This is a best practices question. In QML, is it preferable to use the Item type as the root element for all custom QML components or is it acceptable to use say, Rectangle, ColumnLayout, or anything else as the root element? After all, Rectangle and ColumnLayout inherit from Item so in a sense, if either one of those are used, its still an Item root element. Are there any known drawbacks for not using the actual Item QML type (base type) as a custom component's root element?
No. You should use whatever works best for your requirements. There are things to keep in mind for users of that components (such as default properties, sizing behaviour, etc.), but nothing that says you should use Item as the root element.
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I want to subclass Grid to use the yogalayout library to calculate its children's positions and locations. I'm following instructions to create a custom panel. I see that when a child changes size, Grid knows to do a layout, but my control does not (ie, neither MeasureOverride nor ArrangeOverride() is called).
How can I know when a child (or, worse, a child of a child) size changes?
I have created a sample project https://github.com/arolson101/PanelTest that reproduces the issue I'm talking about.
(Note: I'm changing the question which previously mentioned StackPanel to instead mention Grid; I'm not convinced that it's unique to the Grid, but that was the way I was able to make a simple repro case.)
I see that when a child changes size, StackPanel knows to do a layout, but my control does not (ie, neither MeasureOverride nor ArrangeOverride() is called).
If you have not specific width and height property for the children element, when you get it's property, it will return NaN, And you could not set value with Width = newWidth, it can't also invoke the size change event, please call SetValue method to change the element size like the following. Then it will make MeasureOverride invoked.
MyTextBlock.SetValue(WidthProperty, 15);
I'm working a Vue project, and I'm using Vuex to manage the applications state. I've separated out the view of the app into many small layouts, as Vue components. For example I have a layout for a header and a floating stats panel.
I've written a custom directive for affixing the stats panel. Currently, this works similar to Bootstrap where you set a value, and when the page scrolls beyond that point an affix CSS class gets added to the element. This value is based on the height of the header. As app is responsive, I would rather have this value computed from the header outerHeight property.
Now, I can think of several ways on how to accomplish this, however I'm not sure the proper Vue way to do it.
I could listen for resize events and have the header update it's height in the Vuex store. However, it seems poor practice to have the store manage presentation data.
I could pass the id of the header to the affix directive, and use getElementById to check the height. But this is bypassing Vue completely.
I could add a method to the header to return its' height, and have the parent component that holds both the header and stats panel use that to update the affix value. This however, gets messy if header and stats don't share the same parent.
Are there any other options? What would be best practice? Thanks!
I would surely go with #1 - share it through Vuex. Keep in mind that Vuex is just a stage manager. There are no rules what kind of data you want to store. Furthermore, I think it would be best to use it, as more component may rely on this kind of data, and it will be the only source of truth, that is mutated in a predictable way. All other options include coupling components/instances/elements on the page, and therefore the bigger the connection between the height and the page gets, the more complex those connections will grow.
Plus it will be reactive, so just using actions/mutations you will have it updated everywhere, and therefore your page will look responsive.
The documentation for HBox and VBox includes the statement:
Deprecated: Use Box instead, which is a very quick and easy change.
But we recommend switching to Grid, since Box will go away eventually.
However, it isn't obvious what the "quick and easy change" should be.
How do you use Box and/or Grid to achieve the functionality of VBox or HBox?
One of the big changes in gtkmm3:
Gtk::Box, Gtk::ButtonBox, Gtk::IconView, Gtk::Paned, Gtk::ProgressBar,
Gtk::ScaleButton, Gtk::ScrollBar and Gtk::Separator now derive from
Gtk::Orientable, allowing their orientation (vertical or horizontal)
to be specified without requiring the use of a derived class such as
Gtk::HBox.
Although Grid isn't mentioned above, both containers now have a method set_orientation; Box can also take it in the constructor. So for Box, set the orientation and use your usual pack_start, pack_end.
With Grid, if you scrutinize the documentation, you'll see this line:
Grid can be used like a Box by just using Gtk::Container::add(), which
will place children next to each other in the direction determined by
the orientation property.
So, it should be as simple as setting the orientation and then add your child widgets.
There is a problem with sencha touch 2.
I am trying to understand how can I implement the same functionality which provides navigation view in sencha touch 2, but ....
Each item of the 'Ext.NavigationView' component should have it's own unique set of 'navigationBar' elements. I mean set of buttons, for example.
I know that I can do something like this:
this.getMain().getNavigationBar().rightBox.removeAll();
this.getMain().getNavigationBar().rightBox.add(this.getSettingButton());
//where 'getSettingButton' predefined by me a button
And do this action each time when 'push' event happens (clear 'navigationBar' and add appropriate set of buttons)
Of course, I even can implement 'Ext.Panel' with 'layout: card' and set of 'Ext.panel' elements in the 'items' property, each of which will be have unique 'toolbar'.
To control the behavior I can use 'setActiveItem' method.
But, I think each of these approaches is a bit weird, isn't it?
I expected that would be much more natural approach to implement it.
Most likely I don't know what I need. Confirm my doubts. What is the best way to do it.
Currently, Ext.NavigationView tends to perform navigation between "simple" views. "Simple" here means that your views are just panel with innerHTML, not the "complicated" ones with functional buttons, toolbars, etc.
As far as I know, there're 2 ways you could try:
If you still want to use Ext.NavigationView, you can customize your NavigationBar with titles, items (buttons, spacers, etc.) as normal components through navigationBar config, getter and setter.
(recommended) If your views are completely different from each other, you should use many Ext.Container with different items of your choice (for eg. first container with simple HTML announcement, second one with some extra Ext.Button, and so on). Simple use animateActiveItem() for animated navigation. This way is much more flexible, I suppose.
As I understand it, a Panel isn't meant to have any visible "chrome." The StackPanel, Grid and Canvas don't have any visible elements (with the exception of the gridlines, which they say are only for debugging layout.)
In my example, I am going to create a Custom Panel that uses Attached Properties to lay out its children controls. However, I want my Custom Panel to present a visible "grid" of sorts in the background. The look of the grid (sizing and positioning) will depend on the size and position of the child elements.
What are some of the ways to achieve this? Being very new to Silverlight and XAML in general, my first guess was to create a Custom Control which includes my custom panel for layout.
I think I'll be able to figure out the specific code, but I need to be pointed in the right direction in terms of what building blocks are appropriate for this scenario.
You are correct that custom Panels cannot show any extra chrome; they can only display their Children (Grid being an exception).
To do what you want to do, you could create a custom Panel which just adds extra Children to display the chrome. This would not be a good design though (since users of the Panel would see these extra items in the Children collection).
The best idea is to do what you said: create a custom Control that exposes a Children property. This control could internally use a private custom Panel to lay out these elements (e.g. TabControl uses a special TabPanel for laying out the tabs). In the Controls default template, you might want to use TemplateBinding on the Panels' Children property to your Control's Children property.
Panel can add Adorners to its children, read this article about adorners: http://msdn.microsoft.com/en-us/library/ms743737.aspx