ui/ncurses/nc-config: Draw config form into a scrollable pad

Currently, when the config form is larger than the screen size, the form
fails to draw.

This change draws the config screen onto a pad instead, which we can
scroll.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

diff --git a/ui/ncurses/nc-config.c b/ui/ncurses/nc-config.c
index 49f2e2f6093255c1ca2331634e4c9509d013c263..0f357024a0f3376af47dd9c2e5ec8a400442b88b 100644 (file)
--- a/ui/ncurses/nc-config.c
+++ b/ui/ncurses/nc-config.c
@@ -43,9 +43,13 @@ struct config_screen {
        struct nc_scr           scr;
        struct cui              *cui;
        struct nc_widgetset     *widgetset;
+       WINDOW                  *pad;
+
        bool                    exit;
        void                    (*on_exit)(struct cui *);
 
+       int                     scroll_y;
+
        int                     label_x;
        int                     field_x;
        int                     network_config_y;
@@ -89,6 +93,16 @@ static struct config_screen *config_screen_from_scr(struct nc_scr *scr)
        return config_screen;
 }
 
+static void pad_refresh(struct config_screen *screen)
+{
+       int y, x, rows, cols;
+
+       getmaxyx(screen->scr.sub_ncw, rows, cols);
+       getbegyx(screen->scr.sub_ncw, y, x);
+
+       prefresh(screen->pad, screen->scroll_y, 0, y, x, rows, cols);
+}
+
 static void config_screen_process_key(struct nc_scr *scr, int key)
 {
        struct config_screen *screen = config_screen_from_scr(scr);
@@ -98,7 +112,7 @@ static void config_screen_process_key(struct nc_scr *scr, int key)
        if (screen->exit)
                screen->on_exit(screen->cui);
        else if (handled)
-               wrefresh(screen->scr.main_ncw);
+               pad_refresh(screen);
 }
 
 static void config_screen_resize(struct nc_scr *scr)
@@ -112,7 +126,7 @@ static int config_screen_post(struct nc_scr *scr)
        struct config_screen *screen = config_screen_from_scr(scr);
        widgetset_post(screen->widgetset);
        nc_scr_frame_draw(scr);
-       wrefresh(scr->main_ncw);
+       pad_refresh(screen);
        return 0;
 }
 
@@ -486,11 +500,50 @@ static void config_screen_setup_widgets(struct config_screen *screen,
                        cancel_click, screen);
 }
 
+static void config_screen_widget_focus(struct nc_widget *widget, void *arg)
+{
+       struct config_screen *screen = arg;
+       int w_y, w_height, s_max;
+
+       w_y = widget_y(widget);
+       w_height = widget_height(widget);
+       s_max = getmaxy(screen->scr.sub_ncw);
+
+       if (w_y < screen->scroll_y)
+               screen->scroll_y = w_y;
+
+       else if (w_y + w_height + screen->scroll_y > s_max - 1)
+               screen->scroll_y = 1 + w_y + w_height - s_max;
+
+       else
+               return;
+
+       pad_refresh(screen);
+}
+
+
 void config_screen_update(struct config_screen *screen,
                const struct config *config,
                const struct system_info *sysinfo)
 {
        bool repost = false;
+       int height;
+
+       /* The size of the pad we'll need depends on the number of interfaces.
+        *
+        * We use N_FIELDS (which is quite conservative, as some fields share
+        * a line) as a base, then add 3 (as the network select field is
+        * takes 3 lines), and n_interfaces (as the network interface field
+        * has n_interfaces lines).
+        */
+       height = N_FIELDS + 3;
+       if (sysinfo)
+               height += sysinfo->n_interfaces;
+       if (!screen->pad || getmaxx(screen->pad) < height) {
+               if (screen->pad)
+                       delwin(screen->pad);
+               screen->pad = newpad(height, COLS);
+       }
 
        if (screen->widgetset) {
                widgetset_unpost(screen->widgetset);
@@ -499,7 +552,9 @@ void config_screen_update(struct config_screen *screen,
        }
 
        screen->widgetset = widgetset_create(screen, screen->scr.main_ncw,
-                       screen->scr.sub_ncw);
+                       screen->pad);
+       widgetset_set_widget_focus(screen->widgetset,
+                       config_screen_widget_focus, screen);
 
        if (!config || !sysinfo) {
                config_screen_setup_empty(screen);
@@ -513,7 +568,15 @@ void config_screen_update(struct config_screen *screen,
        if (repost)
                widgetset_post(screen->widgetset);
 
-       wrefresh(screen->scr.main_ncw);
+       pad_refresh(screen);
+}
+
+static int config_screen_destroy(void *arg)
+{
+       struct config_screen *screen = arg;
+       if (screen->pad)
+               delwin(screen->pad);
+       return 0;
 }
 
 struct config_screen *config_screen_init(struct cui *cui,
@@ -524,6 +587,7 @@ struct config_screen *config_screen_init(struct cui *cui,
        struct config_screen *screen;
 
        screen = talloc_zero(cui, struct config_screen);
+       talloc_set_destructor(screen, config_screen_destroy);
        nc_scr_init(&screen->scr, pb_config_screen_sig, 0,
                        cui, config_screen_process_key,
                        config_screen_post, config_screen_unpost,
@@ -545,5 +609,7 @@ struct config_screen *config_screen_init(struct cui *cui,
 
        config_screen_update(screen, config, sysinfo);
 
+       wrefresh(screen->scr.main_ncw);
+
        return screen;
 }