tdf#142560 handle cached glpyh items in ImplGlyphFallbackLayout

Fallback layout beyond level1 isn't generated because pre-caculated
glyph items does not contain glyph items that needs to fallback, i.e.
when calling ImplLayoutArgs::PrepareFallback. Hence it produce no
maFallbackRuns and maRuns. The patch changes
ImplLayoutArgs::PrepareFallback so that it use pre-caculated glyph
items in the next level to create maRuns to ensure the same fallback
layouts are genrated as layouts generated without pre-caculated glyph
items.

Change-Id: I672f3be6c4915892792b3cb968ad4a325465ccc0
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/117105
Tested-by: Jenkins
Reviewed-by: Mark Hung <marklh9@gmail.com>
(cherry picked from commit 10ea27faec115d4cffd6f66cee8f688399e1e0b2)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/117570
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>

1 files changed, 16 insertions, 1 deletions

diff --git a/vcl/source/gdi/sallayout.cxx b/vcl/source/gdi/sallayout.cxx
index 9f4757148b36..7b8f2c2a2a05 100644
--- a/vcl/source/gdi/sallayout.cxx
+++ b/vcl/source/gdi/sallayout.cxx
@@ -486,8 +486,23 @@ void ImplLayoutArgs::AddRun( int nCharPos0, int nCharPos1, bool bRTL )
     maRuns.AddRun( nCharPos0, nCharPos1, bRTL );
 }
 
-bool ImplLayoutArgs::PrepareFallback()
+bool ImplLayoutArgs::PrepareFallback(const SalLayoutGlyphsImpl* pGlyphsImpl)
 {
+    // Generate runs with pre-calculated glyph items instead maFallbackRuns.
+    if( pGlyphsImpl != nullptr )
+    {
+        maRuns.Clear();
+        maFallbackRuns.Clear();
+
+        for (auto const& aGlyphItem : *pGlyphsImpl)
+        {
+            for(int i = aGlyphItem.charPos(); i < aGlyphItem.charPos() + aGlyphItem.charCount(); ++i)
+                maRuns.AddPos(i, aGlyphItem.IsRTLGlyph());
+        }
+
+        return !maRuns.IsEmpty();
+    }
+
     // short circuit if no fallback is needed
     if( maFallbackRuns.IsEmpty() )
     {