X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/f172cb8200f08ba1c6735a0d507991c877c0d68f..53c43278a9d71e15f43cbe359abea50d3775d8ad:/src/msw/printwin.cpp

diff --git a/src/msw/printwin.cpp b/src/msw/printwin.cpp
index 2ccf24961c..587a4749fc 100644
--- a/src/msw/printwin.cpp
+++ b/src/msw/printwin.cpp
@@ -39,12 +39,17 @@
     #include "wx/intl.h"
     #include "wx/log.h"
     #include "wx/dcprint.h"
+    #include "wx/dcmemory.h"
+    #include "wx/image.h"
 #endif
 
+#include "wx/msw/dib.h"
+#include "wx/msw/dcmemory.h"
 #include "wx/msw/printwin.h"
 #include "wx/msw/printdlg.h"
 #include "wx/msw/private.h"
 #include "wx/msw/dcprint.h"
+#include "wx/msw/enhmeta.h"
 
 #include <stdlib.h>
 
@@ -282,7 +287,7 @@ bool wxWindowsPrinter::Print(wxWindow *parent, wxPrintout *printout, bool prompt
 
 wxDC *wxWindowsPrinter::PrintDialog(wxWindow *parent)
 {
-    wxDC *dc = (wxPrinterDC*) NULL;
+    wxDC *dc = NULL;
 
     wxWindowsPrintDialog dialog(parent, & m_printDialogData);
     int ret = dialog.ShowModal();
@@ -419,6 +424,53 @@ void wxWindowsPrintPreview::DetermineScaling()
     m_previewScaleY = float(logPPIScreenY) / logPPIPrinterY;
 }
 
+bool wxWindowsPrintPreview::RenderPageIntoBitmap(wxBitmap& bmp, int pageNum)
+{
+    // The preview, as implemented in wxPrintPreviewBase (and as used prior to
+    // wx3) is inexact: it uses screen DC, which has much lower resolution and
+    // has other properties different from printer DC, so the preview is not
+    // quite right.
+    //
+    // To make matters worse, if the application depends heavily on
+    // GetTextExtent() or does text layout itself, the output in preview and on
+    // paper can be very different. In particular, wxHtmlEasyPrinting is
+    // affected and the preview can be easily off by several pages.
+    //
+    // To fix this, we render the preview into high-resolution enhanced
+    // metafile with properties identical to the printer DC. This guarantees
+    // metrics correctness while still being fast.
+
+
+    // print the preview into a metafile:
+    wxPrinterDC printerDC(m_printDialogData.GetPrintData());
+    wxEnhMetaFileDC metaDC(printerDC,
+                           wxEmptyString,
+                           printerDC.GetSize().x, printerDC.GetSize().y);
+
+    if ( !RenderPageIntoDC(metaDC, pageNum) )
+        return false;
+
+    wxEnhMetaFile *metafile = metaDC.Close();
+    if ( !metafile )
+        return false;
+
+    // now render the metafile:
+    wxMemoryDC bmpDC;
+    bmpDC.SelectObject(bmp);
+    bmpDC.Clear();
+
+    wxRect outRect(0, 0, bmp.GetWidth(), bmp.GetHeight());
+    metafile->Play(&bmpDC, &outRect);
+
+
+    delete metafile;
+
+    // TODO: we should keep the metafile and reuse it when changing zoom level
+
+    return true;
+}
+
+
 /****************************************************************************
 
   FUNCTION: wxAbortProc()