getPngLayer: '.png' Layer
In cartography: Thematic Cartography

getPngLayer

R Documentation

`.png` Layer

Description

Get a RasterBrick from a .png image cut using the shape of a spatial object. The .png file could be either a local file or extracted from a given url.

Usage

getPngLayer(
  x,
  pngpath,
  align = "center",
  margin = 0,
  crop = FALSE,
  mask = TRUE,
  inverse = FALSE,
  dwmode = "curl",
  ...
)

Arguments

`x`	an `sf` object, a simple feature collection (POLYGON or MULTIPOLYGON) or a tile (see `getTiles`).
`pngpath`	local path or url of a `.png` file.
`align`	set how the `.png` file should be fitted within `x`. Possible values are `'left','right','top', 'bottom'` or `'center'`.
`margin`	inner margin, zooms out the `.png` over `x`. If 0 then `.png` is completely zoomed over `x`.
`crop`	`TRUE` if results should be cropped to the specified `x` extent.
`mask`	`TRUE` if the result should be masked to `x`.
`inverse`	logical. If `FALSE`, overlapped areas of `x` on `pngpath` are extracted, otherwise non-overlapping areas are returned. See `mask`.
`dwmode`	Set the download mode. It could be `'base'` for `download.file` or `'curl'` for `curl_download`.
`...`	additional arguments for downloading the file. See `download.file` or `curl_download`.

Details

The effect of align would differ depending of the aspect ratio of x and pngpath. To obtain a fitted tile from pngpath given that x is the tile to fit, set margin = 0 , crop = TRUE.

Value

A RasterBrick object is returned.

Note

The accuracy of the final plot would depend on the quality of the .png file, the scale of x and the resolution setup of the graphic device. Exporting to svg is highly recommended.

Author(s)

dieghernan, https://github.com/dieghernan/

Examples

library(sf)
mtq <- st_read(system.file("gpkg/mtq.gpkg", package = "cartography"))
#Local file
dirpng <- system.file("img/LogoMartinique.png", package = "cartography")
mask <- getPngLayer(mtq, dirpng)

## Not run: 
#Remote file
urlpng <- "https://i.imgur.com/gePiDvB.png"
masksea <- getPngLayer(mtq, urlpng, mode = "wb", inverse = TRUE)

## End(Not run)

cartography documentation built on Sept. 14, 2023, 5:08 p.m.