Hide UI elements on smaller terminals

This helps usability on smaller terminals.

Hide the status bar first, then the summary and then the titles,
since that is the approximate order of usefulness.

1 files changed, 27 insertions, 13 deletions

diff --git a/iotop/ui.py b/iotop/ui.py
index d43f279..30efa73 100644
--- a/iotop/ui.py
+++ b/iotop/ui.py
@@ -436,8 +436,6 @@ class IOTopUI(object):
             stats_lambda = lambda p: p.stats_delta
         processes.sort(key=lambda p: key(p, stats_lambda(p)),
                        reverse=self.sorting_reverse)
-        if not self.options.batch:
-            del processes[self.height - 2:]
         return list(map(format, processes))
 
     def refresh_display(self, first_time, total, current, duration):
@@ -474,10 +472,33 @@ class IOTopUI(object):
             sys.stdout.flush()
         else:
             self.win.erase()
+
+            if Stats.has_blkio_delay_total:
+                status_msg = None
+            else:
+                status_msg = ('CONFIG_TASK_DELAY_ACCT not enabled in kernel, '
+                              'cannot determine SWAPIN and IO %')
+
+            len_summary = len(summary)
+            len_titles = int(bool(titles))
+            len_status_msg = int(bool(status_msg))
+            max_lines = self.height - len_summary - len_titles - len_status_msg
+            if max_lines < 5:
+                titles = []
+                len_titles = 0
+            if max_lines < 6:
+                summary = []
+                len_summary = 0
+            if max_lines < 7:
+                status_msg = None
+                len_status_msg = 0
+            max_lines = self.height - len_summary - len_titles - len_status_msg
+            num_lines = min(len(lines), max_lines)
+
             for i, s in enumerate(summary):
                 self.win.addstr(i, 0, s[:self.width])
-            self.win.hline(len(summary), 0, ord(' ') | curses.A_REVERSE,
-                           self.width)
+            if titles:
+                self.win.hline(len_summary, 0, ord(' ') | curses.A_REVERSE, self.width)
             pos = 0
             remaining_cols = self.width
             for i in range(len(titles)):
@@ -490,19 +511,12 @@ class IOTopUI(object):
                     title += self.sorting_reverse and '>' or '<'
                 title = title[:remaining_cols]
                 remaining_cols -= len(title)
-                self.win.addstr(len(summary), pos, title, attr)
+                self.win.addstr(len_summary, pos, title, attr)
                 pos += len(title)
-            if Stats.has_blkio_delay_total:
-                status_msg = None
-            else:
-                status_msg = ('CONFIG_TASK_DELAY_ACCT not enabled in kernel, '
-                              'cannot determine SWAPIN and IO %')
-            num_lines = min(len(lines),
-                            self.height - len(summary) - int(bool(titles)) - int(bool(status_msg)))
             for i in range(num_lines):
                 try:
                     def print_line(line):
-                        self.win.addstr(i + len(summary) + 1, 0, line)
+                        self.win.addstr(i + len_summary + len_titles, 0, line)
                     try:
                         print_line(lines[i])
                     except UnicodeEncodeError: