Question

我在详细信息模式下有一个VB6列表视图，显示了X个项目。我想创建某种自动高度函数，根据指定的宽度和项目数来评估高度。

以下代码无效：

Public Declare Function MessageSend Lib "user32" Alias "SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long

Public Const LVM_FIRST As Long = &H1000
Public Const LVM_APPROXIMATEVIEWRECT    As Long = (LVM_FIRST + 64)

Public Sub GetAutoWidth(lvw as ListView)
    result = MakeLPAram(-1, 0)
    MessageSend lvw.hWnd, LVM_APPROXIMATEVIEWRECT, -1&, result
    lvw.height = loWord(result) * Screen.TwipsPerPixelX
End Sub

Public Function LoWord(value As Long) As Long
    LoWord = (value And &HFFFF&)
End Function

Public Function MakeLPAram(wLow As Long, wHigh As Long) As Long
    MakeLPAram = MakeLong(wLow, wHigh)
End Function

Public Function MakeLong(wLow As Long, wHigh As Long) As Long
    MakeLong = LoWord(wLow) Or (&H10000 * LoWord(wHigh))
End Function

任何人都可以帮我吗？

Answer 1

首先，您不在此处保存LVM_APPROXIMATEVIEWRECT消息的返回值：

MessageSend lvw.hWnd, LVM_APPROXIMATEVIEWRECT, -1&, result

您应该，因为返回值正是您首先发送消息的原因：

返回值

返回一个保存近似宽度的DWORD值（在LOWORD中）   和显示项目所需的高度（在HIWORD中），以像素为单位。

其次，您的命名（GetAutoWidth），问题标题（“计算ListView高度”）和您的代码（lvw.height = loWord(result) * Screen.TwipsPerPixelX）非常不一致。

第三，阅读以下MSDN文章，因为您打包/解包单词和双字的代码也存在缺陷：

How to Mimic HIWORD, LOWORD, HIBYTE, LOBYTE C Macros in VB

How To Package HiWord/LoWord Values Into a Long Parameter

WinApi：计算ListView高度

1 个答案: