I'd like to use Purescript to draw an image to a canvas. When I did this in Javascript, it looked something like the following:
window.onload = function() {
var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
var img=document.getElementById("scream"); // THIS LINE IN PURESCRIPT???
ctx.drawImage(img,10,10);
};
I'm using purs 0.12. I have installed Graphics.Canvas and I can use it to draw rectangles and ellipses and such. But I can't figure out the API to drawImage. I also can't figure out in what library the Purescript equivalent of getElementbyId() resides.
Use Pursuit to search for definitions such as getElementById.
tryLoadImage takes a callback as an argument. The callback is what receives the CanvasImageSource. You may wish to use Aff or at least ContT to help.
Related
I'm trying to create an interactive map out of an image using Folium as part of a Django project in which I want to display the generated HTML on a website.
I want to be able to see only the image upon which I place markers etc., not the actual world map that is by default created.
The image is a map of a fantasy world.
I found this tutorial and tried to apply it to Folium and that generally worked. I'm essentially adding an Image Overlay with "my" map to a map-object. However, that does not remove the original real-world map, meaning when I then save this map, it still also displays a world map that I do not care about in the lower left corner attached to my image overlay.
import folium
def create_aldrune_map():
base_map = folium.Map(crs='Simple', zoom_start=4)
aldrune_overlay = folium.raster_layers.ImageOverlay(
image='Path/To/Image',
bounds=[[0, 0], [1000, 1300]],
zindex=1)
aldrune_overlay.add_to(base_map)
base_map.fit_bounds(bounds=[[0, 0], [1000, 1300]])
base_map.save('Path/To/Output')
How do I get rid of the real-world map?
Let me quote from the Folium documentation, emphasis mine:
class folium.folium.Map(location=None, width='100%', height='100%', left='0%', top='0%', position='relative', tiles='OpenStreetMap',
(snip)
, **kwargs)
Parameters
tiles (str, default 'OpenStreetMap') – Map tileset to use. Can choose from a list of built-in tiles, pass a custom URL or pass None to create a map without tiles. For more advanced tile layer options, use the TileLayer class.
Therefore you probably want something like:
base_map = folium.Map(crs='Simple', zoom_start=4, tiles=None)
How to use CSS customization directly from Vala? Not like in this example with file. Let's say I want the button to turn red by clicking on it, without using an external css file, as this action is too simple to create a css file with a single field.
I mean smth like this:
label.set_styleSheet("font-size: 17px;")
You still have to create a CssProvider, like in the code you linked to:
var screen = this.get_screen ();
var css_provider = new Gtk.CssProvider();
You can call load_from_data () instead of load_from_path () to load it from a string in memory instead of a file:
https://valadoc.org/gtk+-3.0/Gtk.CssProvider.load_from_data.html
css_provider.load_from_data(".my_class { font-size: 17px; }");
Gtk.StyleContext.add_provider_for_screen(screen, css_provider, Gtk.STYLE_PROVIDER_PRIORITY_USER);
When the CSS provider has loaded the custom styles to be used, you can manipulate every Gtk+ widget with get_style_context ().
The style context has methods to add, remove and query a class, etc.
https://valadoc.org/gtk+-3.0/Gtk.StyleContext.html
label.get_style_context().add_class("my_class");
Since you only have to setup the style provider once, I don't think it is too much overhead.
For anyone who is reading this I have posted both examples with and without file to Git https://gitlab.com/gavr123456789/vala-css-examples/tree/master
Is there any way to load a GeoJson file with "simplestyle" (for example, created with geojsonio) directly into Leaflet, so it could use the color, stroke and other properties?
It seems that it is supported in the mapbox, but what about leaflet itself?
Thanks,
Alex
This isn't supported out-of-the-box by Leaflet but you could write your own logic using the pointToLayer function of L.GeoJSON:
Function that will be used for creating layers for GeoJSON points (if not specified, simple markers will be created)
http://leafletjs.com/reference.html#geojson-pointtolayer
new L.GeoJSON(collection, {
pointToLayer: function (feature, latlng) {
// Return a custom marker
}
});
In that function you have access to each feature's properties so you can return a custom marker based on them. Hope that helps, also found the following gist on github which shows a implementation which might do what you are looking for:
https://gist.github.com/tmcw/3861338
I am following markercluster examples from Mapbox library, but can't solve my problem. If you guys take a look at my working example here, you will notice this line of code:
L.mapbox.featureLayer(markerLayer).on('ready', function(e) {
What I initally thought was I could put markers inside of markercluster featureLayer, but I guess it was a wrong approach. Any solutions? Thanks.
Example following here
The mapbox example you refer to makes an AJAX call to retrieve the GeoJSON data, hence it needs to attach an on "ready" listener.
In your case your GeoJSON data is defined in your scripts, so the "ready" event will not be triggered (besides, you should use L.mapbox.featureLayer with your GeoJSON object directly, not a Feature Layer).
You can simply use the eachLayer method to iterate through all created markers within the Feature Layer, and add them into your Marker Cluster Group.
var clusterGroup = new L.MarkerClusterGroup();
var markerLayer = L.mapbox.featureLayer(markers).eachLayer(function(layer) {
clusterGroup.addLayer(layer);
});
map.addLayer(clusterGroup);
Updated Plunker: http://plnkr.co/edit/fN6xYcn1Lg532eLe39IS?p=preview
How do you manually trigger the native popup on a Leaflet polygon?
I can bind the native popup to each layer like this:
geojsonLayer.on("featureparse", function (e){
// bind the native popup
var popupContent = "popup content goes here";
e.layer.bindPopup(popupContent);
});
And I have manually assigned an ID to each polygon so I can reference them later like this:
map._layers['poly0']
I've tried triggering the popup like this:
map._layers['poly0'].openPopup();
But that gives me an error like this:
map._layers['poly0'].openPopup is not a function
Any idea where I'm going wrong?
openPopup for vector layers only recently appeared in the latest version, it wasn't there before.
Also, check out the Leaflet 0.4 release announcement: http://leaflet.cloudmade.com/2012/07/30/leaflet-0-4-released.html (and note that GeoJSON API was changed and it's not backwards compatible, so you also have to update your code)