使用 gmaps4rails 动态加载 Google 地图标记 [英] Dynamically load Google Maps Markers with gmaps4rails

问题描述

如何使用 gmaps4rails 仅加载地图边界内的标记?当然，在平移和/或缩放后加载新的.

How do I load only markers that are inside the map bounds with gmaps4rails? And of course load new ones after pan and/or zoom.

与此直接相关，如何获取地图的当前边界和缩放级别?

Directly related to that, how can I get the current boundaries and zoomlevel of the map?

推荐答案

我是这样做的，我只在用户完成平移或缩放后替换标记，如果您需要不同的行为，则使用不同的事件侦听器:

Here is how I did it, I only replace the markers after the user finishes panning or zooming, if you require different behavior then use a different event listener:

在您看来 (index.html.erb):

In your view (index.html.erb):

<%= gmaps({ "map_options" => { "zoom" => 15, 
                               "auto_adjust" => false, 
                               "detect_location" => true, 
                               "center_on_user" => true }}, false, true) %>

在您的视图底部添加:

<script type="text/javascript" charset="utf-8">

function gmaps4rails_callback() {
    google.maps.event.addListener(Gmaps4Rails.map, 'idle', function () {
        var bounds = Gmaps4Rails.map.getBounds();
        drawItems(bounds);
    });
}

</script>

在 application.js(使用 jQuery)中:

In application.js (using jQuery):

function drawItems(theBounds) {
    var url = '/venues.json/?sw_y=' + theBounds.getSouthWest().lng() + 
                           '&sw_x=' + theBounds.getSouthWest().lat() + 
                           '&ne_y=' + theBounds.getNorthEast().lng() +
                           '&ne_x=' + theBounds.getNorthEast().lat();
    $.get(url, function(newItemData) {
        Gmaps4Rails.replace_markers(newItemData);
    });
}

venues_controller#index:

venues_controller#index:

def index
    # Only pull venues within the visible bounds of the map
    if (params[:sw_y] && params[:sw_x] && params[:ne_y] && params[:ne_x])
        bounds = [ [params[:sw_x].to_f, params[:sw_y].to_f], 
                 [params[:ne_x].to_f, params[:ne_y].to_f] ]
        @venues_within_bounds = Venue.within_bounds(bounds)
    else
        @venues_within_bounds = Venue.all
    end   

    respond_to do |format|
        format.html # index.html.erb
        format.json { 
            @data = @venues_within_bounds.collect {|v| {
                     :longitude => v.longitude, 
                     :latitude => v.latitude, 
                     :picture => v.marker_picture, 
                     :title => v.marker_title 
            }
            render :json => @data
        }
    end
end

Venue.rb 模型(使用 mongodb 和 mongoid):

Venue.rb model (using mongodb and mongoid):

def self.within_bounds(bounds)
    self.where(:location.within => {"$box" => bounds })
end

这篇关于使用 gmaps4rails 动态加载 Google 地图标记的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！