sc lok: Implement hi-dpi and zoom for spreadsheets.

A bit different approach than trying to paint different zoom levels at
the samet time, because it is terribly hard to achieve with Calc -
things misalign, because Calc tries to fit the lines into the pixels
etc.

Instead, always paint the spreadsheet at 100%, but use cairo to scale the
actual painting.

Change-Id: I228a9dd41bf29862bdd188825d12e61e1c86cccc

1 files changed, 13 insertions, 0 deletions

diff --git a/desktop/source/lib/init.cxx b/desktop/source/lib/init.cxx
index 7527c1b857d2..5b5381c002fa 100644
--- a/desktop/source/lib/init.cxx
+++ b/desktop/source/lib/init.cxx
@@ -2104,6 +2104,19 @@ static void doc_paintTile(LibreOfficeKitDocument* pThis,
         return;
     }
 
+    // Painting of zoomed or hi-dpi spreadsheets is special, we actually draw
+    // everything at 100%, and only set cairo's scale factor accordingly, so
+    // that everything is painted bigger or smaller.  This is different to
+    // what Calc's internal scaling would do - because that one is trying to
+    // fit the lines between cells to integer multiples of pixels.
+    comphelper::ScopeGuard dpiScaleGuard([]() { comphelper::LibreOfficeKit::setDPIScale(1.0); });
+    if (doc_getDocumentType(pThis) == LOK_DOCTYPE_SPREADSHEET)
+    {
+        double fDPIScaleX = (nCanvasWidth * 3840.0) / (256.0 * nTileWidth);
+        assert(fabs(fDPIScaleX - ((nCanvasHeight * 3840.0) / (256.0 * nTileHeight))) < 0.0001);
+        comphelper::LibreOfficeKit::setDPIScale(fDPIScaleX);
+    }
+
 #if defined(UNX) && !defined(MACOSX) && !defined(ENABLE_HEADLESS)
 
 #if defined(IOS)