Bottom-Up 1

Warning: Extremely Boring, Project-Specific Post

I'm ignoring the work that has already been done on this, for the moment, and imagining how I would do it if I were starting from scratch.

There are two components that would need to be implemented: the jre emulation layer, and the SWT emulation layer. GWT already provides a JRE emulation layer, but it will likely be necessary to enhance it.

SWT is big. All we really care about is GraphicsContext and event handling.

The graphics part should slot nicely into the way SWT graphics is already organized, in that it has different drawing backends. We just need to use the API exposed by GWTCanvas. It should be possible to look to swt graphics for guidance on this, in that it already supports many different target implementations.

Draw2d may have other dependencies on SWT beyond GC and events. Here's a bit of script I used to found out what dependencies org.eclipse.draw2d has on SWT:

jacob@jacob-laptop:~/workspace/gsoc-phase-1/org.eclipse.draw2d$ grep -o -r "import org.eclipse.swt.*" . | sed 's/[^:]*:\(.*\)/\1/' | sort | uniq

import org.eclipse.swt.accessibility.ACC;
import org.eclipse.swt.accessibility.AccessibleAdapter;
import org.eclipse.swt.accessibility.AccessibleControlAdapter;
import org.eclipse.swt.accessibility.AccessibleControlEvent;
import org.eclipse.swt.accessibility.AccessibleControlListener;
import org.eclipse.swt.accessibility.AccessibleEvent;
import org.eclipse.swt.accessibility.AccessibleListener;
import org.eclipse.swt.events.ControlAdapter;
import org.eclipse.swt.events.ControlEvent;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.events.DisposeListener;
import org.eclipse.swt.events.FocusEvent;
import org.eclipse.swt.events.FocusListener;
import org.eclipse.swt.events.KeyAdapter;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.events.KeyListener;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.MouseListener;
import org.eclipse.swt.events.MouseMoveListener;
import org.eclipse.swt.events.MouseTrackAdapter;
import org.eclipse.swt.events.MouseTrackListener;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.TraverseEvent;
import org.eclipse.swt.events.TraverseListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.Cursor;
import org.eclipse.swt.graphics.Font;
import org.eclipse.swt.graphics.FontData;
import org.eclipse.swt.graphics.FontMetrics;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.LineAttributes;
import org.eclipse.swt.graphics.PaletteData;
import org.eclipse.swt.graphics.Path;
import org.eclipse.swt.graphics.PathData;
import org.eclipse.swt.graphics.Pattern;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.graphics.RGB;
import org.eclipse.swt.graphics.TextLayout;
import org.eclipse.swt.graphics.TextStyle;
import org.eclipse.swt.graphics.Transform;
import org.eclipse.swt.printing.Printer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTError;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.widgets.Canvas;
import org.eclipse.swt.widgets.Caret;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Shell;

GWT modules will glue the project together. There will be a top-level example module which has an entry point, and imports the modules for SWT emulation and JRE emulation. That's basically it.