wchntGraphics

wchntGraphics is the portable drawing surface available to Target code. It is what your %step (or %init) uses to draw to the window or canvas, and it exposes the same API on both the OpenFL and browser-canvas hosts.

It is deliberately small: just enough to draw rectangles, circles, outlines, and text, so that Schema / Construction / Methods stay platform-independent and only the Target draws.

The v1 API

Method	What it does
`clear()`	Fill the whole surface with the background colour.
`beginFill(color)`	Set the fill colour used by the following shapes.
`endFill()`	Finish the current fill.
`lineStyle(thickness, color)`	Switch to outlining: the next `drawRect` is stroked, not filled.
`drawRect(x, y, width, height)`	Draw a rectangle (filled, or outlined if `lineStyle` was set).
`drawCircle(x, y, radius)`	Draw a filled circle centred at `(x, y)`.
`fillText(text, x, y)`	Draw text at `(x, y)`.

Colours are 24-bit integers written in hex: 0xRRGGBB. For example 0xf2f2f2 is a light grey and 0x00ff00 is green.

An optional alpha is accepted by beginFill and lineStyle on the OpenFL host (beginFill(color, alpha)); the browser-canvas harness currently ignores it.

Typical usage

Clear, then fill the background and draw a ball:

wchntGraphics.clear();
wchntGraphics.beginFill(0x2a2a2a);
wchntGraphics.drawRect(0, 0, 800, 600);
wchntGraphics.endFill();
wchntGraphics.beginFill(0xf2f2f2);
wchntGraphics.drawCircle(b.x, b.y, b.rad);
wchntGraphics.endFill();

Outline a rectangle instead of filling it:

wchntGraphics.lineStyle(2, 0x00ff00);
wchntGraphics.drawRect(r.x, r.y, r.width, r.height);

Paths (browser canvas only)

The browser harness additionally provides moveTo(x, y) and lineTo(x, y) so you can draw arbitrary polygons. Follow them with endFill() to fill the path:

wchntGraphics.beginFill(0x00ff00);
wchntGraphics.moveTo(0, 0).lineTo(50, 0).lineTo(25, 40).lineTo(0, 0);
wchntGraphics.endFill();

moveTo / lineTo are not part of the OpenFL wchntGraphics wrapper yet. On OpenFL, use a @Graphics/g parameter in ## Target Methods and pass the raw graphics object instead — see below.

Passing wchntGraphics to Target Methods

You can hand wchntGraphics into a @Graphics/g method and call it there. The calls chain in source; the compiler unrolls the Void chain for you:

Shape::draw : Void = { @Graphics/g |
  g.beginFill(15316448).drawCircle(x, y, radius).endFill()
}

Then, from Target:

for (var s of assemblage.shapes) {
    s.draw(wchntGraphics);
}

The canonical examples show all of this in action: bounce (fill + circle), pollution (outline + text), and shapes (paths via @Graphics/g).