.lpszClassName    = szWindowClass;
    wcex.hIconSm        = LoadIcon(wcex.hInstance, (LPCTSTR)IDI_SMALL);

    return RegisterClassEx(&wcex);
}

//
//   FUNCTION: InitInstance(HANDLE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   HWND hWnd;

   hInst = hInstance; // Store instance handle in our global variable

   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

//
//  FUNCTION: WndProc(HWND, unsigned, WORD, LONG)
//
//  PURPOSE:  Processes messages for the main window.
//
//  WM_COMMAND    - process the application menu
//  WM_PAINT    - Paint the main window
//  WM_DESTROY    - post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    int wmId, wmEvent;
    PAINTSTRUCT ps;
    HDC hdc;
    TCHAR szHello[MAX_LOADSTRING];
    LoadString(hInst, IDS_HELLO, szHello, MAX_LOADSTRING);
    static POINT apt[MARKER_MAX];
    static int napt=0;
    int i;

    switch (message) 
    {
        case WM_LBUTTONDOWN:
            if(napt<MARKER_MAX)
            {
                apt[napt].x= LOWORD(lParam);
                apt[napt].y= HIWORD(lParam);
                napt++;
                InvalidateRect(hWnd,NULL,TRUE);
            }
            break;
        case WM_RBUTTONDOWN:
            napt=0;
            InvalidateRect(hWnd,NULL,TRUE);
            break;
        case WM_COMMAND:
            wmId    = LOWORD(wParam); 
            wmEvent = HIWORD(wParam); 
            // Parse the menu selections:
            switch (wmId)
            {
                case IDM_ABOUT:
                   DialogBox(hInst, (LPCTSTR)IDD_ABOUTBOX, hWnd, (DLGPROC)About);
                   break;
                case IDM_EXIT:
                   DestroyWindow(hWnd);
                   break;
                default:
                   return DefWindowProc(hWnd, message, wParam, lParam);
            }
            break;
        case WM_PAINT:
            hdc = BeginPaint(hWnd, &ps);
            // TODO: Add any drawing code here...
            RECT rt;
            GetClientRect(hWnd, &rt);
            DrawText(hdc, szHello, strlen(szHello), &rt, DT_CENTER);
            //-------Ve Marker------------
            for(i=0;i<napt;i++)
                DrawMarker(hdc,apt[i],MARKER_SIZE);
            EndPaint(hWnd, &ps);
            break;
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
        default:
            return DefWindowProc(hWnd, message, wParam, lParam);
   }
   return 0;
}

// Mesage handler for about box.
LRESULT CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
        case WM_INITDIALOG:
                return TRUE;

        case WM_COMMAND:
            if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) 
            {
                EndDialog(hDlg, LOWORD(wParam));
                return TRUE;
            }
            break;
    }
    return FALSE;
}

void InvertPixel(HDC hdc, int x, int y)
{
    COLORREF crColor= GetPixel(hdc,x,y);
    SetPixel(hdc,x,y,~crColor & RGB(255,255,255));
}

void DrawMarker(HDC hdc, POINT pt, int size)
{
    int i, x=pt.x, y=pt.y;
    InvertPixel(hdc,x,y);
    for(i=0;i<size;i++)
    {
        InvertPixel(hdc,x+i,y);
        InvertPixel(hdc,x-i,y);
        InvertPixel(hdc,x,y+i);
        InvertPixel(hdc,x,y-i);
    }
}

[anbinhtrong]

Ở đây ta dùng hàm wsprintf để gán chuỗi số marker vào cho biến szHello:
Cú pháp:

int wsprintf(
  __out  LPTSTR lpOut,
  __in   LPCTSTR lpFmt,
  __in    ...
);

//-------Dem so Marker------------
wsprintf(szHello,"So marker: %d",napt);
DrawText(hdc, szHello, strlen(szHello), &rt, DT_CENTER);
//-------Ve Marker------------

[anbinhtrong]

Dùng sự kiện WM_CHAR để bắt ký tự chữ thường dùng( không phải kí tự đặc biết). Kí tự được lưu trong wParam.

case WM_CHAR:
    switch(wParam)
    {
        case '+': marker_size++;
            break;
        case '-': if (marker_size>0) marker_size--;
            break;
    }
    InvalidateRect(hWnd,NULL,TRUE);
    break;

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