windows 64 位的 LVITEM

LVITEM for windows 64 bit

很长一段时间我都尝试使用带有LVIF_TEXT掩码的LVM_GETITEMW消息来获取ListView的文本。我的程序在 32 位架构下运行,但在 64 位架构下运行失败。

我发现问题出在 LVITEM 结构上。很快,我的问题是哪种结构适合 64 位以及为什么。

我用作 LVITEMW 结构的结构具有以下字段:

('mask', c_uint32),
('iItem', c_int32),
('iSubItem', c_int32),
('state', c_uint32),
('stateMask', c_uint32),
('pszText', c_uint32),
('cchTextMax', c_int32),
('iImage', c_int32),
('lParam', c_uint64),
('iIndent', c_int32),
('iGroupId', c_int32),
('cColumns', c_uint32),
('puColumns', c_uint32),
('piColFmt', c_int32),
('iGroup', c_int32)

(用python 2.7 ctypes写的,但这只是一种写法-语言真的无关紧要)。

这些字段与 documented.

经过大量谷歌搜索后,我发现这个 forum 正是我所需要的 - 64 位解决方案!

所以在 64 位中,结构应该有更多 "spaces",并且应该看起来像这样(指针现在是 64 位的,stateMask 也是 64 位的。这有点不同根据论坛的建议但也有效):

('mask', c_uint32),
('iItem', c_int32),
('iSubItem', c_int32),
('state', c_uint32),
('stateMask', c_uint64), <-- Now 64 bit
('pszText', c_uint64), <-- Now 64 bit which makes sense since this is a pointer
('cchTextMax', c_int32),
('iImage', c_int32),
('lParam', c_uint64),
('iIndent', c_int32),
('iGroupId', c_int32),
('cColumns', c_uint32),
('puColumns', c_uint64), <-- Now 64 bit which makes sense since this is a pointer
('piColFmt', c_int64), <-- Now 64 bit which makes sense since this is a pointer
('iGroup', c_int32)

论坛建议有:

('mask', c_uint32),
('iItem', c_int32),
('iSubItem', c_int32),
('state', c_uint32),
('stateMask', c_uint64),
('pszText', c_uint64),
('cchTextMax', c_int32),
('iImage', c_int64), <-- Now 64 bit
('lParam', c_uint32),
('iIndent', c_int32),
('iGroupId', c_int32),
('cColumns', c_uint32),
('puColumns', c_uint32),
('piColFmt', c_int32),
('iGroup', c_int64), <-- Now 128 bit all together
('iGroup2', c_int64) <-- continuation

这也有效,在我需要的列表中,这是 pszText 指向的文本。

我的问题是:

  1. 这有任何记录吗?
  2. 为什么 stateMask 应该是 c_uint64 - 它不应该总是和 state 一样大吗?
  3. 哪个是真正的 64 位结构?

谢谢!

感谢 Raymond Chen 的评论,我才找到答案!

大约 data alignment。每个指针都应该是8个字节,并且还应该对齐到一个可以被8整除的地址,所以有时候指针前应该有一个padding。此外,结构的大小应该可以被 min(max(sizeof(each field in the struct)), 8) 整除,在我们的例子中是 8,因为指针的大小是 8.

class LVITEMW_explicit(ctypes.Structure):
    _pack_ = 1
    _fields_ = [
        ('mask', c_uint32),         # 0
        ('iItem', c_int32),         # 4
        ('iSubItem', c_int32),      # 8
        ('state', c_uint32),        # 12
        ('stateMask', c_uint32),    # 16
        ('padding1', c_int),
        ('pszText', c_uint64),      # 20 --> 24 after padding (A pointer)
        ('cchTextMax', c_int32),    # 32
        ('iImage', c_int32),        # 36
        ('lParam', c_uint64),       # 40 (On 32 bit should be c_long which is 32 bits)
        ('iIndent', c_int32),       # 48
        ('iGroupId', c_int32),      # 52
        ('cColumns', c_uint32),     # 56
        ('padding2', c_int),
        ('puColumns', c_uint64),    # 60 --> 64 after padding (A pointer)
        ('piColFmt', c_int64),      # 72 (A pointer)
        ('iGroup', c_int32),        # 80
        ('padding3', c_int32),      # The total length was 84 before padding3 was added, which is not dividable by 8
    ]

或者这真的应该写成 - 没有 _pack_ = 1:

class LVITEMW(ctypes.Structure):
    _fields_ = [
        ('mask', c_uint32),
        ('iItem', c_int32),
        ('iSubItem', c_int32),
        ('state', c_uint32),
        ('stateMask', c_uint32),
        ('pszText', c_uint64),
        ('cchTextMax', c_int32),
        ('iImage', c_int32),
        ('lParam', c_uint64), # On 32 bit should be c_long
        ('iIndent', c_int32),
        ('iGroupId', c_int32),
        ('cColumns', c_uint32),
        ('puColumns', c_uint64),
        ('piColFmt', c_int64),
        ('iGroup', c_int32),
    ]

确实ctypes.sizeof(LVITEMW) returns 88,与ctypes.sizeof(LVITEMW_explicit)相同。

再次感谢您的宝贵意见!