Can images be read from an iPhone programatically

问题:

When an iPhone is connected to a Win7 computer, the images can be viewed using Explorer (and the open file dialog of my app). However, the file location does not contain a drive letter.

For example Computer\Apple iPhone\Internal Storage\DCIM\800AAAAA\IMG_0008.JPG instead of E:\DCIM\800AAAAA\IMG_0008.JPG which is common of sdcards, usb drives, etc...

I've tried using CreateFileW to read images from an iPhone but it fails with '(Error Code: 3) The system cannot find the path specified.' I've also tried accessing them with Chrome and it fails too.

Any suggestions?

回答1:

The folder is actually what is referred to as a 'Virtual Folder' and does not have a full path on the file system. You will need to use the shell item returned from the open dialog to get the content of the file rather than using CreateFile.

The data should be accessible, but you should follow the instructions from the MSDN documentation. I'm sure there are probably better examples (as this only gives guidelines).

edit the rough process is to get the IShellItem from IFileOpenDialog, then to bind to the stream and then read the stream (assuming reading only) - bear in mind that this code is pretty much without error handling or checking or safety:

if (pitem->GetDisplayName(SIGDN_NORMALDISPLAY, &destName) == S_OK) {
    std::cout << destName << std::endl;
    CoTaskMemFree(destName);
}
IStream *pistream;
if (pitem->BindToHandler(0, BHID_Stream, IID_PPV_ARGS(&pistream)) == S_OK) {
    char input[1024];
    long to_read = 1024;
    unsigned long read;
    while (S_OK == pistream->Read(input, to_read, &read)) {
       std::cout << input << std::endl;
    }
    pistream->Release();
}
pitem->Release();

回答2:

Most often such a device is inserted in the Windows Explorer as a Shell Namespace Extension and not like an USB stick with drive letter. Most of the normal file commands like CopyFile(..), FindFirst() or GetFileInfo(..) can not be used directly in such a Shell Namespace extension. Only the CopyHere(..) is working. I needed long time to figure out how to enumerate the files on a digicam and now also on an Android device with an vb.net program and to copy my pictures to my Windows PC:

Public Const MyComputer As Integer = &H11&

Sub EnumMyComputer()
  Dim oItem As Object
  Dim res As Integer

  For Each oItem In DirectCast(CreateObject("Shell.Application").Namespace(MyComputer).Items, System.Collections.IEnumerable)
    Debug.Print(oItem.Type.ToString)
    if oItem.Type.ToString="Tragbares Medienwiedergabegerät" then '<- check, adopt!
      res = EnumNamespaceItems(oItem, "", oItem.Name.ToString, 0)
    End If
  Next oItem
End Sub

Function EnumNamespaceItems(oItem As Object, SrcCPath As String, SrcDPath As String, folderLevel As Integer) As Integer
  Dim y As Object
  Dim tempFullFileName As String

  Debug.Print(StrDup(folderLevel, "  ") & "\" & oItem.Name.ToString & "  (" & oItem.Path.ToString & ")")
  For Each y In DirectCast(oItem.GetFolder.items, System.Collections.IEnumerable)
    'Debug.Print(StrDup(folderLevel, "  ") & SrcDPath & y.Name.ToString)
    If y.IsFolder = True Then
      Dim n1 As Integer
      n1 = EnumNamespaceItems(y, SrcCPath & y.Path.ToString & "\", SrcDPath & y.Name.ToString & "\", 1 + folderLevel)
      If n1 < 0 Then 'failure: Cancel
        EnumNamespaceItems = n1
        Exit Function
      End If
    Else 'it's a file:
      Debug.Print(StrDup(folderLevel, "  ") & " " & y.Name.ToString)
      tempFullFileName = System.IO.Path.GetTempPath() & y.Name.ToString
      ' CopyFile is not possible here if SrcCPath is like "::{…}…":
      ' My.Computer.FileSystem.CopyFile(SrcCPath & y.Name.ToString , fFile.FullName)
      Dim suc As Integer = CopyHereFileWait(y, My.Computer.FileSystem.SpecialDirectories.Temp)
      If suc >= 0 Then 'now we can do things like this:
        Dim MyFileInfo As System.IO.FileInfo = My.Computer.FileSystem.GetFileInfo(tempFullFileName)
        Dim fileDate As Date = MyFileInfo.LastWriteTime
      End If 'suc
    End If 'else y.IsFolder
  Next y
  EnumNamespaceItems = 0
End Function


Function CopyHereFileWait(sourceNamespaceObject As Object, targetFolder As String) As Integer
  Dim fsMyStream As System.IO.FileStream
  Dim n1 As Integer
  Dim taregetFullFileName As String

  n1 = Len(targetFolder)
  If Mid(targetFolder, n1, 1) = "\" Then
    targetFolder = Microsoft.VisualBasic.Left(targetFolder, n1 - 1)
  End If
  taregetFullFileName = targetFolder & "\" & sourceNamespaceObject.Name.ToString
  Dim oNsTargetFolder As Object
  oNsTargetFolder = CreateObject("Shell.Application").Namespace(CStr(targetFolder))
  oNsTargetFolder.copyHere(sourceNamespaceObject)
  'returns immediately and is doing the work in the background
  n1 = 0
  Do
    Threading.Thread.Sleep(50) 'ms
    Try
      fsMyStream = System.IO.File.Open(taregetFullFileName, IO.FileMode.Open, IO.FileAccess.ReadWrite)
      fsMyStream.Close()
      CopyHereFileWait = n1
      Exit Function
    Catch ex As Exception
      Debug.Print(ex.Message)
    End Try
    n1 = n1 + 1
  Loop While n1 < 400 'timeout 400*50ms = 20s
  CopyHereFileWait = -n1
End Function

You may add to check for folders with y.Name.ToString="DCIM" (on folderLevel=1) and for files with ".jpg".