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Element Icon Ink Canvas
Info
Category: Behavioural Input AddIn: Base Elements
Creator: OkazoLab Team Scope: Parent Event
Owns Snippets: no Usage: Snippets

Synchronized Internal Actions

Experiment StartParent Event OnsetStatus change between Onset/OffsetParent Event OffsetExperiment End
Shows the canvas area and starts to record drawing movements, as a pen or mouse is pressed within the canvas area. Hides the canvas area and stops recording drawing movements.

Properties

Generic Properties

NameDescriptionConstraintsValue TypeUpon Runtime Change
Settings
Reset On OnsetDefines whether the old canvas strokes and text recognition results are erased on the onset of the parent event..Boolean.
Normal Tip ModeSpecifies the mode of the pointing device as it interacts with the canvas.enum, Int32.
Inverted Tip ModeSpecifies the mode of the inverted pointing device as it interacts with the canvas (e.g. with the inverted tip of a stylus).enum, Int32.
Drawing Attributes
Behold PressureDefines whether the thickness of a rendered stroke changes according the amount of pressure applied (if an input device can report a pressure).Boolean.
Is HighlighterDefines whether the rendered stroke looks like a highlighter (semi-transparent)..Boolean.
Pen SizeDefines a size of the drawing pen..clSize.
Pen ColourDefines a color of the drawing pen..stColor.
Drawn ColorDefines a color that highlights the currently drawing stroke. When a stroke is finished, it turns back to the pen color. No highlighting is applied, when the transparent color (0,255,255,255) is selected..stColor.
SmoothingDefines whether Bezier smoothing is automatically applied for stroke rendering on the canvas area..Boolean.
Pen ShapeDefines a shape of the drawing pen. Assign 0 for rectangle and 1 for ellipse..enum, Int32.
Canvas BackgroundDefines the background of the ink canvas..stColor
Actions
Clear Canvas NowSet to true to clear the canvas area and erase all recorded strokes...
Save Ink File NowAssign a fully specified filename to save the current strokes to a file at runtime..
Open Ink File NowAssign a fully specified filename to load strokes from a file at runtime. Only the Ink Serialized Format (.isf) files are supported...
Recognize Text NowAssign true to initiate text recognition on the canvas. The result is returned via Recognized Text property...
Runtime Status
Stroke NumberReturns a number of drawn strokesInt32.
Recognized TextReturn a recognized text in a result of the Recognize Text actionString.
Recognition Confidence Return a confidence rank in results of the Recognize Text actionString.

+=== Properties inherited from clVisualElement ===
NameDescriptionConstraintsValue TypeUpon Runtime Change
VISUAL APPEARANCE
Alpha MaskingDefines whether the visual content rendered by this element will be used as an opacity mask which is applied onto the given event surface. The active opacity mask allows one to expose pixels of the parent event surface through a solid background of the given event. If the value is true, the darker pixels of the content will make more transparent holes on the entire event surface.Boolean
AntiAliasingIf true, the rendered content will be anti-aliased for smoother visual appearance. If false, rendering will be authentic to its source, e.g. a bitmap. Boolean
PositionDefines the position of the element viewport on the screen. The position can be set in any of three coordinate systems: a) pixels, b) polar, c) central. clPoint
SizeDefines the size of the element viewport on the screen. The size can be set in any of three coordinate systems: a) pixels, b) visual degrees, c) 'relative-to-screen' size. clSize
Z OrderIndicates the current depth order of the element viewport on the surface of the parent event. The greatest number corresponds to the top position. The order can be changed by moving the element up and down in the element list.Int32
Pivot PointDefines the pivot point (coordinate and the rotation centers) within the element viewport. stAlignment or Int32
VisibleDefines whether the element is currently visible on the event surface. The property is convenient for switching visual content on and off. Boolean
RotationDefines the rotation angle (in degrees) of element viewport relative to the its pivot point. Double in the range 0..360
EFFECTS
Transparent ColorThe color of the original pixels of rendered content that will be set as transparent. stColor
Transparency ToleranceTolerance ratio for choosing colors that become transparent. Zero means that effect is not applied, 1 denotes that all colors will become trasparent. Int32, range (0..100)
Color MaskProduces 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 doesn't change the original pixels. stColor
OpacityOpacity of the rendered content. Int32, range (0..100)
ContrastContrast of the rendered content. Int32, range (-100..100)
BrightnessDefines the brighness of the rendered content. Int32, range (-100..100)
SaturationSaturation of the rendered content. Double
PixelationDefines the pixel scale of the rendering. Int32, range (0..100)
BlurringThe radius used in the gaussian blur of rendered content, as a pixel-based factor. The default is 0 which means no blurring. Int32
POSITIONAL JITTER
Reset JitterSet to true at runtime to reset the current positional jitter.Boolean, set true for action
Current JitterJitter range, in pixels (non inclusive)..clSize
Jitter RangeJitter range, centered at the original position of the element.. clSize

+=== Properties inherited from clElement === Inherited properties of clElement
NameDescriptionConstraintsValue TypeUpon Change
Control
Is EnabledIf set to false the element is completely omitted when the experiment is run.Boolean
TitleTitle of the element.String



The Ink canvas element defines a screen area that receives and displays drawing and writing strokes made by a participant. The strokes can be done with a pen tablet, touchscreen or mouse. The element records explicit statistics of the drawing process, including stroke timing and coordinates/pressure of each dot. (See the demo video below) The element can also recognize handwritten text at request.


Demo video



Snapshots

Experiment Run

Experiment Run

After experiment  Picture Stays in InkCanvas

After experiment
Picture Stays in InkCanvas

Cat Recognized correctly

Cat Recognized correctly

Recorgnized that user  wrote wrong word

Recorgnized that user
wrote wrong word


Practical Use

Creating the Ink Canvas element

  1. Add a new Ink Canvas element to the chosen event.
  2. Adjust the canvas area either in the event surface editor or via element's Position and Size properties.
  3. Adjust other properties of the Ink Canvas canvas element. For example, you can define the canvas background, stroke color and different drawing modes.
  4. Double-click on the canvas area in the event surface editor and try to draw several strokes for testing. Make a double-click again to exit the test mode.
  5. Write code that resets the canvas, requests text recognition and records drawing results in accordance with a logic of your experiment. To control the element at runtime, create proxy variable for the element's properties.
  6. Start the experiment. After the onset of the parent event the element becomes functional.

Saving the drawing results at runtime

  1. Add a new Ink Canvas element to the chosen event and prepare it as described above.
  2. Create proxy variables for the following properties: 'Save Ink File Now' and 'Clear Canvas Now'.
  3. Add the following code in a snippet that is called after a participant completes drawing:
    
    
    SaveInkFileNow="C:\\Data\\Participant_"+ParticipantCode+"_"+DrawingNumber+".csv";
    ClearCanvasNow=true;

    This code saves the collected stroke statistics and resets the made drawing. Note that you need to declare and adjust global variables ParticipantCode and DrawingNumber to form an unique file name (you can use other ID variables).

Using the Ink Canvas element to recognize handwritten text

  1. Add a new Ink Canvas element to the chosen event and prepare it as described above.
  2. Create proxy variables for the following properties: 'Recognize Text Now', 'Recognized Text' and 'Recognition Confidence'.
  3. Add the following code in a snippet that is called after a participant completes writing:
    
    
    RecognizeTextNow=true;
  4. Add the following code in a subsequent snippet that is called after (importantly!) the 'RecognizeTextNow' snippet:
    
    
    string S=RecognizedText; // string S now contains a text recognized by the Ink Canvas;
    string C=RecognitionConfidence; // string C now contains one of the confidence ranks, e.g. 'week', 'average', 'strong'

    if you try to read the RecognizedText or RecognitionConfidence variables before or simultaneously with the 'RecognizeTextNow=true' command, the results wont be yet updated.

Notes

  • When the Ink Canvas element is used in the preview or debug modes, you may see flickering artefacts while doing drawing. Do not worry, these artefacts wont appear, when an experiment is run in he full screen mode.
  • When the Ink Canvas element recognizes handwritten text, it considers all strokes made on the canvas from the left-top to the bottom-right. Thus, the recognition result may contain a text sentence, if multiple words are written on the canvas.
  • When the Reset On Onset property is set to true, the canvas area (all existing strokes) is cleared on the onset of the parent event.
  Name Size
- InkCamel.png 528.37 KB
- InkCamel2.png 742.35 KB
- InkCamel2_sm.jpg 34.75 KB
- InkCamel_sm.jpg 27.46 KB
- InkCanvas.png 3.16 KB
- InKCat.png 196.33 KB
- InKCat_sm.jpg 20.31 KB
- InkHorse.png 252.10 KB
- InkHorse_sm.jpg 23.70 KB

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