Gesture recognition

You can easily use these class to create new gesture, and compare them:

from kivy.gesture import Gesture, GestureDatabase

# Create a gesture
g = Gesture()
g.add_stroke(point_list=[(1,1), (3,4), (2,1)])
g.normalize()

# Add him to database
gdb = GestureDatabase()
gdb.add_gesture(g)

# And for the next gesture, try to find him !
g2 = Gesture()
# ...
gdb.find(g2)

Warning

you don’t really want to start from such an example, this is more to get the idea how one would construct gestures dynamically, but you would need a lot more points, it’s better to record gestures in a file, and reload them to compare latter, look into the examples/gestures directory for an example of how to do that.

class kivy.gesture.Gesture(tolerance=None)

A python implementation of a gesture recognition algorithm by Oleg Dopertchouk: http://www.gamedev.net/reference/articles/article2039.asp

Implemented by Jeiel Aranal (chemikhazi@gmail.com), released into the public domain.

add_stroke(point_list=None)

Adds a stroke to the gesture and returns the Stroke instance. Optional point_list argument is a list of the mouse points for the stroke.

dot_product(comparison_gesture)

Calculates the dot product of the gesture with another gesture

get_rigid_rotation(dstpts)

Extract the rotation to apply to a group of points to minimize the distance to a second group of points. The two groups of points are assumed to be centered. This is a simple version that just pick an angle based on the first point of the gesture.

get_score(comparison_gesture, rotation_invariant=True)

Returns the matching score of the gesture against another gesture

normalize(stroke_samples=32)

Runs the gesture normalization algorithm and calculates the dot product with self

class kivy.gesture.GestureDatabase

Bases: object

Class to handle a gesture database.

add_gesture(gesture)

Add a new gesture in database

find(gesture, minscore=0.9, rotation_invariant=True)

Find current gesture in database

gesture_to_str(gesture)

Convert a gesture into a unique string

str_to_gesture(data)

Convert a unique string to a gesture

class kivy.gesture.GestureStroke

Gestures can be made up of multiple strokes

add_point(x=x_pos, y=y_pos)

Adds a point to the stroke

center_stroke(offset_x, offset_y)

Centers the stroke by offseting the points

normalize_stroke(sample_points=32)

Normalizes strokes so that every stroke has a standard number of points. Returns True if stroke is normalized, False if it can’t be normalized. sample_points control the resolution of the stroke.

points_distance(point1=GesturePoint, point2=GesturePoint)

Returns the distance between two GesturePoint

scale_stroke(scale_factor=float)

Scales the stroke down by scale_factor

stroke_length(point_list=None)

Finds the length of the stroke. If a point list is given, finds the length of that list.