rhbz#876742 speed up table manipulation in Impress

It turns out this is not actually a performance problem but an oversight
in implementation (or a bug, if you want .-)

Every manipulation with a table (e.g., move, resize; actually even a
selection of the table) leads to creation of a full copy of the table
(SdrObject::getFullDragClone()). One of the actions the table copy impl.
does is to call sdr::CellProperties::SetStyleSheet() on every cell of
the new table. CellProperties is derived from
sdr::properties::TextProperties and CellProperties::SetStyleSheet() just
passes the call to TextProperties::SetStyleSheet(). This is where the
trouble begins :-)

The SDR representation of a table, SdrTableObj, is derived from
SdrTextObj. Because of that, SdrTextObj needs to be able to contain more
than one SdrText (because a table needs one for every cell). This is
handled correctly by TextProperties. But, because there is no SDR
representation of a single cell, CellProperties uses the SdrTableObj as
the SDR object it works on. Therefore TextProperties::SetStyleSheet()
processes all SdrText objects of the _whole table_, not just a single
cell. And this is repeated for every other cell...

Change-Id: Iab2e2d0e1e8038710645c0bd24666e6032b0a003

3 files changed, 48 insertions, 1 deletions

diff --git a/svx/inc/svx/itextprovider.hxx b/svx/inc/svx/itextprovider.hxx
new file mode 100644
index 000000000000..3202e4d65495
--- /dev/null
+++ b/svx/inc/svx/itextprovider.hxx
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#if !defined SVX_ITEXTPROVIDER_HXX_INCLUDED
+#define SVX_ITEXTPROVIDER_HXX_INCLUDED
+
+#include <sal/types.h>
+
+#include <svx/svxdllapi.h>
+
+class SdrText;
+
+namespace svx
+{
+
+    /** This interface provides access to text object(s) in an SdrObject.
+
+     */
+    class SVX_DLLPUBLIC ITextProvider
+    {
+    public:
+        /** Return the number of texts available for this object. */
+        virtual sal_Int32 getTextCount() const = 0;
+
+        /** Return the nth available text. */
+        virtual SdrText* getText(sal_Int32 nIndex) const = 0;
+
+    protected:
+        ~ITextProvider() {}
+    };
+
+}
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/svx/inc/svx/sdr/properties/textproperties.hxx b/svx/inc/svx/sdr/properties/textproperties.hxx
index ac6a613e2c2a..456b104e60ec 100644
--- a/svx/inc/svx/sdr/properties/textproperties.hxx
+++ b/svx/inc/svx/sdr/properties/textproperties.hxx
@@ -20,6 +20,7 @@
 #ifndef _SDR_PROPERTIES_TEXTPROPERTIES_HXX
 #define _SDR_PROPERTIES_TEXTPROPERTIES_HXX
 
+#include <svx/itextprovider.hxx>
 #include <svx/sdr/properties/attributeproperties.hxx>
 #include "svx/svxdllapi.h"
 
@@ -45,6 +46,9 @@ namespace sdr
             // react on ItemSet changes
             virtual void ItemSetChanged(const SfxItemSet& rSet);
 
+            /// Get the TextProvider related to our SdrObject
+            virtual const svx::ITextProvider& getTextProvider() const;
+
         public:
             // basic constructor
             explicit TextProperties(SdrObject& rObj);
diff --git a/svx/inc/svx/svdotext.hxx b/svx/inc/svx/svdotext.hxx
index 30a923bb566a..a5df49bdd24f 100644
--- a/svx/inc/svx/svdotext.hxx
+++ b/svx/inc/svx/svdotext.hxx
@@ -21,6 +21,7 @@
 #define _SVDOTEXT_HXX
 
 #include <vcl/field.hxx>
+#include <svx/itextprovider.hxx>
 #include <svx/svdoattr.hxx>
 #include <svx/svdtrans.hxx> // GeoStat
 #include <tools/datetime.hxx>
@@ -123,7 +124,7 @@ namespace sdr
 //   SdrTextObj
 //************************************************************
 
-class SVX_DLLPUBLIC SdrTextObj : public SdrAttrObj
+class SVX_DLLPUBLIC SdrTextObj : public SdrAttrObj, public svx::ITextProvider
 {
 private:
     // Cell needs access to ImpGetDrawOutliner();