在PreTranslateMessage函数中捕获 WM_MOUSEWHEEL消息，怎么判断滚轮的方向？

[windforce1210]

由于程序里加入了其他的消息相应类，所以对话框本身的OnMouseWheel函数，不响应鼠标滚轮了，只能用PreTranslateMessage函数里判断WM_MOUSEWHEEL消息来相应，但是在PreTranslateMessage里怎么判断滚轮的方向啊？求指导！！！

[m0_46195138]

@nicklisir 这个zDelta上下滚都是正值，没有负值的出现

[nicklisir]

short zDelta 正负 判断下据可以

[windforce1210]

在OnMouseWheel这个函数下，可以用short zDelta，可以在PreTranslateMessage这个函数下，没有这个参数传进来啊？？

[schlafenhamster]

zDelta The value of the high-order word of wParam. Indicates the distance that the wheel is rotated, expressed in multiples or divisions of WHEEL_DELTA, which is 120. A positive value indicates that the wheel was rotated forward, away from the user; a negative value indicates that the wheel was rotated backward, toward the user.

[schlafenhamster]

MSG Structure The MSG structure has the following form: typedef struct tagMSG { // msg HWND hwnd; UINT message; WPARAM wParam; LPARAM lParam; DWORD time; POINT pt; } MSG;

[windforce1210]

引用 4 楼 schlafenhamster 的回复:

MSG Structure The MSG structure has the following form: typedef struct tagMSG { // msg HWND hwnd; UINT message; WPARAM wParam; LPARAM lParam; DWORD time; POINT pt; } MSG;

你好！看了你给的说明，是wParam这个参数高位一个字的数据，但我看了wParam这个参数的内存，向上是是 00 00 78 00 00 00 00 00 向下是00 00 88 ff ff ff ff ff 请问这个怎么对应啊？

[schlafenhamster]

int zDelta=HIWORD(wParam);

[zgl7903]

WM_MOUSEWHEEL fwKeys = LOWORD(wParam); // key flags zDelta = (short) HIWORD(wParam); // wheel rotation xPos = (short) LOWORD(lParam); // horizontal position of pointer yPos = (short) HIWORD(lParam); // vertical position of pointer