Zoom
Zoombox
The zoombox behavior is simialr as plotly library. When the initial touch and the current touch is lower than dp(20), you can zoom horizontally or vertically. Otherwise, it's only a normal zoombox.
Note
Minimum zoom box is set to dp(20). So if the zoombox is lower than that, zoombox action will be cancel. The user can change this minimum value with "minzoom" kivy property.
horizontal and vertical zoom
If the user what to zoom with 2 fingers in horizontal or vertical only, you can set auto_zoom kivy property to True.
You can also set the angle detection limit (defaul 15deg)
To better understand this option, see ithe image above (with 15deg angle detection):