UXGdiGraphics

UXGdiGraphics is the Win32 realization of UXGraphics, and the first sibling of UXGemGraphics.

#use <UXKit>            // or #import "UXGdiGraphics.xc"

The same primitives, a different surface

Every drawRect in the toolkit calls the same small set of methods. This class implements them over a device context rather than a VDI workstation.

Incoming coordinates are bounds-relative, and the bound origin makes them absolute, as on GEM. Because the contract does not change, a view’s drawing body is written once and is correct on every backend.

GDI’s y grows down, as GEM’s does, so nothing needs flipping.

Two implementations define the protocol

This class shows that UXGraphics is an interface and not a description of the VDI. Two implementations satisfy it: one over an early-80s workstation model, the other over a device-context model. The later backends implement the same methods.

It has no theme art

hasThemeArt()      // false

Windows has no equivalent of GEM’s drawable theme slices, so drawTheme has nothing to call and the toolkit draws the pieces itself.

Answering false is safe because there is a neutral fallback. A capability query asks whether the backend can do something, not whether it must, and the toolkit always has an answer for no.

It strokes natively

strokesNatively()      // true

UXPainter.strokePath hands GDI the path, and GDI draws the curve at its own precision with its own joins, instead of the toolkit offsetting a whole-pixel polyline.

Arrowheads stay neutral, because GDI has none. All six hosted backends use this split: the platform draws what it draws well, and the toolkit draws what no platform has.

Pens map to a colour table

The toolkit draws with VDI pen indices. This vocabulary keeps the index-to-RGB table (penColor) that converts them for GDI.

UXCanvasGraphics mirrors the same table, split per channel because the host import signature takes r, g and b separately. Keeping the table in several places has a maintenance cost; in return a pen number means the same colour on every backend.

fillRectRGB and fillPolygonRGB are the true-colour entry points for UXColor-driven drawing that bypasses the palette.