TUI window resize should not need invisibility

When resizing a window, the TUI currently first makes it invisible,
then changes the size, and then restores its visibility.

I think this is done because curses doesn't truly support resizing a
window -- there is a "wresize" extension, but the man page says it
isn't available in all versions of curses.

First, this is probably not a major problem any more.  I imagine most
of those old systems are gone now.

Second, I think it's a better API to have this detail hidden inside of
the resize method.

This patch changes the code to follow this idea, and changes the
ordinary resize method to use wresize when it is available.  The
special case for the command window is also moved to methods on the
command window.

gdb/ChangeLog
2019-08-15  Tom Tromey  <tom@tromey.com>

	* tui/tui-layout.c (show_layout, show_source_disasm_command)
	(show_data): Don't change window visibility.
	(tui_gen_win_info::resize): Remove special case for command
	window.  Use wresize, when available.
	(show_source_or_disasm_and_command): Don't change window
	visibility.
	* tui/tui-command.h (struct tui_cmd_window) <resize>: Declare.
	<make_visible>: New method.
	* tui/tui-command.c (tui_cmd_window::resize): New method.

3 files changed, 63 insertions, 23 deletions

diff --git a/gdb/tui/tui-command.c b/gdb/tui/tui-command.c
index 034abd5..ddbd8bc 100644
--- a/gdb/tui/tui-command.c
+++ b/gdb/tui/tui-command.c
@@ -25,6 +25,7 @@
 #include "tui/tui-win.h"
 #include "tui/tui-io.h"
 #include "tui/tui-command.h"
+#include "tui/tui-wingeneral.h"
 
 #include "gdb_curses.h"
 
@@ -48,6 +49,40 @@ tui_cmd_window::max_height () const
   return tui_term_height () - 4;
 }
 
+void
+tui_cmd_window::resize (int height_, int width_, int origin_x, int origin_y)
+{
+  width = width_;
+  height = height_;
+  if (height > 1)
+    {
+      /* Note this differs from the base class implementation, because
+	 this window can't be boxed.  */
+      viewport_height = height - 1;
+    }
+  else
+    viewport_height = 1;
+  origin.x = origin_x;
+  origin.y = origin_y;
+
+  if (handle == nullptr)
+    tui_make_window (this);
+  else
+    {
+      /* Another reason we don't call the base class method here is
+	 that for the command window in particular, we want to avoid
+	 destroying the underlying handle.  We don't currently track
+	 the contents of this window, and so have no way to re-render
+	 it.  However we can at least move it and keep the old size if
+	 wresize isn't available.  */
+#ifdef HAVE_WRESIZE
+      wresize (handle, height, width);
+#endif
+      mvwin (handle, origin.y, origin.x);
+      wmove (handle, 0, 0);
+    }
+}
+
 /* See tui-command.h.  */
 
 void
diff --git a/gdb/tui/tui-command.h b/gdb/tui/tui-command.h
index 1892956..1fce0a1 100644
--- a/gdb/tui/tui-command.h
+++ b/gdb/tui/tui-command.h
@@ -56,6 +56,13 @@ struct tui_cmd_window : public tui_win_info
     return false;
   }
 
+  void resize (int height, int width, int origin_x, int origin_y) override;
+
+  void make_visible (bool visible) override
+  {
+    /* The command window can't be made invisible.  */
+  }
+
   int start_line = 0;
 
 protected:
diff --git a/gdb/tui/tui-layout.c b/gdb/tui/tui-layout.c
index 4ea604a..e0e804b 100644
--- a/gdb/tui/tui-layout.c
+++ b/gdb/tui/tui-layout.c
@@ -76,9 +76,7 @@ show_layout (enum tui_layout_type layout)
 
   if (layout != cur_layout)
     {
-      /* First make the current layout be invisible.  */
       tui_make_all_invisible ();
-      tui_locator_win_info_ptr ()->make_visible (false);
       switch (layout)
 	{
 	case SRC_DATA_COMMAND:
@@ -506,7 +504,6 @@ show_source_disasm_command (void)
 		       tui_term_width (),
 		       0,
 		       0);
-  TUI_SRC_WIN->make_visible (true);
   TUI_SRC_WIN->m_has_locator = false;
 
   struct tui_locator_window *locator = tui_locator_win_info_ptr ();
@@ -519,14 +516,12 @@ show_source_disasm_command (void)
 			  tui_term_width (),
 			  0,
 			  src_height - 1);
-  TUI_DISASM_WIN->make_visible (true);
   locator->resize (2 /* 1 */ ,
 		   tui_term_width (),
 		   0,
 		   (src_height + asm_height) - 1);
   TUI_SRC_WIN->m_has_locator = false;
   TUI_DISASM_WIN->m_has_locator = true;
-  locator->make_visible (true);
   tui_show_locator_content ();
   TUI_DISASM_WIN->show_source_content ();
 
@@ -536,7 +531,6 @@ show_source_disasm_command (void)
 		       tui_term_width (),
 		       0,
 		       tui_term_height () - cmd_height);
-  TUI_CMD_WIN->make_visible (true);
   current_layout = SRC_DISASSEM_COMMAND;
 }
 
@@ -558,7 +552,6 @@ show_data (enum tui_layout_type new_layout)
   if (tui_win_list[DATA_WIN] == nullptr)
     tui_win_list[DATA_WIN] = new tui_data_window ();
   tui_win_list[DATA_WIN]->resize (data_height, tui_term_width (), 0, 0);
-  tui_win_list[DATA_WIN]->make_visible (true);
 
   if (new_layout == SRC_DATA_COMMAND)
     win_type = SRC_WIN;
@@ -583,11 +576,11 @@ show_data (enum tui_layout_type new_layout)
 		   tui_term_width (),
 		   0,
 		   total_height - 1);
-  base->make_visible (true);
+  TUI_CMD_WIN->resize (TUI_CMD_WIN->height, tui_term_width (),
+		       0, total_height);
+
   base->m_has_locator = true;
-  locator->make_visible (true);
   tui_show_locator_content ();
-  TUI_CMD_WIN->make_visible (true);
   current_layout = new_layout;
 }
 
@@ -595,20 +588,29 @@ void
 tui_gen_win_info::resize (int height_, int width_,
 			  int origin_x_, int origin_y_)
 {
-  int h = height_;
-
   width = width_;
-  height = h;
-  if (h > 1)
-    {
-      viewport_height = h - 1;
-      if (type != CMD_WIN)
-	viewport_height--;
-    }
+  height = height_;
+  if (height > 1)
+    viewport_height = height - 2;
   else
     viewport_height = 1;
   origin.x = origin_x_;
   origin.y = origin_y_;
+
+  if (handle != nullptr)
+    {
+#ifdef HAVE_WRESIZE
+      wresize (handle, height, width);
+      mvwin (handle, origin.y, origin.x);
+      wmove (handle, 0, 0);
+#else
+      tui_delete_win (handle);
+      handle = NULL;
+#endif
+    }
+
+  if (handle == nullptr)
+    tui_make_window (this);
 }
 
 /* Show the Source/Command or the Disassem layout.  */
@@ -647,11 +649,8 @@ show_source_or_disasm_and_command (enum tui_layout_type layout_type)
 		    tui_term_width (),
 		    0,
 		    0);
-  win_info->make_visible (true);
-
 
   win_info->m_has_locator = true;
-  locator->make_visible (true);
   tui_show_locator_content ();
   win_info->show_source_content ();
 
@@ -661,6 +660,5 @@ show_source_or_disasm_and_command (enum tui_layout_type layout_type)
 		       tui_term_width (),
 		       0,
 		       src_height);
-  TUI_CMD_WIN->make_visible (true);
   current_layout = layout_type;
 }