Thread: help on pixels

For your purposes, you can use NULL or 0 as the first parameter to MessageBox in place of hwnd.

hah, oh yeah, gues i shoulda edited it a little more for general needs. if you want to see the hex value then you can use a statement kinda like this

Code:

sprintf(chPixColor,"R=%d G=%d B=%d hex=%p",GetRValue(pixColor),GetGValue(pixColor),GetBValue(pixColor),pixColor);

and from msdn:

The low-order byte contains a value for the relative intensity of red; the second byte contains a value for green; and the third byte contains a value for blue. The high-order byte must be zero. The maximum value for a single byte is 0xFF.

i had that problem once when i was trying to point at an hdc that was specified in another function, lets see your source and see where the problem is

ok, the problem is that you delete your dc then try to get a pixel from it. move the call down after you get the pixel and try that

also make sure that there is not white under point 600 400 or it will return 255 255 255 because that is white anyway.

alternately you could do something like this

Code:

#include <cstdio>
#include <windows.h> 
#include <string.h> 
#include <stdlib.h> 
#include <conio.h>
#pragma comment(lib, "gdi32.lib")

int main()
{
COLORREF pixColor;
HDC hdcScrn;
POINT pt;
char chPixColor[1024];
char chMouseLoc[1024];
GetCursorPos(&pt);
while(pt.x<1000)
{
 GetCursorPos(&pt);
 hdcScrn=CreateDC("DISPLAY",0,0,0);
 pixColor = GetPixel(hdcScrn,pt.x,pt.y);
 sprintf(chPixColor,"R=%d G=%d B=%d",GetRValue(pixColor),GetGValue(pixColor),GetBValue (pixColor));
 sprintf(chMouseLoc,"Pixel Color @ x=%d y=%d",pt.x,pt.y);
 MessageBox(NULL,chPixColor,chMouseLoc,0);
}
DeleteDC(hdcScrn);
return 0; 
}

that will get the mouse x and y and get the color and will do so as long as your mouse x is less than 1000. my resolution is set at 1280x1024 so my mouse x can go past 1000 but if yours is lower than that then you will have to stop the program using task manager so if you use this then be sure to change the size to fit your screen. also you can just use the spacebar to hit ok and move the mouse wherever.

glad to have been of assistance. I guess that is what these boards are for because I was once in your position in this area. and I still am in other areas.