尝试使用LoadImage加载应用程序的图标，但该函数返回0

问题描述

我正在尝试使用 LoadImage WinAPI函数加载应用程序的图标，但由于某种原因它总是返回0.。

I am trying to load an application's icon(s) using the LoadImage WinAPI function, but for some reason it always returns 0.

我已阅读，但我无法理解我做错了什么。除了尝试将 IconPtr 转换为 Icon （因为 IconPtr）时，我没有例外为0）。

I have read the documentation, but I cannot understand what I've done wrong. I get no exceptions except for when trying to convert IconPtr to Icon (which is becasue IconPtr is 0).

Public Shared Function ExtractAssociatedIconArray(ByVal File As String, ByVal Sizes() As Size) As Icon()
    Dim ReturnArray(Sizes.Length) As Icon
    Dim Index As Integer = 0

    For Each s As Size In Sizes
        'IconPtr is always zero for some reason.
        Dim IconPtr As IntPtr = NativeMethods.LoadImage(Nothing, File, NativeMethods.Enumrations.IMAGE_ICON, s.Width, s.Height, NativeMethods.Enumrations.LR_DEFAULTCOLOR Or NativeMethods.Enumrations.LR_LOADFROMFILE)
        ReturnArray(Index) = Icon.FromHandle(IconPtr)
        Index += 1
    Next

    Return ReturnArray
End Function

NativeMethods 类：

Public Class NativeMethods
    <DllImport("user32.dll", SetLastError:=True)> _
    Public Shared Function LoadImage(ByVal hInst As IntPtr, _
                     ByVal lpszName As String,
                     ByVal uType As UInt32, _
                     ByVal cxDesired As Integer, _
                     ByVal cyDesired As Integer, _
                     ByVal fuLoad As UInt32) As IntPtr
    End Function

    Public Enum Enumrations As UInteger
        '' LoadImage ''
        IMAGE_BITMAP = 0
        IMAGE_ICON = 1
        IMAGE_CURSOR = 2
        LR_CREATEDIBSECTION = &H2000
        LR_DEFAULTCOLOR = &H0
        LR_DEFAULTSIZE = &H40
        LR_LOADFROMFILE = &H10
        LR_LOADMAP3DCOLORS = &H1000
        LR_LOADTRANSPARENT = &H20
        LR_MONOCHROME = &H1
        LR_SHARED = &H8000
        LR_VGACOLOR = &H80
    End Enum
End Class

用法示例：

Dim Icons() As Icon = ExtractAssociatedIconArray("C:\MyApp.exe", New Size() {New Size() {48, 48}})

推荐答案

感谢您的帮助和建议。

我设法通过使用 ExtractIconEx 函数解决了我自己的问题。

I managed to solve my own problem by using the ExtractIconEx function instead.

Public Shared Function ExtractAssociatedIcons(ByVal File As String) As AssemblyIconCollection
    Dim IconCount As Integer = NativeMethods.ExtractIconEx(File, -1, Nothing, Nothing, 0)
    Dim AssemblyIcons As New AssemblyIconCollection

    'The 'Icon handle' arrays.
    Dim LargeIcons(IconCount) As IntPtr
    Dim SmallIcons(IconCount) As IntPtr

    'Extract icons into the two arrays of handles.
    NativeMethods.ExtractIconEx(File, 0, LargeIcons, SmallIcons, IconCount)

    'Add each large icon to the "LargeIcons" list.
    For Each ptr As IntPtr In LargeIcons
        If ptr = IntPtr.Zero Then Continue For

        Dim Ico As Icon = Icon.FromHandle(ptr)
        If Ico.Width < 25 Or Ico.Height < 25 Then Continue For
        AssemblyIcons.LargeIcons.Add(Ico)
    Next

    'Add each small icon to the "SmallIcons" list.
    For Each ptr As IntPtr In SmallIcons
        If ptr = IntPtr.Zero Then Continue For

        Dim Ico As Icon = Icon.FromHandle(ptr)
        If Ico.Width > 24 Or Ico.Height > 24 Then Continue For
        AssemblyIcons.SmallIcons.Add(Ico)
    Next

    'Return the output class.
    Return AssemblyIcons
End Function

我的 AssemblyIconCollection class：

Public NotInheritable Class AssemblyIconCollection
    ''' <summary>
    ''' Gets or sets the large icons found in the assembly.
    ''' </summary>
    ''' <remarks></remarks>
    Public Property LargeIcons As List(Of Icon)

    ''' <summary>
    ''' Gets or sets the small icons found in the assembly.
    ''' </summary>
    ''' <remarks></remarks>
    Public Property SmallIcons As List(Of Icon)

    Public Sub New()
        Me.LargeIcons = New List(Of Icon)
        Me.SmallIcons = New List(Of Icon)
    End Sub
End Class

ExtractIconEx 声明：

Public Class NativeMethods
    <DllImport("shell32.dll", CharSet:=CharSet.Auto)> _
    Public Shared Function ExtractIconEx(ByVal szFileName As String, _
         ByVal nIconIndex As Integer, _
         ByVal phiconLarge() As IntPtr, _
         ByVal phiconSmall() As IntPtr, _
         ByVal nIcons As UInteger) As UInteger
    End Function
End Class

用法：

Dim Icons As AssemblyIconCollection = ExtractAssociatedIcons("C:\myfile.exe")

'Iterating every large icon.
For Each LargeIcon As Icon In Icons.LargeIcons
    'Do stuff.
Next

'Iterating every small icon.
For Each SmallIcon As Icon In Icons.SmallIcons
    'Do stuff.
Next

这篇关于尝试使用LoadImage加载应用程序的图标，但该函数返回0的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！