Hi, I'm reading Programming Windows Fifth Edition by Charles Petzold. In the part I'm
reading, it talks about GDI functions. I'm trying to get the pixels that are 1 to 100 + the
mouse x coordinate and the y coorinate, then draw them on my window. It's hard to explain. I want it to make a complete copy of the 100x100 box from the mouse position. Look at my drawing:
100px
*----------
|----------|
|----------| 100px
|----------|
------------
The * is the cursor. I want to get all of the pixels, then draw them on my window. It's like a copy of what's around the mouse. I tried it, but the box just goes black then white.
#include <windows.h>
#include <stdio.h>
#define ID_TIMER 1
/* Declare Windows procedure */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);
/* Make the class name into a global variable */
char szClassName[ ] = "WindowsApp";
int WINAPI WinMain (HINSTANCE hThisInstance,
HINSTANCE hPrevInstance,
LPSTR lpszArgument,
int nFunsterStil)
{
HWND hwnd; /* This is the handle for our window */
MSG messages; /* Here messages to the application are saved */
WNDCLASSEX wincl; /* Data structure for the windowclass */
/* The Window structure */
wincl.hInstance = hThisInstance;
wincl.lpszClassName = szClassName;
wincl.lpfnWndProc = WindowProcedure; /* This function is called by windows */
wincl.style = CS_DBLCLKS; /* Catch double-clicks */
wincl.cbSize = sizeof (WNDCLASSEX);
/* Use default icon and mouse-pointer */
wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
wincl.lpszMenuName = NULL; /* No menu */
wincl.cbClsExtra = 0; /* No extra bytes after the window class */
wincl.cbWndExtra = 0; /* structure or the window instance */
/* Use Windows's default color as the background of the window */
wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;
/* Register the window class, and if it fails quit the program */
if (!RegisterClassEx (&wincl))
return 0;
/* The class is registered, let's create the program*/
hwnd = CreateWindowEx (
0, /* Extended possibilites for variation */
szClassName, /* Classname */
"Windows App", /* Title Text */
WS_OVERLAPPEDWINDOW, /* default window */
CW_USEDEFAULT, /* Windows decides the position */
CW_USEDEFAULT, /* where the window ends up on the screen */
544, /* The programs width */
375, /* and height in pixels */
HWND_DESKTOP, /* The window is a child-window to desktop */
NULL, /* No menu */
hThisInstance, /* Program Instance handler */
NULL /* No Window Creation data */
);
/* Make the window visible on the screen */
ShowWindow (hwnd, nFunsterStil);
/* Run the message loop. It will run until GetMessage() returns 0 */
while (GetMessage (&messages, NULL, 0, 0))
{
/* Translate virtual-key messages into character messages */
TranslateMessage(&messages);
/* Send message to WindowProcedure */
DispatchMessage(&messages);
}
/* The program return-value is 0 - The value that PostQuitMessage() gave */
return messages.wParam;
}
void PaintRoutine (HDC hdc, COLORREF crColor, int cxClient, int cyClient, int sx, int sy)
{
HBRUSH hBrush ;
RECT rect ;
hBrush = CreateSolidBrush (crColor) ;
SetRect (&rect, sx, sy, cxClient, cyClient) ;
FillRect (hdc, &rect, hBrush) ;
DeleteObject (SelectObject (hdc, GetStockObject (WHITE_BRUSH))) ;
return;
}
/* This function is called by the Windows function DispatchMessage() */
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message) /* handle the messages */
{
case WM_DESTROY:
PostQuitMessage (0); /* send a WM_QUIT to the message queue */
break;
case WM_CREATE:
SetTimer (hwnd, ID_TIMER, 100, NULL) ;
break;
case WM_TIMER:
HDC hDC, hwnddc;
hDC = CreateDC(TEXT("DISPLAY"), NULL, NULL, NULL);
hwnddc = GetDC(hwnd);
POINT pt;
GetCursorPos(&pt);
for (int x = 0; x < 100; x++)
{
for (int y = 0; y < 100; y++)
{
PaintRoutine(hwnddc, GetPixel(hDC, pt.x + x, pt.y + y), 1, 1, 1 + x, 1 + y);
}
}
DeleteDC(hDC);
ReleaseDC(hwnd, hwnddc);
InvalidateRect(hwnd, NULL, false);
break;
default: /* for messages that we don't deal with */
return DefWindowProc (hwnd, message, wParam, lParam);
}
return 0;
}