export addGeoRaster & addGeotiff #25

r-spatial · Jul 19, 2020 · ff4a8e0 · ff4a8e0
1 parent 6f2c88a
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diff --git a/NAMESPACE b/NAMESPACE
@@ -4,6 +4,8 @@ export(addCopyExtent)
 export(addExtent)
 export(addFeatures)
 export(addFgb)
+export(addGeoRaster)
+export(addGeotiff)
 export(addHomeButton)
 export(addImageQuery)
 export(addLocalFile)
@@ -15,6 +17,7 @@ export(addStarsRGB)
 export(addStaticLabels)
 export(addTileFolder)
 export(clip2sfc)
+export(colorOptions)
 export(garnishMap)
 export(removeHomeButton)
 export(removeMouseCoordinates)
@@ -40,5 +43,9 @@ importFrom(raster,projection)
 importFrom(raster,sampleRegular)
 importFrom(sf,st_as_sfc)
 importFrom(sf,st_bbox)
+importFrom(sf,st_is_longlat)
 importFrom(sf,st_transform)
+importFrom(stars,st_as_stars)
+importFrom(stars,st_warp)
+importFrom(stars,write_stars)
 importFrom(stats,quantile)
diff --git a/R/addGeoRaster.R b/R/addGeoRaster.R
@@ -1,3 +1,61 @@
+#' Add stars/raster image to a leaflet map using optimised rendering.
+#'
+#' @details
+#' This uses the leaflet plugin 'georaster-layer-for-leaflet' to render raster data.
+#' See \url{https://github.com/GeoTIFF/georaster-layer-for-leaflet} for details.
+#' The clue is that rendering uses simple nearest neighbor interpolation on-the-fly
+#' to ensure smooth rendering. This enables handling of larger rasters than with
+#' the standard \code{\link[leaflet]{addRasterImage}}.
+#'
+#' @param map the map to add the raster data to.
+#' @param x the stars/raster object to be rendered.
+#' @param group he name of the group this raster image should belong to.
+#' @param layerId the layerId.
+#' @param resolution the target resolution for the simple nearest neighbor interpolation.
+#'   Larger values will result in more detailed rendering, but may impact performance.
+#'   Default is 96 (pixels).
+#' @param opacity opacity of the rendered layer.
+#' @param options options to be passed to the layer.
+#'   See \code{\link[leaflet]{tileOptions}} for details.
+#' @param colorOptions list defining the palette, breaks and na.color to be used.
+#' @param project whether to project the RasterLayer to conform with leaflets
+#'   expected crs. Defaults to \code{TRUE} and things are likely to go haywire
+#'   if set to \code{FALSE}.
+#' @param pixelValuesToColorFn optional JS function to be passed to the browser.
+#'   Can be used to fine tune and manipulate the color mapping.
+#'   See \url{https://github.com/r-spatial/leafem/issues/25} for some examples.
+#' @param ... currently not used.
+#'
+#' @return
+#' A leaflet map object.
+#'
+#' @examples
+#' if (interactive()) {
+#'   library(leaflet)
+#'   library(leafem)
+#'   library(stars)
+#'
+#'   tif = system.file("tif/L7_ETMs.tif", package = "stars")
+#'   x1 = read_stars(tif)
+#'   x1 = x1[, , , 3] # band 3
+#'
+#'   leaflet() %>%
+#'     addTiles() %>%
+#'     leafem:::addGeoRaster(
+#'       x1
+#'       , opacity = 1
+#'       , colorOptions = colorOptions(
+#'         palette = hcl.colors(256, "inferno")
+#'       )
+#'     )
+#' }
+#'
+#' @importFrom stars st_as_stars st_warp write_stars
+#' @importFrom sf st_is_longlat
+#'
+#' @export addGeoRaster
+#' @name addGeoRaster
+#' @rdname addGeoRaster
 addGeoRaster = function(map,
                         x,
                         group = NULL,
@@ -6,13 +64,15 @@ addGeoRaster = function(map,
                         opacity = 0.8,
                         options = leaflet::tileOptions(),
                         colorOptions = colorOptions(),
-                        pixelValuesToColorFn = NULL) {
+                        project = TRUE,
+                        pixelValuesToColorFn = NULL,
+                        ...) {
 
   if (inherits(x, "Raster")) {
     x = stars::st_as_stars(x)
   }
 
-  if (!sf::st_is_longlat(x)) {
+  if (project && !sf::st_is_longlat(x)) {
     x = stars::st_warp(x, crs = 4326)
   }
 
@@ -42,7 +102,92 @@ addGeoRaster = function(map,
 }
 
 
-
+#' Add a GeoTIFF file to a leaflet map using optimised rendering.
+#'
+#' @details
+#' This uses the leaflet plugin 'georaster-layer-for-leaflet' to render GeoTIFF data.
+#' See \url{https://github.com/GeoTIFF/georaster-layer-for-leaflet} for details.
+#' The GeoTIFF file is read directly in the browser using geotiffjs
+#' (\url{https://geotiffjs.github.io/}), so there's no need to read data into
+#' the current R session. GeoTIFF files can be read from the file system or via url.
+#' The clue is that rendering uses simple nearest neighbor interpolation on-the-fly
+#' to ensure smooth rendering. This enables handling of larger rasters than with
+#' the standard \code{\link[leaflet]{addRasterImage}}.
+#'
+#' @param map the map to add the raster data to.
+#' @param file path to the GeoTIFF file to render.
+#' @param url url to the GeoTIFF file to render. Ignored if \code{file} is provided.
+#' @param group he name of the group this raster image should belong to.
+#' @param layerId the layerId.
+#' @param resolution the target resolution for the simple nearest neighbor interpolation.
+#'   Larger values will result in more detailed rendering, but may impact performance.
+#'   Default is 96 (pixels).
+#' @param opacity opacity of the rendered layer.
+#' @param options options to be passed to the layer.
+#'   See \code{\link[leaflet]{tileOptions}} for details.
+#' @param colorOptions list defining the palette, breaks and na.color to be used.
+#' @param pixelValuesToColorFn optional JS function to be passed to the browser.
+#'   Can be used to fine tune and manipulate the color mapping.
+#'   See examples & \url{https://github.com/r-spatial/leafem/issues/25} for some examples.
+#' @param ... currently not used.
+#'
+#' @return
+#' A leaflet map object.
+#'
+#' @examples
+#' if (interactive()) {
+#'   library(leaflet)
+#'   library(leafem)
+#'
+#'   chrpsfl_202004 = "https://data.chc.ucsb.edu/products/CHIRPS-2.0/africa_monthly/tifs/chirps-v2.0.2020.04.tif.gz"
+#'   dsn_202004 = file.path(tempdir(), basename(chrpsfl_202004))
+#'
+#'   download.file(chrpsfl_202004, dsn_202004)
+#'
+#'   tiffl_202004 = gsub(".gz", "", dsn_202004)
+#'   R.utils::gunzip(dsn_202004, tiffl_202004)
+#'
+#'   myCustomJSFunc = htmlwidgets::JS(
+#'     "
+#'       pixelValuesToColorFn = (raster, colorOptions) => {
+#'         const cols = colorOptions.palette;
+#'         var scale = chroma.scale(cols);
+#'
+#'         if (colorOptions.breaks !== null) {
+#'           scale = scale.classes(colorOptions.breaks);
+#'         }
+#'         var pixelFunc = values => {
+#'           let clr = scale.domain([raster.mins, raster.maxs]);
+#'           if (isNaN(values)) return colorOptions.naColor;
+#'           if (values < 120) return colorOptions.naColor;
+#'           return clr(values).hex();
+#'         };
+#'         return pixelFunc;
+#'       };
+#'     "
+#'   )
+#'
+#'   leaflet() %>%
+#'     addTiles() %>%
+#'     addGeotiff(
+#'       file = tiffl_202004
+#'       , opacity = 0.9
+#'       , colorOptions = colorOptions(
+#'         palette = hcl.colors(256, "viridis")
+#'         , breaks = seq(0, 1000, 10)
+#'         , na.color = "transparent"
+#'       )
+#'       , pixelValuesToColorFn = myCustomJSFunc
+#'     )
+#'
+#' }
+#'
+#' @importFrom stars st_as_stars st_warp write_stars
+#' @importFrom sf st_is_longlat
+#'
+#' @export addGeotiff
+#' @name addGeotiff
+#' @rdname addGeotiff
 addGeotiff = function(map,
                       file = NULL,
                       url = NULL,
@@ -51,8 +196,9 @@ addGeotiff = function(map,
                       resolution = 96,
                       opacity = 0.8,
                       options = leaflet::tileOptions(),
-                      colorOptions = colorOptions(),
-                      pixelValuesToColorFn = NULL) {
+                      colorOptions = NULL, #colorOptions(),
+                      pixelValuesToColorFn = NULL,
+                      ...) {
 
   if (inherits(map, "mapview")) map = mapview2leaflet(map)
 
@@ -116,6 +262,15 @@ addGeotiff = function(map,
 
 }
 
+
+#' Color options for addGeoRaster and addGeotiff
+#'
+#' @param palette the color palette to use. Can be a set of colors or a
+#'   color generating function such as the result of \code{\link[grDevices]{colorRampPalette}}.
+#' @param breaks the breaks at which color should change.
+#' @param na.color color for NA values (will map to NaN in Javascript).
+#'
+#' @export
 colorOptions = function(palette = NULL,
                         breaks = NULL,
                         na.color = "#bebebe22") {

diff --git a/man/addGeoRaster.Rd b/man/addGeoRaster.Rd