Stimulus Display¶

Description¶

A stimulus display device.

At present, MWorks creates one (and only one) of these automatically when needed, regardless of whether the experiment file defines one. By including a definition in your experiment file, you can change the display’s default background color and configure its run-time behavior.

Note: Start IO Device, Stop IO Device, and autostart have no effect on this device.

Signature¶

iodevice/stimulus_display

Optional Parameters¶

background_color¶

Default: 0.5,0.5,0.5

The background color, expressed as a comma-separated list of red, green, and blue components. Each component may be described by any valid expression, but the expression must result in a value between 0 and 1 (inclusive).

background_alpha_multiplier¶

Default: 1.0

Controls the transparency of the background. 1.0 is fully opaque, while 0.0 is fully tranparent.

Note: To enable background transparency, you must set #mainScreenInfo’s make_window_opaque key to false. To make the stimulus display window fully transparent, set this parameter and all components of background_color to 0.

redraw_on_every_refresh¶

Default: NO

If YES, the display will be redrawn during every refresh cycle. If NO, the display will be redrawn only when needed or when explicitly requested via Update Stimulus Display.

announce_stimuli_on_implicit_updates¶

Default: YES

Controls the announcement of stimuli during “implicit” display updates (i.e. updates requested by running dynamic stimuli and not triggered by an explicit Update Stimulus Display action). If set to NO, #stimDisplayUpdate events for implicit updates will contain only the number of stimuli displayed (in place of the usual list of stimulus parameters).

capture_format¶

Options: none

JPEG

PNG
Default: none

Format in which to capture display frames.

If none, display frames will not be captured. Otherwise, for every display redraw for which capture_enabled evaluates to true, the contents of the display will be captured in the specified format, at the resolution determined by capture_height_pixels, and stored (as binary data) in the variable #stimDisplayCapture.

capture_height_pixels¶

Default: 0

Height (in pixels) of captured display frames.

If the value of this parameter is less than or equal to zero, frames will be captured at the full height and width of the display. Otherwise, each frame will be scaled down to the specified height, with the width chosen to match the aspect ratio of the display.

Note: The cost of frame capture, in terms of both CPU usage and required storage space, depends almost entirely on the size of the captured frames. If you experience performance issues with capture enabled, try reducing the value of this parameter.

capture_enabled¶

Default: YES

If capture_format is not none, every time the display redraws, it will test the value of this parameter. If the parameter evaluates to a true value (e.g. 1, true), the current frame will be captured.

By setting this parameter to the name of a variable, your experiment can dynamically enable or disable frame capture by assigning a true or false value, respectively, to the variable. This allows you to capture frames only when needed.

autostart¶

Default: NO

If YES, the device will start I/O automatically (as if by an implicit Start IO Device action) when the experiment starts running.

Note: Device I/O will always stop automatically when the experiment stops running, irrespective of this setting.

alt¶

Alternative device to use if this one fails to initialize (e.g. because the required hardware is not available). If #allowAltFailover is set to 0 or false, this parameter is ignored.

Placement¶

Allowed at top level:	Yes
Allowed parent:	Folder