Reduce file size for charts pasted from excel into word

Question

I have been creating reports by copying some charts and data from an excel document into a word document. I am pasting into a content control, so i use ChartObject.CopyPicture in excel and ContentControl.Range.Paste in word. This is done in a loop:

Set ws = ThisWorkbook.Worksheets("Charts")
With ws
For Each cc In wordDocument.ContentControls

    If cc.Range.InlineShapes.Count > 0 Then
        scaleHeight = cc.Range.InlineShapes(1).scaleHeight
        scaleWidth = cc.Range.InlineShapes(1).scaleWidth
        cc.Range.InlineShapes(1).Delete
        .ChartObjects(cc.Tag).CopyPicture Appearance:=xlScreen, Format:=xlPicture
        cc.Range.Paste
        cc.Range.InlineShapes(1).scaleHeight = scaleHeight
        cc.Range.InlineShapes(1).scaleWidth = scaleWidth
    ElseIf ...
Next cc
End With

Creating these reports using Office 2007 yielded files that were around 6MB, but creating them (using the same worksheet and document) in Office 2010 yields a file that is around 10 times as large.

After unzipping the docx, I found that the extra size comes from emf files that correspond to charts that are pasted in using VBA. Where they range from 360 to 900 KB before, they are 5-18 MB. And the graphics are not visibly better.

Even further, it seems to be related to the Chart Style. I created a new spreadsheet and inserted 7 data points and a corresponding 2D pie chart. With the default style, it copied as a 79 KB emf, and with style 26 it copies as a 10 MB emf. When I was using Office 2007, the chart would copy as a 700 KB emf. This is the code:

Sub CopyAndPaste()
    ThisWorkbook.Worksheets("Charts").ChartObjects("Chart 1").CopyPicture Appearance:=xlScreen, Format:=xlPicture
    GetObject(, Class:="Word.Application").ActiveDocument.Range.Paste
End Sub

I am able to CopyPicture with the format xlBitmap, and while that is somewhat smaller, it is larger than the emf generated by Office 2007 and noticeably poorer quality. Are there any other options for reducing the file size? Ideally, I would like to produce a file with the same resolution for the charts as I did using Office 2007. Is there any way that uses VBA only (without modifying the charts in the spreadsheet)? Any way I can easily copy as an object without linking the documents?

Answer 1

"It's an older code, sir, but it checks out."

It's an old question and I have an even older (possible) solution: you can compress your .EMF files as .EMZ by gzipping it. This will reduce your file size while keeping the image quality.

On VB6 I used zlib.dll and the code below. I renamed the function names to english but I kept all comments in portuguese:

Option Explicit

' Declaração das interfaces com a ZLIB
Private Declare Function gzopen     Lib "zlib.dll" (ByVal file As String, ByVal mode As String) As Long
Private Declare Function gzwrite    Lib "zlib.dll" (ByVal file As Long, ByRef uncompr As Byte, ByVal uncomprLen As Long) As Long
Private Declare Function gzclose    Lib "zlib.dll" (ByVal file As Long) As Long
Private Declare Function Compress   Lib "zlib.dll" Alias "compress" (ByRef dest As Any, ByRef destLen As Any, ByRef src As Any, ByVal srcLen As Long) As Long
Private Declare Function Uncompress Lib "zlib.dll" Alias "uncompress" (ByRef dest As Any, ByRef destLen As Any, ByRef src As Any, ByVal srcLen As Long) As Long

' Ler o conteúdo de um arquivo
Public Function FileRead(ByVal strNomeArquivo As String) As Byte()

    Dim intHandle     As Integer
    Dim lngTamanho    As Long
    Dim bytConteudo() As Byte

    On Error GoTo FileReadError

    ' Abrir o documento indicado
    intHandle = FreeFile
    Open strNomeArquivo For Binary Access Read As intHandle

    ' Obter o tamanho do arquivo
    lngTamanho = LOF(intHandle)
    ReDim bytConteudo(lngTamanho)

    ' Obter o conteúdo e liberar o arquivo
    Get intHandle, , bytConteudo()
    Close intHandle

    FileRead = bytConteudo

    On Error GoTo 0
    Exit Function

FileReadError:

    objLogger.GravarEvento "modZLib.FileRead: " & Err.Description & " (" & Err.Number & " - " & Err.Source & ")", logTipoEvento.Erro

End Function

'Compactar um arquivo com o padrão gzip
Public Sub FileCompress(ByVal strArquivoOrigem As String, ByVal strArquivoDestino As String)

    Dim gzFile        As Long
    Dim bytConteudo() As Byte

    On Error GoTo FileCompressError

    ' Ler o conteúdo do arquivo
    bytConteudo = FileRead(strArquivoOrigem)

    ' Compactar o conteúdo
    gzFile = gzopen(strArquivoDestino, "wb")
    gzwrite gzFile, bytConteudo(0), UBound(bytConteudo)
    gzclose gzFile

    On Error GoTo 0
    Exit Sub

FileCompressError:

    objLogger.GravarEvento "modZLib.FileCompress:" & Err.Description & " (" & Err.Number & " - " & Err.Source & ")", logTipoEvento.Erro

End Sub