Revert "core plugin: stop emitting an empty 'alt' tag in cmap output"

This reverts commit a214b9dc2be6b4a9d27196e2c43f7bf2b0ff0002. It turns out the
W3C specification for this part of HTML requires the `alt` attribute if the
`href` attribute is set. We will need to figure out an alternative of what to
set this to for accessibility.

Gitlab: closes #2319, re-opens #265
Reported-by: Albert

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 64fccf4ab2a82c4671aff3bf042144fa453d9d90..338279d0340c2f583c7b5201c4b5cfb92d28e9f1 100644 (file)
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased (7.0.4)]
 
+### Fixed
+
+- The `alt` attributes are once again set in the cmap output. This was a
+  regression in Graphviz 7.0.2, that intentionally removed these but did not
+  account for the W3C specification making these attributes required when the
+  `href` attribute is set. #265, #2319
+
 ## [7.0.3] – 2022-11-26
 
 ### Changed

diff --git a/plugin/core/gvrender_core_map.c b/plugin/core/gvrender_core_map.c
index a5a304e3d26c607281c7cd9cf7803ead9d2eb587..3f62d4a37b444d0c22ac62500af3253161a4eaf8 100644 (file)
--- a/plugin/core/gvrender_core_map.c
+++ b/plugin/core/gvrender_core_map.c
@@ -114,6 +114,17 @@ static void map_output_shape (GVJ_t *job, map_shape_t map_shape, pointf * AF, in
            gvputs_xml(job, tooltip);
            gvputs(job, "\"");
        }
+        /*
+        * alt text is intended for the visually impaired, but such
+        * folk are not likely to be clicking around on a graph anyway.
+        * IE on the PC platform (but not on Macs) incorrectly
+        * uses (non-empty) alt strings instead of title strings for tooltips.
+        * To make tooltips work and avoid this IE issue,
+        * while still satisfying usability guidelines
+        * that require that there is always an alt string,
+        * we generate just an empty alt string.
+        */
+        gvputs(job, " alt=\"\"");
 
         gvputs(job, " coords=\"");
         switch (map_shape) {