graphix-stdlib 0.3.1

A dataflow language for UIs and network programming, standard library
Documentation 
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# The Canvas Widget

The `canvas` widget provides a low-level drawing surface for custom graphics. You can draw lines, circles, rectangles, points, and text labels at specific coordinates, making it perfect for diagrams, plots, and custom visualizations.

## Interface

```graphix
type CanvasLine = {
  color: Color,
  x1: f64,
  x2: f64,
  y1: f64,
  y2: f64
};

type CanvasCircle = {
  color: Color,
  radius: f64,
  x: f64,
  y: f64
};

type CanvasRectangle = {
  color: Color,
  height: f64,
  width: f64,
  x: f64,
  y: f64
};

type CanvasPoints = {
  color: Color,
  coords: Array<(f64, f64)>
};

type CanvasLabel = {
  line: Line,
  x: f64,
  y: f64
};

type CanvasShape = [
  `Line(CanvasLine),
  `Circle(CanvasCircle),
  `Rectangle(CanvasRectangle),
  `Points(CanvasPoints),
  `Label(CanvasLabel)
];

val canvas: fn(
  ?#background_color: &[Color, null],
  ?#marker: &[Marker, null],
  #x_bounds: &{ max: f64, min: f64 },
  #y_bounds: &{ max: f64, min: f64 },
  &Array<&CanvasShape>
) -> Tui;
```

## Parameters

- **background_color** - Background color for the canvas
- **marker** - Marker type: `Dot`, `Braille` (default), or `Block`
- **x_bounds** - X-axis range with `min` and `max` fields (required)
- **y_bounds** - Y-axis range with `min` and `max` fields (required)

## Shape Types

### Line
```graphix
`Line({color: `Red, x1: 0.0, y1: 0.0, x2: 10.0, y2: 5.0})
```

### Circle
```graphix
`Circle({color: `Blue, x: 5.0, y: 5.0, radius: 2.0})
```

### Rectangle
```graphix
`Rectangle({color: `Green, x: 2.0, y: 2.0, width: 3.0, height: 4.0})
```

### Points
```graphix
`Points({color: `Yellow, coords: [(1.0, 1.0), (2.0, 3.0), (3.0, 1.5)]})
```

### Label
```graphix
`Label({line: line("Hello"), x: 5.0, y: 0.5})
```

## Examples

### Basic Usage

```graphix
{{#include ../../examples/tui/canvas_basic.gx}}
```

![Basic Canvas](./media/canvas_basic.png)

### Function Plotting

```graphix
{{#include ../../examples/tui/canvas_plot.gx}}
```

![Scatter Plot](./media/canvas_plot.png)

### Network Diagram

```graphix
{{#include ../../examples/tui/canvas_network.gx}}
```

![Network Diagram](./media/canvas_network.png)

### Animated Graphics

```graphix
{{#include ../../examples/tui/canvas_animated.gx}}
```

![Animated Canvas](./media/canvas_animated.gif)

## Marker Comparison

- **Braille**: Highest resolution, smoothest curves, best for detailed graphics
- **Dot**: Fast rendering, lower resolution, good for simple shapes
- **Block**: High contrast, blocky appearance, good for filled areas

## Coordinate System

- Origin (0, 0) is at the bottom-left
- X increases to the right
- Y increases upward
- Shapes outside bounds are clipped

## See Also

- [chart](chart.md) - For pre-built line charts
- [barchart](barchart.md) - For bar-based visualizations