How can I resize a NSD_SetImageOLE image

I'm using the plugin macro NSD_SetImageOLE from http://nsis.sourceforge.net/NsDialogs_SetImageOLE - And I would like add another macro NSD_SetStretchedImageOLE the same way nsDialog.nsh works.

But I'm not sure is it's even possible, I've found that the resizing of an IPicture can be done by getting the "HBITMAP, BITMAP and BITMAPINFO" and resizing it (quoted from http://www.mofeel.net/958-microsoft-public-vc-mfc/12516.aspx). Anyway, I'm kind of lost trying to covert these methods to NSIS's System::Call style.

Solution

!ifndef IID_IPicture
    !define IID_IPicture {7BF80980-BF32-101A-8BBB-00AA00300CAB}
!endif
!define SRCCOPY 0xCC0020
!include nsDialogs.nsh

!define IMAGEPATH "$sysdir\migwiz\PostMigRes\Web\base_images\Documents.gif" ;"C:\Windows\Web\Wallpaper\Windows\img0.jpg"
!define NEWSIZEW 200
!define NEWSIZEH 100

Page Custom mypagestretchcreate_GDI ; GDI resize
Page Custom mypagestretchcreate_CTL ; Simple control resize


Function mypagestretchcreate_GDI
nsDialogs::Create 1018
Pop $0
System::Call 'oleaut32::OleLoadPicturePath(w "${IMAGEPATH}",i0r2,i0,i0,g"${IID_IPicture}",*i.r9)i.r1'
${If} $1 = 0
    System::Call 'user32::GetDC(i0)i.s'
    System::Call 'gdi32::CreateCompatibleDC(iss)i.r1'
    System::Call 'gdi32::CreateCompatibleBitmap(iss,i${NEWSIZEW},i${NEWSIZEH})i.r2'
    System::Call 'user32::ReleaseDC(i0,is)'
    System::Call $9->3(*i.r3)i.r4 ; IPicture->get_Handle
    ${If} $4 = 0
        System::Call 'gdi32::SetStretchBltMode(ir1,i4)'
        System::Call '*(&i40,&i1024)i.r4' ; BITMAP / BITMAPINFO
        System::Call 'gdi32::GetObject(ir3,i24,ir4)'
        System::Call 'gdi32::SelectObject(ir1,ir2)i.s'
        System::Call '*$4(i40,i.r6,i.r7,i0,i,i.s)' ; Grab size and bits-ptr AND init as BITMAPINFOHEADER
        System::Call 'gdi32::GetDIBits(ir1,ir3,i0,i0,i0,ir4,i0)' ; init BITMAPINFOHEADER
        System::Call 'gdi32::GetDIBits(ir1,ir3,i0,i0,i0,ir4,i0)' ; init BITMAPINFO
        System::Call 'gdi32::StretchDIBits(ir1,i0,i0,i${NEWSIZEW},i${NEWSIZEH},i0,i0,ir6,ir7,is,ir4,i0,i${SRCCOPY})'
        System::Call 'gdi32::SelectObject(ir1,is)'
        System::Free $4
    ${EndIf}
    System::Call 'gdi32::DeleteDC(ir1)'
    System::Call $9->2() ; IPicture->release()
${EndIf}
${NSD_CreateBitmap} 1u 1u ${NEWSIZEW} ${NEWSIZEH} ""
Pop $9
;Not required when the control size matches: ${NSD_AddStyle} $9 ${SS_CENTERIMAGE}
SendMessage $9 ${STM_SETIMAGE} ${IMAGE_BITMAP} $2
nsDialogs::Show
System::Call 'gdi32::DeleteObject(ir2)'
FunctionEnd

Function mypagestretchcreate_CTL
nsDialogs::Create 1018
Pop $2
${NSD_CreateBitmap} 0 1u 70% 50% ""
Pop $3
${NSD_AddStyle} $3 ${SS_REALSIZECONTROL}
File "/oname=$PLUGINSDIR\image.bmp" "${NSISDIR}\Contrib\Graphics\Header\win.bmp"
${NSD_SetImage} $3 "$PLUGINSDIR\image.bmp" $1
nsDialogs::Show
${NSD_FreeImage} $1
FunctionEnd