Signals¶
Overview¶
Signals are the most efficient way for GUI applications to communicate
when events occur to other parts of the application. The Eye uses
pyqtSignal objects. When the Eye starts up, the signals are
connected to various functions, denoted as a pyqtSlot in the control
functions of the Eye. When the signal is activated with the emit method
from anywhere in the Eye, the connected function is called.
Defined¶
The available signals are defined in the
Signals class. All
connections are configured in the
Setup class.
Used¶
The signals used by the Eye can be classified in a few different categories.
Figure needs to be updated - atrophy - atrophy_bg_partial - atrophy_bg_full
GUI needs to be updated - refresh_order_list - update_pane_tree
GUI was changed - axis_limits_changed - axis_scale_changed - axis_field_changed
A button was pushed - current_pane_changed - display_selected_model - remove_data - clear_selection - end_selection
Figure Updates¶
Occasionally the figure itself is out of date. This could be for several reason, such as a new pane is added, the x-axis units have changed, or the cursor moved across the figure. Having the figure update itself constantly just to catch any possible changes would be inefficient. Instead the Eye uses the atrophy system, described in detail in Atrophy System, controlled by the state of three variables:
view.stale
view.stale_background_partial
view.stale_background_full
If the background of the plot has not be changed (ie all axis parameters are the same) then only “view.stale” is atrophied. If the background needs to be updated but the axis scales are still valid, then “view.stale_background_partial” is atrophied. If the axis scale is no longer valid, then “view.stale_background_full” is atrophied. When the figure refresh check next occurs, the stale variables will be checked, and if any are true, then the figure is updated.
GUI Has Changed¶
One of the ways to customize the figure is by changing the values in the control fields in the GUI, such as setting the axis limits or changing the axis scale. When anything in the GUI controls change, the corresponding signal is emitted, which will result in the correct figure update signal being emitted as discussed in Figure Updates. The figure will then refresh to reflect the current state of the controls.
GUI Updates¶
The GUI controls are not the only mechanism through with the figure can be updated. For example, the user could select a range over which the figure should zoom in to. In that case, the limits displayed in the controls are no longer accurate. The GUI update signals tell the controls to refresh to match the current state of the figure. This is the reverse of the signals discussed in GUI Has Changed.