bugfix: don't process most keys if cursor is out of view

I think the only situation this can happen is after pressing C-a to
select a file (that doesn't fit on screen). But it's important for
potential forks, e.g. positioning editors on infinite surfaces.

edit.lua

@@ -330,21 +330,32 @@ function edit.text_input(Editor, t)
   if Editor.search_term then
     Editor.search_term = Editor.search_term..t
     Text.search_next(Editor)
-  elseif Editor.cursor.mode == 'drawing' and Editor.current_drawing_mode == 'name' then
+    return
+  end
+  if edit.to_coord(Editor, Editor.cursor) then return end  -- cursor is off screen
+    -- to be precise, the top-left corner of the cursor is off screen
+    -- for drawings the cursor is large, which can still be a bit strange
+    -- large selections can also be strange, though the actual cursor would still be small
+  if Editor.cursor.mode == 'drawing' and Editor.current_drawing_mode == 'name' then
+    -- TODO: there's a bug here where the point being named may be off screen
+    -- To hit that bug you'd have to press C-n to go into point naming mode
+    -- while the cursor is on screen, then move the page somehow without going
+    -- out of naming mode.
     local before = snapshot(Editor, Editor.cursor.line)
     local drawing = Editor.lines[Editor.cursor.line]
     local p = drawing.points[drawing.pending.target_point]
     p.name = p.name..t
     record_undo_event(Editor, {before=before, after=snapshot(Editor, Editor.cursor.line)})
   else
-    -- why is this here?
     Text.text_input(Editor, t)
   end
   schedule_save(Editor)
 end
 
 function edit.keychord_press(Editor, chord, key)
+  local cursor_on_screen = edit.to_coord(Editor, Editor.cursor)
   if Editor.selection1.line and Editor.cursor.mode == 'text' and
+      cursor_on_screen and
       -- printable character created using shift key => delete selection
       -- (we're not creating any ctrl-shift- or alt-shift- combinations using regular/printable keys)
       (not shift_down() or utf8.len(key) == 1) and
@@ -411,7 +422,7 @@ function edit.keychord_press(Editor, chord, key)
       schedule_save(Editor)
     end
   -- clipboard
-  elseif chord == 'C-a' then
+  elseif chord == 'C-a' and cursor_on_screen then
     Editor.selection1 = {line=1, pos=1}
     Editor.cursor = {mode='text', line=#Editor.lines, pos=utf8.len(Editor.lines[#Editor.lines].data)+1}
   elseif chord == 'C-c' then
@@ -419,13 +430,13 @@ function edit.keychord_press(Editor, chord, key)
     if s then
       love.system.setClipboardText(s)
     end
-  elseif chord == 'C-x' then
+  elseif chord == 'C-x' and cursor_on_screen then
     local s = Text.cut_selection(Editor, Editor.left, Editor.right)
     if s then
       love.system.setClipboardText(s)
     end
     schedule_save(Editor)
-  elseif chord == 'C-v' then
+  elseif chord == 'C-v' and cursor_on_screen then
     -- We don't have a good sense of when to scroll, so we'll be conservative
     -- and sometimes scroll when we didn't quite need to.
     local before_line = Editor.cursor.line
@@ -478,7 +489,7 @@ function edit.keychord_press(Editor, chord, key)
       end
     end
     schedule_save(Editor)
-  else
+  elseif cursor_on_screen then
     Text.keychord_press(Editor, chord)
   end
 end