The canvasposition attribute specifies the location on the screen of the region on the screen on which visual stimuli are positioned and sized.
<defaults>
x value | The horizontal screen coordinate in pixels, percent(default), or points. |
y value | The vertical screen coordinate in pixels, percent(default), or points. |
Canvasposition specifies the location of the center of canvas. Coordinates are relative to the top left corner of the screen. Thus, a position of (0, 0) is the top left corner, and (0, 100%) is the bottom left cornder.
The canvasposition attribute can be used in combination with the canvasassize and canvasaspectratio attributes to define a rectangle on the screen relative to which all visual stimuli and sized and positioned. These attributes that the relative size and position of stimuli on the screen remains the same across monitors of different shapes and sizes..
The following ensures that visual stimuli are presented in a rectangle that has the same proportions as an 8.5 x 11 inch sheet of paper and that has a left margin of 20% relative to the edge of the screen.
<defaults>
/ canvasasposition=(20%, 0)
/ canvasassize=(80%, 100%)
/ canvasaspectratio=(8.5, 11)
</defaults>