Chart Generation¶

The chart_utils service generates South Indian-style horoscope charts as SVG strings. Charts are rasi-based (sign-fixed squares) and include all planetary positions and birth metadata.

Functions¶

`generate_south_indian_chart_svg`¶

generate_south_indian_chart_svg(
    kattams_data: list[KattamDisplayData],
    birth_details: BirthDetails
) -> str

Produces a complete South Indian chart as an SVG string ready to embed in HTML or save as a .svg file.

Parameters

Parameter	Type	Description
`kattams_data`	`list[KattamDisplayData]`	Planetary occupants for each of the 12 houses
`birth_details`	`BirthDetails`	Name, date, time and place labels for the centre box

Returns: str — a self-contained SVG document.

Data Models¶

`BirthDetails`¶

Metadata displayed in the centre info box of the chart.

Field	Type	Description
`name_abbr`	`str`	Short name or initials of the native
`date`	`str`	Birth date label (e.g. `"01-Jan-2000"`)
`time`	`str`	Birth time label (e.g. `"10:30 AM"`)
`place`	`str`	Birth place label (e.g. `"Chennai, India"`)

`KattamDisplayData`¶

Describes what to render in a single house cell (kattam).

Field	Type	Description
`house_number`	`int`	House number 1–12
`rasi_name`	`str`	Zodiac sign occupying this house
`planets`	`list[str]`	Planet codes/labels to display (e.g. `["SU", "MO(R)"]`)

South Indian Layout¶

The chart uses a fixed 4×4 grid. The centre 2×2 cells form the info box. The 12 house cells are arranged clockwise from the top-left corner:

┌──────┬──────┬──────┬──────┐
│  12  │   1  │   2  │   3  │
├──────┼──────┼──────┼──────┤
│  11  │ INFO │ INFO │   4  │
├──────┼ BOX  ┼ BOX  ┼──────┤
│  10  │ INFO │ INFO │   5  │
├──────┼──────┼──────┼──────┤
│   9  │   8  │   7  │   6  │
└──────┴──────┴──────┴──────┘

Sign-fixed: Each cell represents a fixed zodiac sign that never moves.
Rasi 1 (Aries) always occupies the top-left corner cell (cell position 1 in the layout; house number changes depending on the ascendant).
The ascendant (Lagna) cell is highlighted or labeled to indicate the 1st house.

Internal Helpers¶

Function	Description
`process_rasi_data`	Maps planet longitudes to their rasi (sign) numbers
`calculate_planet_positions`	Converts raw `Planet` list to `KattamDisplayData` format
`draw_chart_borders`	Renders the outer grid lines in SVG
`render_center_text`	Writes the `BirthDetails` fields into the centre box
`render_house_and_planets`	Writes the rasi label and planet codes into each house cell

API Endpoint¶

The /api/v1/astro/chart endpoint calls generate_south_indian_chart_svg directly and returns the SVG with Content-Type: image/svg+xml.

GET /api/v1/astro/chart?lat=13.08&lon=80.27&dateandtime=2000-01-01T10:30:00

Embed directly in HTML:

<img src="/api/v1/astro/chart?lat=13.08&lon=80.27&dateandtime=2000-01-01T10:30:00"
     alt="Birth Chart" />

Or as an inline SVG by fetching the response body:

<div id="chart-container"></div>
<script>
  fetch('/api/v1/astro/chart?lat=13.08&lon=80.27&dateandtime=2000-01-01T10:30:00')
    .then(r => r.text())
    .then(svg => document.getElementById('chart-container').innerHTML = svg);
</script>