GestureBuilder class (Android)

Objects of this type hold the touch strokes information needed to replay gesture(objectOrName, touches). An instance of this class is returned by readGesture(gesture-file). Strokes are defined by screen coordinates points, pressure and touch size.

For examples of how GestureBuilder objects can be used to manipulate the gesture information, see How to Use the GestureBuilder class.

int GestureBuilder.areaWidth

The width of the area in which this gesture is defined. This will be the device or emulator screen width.

int GestureBuilder.areaHeight

The height of the area in which this gesture is defined. This will be the device or emulator screen height.

All GestureBuilder methods listed in the Gesture creation and Gesture manipulation section, return the GestureBuilder object itself, unless specified differently.

Gesture creation

This section lists the methods for manually creating a GestureBuilder object.

GestureBuilder(width, height, unit)

GestureBuilder(xml)

Two constructor functions for creating a GestureBuilder object. The width and height are the target screen size. The unit can be either 0 or 1, meaning respectively in pixels or millimeters. The constants GestureBuilder.Pixel and GestureBuilder.MilliMeter can be used as well.

The second constructor function constructs a GestureBuilder object by passing a string containing XML, which should be in the same format as the recorded gesture files.

Object GestureBuilder.addStroke(x, y)

Object GestureBuilder.addStroke(startTime, x, y)

Object GestureBuilder.addStroke(startTime, x, y, pressure)

Object GestureBuilder.addStroke(startTime, x, y, pressure, size)

Starts a new stroke. The whole movement of one finger or pen from touch down to releasing the screen is called a stroke. The touch down coordinate is (x, y). For the non-first stroke, a time offset can be specified in milliseconds using the startTime argument. Strokes cannot be disjointed in time, at least one finger or pen has to be down during the whole gesture. The maximum simultaneous touches is device dependent.

Finally, the pressure and size are relative messure values for respectively pen or finger pressure and size. These should be between 0.0 and 1.0 and when omitted defaults to 0.25.

Object GestureBuilder.curveTo(duration, controlX, controlY, endX, endy)

Object GestureBuilder.curveTo(duration, control1X, control1Y, control2X, control2Y, endX, endy)

Adds a bézier curve movement to the latest added stroke in duration milliseconds. The curve starts with the end coordinate of the last added movement or, if none added to the stroke, the stroke touch down coordinate. The end coordinate is specified with endX and endY. One or two so called control points can be used.

Object GestureBuilder.lineTo(duration, endX, endy)

Adds a line movement to the latest added stroke in duration milliseconds. The line starts with the end coordinate of the last added movement or, if none added to the stroke, the stroke touch down coordinate. The end coordinate is specified with endX and endY.

Object GestureBuilder.build()

Creates the gesture from the added strokes and movements. After calling this method, no strokes or movements can be added.

Gesture manipulation

Object GestureBuilder.accelerate(factor)

Changes stroke speed given a factor. A factor between 0.0 and 1.0 slows down the gesture, above 1.0 will speed it up.

Object GestureBuilder.rotate(degrees)

Object GestureBuilder.rotate(degrees, originX, originY)

Rotates the strokes. The degrees is the agle in degrees in a counter clockwise direction. The originX and originY define the origin of the rotate operation. If omitted, the area center is taken as origin.

Object GestureBuilder.scale(scale)

Object GestureBuilder.scale(scaleX, scaleY)

Object GestureBuilder.scale(scaleX, scaleY, originX, originY)

Changes the size of the strokes. The scaleX is the scale factor in the horizontal direction and scaleY in the vertical direction. The originX and originY define the origin of the scale operation. If omitted, the area center is taken as origin. When also scaleY is omitted, the scaling is homogeneous in both directions.

Object GestureBuilder.translate(x, y)

Moves the strokes. The x and y specifies the movement. A positive value for x moves the strokes to the right and a positive value for y moves the strokes downwards.