What I want to Achive:
Toggling the appearance of an Item, where the components that describe the appearance are loaded dynamically, but common elements are not loaded multiple times.
Lets say, I have a list of elements with an icon (e.g. cover) and a title (e.g. music title).
When clicked/dragged, it shifts the shape, so additional information can be displayed (e.g. duration, artist, ...).
Finally I have a DropArea, in which I can drop those elements. Here I only want to display the icon.
As I am informed correctly, it is not advisable to have all three forms pre-loaded and only shift the visibility and other parameters of the additional objects, as the first list is a ListView.
Therefore I decided, to create multiple components, and then load them with a Loader.
On the other hand, this leads to some overhead, for I load and unload the Icon, that is common to all the components, each time, the shape shifts.
My solution so far is, to load the image outside of the components, re-parenting it each time, the shape shifts. This however feels odd, and I am not sure, if this might not be the less performing way, compared to the "loading everything at once and resetting visiblity and positioners"-approach
What is the proper way to do this?
For the efficiency aspect, the most performing one should be that only dynamically loads something that is really dynamic, and leaves other things static(or so called declarative). In your app, the icon should be declarative, I think.
Regarding with reparenting, actually re-parenting is quite common in Qt Quick programming, especially within dynamically loading context. The parent in Qt Quick is not the same concept of QObject. It's just visual management (not memory management). That's why you can see Qt Quick even provides ParentChange in State/Transition.
Related
The project I'm working on calls for workspace layouts for a large section of it, by which I mean that users can move around panes, resize them, close them, etc., like in VSCode (but more like Emacs since VSCode does not currently support both vertical and horizontal splitting).
The current methodology I'm considering to create a custom LayoutManager that has a json object and injects views into recursive Row and Column objects in a binary-tree-like structure. Before I start this undertaking, I'm wondering if there is a library or set of QtQuick (QML) elements that would let me do this a lot more easily or if there is a better approach to this problem. Or, please just tell me why I'm wrong in doing it this way.
Note: The technologies I'm using are C++ with Qt 5 (currently 5.10).
If you want highly customizable GUI, with the option of persisting UI configuration, it is best to design the whole thing model driven.
QML already has the necessary stuff - list views, repeaters and so on. QML is a little at odds with tree models, but you can essentially fake a tree by using lists of lists.
The model provided here will do the trick, with the added benefit it also supports declarative instantiation. So you can easily set up an initial GUI state declaratively, like you would with normal QML, but then allow the user to make modifications to that initial state which can then be saved and recalled.
Then all you have to do is bind the desired GUI elements to the underlying model data source objects.
I'm creating hundred of buttons at runtime and adding them into layout. Each operation probably trigger many things (repaint, layout rebuild etc) which are not necessary for each button but could be called once add the end when all buttons are created. In Lazarus world (open-source Delphi alternative) is DisableAutoSizing / EnableAutoSizing for form which "hold on" time-consuming triggers. Can't find anything similar for Qt.
I need also such functionality in another case. Let's say that you have complicated UI with a lot of widgets (with childs etc) and you want to totally rearrange UI (change layout, move widgets into another layouts etc). Normally I sometimes see "flickering". I would like to stop application painting - rearrange widgets - enable painting
Edit: Found something setUpdatesEnabled() . Is there anything else?
I'm new to Flash and I trying to do something as following:
I need the ability run several layers of animation (image sequences) in a single file (ex. SWF) which will be loaded and accessed dynamically by Flex - I need to change the content (image sequence) in runtime in order to customize my animation.
What would be the best approach in this case?
Is it the correct direction?
Should I consider creating a SWF for each animation and load it dynamically into my layered SWF?
When you say you need to adjust the image sequence, do you mean customise the order of individual frames, or simply select between a selection of set sequences?
If it's the former, the answer will be a bit more in-depth, if it's the latter and there aren't too many you're probably best off exporting as SWFs, or even as a video file to compress them, then loading them in dynamically. If they're small enough not to add significant weight to your SWF, you could export them as MovieClips in a SWC and create instances of them directly in the code without having to load them in.
Hope this helps (sorry if any of the above is confusing!) - could you give a bit more detail on what you're trying to achieve?
I wanted to consult with the sages here regarding Qt and skinning, get your opinion and chart a path for my development. My requirements are as follows:
My Qt/C++ application (cross platform with Mac, Windows and Linux versions) needs to have modular skins.
A skin is defined as a set of one or more elements: - Window background texture - Look/feel of UI controls such as edit boxes, drop down, radio buttons, buttons etc. - Look/feel of window "caption", resize grips etc.
Skins will be installed with the application installer, allowing the user to choose which one he/she wants to use. Users should be able to change skins on the fly.
Can I go the QML route? should this be custom and based on simple resources which are built into the application? Any design advice will be appreciated.
Thanks.
If I understood you correctly then stylesheet is the best way forward. You can create stylesheets similar to CSS and then pass them as command line option to your application or load on invocation to style your application at runtime. That way you can create multiple stylesheets each having a different look and feel and allow user to load them at will. Since its CSS it doesn't need any new learning and you can keep all your styling outside your source code.
Here are a list of resources that can get you up and running quickly:
http://blog.qt.io/blog/2007/11/27/theming-qt-for-fun-and-profit/
http://doc.qt.io/qt-5/stylesheet.html
I haven't played with QML yet, but you could also create a custom QStyle implementation that supports your resource format. Note that you'd lose style sheet support if you went this route.
Changing window captions is a little trickier if you want portability.
QML, if I understand correctly, doesn't really skin the widgets, it mainly deals with GUI layout etc etc.
QStyle is used to change the looks. It is a bit low-level though, and requires programming, so if you want to load different user-created skins (from an XML or so) it might be tricky to support extensive skinning. Chaining colors and a few items are easy enough though. (There might be someone else who've done something you could re-use.. not sure.)
For modifying widgets, use QStyle::polish(). You could use that to change the background picture (if it's a top-level window, or of a certain class). There are numerous repaint method to change almost every part of every widget.
Store/load the style using QSettings, by reading and setting the desired Style just after QApplication but before your main window is constructed.
While reviewing the tutorials and example Flex projects, they seem to focus mainly on form elements and data grids, rather than delivering content in a more visual way. Which is what I will need for this upcoming project. As a result, I have a gap in my comfort level that I'm hoping that a seasoned Flex developer can help me hurtle.
The project that I have is a collaboration index tool to display customers products and services using an user interface with four separate panels.
the top-left panel will contain a list of categories in a vertical scroll.
The bottom left panel will contain a wheel effect of sub-categories, based on the category chosen.
The top right panel will contain the detail information - The selected Category Title and Description. And below that, the selected sub-category title and description.
The bottom right panel will contain a list of the service and product items that belong to the sub-category. Below each item in the list will be a link-group accordion with url links for more information in each.
There will be an XML file containing the complete data tree driving this collaboration index.
Additionally, depending on the category chosen, color variances will occur in the background of the some of layout sections.
So, It appears that I will need to create a few custom components, maybe adopt a few existing components, and re-skin everything so that it carries a synonymous look and feel to the client's branding.
Although I have a bunch of questions, tackling the first section seems logical, and the first question that comes to mind in this section is: in the top left panel, should the list of categories be standard Flex buttons that are re-skinned? or should they be object instances somehow brought in to Flex.
Then in the second section, I was had seen a component that displayed images in a way that was perfect for this section. But, the items show here would be just visual, rounded corner blocks with subcategory names in them. So, I'm not sure if that component will work or not.
AS3 is very different from AS2. I'm sure you've noticed by now, but it's worth mentioning in case you hadn't.
Flex Components are basically just a package of Flash objects. So you can, sort of, write every Flex component on your own using just Sprites and/or TextFields. This includes skins. A skin is pretty much just a Shape attached to an object with custom drawing.
A button is just a combination of image+textField+skin, with all the events and skin transitions managed for you.
The reason I mention this is that there is no right way to do what you want. If you're using the List control, you should probably write a component that implements IListItemRenderer. Button does, so you can simply override the Button, no problems. You can have buttons with a label + icon. Or just icon. Or just a label. You can also define where the label is positioned relative to the icon (labelPosition="above|below|left|right"). There is a lot of built-in flexibility.
Thanks for the mention of FlexSpaces. Note that it was finally ported to Flex 4 including a first pass conversion to spark controls earlier this year. Still to do: add dependency injection with Spring ActionScript, remove use of Cairngorm 2.x.
I have been developing Flex 4 quite heavily the past 6 months and must say it would make your job very easy.
Here's what I would do:
1) Check out FlexSpaces for the best Flex 3 project architecture. It's a fully featured CMS in Flex with categories, tags, searching, filesystem, collaboration, etc.
2) Download the Flex 4 SDK and install that. There's no need to use Flex 3 anymore, if you're just getting started, DEFINITELY go with Flex 4. If you need custom components, Spark (the new component architecture) has a very simple way of doing them (here's a cool blog post building a Rating Component in Spark that shows you how do it). Flex 4 is backward compatible with Flex 3 components, so you can use projects/components you find on the internet if you want to, no problem.
3) For the top-left category list, if the categories aren't nested, I would use the spark.components.List, (here's one using more complex item renderers). Then just extend the spark.components.supportClasses.ItemRenderer, which acts just like a Skin. If categories are nested, just use the mx.controls.Tree. Check out that FlexSpaces project for that (they show how to use XML/ArrayCollections in the tree, your "object instances brought into flex somehow" question).
4) For the wheel effect, the only thing I don't like about Spark so far is that it's difficult to animate layouts. But people are starting to make 3D layouts, check out Here's 5 3D Layouts for Flex 4 by Ryan Campbell. There's also OpenFlux if you want very easily animated layouts. Flex effects in general are quite clunky, so I end up just using Tweener or TweenMax for animations.
5) As for reskinning, trying to reskin using the Flex 3 architecture would be a monumental task, if you wanted to make it look clean and nice, and it would be insane trying to reuse that code in the next project. For Spark, it's a snap, and it's 100% mxml. Just copy the whole sparkSkins folder from the SDK and start changing things, and you're good to go.
But yeah, that FlexSpaces project is a very solid example for what you're talking about. Totally open source.
Cheers