How can I optimize this code

void inittexture(void)
{
    char* texture = new char[1024 * 1024 * 3];
    HDC hdc;
    hdc = GetDC(NULL);
    for (int y = 0; y < screenheight; y++)
        for (int x = 0; x < screenwidth; x++)
        {
            COLORREF c = GetPixel(hdc, x, y);
            texture[y * 1024 * 3 + x * 3] = GetRValue(c);
            texture[y * 1024 * 3 + x * 3 + 1] = GetGValue(c);
            texture[y * 1024 * 3 + x * 3 + 2] = GetBValue(c);
        }

    glEnable(GL_TEXTURE_2D);
    glGenTextures(1, &screentexture);
    glBindTexture(GL_TEXTURE_2D, screentexture);
    glTexImage2D(GL_TEXTURE_2D, 0, 3, 1024, 1024, 0, GL_RGB, GL_UNSIGNED_BYTE, texture);
    //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    //glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);



    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);


    delete[] texture;
}