I am trying to pass an object reference to the Dart script associated with a Polymer element. I have found the element in the DOM but I can't figure out how to call a method in the Dart associated with the element or any other way to dynamically pass an object to the Polymer element to be displayed.
Basically you just get a reference by using for example querySelector('#someid') and just assign the value to a field or setter or call a method and pass it as an argument.
querySelector('#someid').someField = someValue;
querySelector('#someid').setValue(someValue);
This might produce a hint in DartEditor but should still work when the code is executed. To get rid of the hint you can "cast" like
(querySelector('#someid') as MyComponent).someField = someValue;
querySelector('#someid') as MyComponent).setValue(someValue);
You need to import MyComponent to make this work.
If this doesn't something with your code might be wrong. For example the main() method if you have one. See how to implement a main function in polymer apps for more details.
If nothing of the above works, please add code to your question that shows what you're trying to accomplish.
Related
It seems when I call Gdk.Seat.grab() in GJS I get an error:
Gjs-WARNING **: JS ERROR: TypeError: Gdk.Seat.grab is not a function
This function and class is listed in the GJS Docs, but maybe I'm calling it wrong? If I call typeof on Gdk.Seat.grab it comes back undefined. Is this not possible, or is there another way I can grab focus in this way?
My use case is gathering a keybinding from a user, for which I can use Gtk.CellRendererAccel, but I would prefer not to use a Gtk.TreeView. The docs say about CellRenderers that:
These objects are used primarily by the GtkTreeView widget, though they aren’t tied to them in any specific way.
and...
The primary use of a GtkCellRenderer is for drawing a certain graphical elements on a cairo_t.
Which implies I could use it outside of TreeView, but with no hints as to how.
grab() is a method of Gdk.Seat, so you need a Gdk.Seat object to call it on. It looks like you're calling it as a static method, Gdk.Seat.grab(). So, you'll need something like Gdk.DeviceManager.get().get_default_display().get_default_seat() or you can get a Gdk.Seat object from a Gdk.Event.
It's not clear from the described use case what you are trying to do with the grab, but there may be an easier way to accomplish it.
Once again, a Dart/Polymer related question.
I wanted to use the Parse.com JavaScript library, but since it's not available in Dart I've written Wrapper classes which store a JsObject and delegate all calls from Dart to the corresponding JavaScript object. Basically it's like a proxy.
Guess what, it works pretty great.
However, my observables don't. To understand this, you have to take a look at the following structure of one of my "proxy"-classes.
class ParseObject extends Observable {
JsObject _jsDelegate = new JsObject(context['Parse']['ParseObject']);
void set(String key, dynamic value) {
_jsDelegate.callMethod('set', [key, jsify(value)];
}
dynamic get(String key) {
return dartify(_jsDelegate.callMethod('get', [key]));
}
}
The HTML code of my Polymer Element looks like this:
<div>Name: {{project.get('name')}}</div>
Since the data binding is only evaluate in case the parameter of the method changed, it will never be updated and thus even though the name is changed, the old one will stay in place.
The solution I came up with is to store all the values the user is setting in the ParseObject#set(String, dynamic) method into a Map which is observable. This works but I think it's quiete dirty since I have to make sure that both Maps, the one in Dart and the one in the ParseObject's JavaScript representation equal.
Thus I am looking for a better solution and I think of some kind of method to tell Polymer to reevaluate it's data bindings.
Does such a method exist or are there any other possibilities to address this problem?
Extending observable by itself does nothing yet.
You need to annotate the getters with #observable (and if you are not using Polymer, you also need to add the observable transformer to pubspec.yaml). You can't make functions observable (this works in Polymer elements but not in Observable model classes. For more details about observable see for example Implement an Observer pattern in Dart or Dart: #observable of getters
Is there a procedure to call an "init" method on a polymer element in Dart in order to populate it?
I have a polymer template (still not sure it's correct) and I want to populate it with the results of an HttpRequest. I can populate with a static list, but not sure how to populate it with a dynamic list made via an http call.
Are there examples anywhere?
I'm still trying to come up to speed on Dart and Polymer ...
My hacks are at https://gist.github.com/fils/6270699
Have you considered putting the init code inside a created() lifecycle method? You can see an example of that at https://github.com/dart-lang/web-ui/blob/polymer/example/todomvc/web/todo_row.dart
I have a function that accepts CanvasRenderingContext2D as a parameter and does the drawing. Whenever I try to pass it, I get this:
CanvasRenderingContext2D is not assignable to CanvasRenderingContext2D
That function looks like this:
void draw(CanvasRenderingContext2D context) {
...
}
I thought everything is passed as a reference in Dart (just like JS), which shouldn't cause such problems. Is there a way to say I want a reference to the object and not the object it self? Or is there something else I should know?
EDIT:
The problem was that in one file I imported dart:html and in another I had dart:dom. The names for corresponding interfaces are the same but they are different.
This is likely because you are using dart:dom and dart:html in the same application. To avoid such errors you should import one of them with a namespace
#import('dart:html');
#import('dart:dom', prefix: 'dom');
then you can access code defined in both of them as
window // dart:html window
dom.window // dart:dom window
for more information see this answer
I would like to do coloring in Eclipse without using the presentation reconciler. Therefore, first, I need to figure out how to associate a TextPresentation object with either my editor or document, but I am having difficulty finding out how to link it either of those. Normally, the CreatePresentation in the IPResentationReconciler interface would give the style range to the textpresentation, and from there Eclipse would know what to do with that presentation object. Is there some way to use a TextPresentation object without the use of PresentationReconciler? It would be nice if I could do coloring without the use of reconciler. Thank you.
I finally figured out how to achieve the coloring without the use of Reconcilers.
I discovered that first I needed a way to obtain a reference to my SourceViewer object, as I am extending TextEditor. I also discovered that I could implement the TextListener interface and add my own listener to the SourceViewer object. One must be careful, however, as calling the getSourceViewer() method can result in null if not called at the appropriate spot. Originally, I overwrote the init(...) function in my editor class and made the getSourceViewer() call, but it still resulted in null. After doing a bit of research, I discovered that I could properly obtain a reference to the SourceViewer object by overriding the createPartControl method. I first call super.createPartControl(...) and then make a call to getSourceViewer(). After I obtained that reference, I used that with my listener class I created and was able to do the coloring myself with the setTextColor method the SourceViewer object has. Hope this helps others in the same situation.