ncmultiselector: support pgup/pgdown #862

doc/man/man3/notcurses_multiselector.3.md

@@ -56,10 +56,21 @@ typedef struct ncmultiselector_options {
 
 # NOTES
 
-Currently, the **ncplane** **n** provided to **ncmultiselector_create** must
-not be **NULL**, though the **ncmultiselector** will always get its own plane,
-and this plane will not (currently) be bound to **n**.
-
+Currently, the **ncplane** **n** provided to **ncmultiselector_create**
+must not be **NULL**, though the **ncmultiselector** will always get its
+own plane, and this plane will not (currently) be bound to **n**.
+**ncmultiselector_selected** returns a bitmap corresponding to the
+currently-selected options.
+
+**ncmultiselector_plane** will return the **ncplane** on which the widget is
+drawn.
+
+While the **ncmultiselector** can be driven entirely by client code,
+input can be run through **ncmultiselector_offer_input** to take
+advantage of common controls. It will handle the up and down arrows,
+along with PageUp and PageDown, and space to select/deselect options.
+If the mouse is enabled, the mouse scrollwheel and mouse clicks on the scroll
+arrows will be handled.
 
 # RETURN VALUES
 

src/lib/selector.c

@@ -697,6 +697,7 @@ const char* ncmultiselector_nextitem(ncmultiselector* n){
 }
 
 bool ncmultiselector_offer_input(ncmultiselector* n, const ncinput* nc){
+  const int items_shown = ncplane_dim_y(n->ncp) - 4 - (n->title ? 2 : 0);
   if(nc->id == ' '){
     n->items[n->current].selected = !n->items[n->current].selected;
     ncmultiselector_draw(n);
@@ -708,10 +709,18 @@ bool ncmultiselector_offer_input(ncmultiselector* n, const ncinput* nc){
     ncmultiselector_nextitem(n);
     return true;
   }else if(nc->id == NCKEY_PGDOWN){
-    ncmultiselector_nextitem(n); // FIXME should be a page's worth, or go to bottom
+    if(items_shown > 0){
+      for(int i = 0 ; i < items_shown ; ++i){
+        ncmultiselector_nextitem(n);
+      }
+    }
     return true;
   }else if(nc->id == NCKEY_PGUP){
-    ncmultiselector_previtem(n); // FIXME should be a page's worth, or go to top
+    if(items_shown > 0){
+      for(int i = 0 ; i < items_shown ; ++i){
+        ncmultiselector_previtem(n);
+      }
+    }
     return true;
   }else if(nc->id == NCKEY_SCROLL_UP){
     ncmultiselector_previtem(n);