Capturing bitmap fast eating RAM - c++

Question

This code is eating up my RAM at 1 to 2 percent a second (6 GB total).
Could anyone tell me what's wrong? Thanks in advance. I'm new to this, so if I sound like a complete idiot, I am. I'd like an answer fast.
#include <windows.h>
#include <iostream>
#include <stdio.h>
using namespace std;
/* Globals */
int ScreenX = 0;
int ScreenY = 0;
BYTE* ScreenData = 0;
void ScreenCap()
{
HDC hScreen = GetDC(GetDesktopWindow());
//hScreen2 = hScreen;
if (ScreenX == 0)
{
ScreenX = GetDeviceCaps(hScreen, HORZRES);
ScreenY = GetDeviceCaps(hScreen, VERTRES);
}
HDC hdcMem = CreateCompatibleDC (hScreen);
HBITMAP hBitmap = CreateCompatibleBitmap(hScreen, ScreenX, ScreenY);
HGDIOBJ hOld = SelectObject(hdcMem, hBitmap);
BitBlt(hdcMem, 0, 0, ScreenX, ScreenY, hScreen, 0, 0, SRCCOPY);
SelectObject(hdcMem, hOld);
BITMAPINFOHEADER bmi = {0};
bmi.biSize = sizeof(BITMAPINFOHEADER);
bmi.biPlanes = 1;
bmi.biBitCount = 32;
bmi.biWidth = ScreenX;
bmi.biHeight = -ScreenY;
bmi.biCompression = BI_RGB;
bmi.biSizeImage = 0;// 3 * ScreenX * ScreenY;
if(ScreenData)
free(ScreenData);
ScreenData = (BYTE*)malloc(4 * ScreenX * ScreenY);
GetDIBits(hdcMem, hBitmap, 0, ScreenY, ScreenData, (BITMAPINFO*)&bmi, DIB_RGB_COLORS);
ReleaseDC(GetDesktopWindow(),hScreen);
DeleteDC(hdcMem);
}
inline int PosB(int x, int y)
{
return ScreenData[4*((y*ScreenX)+x)];
}
inline int PosG(int x, int y)
{
return ScreenData[4*((y*ScreenX)+x)+1];
}
inline int PosR(int x, int y)
{
return ScreenData[4*((y*ScreenX)+x)+2];
}
bool ButtonPress(int Key)
{
bool button_pressed = false;
while(GetAsyncKeyState(Key))
button_pressed = true;
return button_pressed;
}
int main()
{
while (true)
{
ScreenCap();
/*for (int x = 1; x < ScreenX; x++)
{
for (int y = 1; y < ScreenY; y++)
{
int Red = PosR(x, y);
int Green = PosG(x, y);
int Blue = PosB(x, y);
if (Red == 22 && Green == 58 && Blue == 89)
{
cout << ">:D";
POINT pos;
GetCursorPos(&pos);
int DX = 683 - x;
int DY = 683 - y;
/*COLORREF col = GetPixel(hScreen2, DX - pos.x + 1, pos.y - DY + 1);
int red = GetRValue(col);
int blue = GetBValue(col);
int green = GetGValue(col);
if (red == 22 && green == 58 && blue == 89)
{
break;
}
//SetCursorPos(x + DX, y + DY);
SetCursorPos(DX - pos.x + 1, pos.y - DY + 1);
cout << DX - pos.x << ", " << pos.y - DY + 1 << endl;
break;
}
}
}*/
}
system("PAUSE");
return 0;
}

Answer 1

You keep creating new bitmaps and never delete them.
Even better than freeing them each time would be to reuse the previous bitmap unless the screen size actually changed. Ditto for ScreenData. Reallocating unnecessarily is a performance killer.
You also aren't selecting the original object back in before destroying the DC, which is a problem.