C / C++ / MFC

POINT pt;
BITMAP Bitmap;
HANDLE hBitmap = 0;
HDC hBitmapMemoryDC = 0;
RECT ClientRect;
HBITMAP hOffScreenBitmap = 0;
HDC hOffScreenMemoryDC = 0;


LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    PAINTSTRUCT ps;
    HDC hdc;

    switch (message)
    {
    case WM_CREATE:
        hBitmap = ::LoadImage(hInst, MAKEINTRESOURCE(IDB_BITMAP1), IMAGE_BITMAP, 0, 0, LR_CREATEDIBSECTION);
        ::GetObject(hBitmap, sizeof(Bitmap), &Bitmap);
        hBitmapMemoryDC = ::CreateCompatibleDC(0);
        ::SelectObject(hBitmapMemoryDC, hBitmap);
        break;
    case WM_PAINT:
        hdc = BeginPaint(hWnd, &ps);
        // blt the bitmap to the offscreen buffer
        ::StretchBlt(hOffScreenMemoryDC, 0, 0, ClientRect.right, ClientRect.bottom, hBitmapMemoryDC, 0, 0, Bitmap.bmWidth, Bitmap.bmHeight, SRCCOPY);
        // draw crosshairs on the offscreen buffer
        ::MoveToEx(hOffScreenMemoryDC, pt.x , 0 , NULL); 
        ::LineTo(hOffScreenMemoryDC, pt.x, ClientRect.bottom); 
        ::MoveToEx(hOffScreenMemoryDC, 0, pt.y, NULL); 
        ::LineTo(hOffScreenMemoryDC, ClientRect.right, pt.y); 
        // blt the offscreen buffer to the screen
        ::BitBlt(hdc, 0, 0, ClientRect.right, ClientRect.bottom, hOffScreenMemoryDC, 0, 0, SRCCOPY);
        EndPaint(hWnd, &ps);
        break;
    case WM_MOUSEMOVE:
        pt.x = LOWORD(lParam);
        pt.y = HIWORD(lParam);
        ::InvalidateRect(hWnd,NULL,FALSE); // changed to FALSE since we draw the entire client area
        ::UpdateWindow(hWnd);
        break;	
    case WM_ERASEBKGND:
        // We draw the background in WM_PAINT - don't do it here!
        return 1;
    case WM_SIZE:
        ClientRect.left = 0;
        ClientRect.top = 0;
        ClientRect.right = LOWORD(lParam);
        ClientRect.bottom = HIWORD(lParam);
        // (Re)Create the offscreen buffer
        if (hOffScreenBitmap != 0)
            ::DeleteObject(hOffScreenBitmap);
        if (hOffScreenMemoryDC != 0)
            ::DeleteDC(hOffScreenMemoryDC);
        hdc = ::GetDC(hWnd);
        hOffScreenMemoryDC = ::CreateCompatibleDC(hdc);
        hOffScreenBitmap = ::CreateCompatibleBitmap(hdc, ClientRect.right, ClientRect.bottom);
        ::SelectObject(hOffScreenMemoryDC, hOffScreenBitmap);
        ::ReleaseDC(hWnd, hdc);
        break;
    case WM_DESTROY:
        if (hBitmap != 0)
            ::DeleteObject(hBitmap);
        if (hBitmapMemoryDC != 0)
            ::DeleteDC(hBitmapMemoryDC);
        if (hOffScreenBitmap != 0)
            ::DeleteObject(hOffScreenBitmap);
        if (hOffScreenMemoryDC != 0)
            ::DeleteDC(hOffScreenMemoryDC);
         PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

Mark Salsbery
Microsoft MVP - Visual C++

modified on Thursday, May 26, 2011 8:30 PM

Berlus wrote:

void operator(MyStruct& ms)

Berlus wrote:

I need help in converting these two function into one function (since basicaly it is the same code).

using std;
struct MyStruct {
   int a;     // just an example
   double b;  // just an example
   //...
};
// this implements the streaming operator for all classes derived from std::ostream
ostream& operator<<(ostream& output, MyStruct& ms) {
    output << "    a: " << ms.a << endl;
    output << "    b: " << ms.b << endl;
    return output;
}

int main () {
   MyStruct ms;
   ms.a = 3;
   ms.b = 3.1415926;
   ofstream myfile("test.txt");
   myfile << ms; // writes to file
   cout << ms; // writes to console
}

#include <iostream>
#include <fstream>
using namespace std;


struct MyStruct
{
	ostream& operator<<(ostream& output) {
		output << "    a: " << a << endl;
		output << "    b: " << b << endl;
		return output;
	}

	int a;
	double b;
};

int main(void)
{
  MyStruct ms;
  ms.a = 5;
  ms.b = 4.2;

  cout << ms;

  // Write to a file without changing methods in MyStruct
  ofstream  my_file("me.txt");
  my_file << ms;
  
  return 0;
}

struct MyStruct {
   int a;
   MyStruct(int value) : a(value) {} // conversion constructor, for implicit casting of int to MyStruct
   MyStruct operator-(const MyStruct& op2) {
      return (a-op2.a);
   }
};

struct MyStruct {
   int a;
   MyStruct(int value) : a(vlaue) {}
};
MyStruct operator-(const MyStruct& op1, const MyStruct& op2) {
   return op1.a - op2.a;
}

Richard MacCutchan wrote:

Show the contents of your URL so people can see if it is valid.

• what you are trying to achieve
• what your code is doing
• what are the actual values of any variables that the code is using
• what results you are seeing