LaTeX reader: support alt text on images. (#8745)

Closes: #8743

src/Text/Pandoc/Readers/LaTeX.hs

@@ -213,7 +213,7 @@ mkImage options (T.unpack -> src) = do
    let kvs = map replaceTextwidth
              $ filter (\(k,_) -> k `elem` ["width", "height"]) options
    let attr = ("",[], kvs)
-   let alt = str "image"
+   let alt = maybe (str "image") str $ lookup "alt" options
    defaultExt <- getOption readerDefaultImageExtension
    let exts' = [".pdf", ".png", ".jpg", ".mps", ".jpeg", ".jbig2", ".jb2"]
    let exts  = exts' ++ map (map toUpper) exts'
@@ -1171,9 +1171,7 @@ figure' = try $ do
   innerContent <- many $ try (Left <$> label) <|> (Right <$> block)
   let content = walk go $ mconcat $ snd $ partitionEithers innerContent
   st <- getState
-  let caption' = case sCaption st of
-                   Nothing   -> B.emptyCaption
-                   Just capt -> capt
+  let caption' = fromMaybe B.emptyCaption $ sCaption st
   let mblabel  = sLastLabel st
   let attr     = case mblabel of
                    Just lab -> (lab, [], [])
@@ -1190,7 +1188,7 @@ figure' = try $ do
 
   where
   -- Remove the `Image` caption b.c. it's on the `Figure`
-  go (Para [Image attr _ target]) = Plain [Image attr [] target]
+  go (Para [Image attr [Str "image"] target]) = Plain [Image attr [] target]
   go x = x
 
 coloredBlock :: PandocMonad m => Text -> LP m Blocks

test/command/8745.md

@@ -0,0 +1,52 @@
+# Alt text on images
+
+```
+% pandoc -f latex -t native
+\documentclass[12pt]{article}
+\usepackage{graphicx}
+\begin{document}
+Sample text
+\begin{figure}[ht]
+    \includegraphics[alt={Upside down painting},width=0.5\textwidth]{New_York_City_I.jpg}
+    \caption{New York City by Piet Mondrian (Wikipedia)}
+    \label{fig:Mondrian}
+\end{figure}
+\includegraphics[alt={Face of a mandrill}]{mandrill.jpg}
+\end{document}
+^D
+[ Para [ Str "Sample" , Space , Str "text" ]
+, Figure
+    ( "fig:Mondrian" , [] , [] )
+    (Caption
+       Nothing
+       [ Plain
+           [ Str "New"
+           , Space
+           , Str "York"
+           , Space
+           , Str "City"
+           , Space
+           , Str "by"
+           , Space
+           , Str "Piet"
+           , Space
+           , Str "Mondrian"
+           , Space
+           , Str "(Wikipedia)"
+           ]
+       ])
+    [ Para
+        [ Image
+            ( "" , [] , [ ( "width" , "50%" ) ] )
+            [ Str "Upside down painting" ]
+            ( "New_York_City_I.jpg" , "" )
+        ]
+    ]
+, Para
+    [ Image
+        ( "" , [] , [] )
+        [ Str "Face of a mandrill" ]
+        ( "mandrill.jpg" , "" )
+    ]
+]
+```