I need to display many markers on a WPF image. The markers can be lines, circles, squares, etc. and there can be several hundreds of them.
Both the image source and the markers data are updated every few seconds. The markers are associated with specific pixels on the image and their size should be absolute in relation to the screen (i.e. when I move the image the markers should move along with it, but if i zoom in, they should take the same space of the screen as before).
Currently, I've implemented this using the AdornerLayer. This solution has several problems but the most significant one is that the UI doesn't fare well under the load even for 120 such markers.
I wanted to ask what would be the best way to go about implementing this? I thought of two solutions:
Inherit from Canvas and make sure it is invalidated not for every
added marker but for a range of markers at once
Create a control that holds an image and change its OnDraw to draw all the markers
I would appreciate some pointers from someone with experience with a similar problem.
Your use case looks quite specialized, so a specialized solution seems in order. I'd try a variant of your second option — extend Image, overriding its OnRender method.
Related
My aim is to have 3 images shrink, grow, and move along a horizontal axis depending on selection. Using Auto Layout seems to make the images jump about as they try to fulfil the Top space to superview / Bottom space to superview constraints.
So to combat this I have put all the images inside their own UIView. The UIView is set to the maximum size the images can grow to, it is centred on the horizontal axis. So now all the images must do is stay centred inside their corresponding UIView. This has fixed my problem as the UIViews perform the horizontal translation, while the images shrink/grow inside while remaining centred. My question is - is this the correct way to do this? It seems very long and like I am perhaps misusing the ability of Auto Layout. I have to perform similar tasks with more images and so any advice is welcome! Thanks.
I've just written a little essay on this topic here:
How do I adjust the anchor point of a CALayer, when Auto Layout is being used?
Basically autolayout does not play at all well with any kind of view transform. The easiest solution is to take your view out of autolayout's control altogether, but alternatively you can give it only constraints that won't fight back against the particular kind of transform you intend to apply. That second solution sounds like just the sort of thing you're doing.
What is the best way to manage a very large amount of images (10,000+) in WPF? This is for a 2d tile map editor similar to this : http://www.mapeditor.org/ .
At the moment i have a canvas with all tiles as an image and a list box which contains the different images to choose from. Each tile is added to the canvas as children and then stored in a list for later access. You paint into the canvas by setting the Source property of a tile to the one selected in the listbox. It works well with around 50x50 tile maps but anything above that causes loading delays, in general slow application.
Any suggestions on this? Would QT maybe be more suited instead of wpf?
Thanks in advance
Check out Implementing virtualized panel series of articles.
Virtualized panels are efficient, because:
Only the displayed elements (and a few extra around the borders to enable smooth scrolling) are in the memory (and rendered).
Elements are reused, instead of being repeatedly created and discarded - an old cell is simply filled with new content (supplied with new DataContext) and used in new location.
You might also try to use WPF's DataGrid for this, it supports virtualization out of the box and is essentially what are you trying to do.
WPF is certainly able to do this, if implemented properly (if you can do that in JavaScript, you can certainly do it in WPF as well).
How can I wrap shapes around the world, so that a shape is shown more than once at low zoom?
Example:
I draw a polygon over USA.
I zoom out so that I can see two USA's.
I only see one polygon: ( I want to see two!
The map data effectively has 2 USAs. That implies you should actually want 2 polygons, one of which will be hidden most of the time.
Might as well cater for the worst case and treat a single USA as the exception rather than the rule.
You can't.
As others have already pointed out, the fact that, at far zoom levels certain features get repeated on either side of the map is an unwanted but inevitable side-effect of a projected surface that enables continuous scrolling. This has only been an issue in recent versions of the Bing Maps control - the earlier v6.x control prevented the map from panning across the 180th meridian.
I cannot think of any possible reason why you'd ever want to show two USAs, let alone target data to be positioned on each one. So the solution is to modify either the zoom level at which the map is displayed, or the size of the application window in which it is being displayed so that this situation doesn't occur.
Given a WPF Application running full screen, a fair amount of controls some of which will animate from off screen to center. I was wondering if there are any special ways to save on the amount of time required to optimize an application for different screen resolutions?
For example, using Blend I've setup some text, which is originally off screen to scroll into view. Now in design mode the start positions are static. If resolution changes the start positions will obviously not be correct.
So I guess to correct this, during app startup. I need to
Check resolution
Move the text box to the desired start location
Adjust the storyboard as required, so the frames all have correct co-ordinates depending on the res of the screen.
I don't mind doing all of this, but if there is an easier way please share!
Thanks
In WPF layout of controls should be made in such way, that when size of window or content changes, controls automaticaly resize/reposition themselves to reflect this change.
This is highly affected how your layout is made, especialy by using specific panels, that do layout of their child elements.
This is also made obvious by using device-independent units for sizes, margins and sometimes positions of controls. And also allows different kind of zooming and scaling of whole UI without any need to redesign the whole thing.
If you are trying to position your controls absolutely, either by using Canvas panel or margins, your are doing it totaly wrong.
In WPF, scene is measured in abstract units, not pixels, and controls are freely scaled. There should be no problems to center something, or what?
I have an app that creates a variable number of ScatterviewItems based on which tagged object is placed on the surface table.
The ScatterViewItems are added programatically to the ScatterView based on info looked up in a DB
The Scatterview does a good job of displaying this info
However, I would like them to be
evenly distributed across the table and
not have any items overlapping
Any ideas how to do that?
Sounds like you need collision detection.
There's two parts to this problem: detection and resolution. Detection is seeing if any item's bounding intersects with any other item's bounding. If the items are retangular or circular this is pretty straightforeward. It can get complex if you're dealing with other geometries.
Resoltion is what to do once you've detected a collision. Google will help you find the myriad algorithms for this. Here's a couple links to stackoverflow discussions: WPF: Collision Detection with Rotated Squares, Applying Coefficient of Restitution in a collision resolution method, Best way to detect collision between sprites?.
You can implement collision to work so that items bound off of each other as they scatter. Depending on the number of items, this might cause so much collision that the items don't scatter well. If this happens, just run the collision detection one items have stopped moving.
UniformGrid ?
You can also create your own panel by iheriting from Panel.
You will find some uber-valuable info in the Dr. WPF ItemsControl How-To series : http://drwpf.com/blog/itemscontrol-a-to-z/
That's a must-read, period.
ScatterViewItem has properties Center and Orientation which you can use to programmatically position items. If you know the size of each item you should be able to use these properties to position them in whichever way is ideal for your situation. By hooking into the Loaded event of each and checking ActualWidth/ActualHeight, you can get the dimensions. If you can use a fixed initial size for all of your SVIs, that's even easier.
You could lay them out by calculating a simple grid (plus some randomness to make it look more natural), or you may be looking for what's called a "force directed layout", which gives each object a repellent force relative to its size. After a while the elements will naturally be evenly spaced from one another, though they may still overlap if they run out of room. I haven't seen a WPF example of this, but see flare.prefused.org/demo (layout > force) for what I mean in Flash.