# Plot to PNG

A console program that creates a `TAtlasPlot` in code, adds a bar series and a
line series with a trend line, and exports the chart as PNG, SVG and CSV without
ever showing a window. It then verifies the files it wrote and exits with code 0.

## What it demonstrates

- `AddSeries`, `AddY` with category text, `Marks`, `ShowPoints`, `LineWidth`
- `Title`, `Footnote`, `LegendPosition`, axis titles
- `AddTrendLine` (a least-squares snapshot)
- `SaveToFile` choosing PNG, SVG or CSV by extension, at a given pixel size
- `DataFromCSV` / `DataToCSV` round trip
- `EAtlasPlotError` on invalid input, leaving the chart unchanged
- `BeginUpdate` / `EndUpdate` around bulk changes

## Build and run

Open `PlotToPng.dpr` in Delphi 13; the IDE creates the project file. Add the Atlas Plot `src` folder to the project's search path, then build and run for Win32 or Win64. No packages need to be installed. The program needs no input. It checks its own results and stops with an error if any of them differs from the output below.

The program writes `plot-output/orders.png`, `orders.svg` and `orders.csv` in its current directory.

## Expected output

```
  ok: chart has two data series and one trend line
  ok: a trend line has exactly two points
Exporting to ...\plot-output
  ok: PNG file has content
  ok: PNG is 800 x 500
  ok: SVG root has the requested size
  ok: SVG contains the title
  ok: SVG shows category ticks from the point text
  ok: SVG clips the series to the plot area
  ok: CSV header is series,kind,x,y,text
  ok: CSV has one row per point
  ok: first row is the first order bar
  ok: numbers use a decimal point regardless of locale
  ok: the trend line is exported as a series
  ok: CSV import recreates all three series
  ok: series kinds survive the round trip
  ok: import and export are symmetric
  ok: a value beyond 1E100 is rejected and nothing changes
  ok: no partial files are left behind
PlotToPng: all checks passed
```

## Adapting it

Replace the `Months`, `OrderCounts` and `Revenue` constants with your own data,
or load a CSV file with `Plot.DataFromCSV(TFile.ReadAllText(...))` instead of
calling `AddY`. Change the extension in `SaveToFile` to `.bmp` or `.emf` for the
other image formats, or call `RenderTo(Printer.Canvas, ...)` to print.