In many occasions JavaFX needs to be customized with classes that extend existing ones. I tried this approach, for example to add a method to the NumberAxis class that would enable the label of the axis to be rotated.
But I got a "NumberAxis is declared final, can't be extended" compiler error. I wonder how people who extend classes do? Do they have access to the source code of javafx, modify it to make some classes not final, and recompile it? (sounds tricky! )
Making lots of classes final in the JavaFX framework was an intentional decision by the framework developers. To get a flavor of why it's done, see the Making Color Final proposal. That's just an example, there are other reasons. I think experience with subclassing in the Swing framework was that it caused errors and maintenance issues that the JavaFX designers wanted to avoid, so many things are made final.
There are other way to extend functionality than to directly subclass. Some alternatives for your rotation example:
aggregation: include the NumberAxis as a member of new class (e.g. NumberAxisWithRotatableText) which adds an accessor to get the underlying NumberAxis node and a method to perform the rotation (e.g. via a lookup as explained below).
composition: for example extend Pane, add a NumberAxis, disable the standard text drawing on the axis and add rotated labels yourself as needed.
css stylesheet: for example use a selector to lookup the text in the NumberAxis and the -fx-rotate attribute to rotate it.
node lookup: Use a node.lookup to get at the underlying text node, and apply the rotation via an API.
skin: All controls have a skin class attached them, replace the default skin class with a custom one.
subclass an alternate class: Subclass the abstract ValueAxis class rather than the final NumberAxis class.
Source code for JavaFX is available with build instructions. However, I don't recommend hacking a personal copy of the source code to remove final constructs unless you also submit it as an accepted patch to the JavaFX system so that you can be sure that your app won't break on a standard JavaFX install.
If you really think it is a good idea for a given class to be subclassable, then log a change request. Sometimes the JavaFX developers are overzealous and make stuff final which would be better not being final. NumberAxis perhaps falls into that category.
Related
I've read the documentation of this attribute:
An additional flag to be used with 'snap'. If set, the view will be snapped to its top and bottom margins, as opposed to the edges of the view itself.
https://developer.android.com/reference/com/google/android/material/appbar/AppBarLayout.LayoutParams.html#scroll_flag_snap
But I can't observe any actual effect in my app. What margin are they talking about? Every margin on the CollapsingToolbarLayout (on which this attribute is set) completely destroys the layout.
Not sure if it's useful yet, but here is the difference:)
If you pass snap as scroll flag, then it will move your view (in my case this search bar, it's linearLayout) to it's edge NOT INCLUDING the margin_layout
Then I've tried snap|snapMargin and it moved with the margin
P.S. No idea why snapMargin doesn't work without snap ¯\_(ツ)_/¯
This attribute is responsible for a scrolling behavior of AppBarLayout and its children. You can apply it directly to AppBarLayout or on the inside views, in the xml layout of your AppCompatActivity. It has to be an instance of AppCompatActivity if you want to use AppBar features. Also, the design library must be included in Gradle dependencies, like so: implementation 'com.android.support:design:26.1.0'
Please refer this link:-[https://medium.com/#tonia.tkachuk/appbarlayout-scroll-behavior-with-layout-scrollflags-2eec41b4366b][1]
When creating a WatchKit (WatchOS) Interface controller in the storyboard designer/editor, I cannot set it's class to something that is not itself type WKInterfaceController nor an immediate derived child of WKInterfaceController.
Basically in the hope of abstraction and better code reuse, better design overall, I would like to be able to use classes that are how to say, a more distant relative of their base WKInterfaceController
Basically right now it seems that your stuck using the storyboard designer to make a new WatchOS project. And using the storyboard designer you only have the option to select the WKInterfaceController class:
public partial class WKInterfaceController
or one that directly inherits from it:
public partial class ChildInterfaceController : WKInterfaceController
but nothing else such as:
public partial class GrandChildInterfaceController: ChildInterfaceController
So is there any way to do this that doesn't risk the chance of getting corrupted when you reenter the storyboard designer at some point?
Note: I've already asked if it is possible to avoid using a storyboard all together, but that has gone unanswered so I'm assuming no.
For clarity I'm talking about this dialog for "class":
I want to detect the scroll of tableview in my class. I used decelerationEnded method of UITableViewDelegate but it got crashed.
Ideally you should be using a UITableViewSource assigned to your UITableView.Source property. You no longer require a delegate class, you can override all of the necessary methods within the source, which is the currently preferred method of achieving the result your after. You are most likely looking to override the method called 'Scrolled' within the UITableViewSource. However I would suggest making use of 'DecelerationEnded' as well if you're trying to do something depending on if your scroll view is at the 'bottom' or 'top' of the UITableViews content (That's just a little tip based off of some experience with this in a recent project.)
If I declare something like
#FXML
private final static double PREF_SPACING = 10d;
or
#FXML
private Insets insets = new Insets(10d);
in the controller class,
is there a way to use their values in Scene Builder?
When I want to change the value, I want to change
it only once, in the controller class.
PRELIMINARY ANSWER
I haven't yet tried all of the techniques below, but it seems to be the way you would do it from reading the documentation. If I get some time, I'll try it out later and update this answer with results (or somebody else can do this and post a new answer or edit this one to create a definitive answer). I just wanted to publish something now to point you in what I believe to be the right direction.
If the below is not what you are looking for, add a few more specifics to your questions to fully describe what you want.
Don't using the #FXML annotation here. #FXML is for injecting values from the markup into the controller, not the other way around.
For your first example which is a constant, let's say your controller class is:
class MyControllerType {
public final static double PREF_SPACING = 10d;
}
Then in your fxml, reference the constant:
<?import MyControllerType?>
...
<VBox>
<spacing><MyControllerType fx:constant="PREF_SPACING"/></spacing>
</VBox>
For your second sample which is not a constant or a part of the SceneGraph, you can use an fx:define element to instantiate an instance of the class. Note that you can't directly instantiate an Insets class from FXML as it has no builder class nor zero length constructor. So what you might be able to do is create another placeholder class for the information and instantiate a reference to that in your FXML (or you can create a Builder that FXML can use to instantiate the Insets).
class InsetsHolder {
private Insets insets = new Insets(10d);
public Insets getInsets();
}
<?import InsetsHolder?>
<fx:define>
<InsetsHolder fx:id="i"/>
</fx:define>
<VBox>
<Button text="Click Me!" VBox.margin="$i.insets"/>
</VBox>
SceneBuilder should be able to read fxml files which use the fx:define and fx:constant notation, as well as (possibly) make use of the reference expression $i.insets. SceneBuilder might not have any UI to allow you to edit the values from within the SceneBuilder application, so you will probably need to hand edit the fxml file portions related to the fx:define and fx:constant elements if you wish to make use of these structures.
There is an executable example of using an fx:define element in this mailing list post on designing resolution independent units in FXML.
In general, I think I'd be a bit cautious of maintaining these kind of dependencies between fxml and java code. It may be more prudent to do more of this kind of stuff in plain Java code within the context of the controller initialize method as scottb suggests.
The #FXML annotation enables the JavaFX objects whose names you defined (fx:id) to have their references reflectively injected into nonpublic fields in the controller object as the scene graph is loaded from the fxml markup.
To the best of my knowledge, this is a one way operation. There is no provision for having named static class variables in the controller object injected into the scene graph during loading.
You can accomplish something very similar to what you are requesting by defining the values that you want set as class variables in your controller object's class, and then setting the appropriate object properties programmatically (rather than in markup) in the initialize() method of your controller object.
The initialize() method is called (if it is present) after the loading of the scene graph is complete (so all the GUI objects will have been instantiated) but before control has returned to your application's invoking code.
I'm trying to build a Monogame view inside a RelativeLayout from my MvvmCross monodroid Activity view.
An android Activity inherits from Microsoft.Xna.Framework.AndroidGameActivity to be able to run a Monogame inside a RelativeLayout (working).
My MvvmCross Activity inherits from MvxBindingActivityView(working).
So, I need a way to run the game and bind some datas within the same activity.
Thanks in advance for your help.
Loosely speaking, you can translate any Activity to an MvxActivity by inheriting some interfaces and by then cutting and pasting a small amount of code which does the basic loading and assignation of the ViewModel.
e.g. see the #Region and IMvxAndroidView<TViewModel> added to make MvxActivityView.cs from a normal Activity.
e.g. it's the same region and interface used for adapting a specialised Activity like Google's MapActivity into MvxMapActivityView.cs
At this level, the Activity/View has a ViewModel which can be used in C# code, but has no clever xml inflation - it has no clever Binding support.
Code can be written at this level - I've shipped apps without binding - but many users prefer to add DataBinding too...
To add this DataBinding support, you need to add a bit more code which provides BindingInflate, storage of bindings, disposal of bindings, etc.
e.g. a raw MvxActivityView is extended using the IMvxBindingActivity interface and a #region like: MvxBindingActivityView.cs
e.g. MvxMapActivityView is extended using the same region and interface: MvxBindingMapActivityView.cs
So to extend your the custom AndroidGameActivity:
Inherit from AndroidGameActivity to get ViewModelOwningGameActivity<T> and cut and paste the IMvxAndroidView<TViewModel> interface and #region from MvxActivityView<T> to provide the ViewModel methods, fields and properties.
Then assuming you want binding:
Inherit from ViewModelOwningGameActivity<T> to get BindingGameActivity<T> and cut and paste the IMvxBindingActivity and #region from MvxBindingActivityView<T> to get the binding methods
For specialist Activities you may want to add more - e.g. you may could add some custom helper methods for the MapActivity to plot points and lines, or for GameActivity to do whatever games do... but this is up to individual implementations.
Sorry about the cut and paste of code required in adapting Activities - I have tried to keep this to a minimum. However, writing Mvx is the one time so far that I've really wanted Multiple Inheritance or Mixins in C#