Keypad press function

Shortcuts and menus to graphical utilities (scale, zoom, translation and initialization)

This function consists of a set of figure callbacks adding graphical utilities through keypad and context menus. The created shortcuts allow, in the specified axes, the following operations :
- Keypad press function :
+ zoom : [-] [+]
+ translation : [7] [8] [9] [4] [6] [1] [2] [3]
+ initialization : [5]
- Context menus (right click) :
+ "Scale" :
. "Linear scale"
. "Linear-log. scale"
. "Log.-linear scale"
. "Log. scale"
+ "Zoom" :
. "X only"
. "Y only"
. "XY"