---
title: "Plotting"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Plotting}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
```

```{r setup}
```

The package provides basic plotting functionality via \code{plot} function that uses [ggplot2](https://ggplot2.tidyverse.org/) as a back end. This means that you can extend the plot by adding further layers and geoms. Below is the basic code that shows how to use [ggplot2](https://ggplot2.tidyverse.org/) to generate a custom plot replicating the \code{plot}.
```{r out.width='100%', fig.width=10, fig.height=8}
library(eyelinkReader)
library(ggplot2)

data(gaze)

# extracting fixations and saccades for the first trial
fixations <- gaze$fixations[gaze$fixations$trial == 1, ]
saccades <- gaze$saccades[gaze$saccades$trial == 1, ]

 ggplot() +
  
  # enforce same scaling, as on the screen
  coord_equal(expand=FALSE) +
   
  # define screen limits and INVERSE y-axis to match Eyelink
  scale_x_continuous(name = "x", limits = gaze$display_coords[c(1, 3)]) +
  scale_y_reverse(name = "y", limits = gaze$display_coords[c(4, 2)]) +
   
  # draw fixations as circles
  geom_point(data = fixations, aes_string(x = "gavx", y = "gavy", size = "duration"), alpha=0.3) +
   
  # draw saccades as line segments
  geom_segment(data = saccades, aes_string(x = "gstx", y = "gsty", xend = "genx", yend = "geny", color = "sttime_rel")) +
   
  # better legend titles
  labs(size = "Fixation duration [ms]",
       color = "Saccade onset [ms]")
```