Show ellipsis for truncated labels

Close #4390

src/terminal.go

@@ -1235,9 +1235,14 @@ func (t *Terminal) ansiLabelPrinter(str string, color *tui.ColorPair, fill bool)
 			return nil, 0
 		}
 		printFn := func(window tui.Window, limit int) {
-			if length > limit {
+			ellipsis := []rune{}
-				trimmedRunes, _ := t.trimRight(runes, limit)
+			ellipsisWidth := 0
-				window.CPrint(*color, string(trimmedRunes))
+			if !fill {
+				ellipsis, ellipsisWidth = util.Truncate(t.ellipsis, limit)
+			}
+			if length > limit-ellipsisWidth {
+				trimmedRunes, _ := t.trimRight(runes, limit-ellipsisWidth)
+				window.CPrint(*color, string(trimmedRunes)+string(ellipsis))
 			} else if fill {
 				window.CPrint(*color, util.RepeatToFill(text, length, limit))
 			} else {

test/test_layout.rb

@@ -992,6 +992,36 @@ class TestLayout < TestInteractive
     tmux.until { assert_block(block, it) }
   end
 
+  def test_label_trunction
+    command = <<~CMD
+      seq 10 | #{FZF} --style full --border --header-lines=1 --preview ':' \\
+        --border-label "#{'b' * 1000}" \\
+        --preview-label "#{'p' * 1000}" \\
+        --header-label "#{'h' * 1000}" \\
+        --header-label "#{'h' * 1000}" \\
+        --input-label "#{'i' * 1000}" \\
+        --list-label "#{'l' * 1000}"
+    CMD
+    writelines(command.lines.map(&:chomp))
+    tmux.send_keys("sh #{tempname}", :Enter)
+    tmux.until do |lines|
+      text = lines.join
+      assert_includes text, 'b··'
+      assert_includes text, 'l··p'
+      assert_includes text, 'p··'
+      assert_includes text, 'h··'
+      assert_includes text, 'i··'
+    end
+  end
+
+  def test_separator_no_ellipsis
+    tmux.send_keys %(seq 10 | #{FZF} --separator "$(seq 1000 | tr '\\n' ' ')"), :Enter
+    tmux.until do |lines|
+      assert_equal 10, lines.match_count
+      refute_includes lines.join, '··'
+    end
+  end
+
   def test_header_border_no_pointer_and_marker
     tmux.send_keys %(seq 10 | #{FZF} --header-lines 1 --header-border sharp --no-list-border --pointer '' --marker ''), :Enter
     block = <<~BLOCK