LOK: add Document::getTileMode()

So that clients can know if they get old-style RGBA or new-style ARGB
output in paintTile().

Change-Id: Icfde4b3259444b3524e64478ccd976664a3fe0ed
(cherry picked from commit fc06f801)

desktop/source/lib/init.cxx

@@ -321,6 +321,7 @@ void        doc_paintTile(LibreOfficeKitDocument* pThis,
                           const int nCanvasWidth, const int nCanvasHeight,
                           const int nTilePosX, const int nTilePosY,
                           const int nTileWidth, const int nTileHeight);
+static int doc_getTileMode(LibreOfficeKitDocument* pThis);
 static void doc_getDocumentSize(LibreOfficeKitDocument* pThis,
                                 long* pWidth,
                                 long* pHeight);
@@ -394,6 +395,7 @@ LibLODocument_Impl::LibLODocument_Impl(const uno::Reference <css::lang::XCompone
         m_pDocumentClass->getPartName = doc_getPartName;
         m_pDocumentClass->setPartMode = doc_setPartMode;
         m_pDocumentClass->paintTile = doc_paintTile;
+        m_pDocumentClass->getTileMode = doc_getTileMode;
         m_pDocumentClass->getDocumentSize = doc_getDocumentSize;
         m_pDocumentClass->initializeForRendering = doc_initializeForRendering;
         m_pDocumentClass->registerCallback = doc_registerCallback;
@@ -965,6 +967,11 @@ void doc_paintTile (LibreOfficeKitDocument* pThis,
 #endif
 }
 
+static int doc_getTileMode(LibreOfficeKitDocument* /*pThis*/)
+{
+    return LOK_TILEMODE_RGBA;
+}
+
 static void doc_getDocumentSize(LibreOfficeKitDocument* pThis,
                                 long* pWidth,
                                 long* pHeight)

include/LibreOfficeKit/LibreOfficeKit.h

@@ -118,6 +118,9 @@ struct _LibreOfficeKitDocumentClass
                        const int nTileWidth,
                        const int nTileHeight);
 
+    /// @see lok::Document::getTileMode().
+    int (*getTileMode) (LibreOfficeKitDocument* pThis);
+
     /// @see lok::Document::getDocumentSize().
     void (*getDocumentSize) (LibreOfficeKitDocument* pThis,
                              long* pWidth,

include/LibreOfficeKit/LibreOfficeKit.hxx

@@ -140,6 +140,16 @@ public:
                                 nTilePosX, nTilePosY, nTileWidth, nTileHeight);
     }
 
+    /**
+     * Gets the tile mode: the pixel format used for the pBuffer of paintTile().
+     *
+     * @return an element of the LibreOfficeKitTileMode enum.
+     */
+    inline int getTileMode()
+    {
+        return mpDoc->pClass->getTileMode(mpDoc);
+    }
+
     /// Get the document sizes in TWIPs.
     inline void getDocumentSize(long* pWidth, long* pHeight)
     {

include/LibreOfficeKit/LibreOfficeKitEnums.h

@@ -33,6 +33,13 @@ typedef enum
 }
 LibreOfficeKitPartMode;
 
+typedef enum
+{
+    LOK_TILEMODE_RGBA,
+    LOK_TILEMODE_ARGB
+}
+LibreOfficeKitTileMode;
+
 typedef enum
 {
     /**