诡异的问题，SetScrollInfo设置滚动条属性无效！！！

[凌乱哥]

我从CWnd派生出了一个图片列表类，自己处理滚动条。
现在新增了一个排序模式需求，切换排序方式后滚动条的相关属性需要改变。
但是发现调用SetScrollInfo设置后无效，因为再用GetScrollInfo发现属性还是原来的值，代码如下：

	SCROLLINFO info;
	ZeroMemory(&info, sizeof(SCROLLINFO));
	GetScrollInfo(SB_VERT, &info, SIF_ALL);//获取原来的属性值
	info.nMin = 0;
	info.nMax = iMaxPos + 15;
	info.nPage = m_cyPanel;
	info.nPos = 0;
	SetScrollInfo(SB_VERT, &info, TRUE);//设置新属性

调试截图如下，获取原来的属性值：


设置新属性：


再次GetScrollInfo：


为什么设置不成功呢？而且SetScrollInfo的返回值是1，GetLastError也为0，属性值就是设置不进去，帮忙看看可能是什么原因

[凌乱哥]

引用 1 楼 zgl7903 的回复:

留意下 fMask 参数 fMask Specifies the scroll bar parameters to set or retrieve. This member can be a combination of the following values: Value Meaning SIF_ALL Combination of SIF_PAGE, SIF_POS, SIF_RANGE, and SIF_TRACKPOS. SIF_DISABLENOSCROLL This value is used only when setting a scroll bar's parameters. If the scroll bar's new parameters make the scroll bar unnecessary, disable the scroll bar instead of removing it. SIF_PAGE The nPage member contains the page size for a proportional scroll bar. SIF_POS The nPos member contains the scroll box position, which is not updated while the user drags the scroll box. SIF_RANGE The nMin and nMax members contain the minimum and maximum values for the scrolling range. SIF_TRACKPOS The nTrackPos member contains the current position of the scroll box while the user is dragging it.

我把上面那段代码的SIF_ALL改成了SIF_RANGE | SIF_PAGE，并且把info.nPos = 0;这行去掉了，还是一样的问题。

[凌乱哥]

引用 1 楼 zgl7903 的回复:

留意下 fMask 参数 fMask Specifies the scroll bar parameters to set or retrieve. This member can be a combination of the following values: Value Meaning SIF_ALL Combination of SIF_PAGE, SIF_POS, SIF_RANGE, and SIF_TRACKPOS. SIF_DISABLENOSCROLL This value is used only when setting a scroll bar's parameters. If the scroll bar's new parameters make the scroll bar unnecessary, disable the scroll bar instead of removing it. SIF_PAGE The nPage member contains the page size for a proportional scroll bar. SIF_POS The nPos member contains the scroll box position, which is not updated while the user drags the scroll box. SIF_RANGE The nMin and nMax members contain the minimum and maximum values for the scrolling range. SIF_TRACKPOS The nTrackPos member contains the current position of the scroll box while the user is dragging it.

我发现只要设置nMax大于或等于nPage，就会有问题，否则就是正常的 但是要出现滚动条就必须把nMax大于nPage吧

[schlafenhamster]

“切换排序方式后滚动条的相关属性需要改变” 即选择项 可能 需要 滚动， CListCtrl::EnsureVisible BOOL EnsureVisible( int nItem, BOOL bPartialOK ); Return Value Nonzero if successful; otherwise zero. 与滚动条无关吧

[凌乱哥]

引用 4 楼 schlafenhamster 的回复:

“切换排序方式后滚动条的相关属性需要改变” 即选择项 可能 需要 滚动， CListCtrl::EnsureVisible BOOL EnsureVisible( int nItem, BOOL bPartialOK ); Return Value Nonzero if successful; otherwise zero. 与滚动条无关吧

我是从CWnd派生出了一个图片列表类的，自己处理滚动条 也就是说比如有10张图片，本来一开始每行6个，两行就显示完了。现在换了个排序方式，分组显示，每行才一两个，所以有很多行，滚动条也就从无到有，并且要能正常滚动。就出现了我这个问题

[schlafenhamster]

只有 GetDataItemHeight（） 才会引起 变化 ！！！

[zgl7903]

留意下 fMask 参数 fMask Specifies the scroll bar parameters to set or retrieve. This member can be a combination of the following values: Value Meaning SIF_ALL Combination of SIF_PAGE, SIF_POS, SIF_RANGE, and SIF_TRACKPOS. SIF_DISABLENOSCROLL This value is used only when setting a scroll bar's parameters. If the scroll bar's new parameters make the scroll bar unnecessary, disable the scroll bar instead of removing it. SIF_PAGE The nPage member contains the page size for a proportional scroll bar. SIF_POS The nPos member contains the scroll box position, which is not updated while the user drags the scroll box. SIF_RANGE The nMin and nMax members contain the minimum and maximum values for the scrolling range. SIF_TRACKPOS The nTrackPos member contains the current position of the scroll box while the user is dragging it.