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1
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2
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3
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4
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- The designer sketches with pen and paper
- The observer interprets the sketch
- The observer and designer interact
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5
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- Conceptual mechanical design
- Client
- Low level sketch understanding
- Recognize sketch as mechanical device
- Server
- Simulate the recognized device
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6
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- Low level sketch processing
- Domain level recognition
- Connection to existing design tools
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7
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- Learn to use the low level recognition toolkit
- Learn how to build a simple sketching interface with the toolkit
- Build your own interface to Xfig
- And now, on to the Toolkit…
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8
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- Given a freehand stroke, generate a geometric primitive
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9
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- Higher level recognition (i.e., can’t recognize squares, rectangles,
domain specific shapes)
- Gesture recognition
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10
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11
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12
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- edu.mit.sketch.toolkit
- Recognition related classes are here
- edu.mit.sketch.geom
- edu.mit.sketch.ui
- User interface related classes
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13
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- edu.mit.sketch.ui
- edu.mit.sketch.toolkit
- StrokeData
- SimpleClassifier
- edu.mit.sketch.geom
- GeneralPath
- Polygon
- Line
- Ellipse
- Point
- Rectangle
- Useful to skim:
- edu.mit.sketch.ui.TicTacToe
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14
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- SketchPanel
- extends javax.swing.JPanel
- Gathers stroke data
- Displays raw strokes as they are drawn
- Has methods for adding and removing StrokeDataListeners
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15
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- This class holds and computes stroke related information such as points
in the stroke, pen speed, curvature…
- The constructor takes an array of points
- SketchPanel creates this object after each mouse up event
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16
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- Constructor takes a StrokeData object
- Has a method int classify()
- This method returns an int indicating the type of the approximation
generated by the toolkit
- Compare the result against the following using a switch statement
- SimpleClassifier.LINE
- SimpleClassifier.ELLIPSE
- SimpleClassifier.POLYGON
- SimpleClassifier.COMPLEX
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17
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- One can also check for a particular type by
- SimpleClassifier.isLine()
- SimpleClassifier.isEllipse()
- SimpleClassifier.isPolygon()
- SimpleClassifier.isComplex()
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18
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- Once the type is determined, the approximation can be accessed by
- Line getLineApproximation()
- Ellipse getEllipseApproximation()
- Polygon getPolygonApproximation()
- GeneralPath getComplexApproximation()
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19
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- Line extends java.awt.geom.Line2D.Double
- Ellipse extends java.awt.geom.Ellipse2D.Double
- Polygon extends java.awt.Polygon (except must be closed explicitly)
- Point extends java.awt.Point
- GeneralPath extends java.lang.Object
- Internally stores a java.awt.geom.GeneralPath instance
- Rectangle extends java.lang.Object
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20
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- GeneralPath consists of a sequence of lines and curves
- Curved portions are described by the end points (u, v) and two control
points
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21
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- PathIterator pi= general_path.getPathIterator( new AffineTransform() );
- int type = 0;
- float coefficients[] = new float[6];
- while ( !pi.isDone() ) {
- type = pi.currentSegment( coefficients );
- switch ( type ) {
- case pi.SEG_CUBICTO :
- Util.printArray( coefficients, 6 );
- break;
- case pi.SEG_LINETO :
- Util.printArray( coefficients, 2 );
- break;
- ...
- default:
- System.out.println( "Error" );
- }
- pi.next();
- }
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22
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- GeneralPath, Line, Point, and Ellipse implement
edu.mit.sketch.geom.GeometricObject
- GeometricObjects are Paintable and Translatable
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23
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24
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- Compile
- Try running TicTacToe
- See how it uses the toolkit and the SimpleClassifier
- Best strategy for understanding the control flow: find the
handleStroke() method in TicTacToe.java
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25
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- java 1.3
- Use the make facility
- Things to watch out for
- Make sure the class path is set up
- There is a DLL for the windows platform
- No static libraries for Unix or Linux
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26
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- Javadoc documentation is included with toolkit
- Questions: contact Metin Sezgin mtsezgin@ai.mit.edu
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Notes
