Crate flo_canvas

flo_canvas provides an abstraction of a 2D vector canvas, and supporting methods to stream updates to implementations.

The main features that this library supports are the set of primitives in the Draw enum, the Canvas type for streaming drawing instructions elsewhere, and the encoding and decoding functions that can be used to send canvas instructions over a byte stream. Encoding uses MIME64 characters, so it's easy to embed encoded canvases in other protocols.

By itself, flo_canvas is an excellent way to describe how a 2D scene should be rendered without needing to depend on a system-specific library.

FlowBetween comes with several implementations of the canvas for generating the final rendered results. Most notably, flo_render_canvas will convert between a stream of Draw instructions and a stream of instructions suitable for rendering with most graphics APIs. The accompanying flo_render can render these instructions to OpenGL or Metal and flo_render_gl_offscreen is available to generate bitmap images on a variety of systems.

canvas.js provides a Javascript implementation that can render the instructions to a HTML canvas, and there are also Quartz and Cairo implementations of the canvas provided in FlowBetween's user interface layers.

Structs

Canvas	A canvas is an abstract interface for drawing graphics. It doesn't actually provide a means to render anything, but rather a way to describe how things should be drawn and pass those on to a renderer elsewhere.
CanvasDecoder	Represents a (stateful) canvas decoder
CanvasGraphicsContext	Graphics context for a Canvas
SpriteId	Identifier of a canvas 'sprite'
Transform2D	Represents a 2D affine transformation matrix

Enums

BlendMode	Blend mode to use when drawing
Color	Representation of a colour
ColorFormat	Possible formats of a colour value
DecoderError	Possible error from the decoder
Draw	Instructions for drawing to a canvas
LineCap	How to cap lines
LineJoin	Possible way to join lines
SpriteTransform	Transformation to apply to a canvas 'sprite'
StreamDecoderError	Error from either a decoder or the stream that's feeding it
WindingRule	How a path should determine if it's an outer edge or not

Traits

CanvasEncoding	Trait implemented by objects that can be encoded into a canvas
GraphicsContext	A graphics context provides the basic set of graphics actions that can be performed
GraphicsPrimitives	GraphicsPrimitives adds new primitives that can be built directly from a graphics context

Functions

decode_drawing	Decodes a canvas drawing represented as an iterator of characters. If there's an error in the stream, it will be the last item decoded.
decode_drawing_stream	Decodes a canvas drawing represented as a stream of characters.
draw_circle	Returns the drawing commands for a circle
draw_rect	Returns the drawing commands for a rectangle
gc_draw_bezier	Draws the specified bezier curve in a graphics context (assuming we're already at the start position)