From 55c1e7025a658db4ec88d9d49a5c897afac23083 Mon Sep 17 00:00:00 2001
From: Adrian Cochrane <adrian@openwork.nz>
Date: Thu, 16 Mar 2023 16:22:48 +1300
Subject: [PATCH] Don't pass empty input to Balkon, is that what's crashing?

---
 Graphics/Layout/Inline.hs | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/Graphics/Layout/Inline.hs b/Graphics/Layout/Inline.hs
index e5941c7..949cf4b 100644
--- a/Graphics/Layout/Inline.hs
+++ b/Graphics/Layout/Inline.hs
@@ -3,8 +3,11 @@ module Graphics.Layout.Inline where
 
 import Data.Text.ParagraphLayout (Paragraph(..), ParagraphOptions(..),
                                     SpanLayout(..), Fragment(..),
-                                    ParagraphLayout(..), layoutPlain)
-import Data.Text.ParagraphLayout.Rect (Rect, width, height, x_min, y_min)
+                                    ParagraphLayout(..), layoutPlain, Span(..))
+import Data.Text.ParagraphLayout.Rect (Rect(..), width, height, x_min, y_min)
+import Data.Text.Internal (Text(..))
+import qualified Data.Text as Txt
+import Data.Char (isSpace)
 import Data.Int (Int32)
 
 import Graphics.Layout.Box (Size(..), CastDouble(..), fromDouble)
@@ -22,13 +25,19 @@ inlineHeight font width self =
     hbScale' font $ height $ layoutPlain' self $ round (hbScale font * width)
 
 inlineSize :: (CastDouble x, CastDouble y) => Font' -> Paragraph -> Size x y
+inlineSize _ self | Txt.all isSpace txt || Txt.null txt = Size (fromDouble 0) (fromDouble 0)
+  where txt = paragraph2text self
 inlineSize font self = Size (c font $ width r) (c font $ height r)
   where r = paragraphRect $ layoutPlain self
 inlineChildren :: [x] -> Paragraph -> [(x, Fragment)]
-inlineChildren vals = concat . map inner . zip vals . spanLayouts . layoutPlain
+inlineChildren _ self | Txt.all isSpace txt || Txt.null txt = []
+  where txt = paragraph2text self
+inlineChildren vals self = concat $ map inner $ zip vals $ spanLayouts $ layoutPlain self
   where inner (x, SpanLayout y) = map (x,) y
 
 layoutPlain' :: Paragraph -> Int32 -> Rect Int32
+layoutPlain' paragraph _ | Txt.all isSpace txt || Txt.null txt = Rect 0 0 0 0
+  where txt = paragraph2text paragraph
 layoutPlain' (Paragraph a b c d) width =
     paragraphRect $ layoutPlain $ Paragraph a b c d { paragraphMaxWidth = width }
 
@@ -41,3 +50,5 @@ fragmentPos :: Font' -> (Double, Double) -> Fragment -> (Double, Double)
 fragmentPos font (x, y) self =
         (x + hbScale' font (x_min r), y + hbScale' font (y_min r))
     where r = fragmentRect self
+
+paragraph2text (Paragraph array off spans _) = Text array off $ sum $ map spanLength spans
-- 
2.30.2