sc tiled rendering: Set some minimal size of the document.

Let's default to 12x36 cells.

Change-Id: Ic39739ec036a6e5867d31b7e05b6da12ce2e46d2
Reviewed-on: https://gerrit.libreoffice.org/16413Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>

sc/inc/document.hxx

@@ -1157,6 +1157,9 @@ public:
                                         SCROW& rEndRow, bool bNotes = true ) const;
     void            InvalidateTableArea();
 
+    /// Return the number of colums / rows that should be visible for the tiled rendering.
+    SC_DLLPUBLIC bool           GetTiledRenderingArea(SCTAB nTab, SCCOL& rEndCol, SCROW& rEndRow) const;
+
     SC_DLLPUBLIC bool           GetDataStart( SCTAB nTab, SCCOL& rStartCol, SCROW& rStartRow ) const;
 
     /**

sc/source/core/data/documen2.cxx

@@ -706,6 +706,21 @@ bool ScDocument::GetDataStart( SCTAB nTab, SCCOL& rStartCol, SCROW& rStartRow )
     return false;
 }
 
+bool ScDocument::GetTiledRenderingArea(SCTAB nTab, SCCOL& rEndCol, SCROW& rEndRow) const
+{
+    if (!GetPrintArea(nTab, rEndCol, rEndRow, false))
+        return false;
+
+    // we need some reasonable minimal document size
+    if (rEndCol < 12)
+        rEndCol = 12;
+
+    if (rEndRow < 36)
+        rEndRow = 36;
+
+    return true;
+}
+
 bool ScDocument::MoveTab( SCTAB nOldPos, SCTAB nNewPos, ScProgress* pProgress )
 {
     if (nOldPos == nNewPos)

sc/source/ui/unoobj/docuno.cxx

@@ -523,7 +523,7 @@ Size ScModelObj::getDocumentSize()
     SCROW nEndRow = 0;
     const ScDocument& rDoc = pDocShell->GetDocument();
 
-    if (!rDoc.GetPrintArea( nTab, nEndCol, nEndRow, false ))
+    if (!rDoc.GetTiledRenderingArea(nTab, nEndCol, nEndRow))
         return aSize;
 
     // convert to twips

sc/source/ui/view/gridwin4.cxx

@@ -971,7 +971,7 @@ void ScGridWindow::PaintTile( VirtualDevice& rDevice,
     SCROW nStartRow = 0, nEndRow = 0;
 
     // size of the document including drawings, charts, etc.
-    pDoc->GetPrintArea(nTab, nEndCol, nEndRow, false);
+    pDoc->GetTiledRenderingArea(nTab, nEndCol, nEndRow);
 
     double fPPTX = pViewData->GetPPTX();
     double fPPTY = pViewData->GetPPTY();