GDI Canvas Element

Summary ¶

	GDI canvas
Info
Category:	Visual Stimuli		AddIn:	Base Layer
Creator:	OkazoLab		Scope:	Parent event
Owns Snippets:	None		Usage:	Stimulus screen

Properties ¶

Name	Description	Constraints	Type	On runtime change
Visual Appearance
Background Color	Background color for canvas.	Normal..	stColor
Alpha Masking	Defines, whether the visual content is used to create an opacity mask on the event surface. If masking is on, the content's pixel luminance (or, its inverse) defines transparency within element's viewport. The alpha masking allows, for example, create transparent holes on the event surface.	Design Time..	Int32
AntiAliasing	if true, the rendered content will be antialiased for smoother visual appeariance. If false, rendering will be authentic to its source, e.g. a bitmap.	Normal..	Boolean
Position	Defines a position of the rendering viewport on the screen	Normal..	clPoint
Size	Defines a size of the element's rendering viewport on the screen	Normal..	clSize
Z Order	Indicates Z Order of the element on the given event	Status..	Int32
Pivot Point	Defines alignment of the pivot point (or, element's position) relative to element's rendering area. The pivot point sets the center of element's rotation and scale directions.	Normal..	stAlig..
Visible	Defines whether the element is visible	Normal..	Boolean
Rotation	Rotation angle in degrees	Normal..	Double
Run Time
Graphics Class	Returns a core GDI+ class (Graphics type) that provides a set of drawing functions. Drawing operations are invoked via class's methods, e.g. GraphicsClass.DrawEllipse(...);	Normal..	Graphi..
Update Canvas Now	Returns a core GDI+ class (Graphics type) that provides a set of drawing functions. Drawing operations are invoked via class's methods, e.g. GraphicsClass.DrawEllipse(...);	Normal..	Boolean
Effects
Transparent Color	The color of the original pixels of rendered content that will be set as transparent	Normal..	stColor
Transparent Tolerance	Tolerance ratio for choosing colors that become transparent. Zero means that effect is not applied, 1 denotes that all colors will become trasparent	Normal..	Int32
Color Mask	Produces a multiplicative combination of the original pixels and the selected mask color (except the alpha channel).  The effect emulates a look through a colored glass.  White or transparent mask color dont change the original pixels	Normal..	stColor
Opacity	Opacity of the rendered content	Normal..	Int32
Contrast	Contrast of the rendered content	Normal..	Int32
Brightness	Brightness the rendered content	Normal..	Int32
Saturation	Saturation of the rendered content	Normal..	Double
Pixelation	Pixelation of the rendered content	Normal..	Int32
Blurring	The radius used in the gaussian blur of rendered content, as a pixel-based factor. The default is 0 which means no blurring.	Normal..	Int32
Scrambling		Normal..	Double
Scrambling Grid Size	Defines a size of the scrambling grid	Normal..	clSize
Positional Jitter
Reset Jitter Now	Runtime command that resets the positional jitter.	Runtime Command..	Boolean
Current Jitter	Returns the current jitter	Status..	clPoint
Jitter Range	Defines a possible range for the random jitter. The range is centered to the position of the element.	Normal..	clSize
Test Jitter	Click to test the current jitter	Design Time..	Boolean
Control
Is Enabled	If set to false the element is completely omitted when the experiment is run	Design Time..	Boolean
Title	Title of the element	Design Time..	String

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Description ¶

Snapshots ¶

Example canvas

Example code

Practical Use ¶

 Graphics.DrawRectangle(new Pen(Color.Red), 20,20,248,162); 

Step by Step: Adding a GDI Canvas element ¶

1. On an event, click "Add Element", under the "VISUAL STIMULI" category, select the "GDI canvas" element.
2. Double click on the black square that appears.
3. Create a proxy variable from the "Graphics" property, e.g "Graphics"
4. In the bottom 'Snippets' panel, under 'Preparation', click on the 'Start' Snippet.
5. add the following code:
   
   

    Graphics.DrawRectangle(new Pen(Color.Red), 20,20,248,162); 

   
   

Notes ¶

• The drawing coordinates in your code have to be inside of the range defined by the size of the GDI Canvas element in pixels, otherwise the drawn content will be cut off.
• The GDI canvas element remembers its rendered state even if the parent event is deactivated and activated again. To clear the drawn graphics use the GDI Clear() function.