Clean up image support and add regression tests

regress/image-placeholder-reflow.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+
+# Kitty placeholder rows stay cell-aligned when a client becomes narrower.
+
+PATH=/bin:/usr/bin
+TERM=screen
+LC_ALL=C.UTF-8
+export TERM LC_ALL
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -Limage-placeholder-outer$$ -f/dev/null"
+TMUX2="$TEST_TMUX -u -Limage-placeholder-inner$$ -f/dev/null"
+TMP=$(mktemp)
+trap "$TMUX kill-server 2>/dev/null; $TMUX2 kill-server 2>/dev/null; rm -f $TMP" 0 1 15
+
+$TMUX2 new-session -d -x 10 -y 4 "
+	i=0
+	while [ \$i -lt 10 ]; do
+		printf '\\364\\216\\273\\256\\314\\205'
+		i=\$((i + 1))
+	done
+	sleep 30" || exit 1
+$TMUX2 set -g status off || exit 1
+$TMUX new-session -d -x 10 -y 4 "$TMUX2 attach-session" || exit 1
+$TMUX set -g status off || exit 1
+sleep 1
+
+$TMUX resize-window -x 5 -y 4 || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ -n "$(sed -n 1p $TMP)" ] || exit 1
+[ -z "$(sed -n 2p $TMP)" ] || exit 1
+$TMUX resize-window -x 10 -y 4 || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ "$(sed -n 1p $TMP | wc -c)" = 61 ] || exit 1
+[ -z "$(sed -n 2p $TMP)" ] || exit 1
+
+exit 0