I have a requirement where I need to highlight the buildings around my current location on a map. I am using Xamarin and was wondering if anyone can point me to a correct library or control that can fulfill my requirement.
I am currently using Mapsui for Xamarin but I don't think it has the feature I am looking for.
If you have access to the geometries of the buildings there are many ways you could implement highlighting.
One way that comes to mind. Create a layer on top of your background layer with the same geometries as data source. Use a ThemeStyle to show only the selected geometry. The ThemeStyle class is created with a callback method which determines the style. In that method you should return no style unless the feature id is the same as selected feature id.
You can take a look at the ThemeStyle sample for a more general use of themes (no highlighting).
Also you could look at Mapsui.Sample.Wpf.Editing. Here is a screenshot of that sample:
I'm analyzing my approach with Gmail's android developer's team approach in order to optimize drawing times and generally create more efficient apps.
My approach:
Below is the hierarchy inside a listview. It's quite straightforward. ExpandableListContentItem extends a Relative layout which has 3 Views:
Gmail app:
The following screenshot is how the listview in Gmail app works (SwipableListView). It's interesting to see that there is only one View (I guess aY extends ConvertationItemView) which in reality is quite more complicated than mine (I see 3 texts, 1 photo, 1 icon/button).
Question:
I would assume that this is a more lightweight approach to get rendered, is it so? Even if it takes me more time to code an optimal single customview per listview item it is worth the performance that it offers?
Finally the only way I know so far is to inflate an existing view inside another which is basically the first approach. I guess now my challenge would be to combine that relativeLayout with the 3 nested views into one. Is that correct?
PS:examples, open source code are welcome.
I would assume that this is a more lightweight approach to get rendered, is it so?
Yes it is. When you consider hierarchy, every parent measures their dimensions and passes it to child views from top to bottom. Reducing layers and having more flat view will save time.
Even if it takes me more time to code an optimal single customview per listview item it is worth the performance that it offers?
Depends on application you are developing. Depends on number of items in a list and how you get them. When you scroll through the list, if you think it is slow you might want to try that approach. I tried it on my previous applications and I could see the difference.
I guess now my challenge would be to combine that relativeLayout with the 3 nested views into one.
I don't know what you mean by combining them but the way Gmail does it that they have their Custom View. You can create your custom view.
Besides that, another thing to consider is overdraw. It is as important as having flat views. If you activate GPU Overdraw from developer tools and look at Gmail app row, you will see 0 overdraw. Make sure your code has no overdraw.
For further reading I would recommend you to check these blogs :
Performance Tuning On Android
Android Performance Case Study
I use MvxImageViewLoader for MvvmCross Xamarin applications.
This component is really great and simplifies the images loading pretty much, but it (at least, out-of-the-box) is pretty basic and most of modern applications require some reacher functionality, for instance, loading/progress images or images nice appearing/transitions (possibly with custom animation).
I see there is DefaultImagePath property, but that's static image, which I can probably use by default, but that's not animated view or something.
So, is there any way to customize/extend the loader behaviour (for default image appearing, images transition (from default to loaded)) etc?
And also I've noticed that the loader caches the image and even if I trigger bound property changing (leaving the image url the same) it does not refresh the image. I guess, "caching" really means caching and so on, but what if I need to change the user icon or something... how can I forse the cache refreshing with the image loader?
Thank you!
So, is there any way to customize/extend the loader behaviour (for default image appearing, images transition (from default to loaded)) etc?
No - advanced features like fade-in/fade-out/animated-placeholder display aren't supported within the standard MvvmCross image view, and no-one that I know of has provided any samples or tutorials about how this can be done.
For adding such functionality, you can use normal software techniques - inheritance, aggregation and cut, copy, paste. e.g. you could simply create your own AgatImageView which had the behaviour your app requires based on MvxImageView.cs.
Some examples of creating your own data-bound controls is given in N=18 and N-19 of http://mvvmcross.wordpress.com/
As you already mentioned in upper comments you may use default iOS' UIActivityIndicatorView for showing progress and you should hide the progress in afterImageChangeAction, you can check if UIImageView.Image field is not null, to make sure that the image is loaded.
Regarding the caching, it's not that easy here. By default MvxImageViewLoader relies on MvvmCross framework's implementation of IMvxFileDownloadCache interface. This interface has only one public method RequestLocalFilePath(), so even if you get an instance from IoC container (Mvx.Resolve()) you won't be able to clean-up the existing cache (to do that you need to reset private _entriesByHttpUrl field of MvxFileDownloadCache class).
If you really need this, you have to copy-paste existing MvxFileDownloadCache class and make your tweaks. But I am not sure about your use-cases where you need this. If you download images from the web, the URL of the image is a sort of a key in the cache, so if you need to reload just change the URL.
Maybe you could use some old-school approach like adding GET parameters to the URL: http://mydomain.com/images/myimage.jpg?timestamp=123456. Usually this helps everywhere :-). Although I didn't test it with MvxImageViewLoader, it's just my best guess.
The image component allows Free Ratio cropping out of the box. I'm a bit baffled at why there is no Aspect Ratio option (keeping height and width constrained to each other), which would work much better for us. Is this an existing feature that can be enabled, or a custom task in Java?
I am using CQ 5.4.
This is OOTB since 5.4 (atleast), though not well documented.. Set up your smart image widget like so:
<image-16x10
jcr:primaryType="cq:Widget"
allowFileReference="{Boolean}true"
cropParameter="./image-16x10/imageCrop"
fileReferenceParameter="fileReference"
name="./image-16x10/file"
requestSuffix=".img.png"
rotateParameter=""
title="16x10"
xtype="html5smartimage">
<cropConfig
jcr:primaryType="nt:unstructured">
<aspectRatios
jcr:primaryType="nt:unstructured">
<aspectRatio-16x10
jcr:primaryType="nt:unstructured"
text="16x10"
value="16,10"/>
</aspectRatios>
</cropConfig>
</image-16x10>
The cropConfig node structure is what youre interested in. text="16x:10" is what will appear in the Crop dropdown, value="16,10" is the actual fixed Crop size for the tool. You can add as many predefined crops you want per html5smartimage widget.
The image-16x10 and aspectRatio-16x10 names aren't required, but not a useful convention to help in maintainability of the config.If you allow multiple aspectRatios then the image-16x10 naming probably doesnt make as much sense tho its not a bad idea to provide semantic naming to your aspectRatio definition node.
If you'd like to generate images with different aspectRatios, try this...
http://experience-aem.blogspot.com/2013/09/cq-image-custom-aspect-ratios-crop.html
The crop parameters are saved in different properties and not "cropParameter" of the html5smartimage widget
That would be a custom JavaScript widget: the one you're using (smart image) does not have an aspect ratio functionality (or just I never seen one), even in 5.6.
You could extend the existing widget, and provide this functionality in your own, using Javascript though -- it's not trivial, but not rocket science either -- see source code for smart image to see how it extends smart panel, and then registers itself into the framework.
Is there some standard way to make my applications skinnable?
By "skinnable" I mean the ability of the application to support multiple skins.
I am not targeting any particular platform here. Just want to know if there are any general guidelines for making applications skinnable.
It looks like skinning web applications is relatively easy. What about desktop applications?
Skins are just Yet Another Level Of Abstraction (YALOA!).
If you read up on the MVC design pattern then you'll understand many of the principles needed.
The presentation layer (or skin) only has to do a few things:
Show the interface
When certain actions are taken (clicking, entering text in a box, etc) then it triggers actions
It has to receive notices from the model and controller when it needs to change
In a normal program this abstraction is done by having code which connects the text boxes to the methods and objects they are related to, and having code which changes the display based on the program commands.
If you want to add skinning you need to take that ability and make it so that can be done without compiling the code again.
Check out, for instance, XUL and see how it's done there. You'll find a lot of skinning projects use XML to describe the various 'faces' of the skin (it playing music, or organizing the library for an MP3 player skin), and then where each control is located and what data and methods it should be attached to in the program.
It can seem hard until you do it, then you realize it's just like any other level of abstraction you've dealt with before (from a program with gotos, to control structures, to functions, to structures, to classes and objects, to JIT compilers, etc).
The initial learning curve isn't trivial, but do a few projects and you'll find it's not hard.
-Adam
Keep all your styles in a separate CSS file(s)
Stay away from any inline styling
It really depends on how "skinnable" you want your apps to be. Letting the user configure colors and images is going to be a lot easier than letting them hide/remove components or even write their own components.
For most cases, you can probably get away with writing some kind of Resource Provider that serves up colors and images instead of hardcoding them in your source file. So, this:
Color backgroundColor = Color.BLUE;
Would become something like:
Color backgroundColor = ResourceManager.getColor("form.background");
Then, all you have to do is change the mappings in your ResourceManager class and all clients will be consistent. If you want to do this in real-time, changing any of the ResourceManager's mappings will probably send out an event to its clients and notify them that something has changed. Then the clients can redraw their components if they want to.
Implementation varies by platform, but here are a few general cross-platform considerations:
It is good to have an established overall layout into which visual elements can be "plugged." It's harder (but still possible) to support completely different general layouts through skinning.
Develop a well-documented naming convention for the assets (images, HTML fragments, etc.) that comprise a skin.
Design a clean way to "discover" existing skins and add new ones. For example: Winamp uses a ZIP file format to store all the images for its skins. All the skin files reside in a well-known folder off the application folder.
Be aware of scaling issues. Not everyone uses the same screen resolution.
Are you going to allow third-party skin development? This will affect your design.
Architecturally, the Model-View-Controller pattern lends itself to skinning.
These are just a few things to be aware of. Your implementation will vary between web and fat client, and by your feature requirements. HTH.
The basic principle is that used by CSS in web pages.
Rather than ever specifying the formatting (colour / font / layout[to some extent]) of your content, you simply describe what kind of content it is.
To give a web example, in the content for a blog page you might mark different sections as being an:
Title
Blog Entry
Archive Pane
etc.
The Entry might be made of severl subsections such as "heading", "body" and "timestamp".
Then, elsewhere you have a stylesheet which specifies all the properties of each kind of element, size, alignment, colour, background, font etc. When rendering the page or srawing / initialising the componatns in your UI you always consult the current stylesheet to look up these properties.
Then, skinning, and indeed editing your design, becomes MUCH easier. You simple create a different stylesheet and tweak the values to your heat's content.
Edit:
One key point to remember is the distinction between a general style (like classes in CSS) and a specific style (like ID's in CSS). You want to be able to uniquely identify some items in your layout, such as the heading, as being a single identifiable item that you can apply a unique style to, whereas other items (such as an entry in a blog, or a field in a database view) will all want to have the same style.
It's different for each platform/technology.
For WPF, take a look at what Josh Smith calls structural skinning: http://www.codeproject.com/KB/WPF/podder2.aspx
This should be relatively easy, follow these steps:
Strip out all styling for your entire web application or website
Use css to change the way your app looks.
For more information visit css zen garden for ideas.
You shouldn't. Or at least you should ask yourself if it's really the right decision.
Skinning breaks the UI design guidelines. It "jars" the user because your skinned app operates and looks totally different from all the other apps their using. Things like command shortcut keys won't be consistent and they'll lose productivity. It will be less handicapped accessible because screen readers will have a harder time understanding it.
There are a ton of reasons NOT to skin. If you just want to make your application visually distinct, that's a poor reason in my opinion. You will make your app harder to use and less likely that people will ever go beyond the trial period.
Having said all that, there are some classes of apps where skinning is basically expected, such as media players and imersive full screen games. But if your app isn't in a class where skinning is largely mandated, I would seriously consider finding other ways to make your app better than your competition.
Depending on how deep you wish to dig, you can opt to use a 'formatting' framework (e.g. Java's PLAF, the web's CSS), or an entirely decoupled multiple tier architecture.
If you want to define a pluggable skin, you need to consider that from the very beginning. The presentation layer knows nothing about the business logic but it's API and vice versa.
It seems most of the people here refer to CSS, as if its the only skinning option.
Windows Media Player (and Winamp, AFAIR) use XML as well as images (if neccesary) to define a skin.
The XML references hooks, events, etc. and handles how things look and react. I'm not sure about how they handle the back end, but loading a given skin is really as simply as locating the appropriate XML file, loading the images then placing them where they need to go.
XML also gives you far more control over what you can do (i.e. create new components, change component sizes, etc.).
XML combined with CSS could give wonderful results for a skinning engine of a desktop or web application.