I'm creating a simple (or so I thought) app that allows a user to drag/drop/reorder items within one of two recyclerview lists, or from one list to another. It should animate as you are dragging items, opening gaps that help you easily drop the item into the target spot. This functionality needs to go both ways between the lists. And for extra fun, drag should start on touch, not long press.
In case it makes any difference I'm trying to stick to MVVM, and my 2 recyclerviews are in 2 different fragments, but combined in one screen for this activity.
I'm a relative newbie to android, and using kotlin.
What I have managed so far
I can achieve a nice animation within one recyclerview, using ItemTouchHelper.
OR
I can achieve drag and drop from one recyclerview to the other, and I can start that on touch rather than long press, using View.OnDragListener.
What I can't seem to do is get both of those working at once--drag to another view, but with those beautiful animations ItemTouchHelper provides as the drag is underway.
I have tested all kinds of combinations of attaching customized drag or touchlisteners to my viewholders or recyclerviews. The closest I've gotten to getting things working is attaching the draglistener to the recyclerviews only, in order to receive the dropped view. Then I have set draglisteners and touchhelpers on the viewholders (via the recyclerview adapter).
With this setup I can drag between or within recyclerviews on touch, and have managed to get an animation AFTER drop by calling onItemMove of my adapter (provided as a parameter in my custom draglistener) from within the ACTION_DROP of my dragListener.
I've been working on this for a VERY LONG TIME and googled the heck out of it without luck. Help deeply appreciated.
Related
I have just recently began learning Swift and Xcode and I have just started programming my first app. At the moment I am using .hidden to hide and show UI elements when the user taps on different functions to switch between different scenes. This seems very messy and unnecessary so I've been trying to figure out a better way to do it. I was experimenting with different things and discovered segues but I am not sure how I would switch to a new scene within a tab without losing the tab bar at the bottom?
Any help would be greatly appreciated.
I thought I would answer my own question now that I have been programming in Swift for a few months now and the answer is obvious...
Rather than hiding and unhiding individual objects, just drag a UIView into the view controller and you can add objects to that. You then simply need to hide the view, to which all of the objects are attached.
I'm an intermediate iOS developer who's trying to jump on the OSX side of things.
I've been struggling to create an accordion-like display of several views, where only one view at a time can be unfolded to occupy the whole parent's view's available space. In other words, click on a view's title bar, it will both open/unfold this view and close/fold the currently open view, with animations'n'all. Oh end, I need the views' contents to be scrollable.
I tried starting from Apple's NSStackView sample code, but first it is not quite what I want, and what's more, I can't figure out how to start from here to end up where I eventually want to be.
Then I tried to master the Auto-Layout facilities but with no success. Truth be told, this whole Auto-Layout thing still confuses me some.
Does any of you have clues as to how I should proceed? Sample code? Tutorials (I tried several Auto-Layout tutorial but at the end of the day they still leave me missing the tricks I'd need to figure...).
Thanks.
/Julian
Check out the sample code: InfoBarStackView. It creates an accordion-like interface, the one difference from what you're describing is it lets multiple views be revealed at the same time (although, that's a simple difference).
It uses NSStackView and autolayout constraints to create the interface and drive the reveal/hide animations.
The stack view could also be put into an NSScrollView to allow the content to be scrollable. (Something similar was done during a WWDC 2013 Cocoa Animation talk).
Although I know of a solution to this problem, I am interested if someone can explain this solution to me. I also wanted to get this out there because I could not find any mention of this problem online, and it took me several hours over several days to track down. I have an NSTableView behaving strangely regarding redraws and its selection. The problem looks like this:
Table contents fades in, instead of appearing instantly upon it's appearance on screen. When scrolling through the contents, the newly appearing rows also fade in. When you make a selection (single or multiple), and scroll it off screen, then make another selection (that should replace, not add-to first selection), the first selection does not get cleared properly. If you scroll back to it, it is still there, in addition to your new selection. This is a display-update problem, not selection problem - i.e. your new selection is valid, it is just displayed wrong.
I tracked this through the NSArrayController I was binding to, the underlying Array, sorting, all the connections, and settings, etc., but all that has nothing to do with it.
What solved the problem was:
In the View Effects (right-most) Inspector, uncheck "Core Animation Layer" for the Window's main view.
Can anyone explain what is happening here, and perhaps improve upon the solution ?
It looks like Core Animation and NSTableView aren't getting along so well. The "fading" effect is a by-product of the way core animation works. When you have core animation in one view, it is also enabled in all of that view's subviews.
I don't recommend using core animation on the Mac unless absolutely necessary, because some interface elements (NSTextView and NSTableView, for example) aren't compatible with it. iOS has much better support for table views and such using core animation, mainly because it was designed with core animation in mind.
I know that some more simple UI elements are compatible (NSTextField and NSButton, for example).
If you absolutely need core animation in the rest of the window, put all the other views in a subview of the content view, while leaving the table view directly in the content view. You can then enable Core Animation in the other view.
Commenters, feel free to add to the list of what is and isn't compatible.
I am trying to create a view for a kind of brainstorming application like, for example, OmniGraffle, with elements that contain textviews and can be dragged around. (Also, the should be connectable with arrows, but that is not (yet) the problem)
I did my homework and searched via google and read books about cocoa, but there seems to be no similar example around.
Since I am also new to cocoa, I’m a bit helpless here.
The thing I am sure of is, that I need a custom view in which I can create my elements - what I tried until now to do that is:
First, I searched for the syntax to add subwindows to a window to create my elements. Subwindows, I imagined, would automatically be movable and come to front and so on.
The problem: As the experienced Cocoa-programmers of you probably are not surprised, I was stunned to find nothing about anything like that - this seems to be something, that is just not intended in Cocoa?!
Then I thought about creating subviews that contain a custom view for the title bar drawing (where the user can click to drag the element) and a NSTextView.
Problems:
I read, that it is not so clever to create dozens of subviews in a window because that would be very slow (or would that be not so bad in this case because all the subviews would be instances of always the same class?).
Also I can’t find out how to load a subview from a nib- or xib-file. Would I need a viewController? Or would that make the dozens-of-instances-problem even worse?
And Apple tells you not to overlap subviews (okay, that would be not so important, but I really wonder how the guys at OmniGroup made OmniGraffle...)
Because of that, I now wanted to do the title-bar-drawing in the surrounding custom view and create the textview programmatically (as I understand, a text-“view“ ist not really a view and takes its functionality from NSCell to reduce all the effort with the views?).
Problems:
Even that failed because I was not able to create a textview that doesn’t fill the complete window (the initWithFrame: of the [[NSScrollView alloc] initWithFrame: aRect] just seems to be ignored or do I get that wrong?).
Also, there should be some buttons on each element in the final application. I imagine that would be easier to accomplish with a subview from a nib-file for each element?
Well, now that nothing works and the more I read, the more problems seem to occur, I am pretty confused and frustrated.
How could I realize such a program? Could someone please push me in the right direction?
I created a class for the draggable elements where I save position, size and text in instance variables. In my view, every new element instance is added to an array (for now, this works without a controller). The array is used to draw all the elements in a loop in drawRect:. For the text of the element I just use a NSTextFieldCell which is set to the saved text from every element in the same loop.
That way it is also possible to overlap the elements.
I’m starting to develop my first full-blown Cocoa application containing a view which I would like to behave (and look) similar to Automator’s AMWorkflowView.
The basic features I’d like to achieve:
Positioning of subviews
Display of subviews in expanded / collapsed states
Multiple selection
Drag and drop
In order to get accustomed to Cocoa, I started with a custom NSView which mainly served as a container for the custom subviews and handled their positioning and multiple selection.
The subviews are also subclasses of NSView, and contain a variable amount of views themselves, like buttons, labels and popup menus, and therefore can have different heights.
This worked quite well, but before going on, I want to make sure to have everything neat and tidy according to the MVC pattern.
I suspect that there already is a class in Cocoa that facilitates the implementation of a view container, like maybe NSCollectionView.
It seems that there is no (easy) way to display differently sized views in an NSCollectionView, though. Should I continue implementing my custom NSView (probably using an NSArrayController for selection and sorting support), or are there better ways to go?
Any help is much appreciated
Unfortunately the answer is you'll have to roll your own. NSCollectionView does not allow for variable-sized items (which also rules out expanded/collapsed states).
For a limited number of items, you can accomplish this rather easily (you just need a container view that arranges the subviews properly when asked to layout, then you need to make sure you re-layout when things change). For many subviews, however, you'll need to take care to be as efficient as possible. This can start with laying out as little as possible (only those "after" the resized view, for example) and get as complex as caching a visual representation of a prototype view, drawing the cached images (fast!) for all but the view being edited, and only using/positioning a "real" view for the view being edited.
Drag and drop works the same as it always has, but none of the above accounts for the pretty animation NSCollectionView gives you. :-) It's fast and beautifully-animated precisely because all the subviews are uniform (so the layout calculations are fast and simple). Once you add irregular sizes, the problem becomes significantly more complicated.
The bottom line: If you need variably-sized views, NSCollectionView will not work and you'll need to roll your own or find someone else's shared code, but performance and beautiful animation will not be easy.