Custom GUI controls

So many controls...

Yet there are never enough. Creating your own custom controls that act just the way you want them is an obsession of almost every GUI programmer. Godot provides plenty of them, but they may not work exactly the way you want. Before contacting the developers with a pull-request to support diagonal scrollbars, at least it will be good to know how to create these controls easily from script.

Drawing

For drawing, it is recommended to check the Custom drawing in 2D tutorial. The same applies. Some functions are worth mentioning due to their usefulness when drawing, so they will be detailed next:

Checking control size

Unlike 2D nodes, “size” is very important with controls, as it helps to organize them in proper layouts. For this, the Control.get_size() method is provided. Checking it during _draw() is vital to ensure everything is kept in-bounds.

Checking focus

Some controls (such as buttons or text editors) might provide input focus for keyboard or joypad input. Examples of this are entering text or pressing a button. This is controlled with the Control.set_focus_mode() function. When drawing, and if the control supports input focus, it is always desired to show some sort of indicator (highight, box, etc) to indicate that this is the currently focused control. To check for this status, the Control.has_focus() exists. Example

func _draw():
    if (has_focus()):
         draw_selected()
    else:
         draw_normal()

Sizing

As mentioned before, size is very important to controls. This allows them to lay out properly, when set into grids, containers, or anchored. Controls most of the time provide a minimum size to help to properly lay them out. For example, if controls are placed vertically on top of each other using a VBoxContainer, the minimum size will make sure your custom control is not squished by the other controls in the container.

To provide this callback, just override Control.get_minimum_size(), for example:

func get_minimum_size():
    return Vector2(30,30)

Or alternatively, set it via function:

func _ready():
    set_custom_minimum_size( Vector2(30,30) )

Input

Controls provide a few helpers to make managing input events much easier than regular nodes.

Input events

There are a few tutorials about input before this one, but it’s worth mentioning that controls have a special input method that only works when:

  • The mouse pointer is over the control.
  • The button was pressed over this control (control always captures input until button is released)
  • Control provides keyboard/joypad focus via Control.set_focus_mode().

This function is Control._gui_input(). Simply override it in your control. No processing needs to be set.

extends Control

func _gui_input(ev):
   if (ev is InputEventMouseButton and ev.button_index==BUTTON_LEFT and ev.pressed):
       print("Left mouse button was pressed!")

For more information about events themselves, check the InputEvent tutorial.

Notifications

Controls also have many useful notifications for which no callback exists, but can be checked with the _notification callback:

func _notification(what):

   if (what==NOTIFICATION_MOUSE_ENTER):
      pass # mouse entered the area of this control
   elif (what==NOTIFICATION_MOUSE_EXIT):
      pass # mouse exited the area of this control
   elif (what==NOTIFICATION_FOCUS_ENTER):
      pass # control gained focus
   elif (what==NOTIFICATION_FOCUS_EXIT):
      pass # control lost focus
   elif (what==NOTIFICATION_THEME_CHANGED):
      pass # theme used to draw the control changed
      # update and redraw is recommended if using a theme
   elif (what==NOTIFICATION_VISIBILITY_CHANGED):
      pass # control became visible/invisible
      # check new status with is_visible()
   elif (what==NOTIFICATION_RESIZED):
      pass # control changed size, check new size
      # with get_size()
   elif (what==NOTIFICATION_MODAL_CLOSED):
      pass # for modal popups, notification
      # that the popup was closed