Keep DataGrid rows compact and readable

etaf-ui.el

@@ -106,6 +106,24 @@ TAB-INDEX, and ARIA-LABEL provide Host identity and presentation."
    ((listp row) (alist-get key row))
    (t nil)))
 
+(defun etaf-ui--grid-display-value (row column)
+  "Return one single-line display value for ROW and COLUMN.
+
+DataGrid columns are tabular tracks, not prose paragraphs.  Keep each cell on
+one visual line and use an ellipsis when a fixed character-width descriptor is
+too small; the original ROW remains intact for selection and callbacks."
+  (let* ((value (format "%s"
+                       (or (etaf-ui--grid-cell-value
+                            row (etaf-ui--column-value column :key)) "")))
+         (width (etaf-ui--column-value column :width)))
+    (if (and (integerp width) (> width 1)
+             (> (string-width value) width))
+        ;; Leave one character of the declared track for inter-column air;
+        ;; Ebox's left justification fills that remainder without changing
+        ;; the stable column geometry.
+        (truncate-string-to-width value (1- width) 0 nil "…")
+      value)))
+
 (defun etaf-ui--grid-header-cell (column)
   "Return one header View for COLUMN."
   (etaf-view
@@ -124,11 +142,9 @@ TAB-INDEX, and ARIA-LABEL provide Host identity and presentation."
 
 (defun etaf-ui--grid-cell (row column)
   "Return one data cell View for ROW and COLUMN."
-  (let ((key (etaf-ui--column-value column :key)))
-    (etaf-view
-     (text :width (etaf-ui--column-value column :width)
-           (expr :value
-                 (format "%s" (or (etaf-ui--grid-cell-value row key) "")))))))
+  (etaf-view
+   (text :width (etaf-ui--column-value column :width)
+         (expr :value (etaf-ui--grid-display-value row column)))))
 
 (defun etaf-ui--grid-cells (row columns)
   "Return data cell Views for ROW and COLUMNS."

tests/etaf-ui-tests.el

@@ -451,6 +451,31 @@
       (when-let ((buffer (get-buffer buffer-name)))
         (kill-buffer buffer)))))
 
+(ert-deftest etaf-ui-data-grid-keeps-long-cells-on-one-line ()
+  "Long tabular values use an ellipsis instead of increasing row height."
+  (let* ((source (etaf-data-memory-source
+                  '((:id 1 :title "The Cathedral and the Bazaar"))
+                  :id-key :id))
+         (controller (etaf-data-controller source :page-size 10 :auto-load t))
+         (buffer-name " *etaf-ui-grid-truncation-test*"))
+    (unwind-protect
+        (progn
+          (etaf-mount
+           buffer-name
+           (etaf-view
+            (data-grid
+             :controller controller
+             :columns '((:key :title :label "Title" :width 22))
+             :row-key (lambda (row) (plist-get row :id)))))
+          (let ((text (etaf-ui-test--text buffer-name)))
+            (should (string-match-p "The Cathedral and th…" text))
+            (should-not (string-match-p "The Cathedral and the Bazaar" text))))
+      (when-let ((runtime (etaf-runtime-for-buffer buffer-name)))
+        (etaf-unmount runtime))
+      (etaf-data-stop controller)
+      (when-let ((buffer (get-buffer buffer-name)))
+        (kill-buffer buffer)))))
+
 (ert-deftest etaf-ui-data-grid-noninteractive-rows-have-no-focus-contract ()
   "Rows without ON-ROW-PRESS have no role, ref callback, or tab stop."
   (let* ((source (etaf-data-memory-source '((:id 1 :name "Ada"))