controllerCircle

Description

Performs a circular movement animation, moving the element in a circular orbit around a center onto the 2D plane. The last performed movement is remembered and at any time during or after it you can order performing it backwards or repeat it.

Applies one translate transform. The eliptical trajectory is described by x_radius and y_radius, and its center is supplied by x_center and y_center. The center coordinates are relative to the element's layout position. If parameter is_path is set (to true), then no translation is applied but its coordinates are kept for other controllers that read a 'path' from this controller.

Parameters

Visit page Controller # Common Parameters for documentation on the parameters, common to all controllers: id, paused and disabled.

Coordinate/Size Parameters: Note that all parameters representing screen coordinates or sizes also accept relative values as percentages of own/parent/viewport/document size or coordinates relative to own/parent/viewport/document's origin. For more information, visit page Controller # Coordinate Parameters.

Parameters of circle():

duration

Duration of the animation in milliseconds. Default value: 1000

x_radius, y_radius

Radiuses of the elliptical trajectory in the 2D plane. Default values: 50, 50

x_center, y_center

The elliptical trajectory's center coordinates in the 2D plane. Default values: 0, 0

angle

Angle (in degrees) specifying the part of ellipse to travel. Positive angles denote clockwise movement. The starting position (angle) can be supplied with the init_angle parameter. Default value: 0

init_angle

Set initial position (angle) onto the elliptical trajectory. Note that the displacement will be applied immediately (when the controller is enabled), not waiting for the movement to be started with any of the start messages. Default value: 0

marked_angle

If different than -1, then the controller will fire event mark each time the rotation passes through this absolute angle. Default value: -1

is_path

If true, then the controller will not apply the translation tranform, but will keep the coordinates, so that other controllers can use them as a 'path'. Default value: false

repeat_start_pos

If true, then every start or start_back message will start a forward/reverse movement from the direction's starting position. If false (by default), then sending these messages when a movement is already started will continue the current movement (if already moving in the same direction), or will start a movement in the opposite direction, but continuing from the current position. This parameter has no effect on the start_new or start_new_back messages, as they start a new movement from the current position in all cases. Default value: false

register_actions

Tells whether to handle the element's show, hide, show_immediately and hide_immediately actions.
Values: false / true / "500" (i.e. react with 500 milliseconds delay) / "500 elm" (i.e. set event handlers with delay 500ms for HTML element #elm's actions). Default value: false

half_step

If set to less than 1, each frame the current angle will step closer to the required angle, where step = half_step * distance_to_required_angle. Values in the range (0 - 1) make sense. Default value: 1

spring_acc

If bigger than 0, the animated angle will behave as if attached to a spring. Bigger values of spring_acc result in stronger pulling of the "spring" and faster motion (i.e. shorter spring period). Note that setting too high of a value will cause a self-amplifying spring motion of the animated angle. What is the highest value before the positive feedback kicks in depends on the value of spring_vdamp, but values up to 2 are always safe. Default value: 0

spring_vdamp

When spring motion is enabled via parameter spring_acc, every frame the current speed of the spring is multiplied by this parameter, effectively slowing the spring motion. Values between 0 and 1 are reasonable, where smaller values result in faster dying of the spring motion and a value of 1 means absolute elasticity of the spring. Default value: 0.92

ease_type

What kind of 'easing' to be applied on the movement.
Currently supported values:

• "linear" - constant speed in all movement parts,
• "ease" - slower start and end of movement, elliptical shape,
• "ease_in" - slower start, fast and sudden end,
• "ease_out" - fast and sudden start, slow end.

Default value: "ease"

ease_amount

Strength of 'easing' to be applied on the movement.
Values in the range (0 - 1] make sense, though values greater than 1 (up to 2-3) can also be of use. Default value: 1

ease_mirror

Tells if the easing applied on 'backwards' movement is the same as the forward easing, or mirrored. If this parameter is set to true and parameter ease_type is "ease_in", then upon a backwards movement, "ease_out" easing will be applied. Default value: false

Accepted Messages

Visit page Controller # Common Messages for documentation on the messages, accepted by all controllers: pause, unpause, enable, disable, params and remove.

Message Parameters: Note that along the message parameters specific to each message type, every message (not only params) accepts as parameters any of the controller parameters, which are set before the message is executed.

Messages accepted by circle():

start

Starts a movement from the current angle to the target angle. The message has no effect if already in the target angle or moving towards it. If currently moving in the 'backwards' direction (from the target to the starting angle, ordered with messages start_back and start_new_back), then the movement direction will be switched to 'forwards' and the 'forward' movement will continue from the current position to the target position. Message params: none

start_back

Starts a 'backwards' movement from the current angle to the starting angle of the current forward movement. The message has no effect if already in the starting angle or moving towards it. Message params: none

start_reverse

Start moving in the reverse direction within the current (or last) movement. Message params: none

start_new

Same as the start message, but does not continue a current movement. It always starts a new movement from the current angle to the supplied target angle. Message params: none

start_new_back

Start the 'backwards' motion (i.e. starting from the target angle) of a new movement. So, calling controller.message('start_new_back', {angle: 20}) will cause the element to jump 20 deegrees clockwise and then start moving backwards to the current angle. Message params: none

pos0

Position the element in the starting angle of the current movement immediately. Message params: none

pos1

Position the element in the target angle of the current movement immediately. Message params: none

Generated Events

Visit page Controller # Common Events for documentation on the events, generated by all controllers: frame, remove, paused, unpaused enabled and disabled.

Events fired by circle():

start

Fired upon starting a (forward) movement, as long as not already on the target angle. Event params: none

half

Fired upon reaching the middle of the current (forward) movement. Event params: none

end

Fired upon reaching the end of the current (forward) movement. Event params: none

cycle

When performing a movement of an angle greater in absolute value than 360 degrees, this event is fired upon passing every 360 degrees (full turn) counting from the starting angle of the movement. Event params: none

mark

If parameter marked_angle is supplied (i.e. is different than -1), then this event is fired upon every passing of this marked angle. The value of the angle is absolute, and not relative to the starting angle for the movement. Event params: none

start_back

Fired upon start of backwards movement. Event params: none

half_back

Fired upon reaching the middle of the current backwards movement. Event params: none

end_back

Fired upon reaching the end of the current backwards movement. Event params: none

cycle_back

Same as the cycle event, but is fired when performing a 'backwards' movement. Note that the event is fired on every passing of the starting angle of the current 'forward' movement, not on every passing of 360 degrees counting from the start of the backwards movement. Event params: none

mark_back

Same as the mark event, but is fired when performing a 'backwards' movement. Event params: none

pos0

Fired upon reaching the starting angle when moving backwards, i.e. it is fired when end_back is fired. Event params: none

pos1

Fired upon reaching the target angle when moving forward, i.e. it is fired when end is fired. Event params: none

Interaction with DOM

• Transforms: Applies one translate transform.
• CSS: Works with any styling. Does not set any style properties.
• Events: Does not set event listeners.

Changes Log

1. Controller introduced in v.0.80

See Also