C++怎么获取后台窗口内一点颜色值

您好，winuser.h头文件中有所有系统颜色的宏定义，不妨在这里找您要的颜色：

/*
* Color Types
*/
#define CTLCOLOR_MSGBOX 0
#define CTLCOLOR_EDIT 1
#define CTLCOLOR_LISTBOX 2
#define CTLCOLOR_BTN 3
#define CTLCOLOR_DLG 4
#define CTLCOLOR_SCROLLBAR 5
#define CTLCOLOR_STATIC 6
#define CTLCOLOR_MAX 7
#define COLOR_SCROLLBAR 0
#define COLOR_BACKGROUND 1
#define COLOR_ACTIVECAPTION 2
#define COLOR_INACTIVECAPTION 3
#define COLOR_MENU 4
#define COLOR_WINDOW 5
#define COLOR_WINDOWFRAME 6
#define COLOR_MENUTEXT 7
#define COLOR_WINDOWTEXT 8
#define COLOR_CAPTIONTEXT 9
#define COLOR_ACTIVEBORDER 10
#define COLOR_INACTIVEBORDER 11
#define COLOR_APPWORKSPACE 12
#define COLOR_HIGHLIGHT 13
#define COLOR_HIGHLIGHTTEXT 14
#define COLOR_BTNFACE 15
#define COLOR_BTNSHADOW 16
#define COLOR_GRAYTEXT 17
#define COLOR_BTNTEXT 18
#define COLOR_INACTIVECAPTIONTEXT 19
#define COLOR_BTNHIGHLIGHT 20
#if(WINVER >= 0x0400)
#define COLOR_3DDKSHADOW 21
#define COLOR_3DLIGHT 22
#define COLOR_INFOTEXT 23
#define COLOR_INFOBK 24
#endif /* WINVER >= 0x0400 */
#if(WINVER >= 0x0500)
#define COLOR_HOTLIGHT 26
#define COLOR_GRADIENTACTIVECAPTION 27
#define COLOR_GRADIENTINACTIVECAPTION 28
#endif /* WINVER >= 0x0500 */
#if(WINVER >= 0x0400)
#define COLOR_DESKTOP COLOR_BACKGROUND
#define COLOR_3DFACE COLOR_BTNFACE
#define COLOR_3DSHADOW COLOR_BTNSHADOW
#define COLOR_3DHIGHLIGHT COLOR_BTNHIGHLIGHT
#define COLOR_3DHILIGHT COLOR_BTNHIGHLIGHT
#define COLOR_BTNHILIGHT COLOR_BTNHIGHLIGHT
#endif /* WINVER >= 0x0400 */

调用DWORD GetSysColor(int nIndex);函数，可以返回颜色的RGB值。