I'd like it if the Layer Control dialog only showed overlays that had elements in the viewport. I setup an example here that illustrates what I mean:
https://jsfiddle.net/7e84rh06/2/
So in that example the "Cities" overlay has no elements but if you click on "Parks" one element for that overlay does appear. So that overlay has elements in the viewport whereas the "Cities" overlay doesn't. Consequently I'd like it if the dialog only showed "Parks". eg. this:
...instead of this:
I'd like this to be dynamic too. eg. if more elements from other overlays enter into the viewport when zooming out then I'd like additional checkboxes to appear in that dialog and if no elements remain in the viewport from an overlay then I'd like that the checkbox corresponding to that overlay to disappear.
Is this even possible?
(SO requires jsfiddle.net links be accompanied by code so... token code)
Building off of Grzgorz T's comments... all the markers can be grouped together in a FeatureGroup and then you can call getBounds() on that. Let's save the resultant LatLngBounds to markerBounds.
Then, you create a function that removes the overlay from the layerControl (layerControl.removeLayer(cities)), calls map.getBounds() and then checks to see if the LatLngBounds returned by getBounds overlaps with bounds from the FeatureGroup. ie. map.getBounds().overlaps(markerBounds). If they do overlap then you readd the overlay. eg. layerControl.addOverlay(cities, 'Cities').
You then run this new function once and you create an event handler to run it every time the moveend event happens. eg. map.on('moveend', function() { callFunc(); });
Related
I'm reading an imageOverlay URL from an ArcGIS webserver that uses the leaflet getBound() coordinates as part of the URL (we have large maps that are filtered for the current window 'extent'). Apologies for not including the actual path (I'm working with sensitive client data). Eg:
http://myarcgiswebserver.com/MapServer/export/dpi=96&format=png32&bbox=27.119750976562504%2C-31.194007509998823%2C32.39044189453126%2C-29.692824739380754&size=1719%2C434
[bbox] = current imageBounds
When dragging my map the imageOverlay url is updated correctly but my leaflet window is no longer aligned to the imageBound values that were set when first adding the imageOverlay which results in a skewed output (this is my assumption):
The only workaround is to remove the existing imageOverlay and add a new one (which ruins the user experience as the map disappears then reappears each time the window is dragged or zoomed).
Am i approaching this problem incorrectly or would the introduction of a function to update the current imageBounds resolve this? Perhaps not a new function but the expansion of setUrl with additional parameters...?
Many thanks for any feedback...
As #ghybs pointed out, your use case might be better served by using the WMS
interface of your ArcGIS server.
Anyway, you say
The only workaround is to remove the existing imageOverlay and add a new one (which ruins the user experience as the map disappears then reappears each time the window is dragged or zoomed).
Well, that glitch is due to you probably doing something like:
Remove old overlay
Add new overlay
Wait until the image is received from the network
Wait one frame so the new overlay is shown
and instead you should be doing something like:
Add new overlay
Wait until the image is received from the network
Remove old overlay
Wait one frame so the new overlay is shown
The problem is just the async wait and the possible race conditions there, but should be easy to hack together, e.g.:
var activeOverlay = null;
var overlayInRequest = null;
map.on('moveend zoomend', {
// If we are already requesting a new overlay, ignore it.
// This might need some additional debouncing logic to prevent
// lots of concurrent requests
if (overlayInRequest) {
overlayInRequest.off('load', showOverlay);
}
overlayInRequest = L.imageOverlay( computeUrl( map.getBounds() ), myOverlayOptions );
overlayInRequest.on('load', showOverlay);
});
function showOverlay(ev) {
activeOverlay.remove();
activeOverlay = overlayInRequest;
activeOverlay.addTo(map);
overlayInRequest = undefined;
}
If you use an ImageOverlay but change its url dynamically, with a new image that reflects a new bounding box, then indeed that is the reason for the behaviour you describe: you display an image that has been generated using a new bbox, but positioned in the initial bbox, since the image overlay remains at the same geographical position on the map.
Instead, it sounds to me that you should use a TileLayer.WMS.
It would automatically manage the bounding box update for you. You may need to find the correct options to fit your service provider required URL syntax, though.
Example: http://playground-leaflet.rhcloud.com/yel/1/edit?html,output
I have a flow panel with many photo-widgets inside (gallery with random number of rows and columns, depends on screen size) for which I want to implement drag and drop behavior to change their order. I am using gwt-dnd library. Its FlowPanelDropController allows you to define your own positioner (delimiter) which shows the candidate location for dropping the dragged widget.
I want this positioner to be the empty space with defined width, and the challenging thing is to implement sliding animation effect for the when positioner is added and removed.
If you are a desktop Picasa app user you know what I mean: the target row slides both sides (little to the left, little to the right) extending the space between the items where you are going to drop a photo.
The whole thing is complex enough, but any help related to how to apply the animation for positioner attach/detach is appreciated. Maybe I need to use a different approach (e.g., use GWT native dnd instead of gwt-dnd lib and no "positioners" at all) if you have any ideas how this could be helpful.
Thanks.
Well, I ended up overriding AbstractPositioningDropController (parent of FlowPanelDropController) and adding some extra features.
1) newPositioner() method now builds the Label, which is vertical space with some small width, height and decoration. This widget's element has constant id (say, "POSITIONER"), which helps to distinguish between multiple positioners if you plan to have several of them while navigating with a drag object over multiple drop targets. Also some transition CSS effects were applied to the Label, which will be responsible for handling animated extension of Label's width.
2) in onEnter() I do the following
...
removePositioner(getPositionerElement());
Widget positioner = newPositioner();
dropTarget.insert(positioner, targetIndex);
animatePositionerExtension();
where getPositionerElement() returns DOM.getElementById(POSITIONER)
At the same time removePositioner(..) resets the id of this element to something abstract and ideally should provide some animation before calling .removeFromParent(). But I didn't have enough time to properly debug this so ended up just removing the old positioner with no animation.
Method animatePositionerExtension() contains the code that changes the width of the positioner widget, so that CSS transition will catch that and provides animation.
All access to positioner widget in the class should be provided through updated methods.
3) onLeave() contains line removePositioner(getPositionerElement());
4) In the end of onMove() I added a couple of lines:
galleryWidget.extendHoveredRow(targetIndex - 1);
animatePositionerExtension();
where extendHoveredRow(hoveredWidgetOrdinal) implemented the logic to "limit" the sliding effect in the single line:
int rowHovered = -1;
public void extendHoveredRow(int hoveredWidgetOrdinal) {
int newRowHovered = getRowByOrdinalHovered(hoveredWidgetOrdinal);
if (rowHovered != newRowHovered) {
// adjust position of items in the previously hovered row
int firstInPreviouslyHoveredRow = (rowHovered - 1) * itemsInARow;
shiftFirstItemLeft(firstInPreviouslyHoveredRow, false);
rowHovered = newRowHovered;
// extend this row
int firstInThisRow = getOrdinalFirstInThisRowByOrdinal(hoveredWidgetOrdinal);
shiftFirstItemLeft(firstInThisRow, true);
}
}
This is in short how I did the thing. And still there's some room for improvements, like adding animated removal.
Again, it's all about overriding DropController and manipulations with elements inside the "gallery" widget. The benefit of this approach is that I remain in the gwt-dnd operations framework, and also reused a bunch of existent code.
Some notes:
CSS transition is not supported in IE pre-9, but this is unrelated to
this topic.
Put a transparent "glass" div on top of the Image widget if you use it
as a face of dragProxy. This will save you tons of time trying to
understand why either setting element's draggable to false, or
calling event.preventDefault() somewhere else, or other workarounds don't work in one or several browsers and the image itself is being dragged instead of the whole dragProxy widget.
In Leaflet, is it possible to define a marker or polyline with {clickable:false}, so that a click is passed through to whatever lies beneath - be it the map or a clickable geometry object?
At the moment I solve this problem by making the marker/polyline clickable and passing the event onwards myself. But this leads to the mouse cursor always showing as the hand symbol. Ideally, the mouse cursor should look like the normal pointer or the hand, depending on whether what is beneath the marker/polyline is clickable.
This may not be the answer you are looking for, but you can use featureGroups to have all of your clickable polylines come to the front so that the actions are surfaced.
var lg_noclick = new L.FeatureGroup().addTo(map);
var lg_click = new L.FeatureGroup().addTo(map);
// Add lines
lg_click.bringToFront();
updated fiddle
Also if you can afford to know your lines before hand, correct ordering of when you add the lines it will work as well.
I know this is not ideal but it suited my situation just fine, so it might be good for you as well.
This hides the icon and brings it back after a second using mouseenter and mouseleave events:
$('.leaflet-marker-icon').mouseenter(function() {
$(this).hide();
});
$('.leaflet-marker-icon').mouseleave(function() {
$(this).delay(1000).show(0);
});
I was studying the jQuery UI Sortable widget and it said that all callback functions receive a ui object. Two of its properties are ui.helper nad ui.item. ui.helper is mentioned to be mostly a clone of ui.item, but I can't get the significance of calling it 'helper'. Also, the offset and position properties are defined in terms of the helper and not the item. What's the difference between the two ?
One of the answers mention that the helper fills the void, but the I read in the docs that the helper element is "used for dragging display". What exactly is this helper element and why is it named so?
From what I understand ui.helper is a "clone" of the ui.item. It is cloned so you can edit it with css and make it look like whatever you want it to look like while you are dragging it and it won't effect the original ui.item. So if you had a box and while it was being dragged you wanted it to turn into a blue box with curved edges but only while it was dragging you can by modifying ui.helper.
The helper is the element that fills the void (with visibility: hidden) when the item is dragged.
I have SWT application that is a set of Groups that contain various controls including a StlyedText widget. They are all laid out using the Form layout.
I want to show a dialog directly below the caret inside of the StyledText. However, I have to position the dialog relative to the parent shell.
My first idea is to get the position of the shell plus the position of the StyledText plus the offset of the caret. When I try to get the position of the StyledText, it says 0,0 (I assume because of my layout choice, the Form layout). I don't see a good way to get the position from the FormData either (it appears to be computed).
I am able to get the position of the mouse cursor, but I would like to have it be right under what the user is typing.
Anyone have any ideas?
In order to get the actual postion, the function toDisplay() should be used. For example:
Point displayPoint = myText.toDisplay(sqlText.getLocation());
That gets me to the position of the Text. I then added the caret position in order to move my dialog window to the line of text that is being written:
Point caretLocation = myText.getCaret().getLocation();
Point calcPoint = new Point(displayPoint.x+caretLocation.x, displayPoint.y+caretLocation.y);
I then used that location to position my dialog window.