Talk at EclipseCon Europe 2012, Ludwigsburg, Germany

1. Share and Enjoy!
Alexander Nyßen
itemis AG
4

2. It‘s Bi!hday Time!
[initial contribution of Draw2d/GEF (MVC) by IBM in 2002]
[Zest joined 2007]

3. GEF 3.x / Zest 1.x
• Mature project with quite long history
• Base technology with lot's of users (direct & indirect
through GMF/Graphiti)
• Stable API, no breaking API changes since 2004 (GEF 3.0)
• Ready for CBI (migration to Git, Maven/Tycho completed)
• But API is organically evolved and there are ~400
bugzillas, out of which several require to break it

4. SomeTopics for a Renewal
• Re-thinking current componentization
• Support for the E4 application model
• Support for rotation and other transformations
• Support for curved connections
• Support for other rendering platforms than SWT
• Multi-touch gestures support
• Revision of the command framework
• Revision of connection handling (clipping container)
• Various renamings and restructurings on the detail level...

5. Zest 2 (since 2010)
• A provisional Zest 2 component was initiated in 2010, to
develop the next generation Zest API.
• Development takes place in parallel to maintenance
of Zest 1.x in its own Git repository.
• API is regarded to be provisional up to the final
graduation.
• Results are not provided as part of GEF 3.x / Zest 1.x but
published via Eclipse Marketplace.

6. GEF4 (since 2011)
• GEF4 was initiated - in analogy to Zest 2 - to develop the next
generation Draw2d and GEF (MVC) API.
• Development is to take place in parallel to maintenance of
Draw2d / GEF (MVC) 3.x in its own repository.
• Results are not provided as part of GEF 3.x / Zest 1.x but on own
update-sites.
• Initial plans (prior to 3.8):
• Create new double-precision Geometry API before 3.8.
• Start to migrate the Draw2d and GEF (MVC) code base
afterwards.

7. GEF4 + Zest 2 = GEF4
Modified plan (prior to Juno):
Unification of both approaches after Juno!

8. GEF4 - A Unified Approach
• A unified approach with a shared code base and a
common namespace (org.eclipse.gef4) for all plug-ins.
• Advantages:
• Clear distinction between GEF proper as the
production component and GEF4 as the provisional one
• Chance to not only refactor GEF components but the
componentization itself, which is only "historically"
justified.

9. GEF4 - Status Quo
• GEF4 Geometry component was initiated in 2011, work
has been finalized with the Juno release:
• Functionally complete (at least for now)
• 344 JUnit tests, ~77% instruction coverage
• GEF4 Graphics component was initiated directly after Juno
and is currently under work
• Initial infrastructure and simple example created

10. GEF4 Geometry
• No distinction in low and high precision, but just a single double-
precision API (with built-in imprecision for comparisons).
• Different geometric abstractions for different purposes:
• Euclidean (Vector, Straight,Angle)
• Projective (Vector3D, Straight3D)
• Planar (Point, Dimension, Line, QuadraticCurve, CubicCurve,
BezierCurve, Polyline, PolyBezier, Ellipse, Rectangle, Pie,Arc, Polygon,
CurvedPolygon, RoundedRectangle, Ring, Region, Path)
• Conversions to/from AWT and SWT (and between them)

11. GEF4 Planar Geometry - Features
• Support for "non-standard" geometries:
• Arbitrary Bezier curves, curved polygons
• Approximation via BezierCurves & Interpolation via PolyBeziers
• Characteristics-related core abstractions (IGeometry,
ICurve, IShape, IMultiShape)
• Construction-related base-classes (AbstractRectangleBased-
Geometry,AbstractPointListBasedGeometry,...)
• Direct support for affine transformations (ITranslatable,
IScalable, IRotatable)
• No direct SWT dependencies (SWT-related conversions
bundled in optional plug-in)

12. GEF4 Planar Geometry - Overview

13. GEF4 Planar Geometry - Abstractions

14. GEF4 Planar Geometry - Base Classes

15. GEF4 Geometry - Examples

16. GEF4 Geometry - Sample Code
// Bezier approximation of curves
BezierCurve[] fromCurve = curve.toBezier();
BezierCurve[] fromShape = shape.getOutline().toBezier();
ICurve[] fromPolyShape = polyShape.getOutlineSegments();
List<BezierCurve> beziers = new ArrayList<BezierCurve>();
for (ICurve c : fromPolyShape)
beziers.addAll(Arrays.asList(c.toBezier()));
// PolyBezier interpolation
PolyBezier interpolation = PolyBezier.interpolateCubic(p0, p1, p2, p3, ...);
// support for affine transformations
Polygon rhomb = new Rectangle(10, 10, 10, 10).getRotatedCCW(Angle.fromDeg(45));
PolyBezier slanted = new Ellipse(100, 100, 100, 50).getRotatedCCW(Angle.fromDeg(30));
Ring rotatedClippingArea = region.getRotatedCCW(Angle.fromDeg(300));

17. GEF4 Graphics - Features
• Support for rendering (planar) geometries, images,
and text on an underlying Canvas/Graphics
• Key abstractions (Font, Image, Color) and transparent
support for multiple widget toolkits (AWT, SWT)*
• Grouping of visual properties according to their
respective usage context (BlitProperties, DrawProperties,..)
• Full push/pop/restore of graphics state
• Extensible image processing support (Pixel-Filter,
Channel-Filter, Convolution-Filter)
*) JavaFX already prototyped byTom Schindl

18. GEF4 Graphics - Overview

19. GEF4 Graphics - Examples

20. GEF4 Graphics - Sample Code
final Ellipse ellipse = new Ellipse(50, 50, 350, 200);
final Rectangle rectangle = new Rectangle(100, 160, 125, 220);
final Polygon triangle = new Polygon(260, 170, 190, 300, 330, 300);
g.drawProperties().setLineWidth(4).setAntialiasing(true);
g.fillProperties().setAntialiasing(true);
g.pushState(); // saves the current set of properties on the stack
g.fillProperties().setColor(new Color(255, 0, 0));
g.drawProperties().setDashArray(25, 10).setColor(new Color(128, 0, 0));
g.fill(ellipse);
g.draw(ellipse.getOutline());
g.restoreState(); // restores the previously saved properties
g.fillProperties().setColor(new Color(0, 0, 255));
g.drawProperties().setLineJoin(LineJoin.ROUND)".setLineCap(LineCap.ROUND);
g.fill(rectangle);
g.draw(rectangle.getOutline());
g.popState(); // removes the previously saved properties from the stack
" " " // and enables the prior set of properties
g.fillProperties().setColor(new Color(0, 255, 0));
g.drawProperties().setColor(new Color(0, 128, 0)).setLineJoin(LineJoin.MITER);
g.fill(triangle);
g.draw(triangle.getOutline());

21. GEF4 - Outlook
• Planned on the short term (Kepler):
• Creation of GEF4 Canvas component (FigureCanvas/
Figures)
• Migration of Zest2 into GEF4 repository and update
site (including adoption of namespace)
• Planned on the mid/long-term :
• Adoption of migrated Zest components to new
GEF4 Geometry, Graphics, Canvas components
• Migration of remaining Draw2d/GEF (MVC) code
base, including re-modularization and adoption

22. And on the very short term...
• ... we are currently implementing Image#toString()...

23. ThankYou! Questions?