I would like to have a collapsable Widget like seen here. The Problem with the accepted solution for me: I want to dynamically change the content of the collapse-widget (adding / removing widgets while it is collapsed or expanded). The provided solution copies the content height on creation, and is thus not responsible as I need.
I already experimented a lot with Layout-SizeConstraint and Widget-Sizehints, but did not manage to adjust the solution there to be responsive.
How can I create a collapsable widget that allows for content size changes?
You should take a look at Qt Animation Framework.
This is for Widgets, but QML also has almost identical functionality. You just define different states (like, for example: "DEFAULT", "COLLAPSED", "EXPANDED") and transition animations (with easing curves, delays and other fancy stuff). If you have more questions regarding states and animation, let me know.
Related
I am using Ubuntu OS.
I am new to GTKMM GUI building application.
I am following the tutorials which they have on their websites.
https://developer.gnome.org/gtkmm-tutorial/stable/sec-helloworld.html.en
I can resize the window with helloworld.set_default_size(500,500);
but I cannot move the position of button("hello world").
It is always aligned at center.
I tried with m_button.set_alignment(0.0,0.0) but nothing seems to be working.
Why it is that much difficult to move button to any position.?
kindly suggest some solution if available.
If you want to place a widget like a button, you have to use some container widget like Gtk::Boxor Gtk::Grid. Inside such container widgets you can place you child widget as you like, but typically not directly per point position.
The container widgets use some internal logic to order and resize the contained widgets.
From the documentation:
Many GUI toolkits require you to precisely place widgets in a window, using absolute positioning, often using a visual editor. This leads to several problems: ...
gtkmm uses the packing system to solve these problems.
You can find the full documentation here:
Multi-item widgets
I did not know if there is a container widget which allows direct positioning by giving a point position. If someone has an additional hint, let us know!
Sometimes automatic is better than manual handling, but sometimes it is not :-)
Lets, for example, we have QHBoxLayout inside QMainWindow.
Lets we have set of the widgets inside above layout.
But (!) few of widgets have discrete visual representations.
In another words they have few states dependent on available space.
For example:
if there are too much available space - it must look like big image + some text
if there available minimal space - it must look like little image
if there available few more than minimal space - it must look like button + label
etc...
So when the user change the main window size our "dynamic" widgets must show own representation dependent on available space.
How it could be achieved in Qt?
UPD: the closest behavior present in the Microsoft ribbon interface
UPD2: the QML closest behavior present in gif below (on part where window resized by user)
UPD3: more complex example - each panel in the menu panel change content elements view and count that depends from available space
There's no magic solution for this. You'll need to implement events/actions to take when the container is resized. It can be as simple or complex as you need. There are several different ways to go about actually implementing it, depending on complexity and scope involved (it is just a few items? the whole UI? etc...).
Here is a very basic (crude but effective) example which moves a toolbar to either be on the same line as another toolbar (for wider window) or to its own line (for narrower window). MdiChild in this case is a QWidget implementation which, obviously, contains other widgets and manages their layout.
void MdiChild::resizeEvent(QResizeEvent * event)
{
QWidget::resizeEvent(event);
if (size().width() > ui->topToolbarLayout->sizeHint().width() + ui->botToolbarLayout->sizeHint().width() + 30) {
ui->botToolbarLayout->removeWidget(modelsToolbar);
ui->topToolbarLayout->insertWidget(1, modelsToolbar);
}
else {
ui->topToolbarLayout->removeWidget(modelsToolbar);
ui->botToolbarLayout->insertWidget(0, modelsToolbar);
}
}
As you can see it has to take the container size into account, and the most direct way to do that is in the QWidget::resizeEvent(). You could do anything here you want... change text buttons to icons, hide/show/move stuff... whatever.
Instead of handling the visual changes in the container, you could of course hook up signals/slots to the contained widgets... eg. a custom signal emit availableSizeChanged(QSize size) from the resizeEvent() handler connect()ed to the contained widget(s).
You may find QStateMachine handy to maintain visual state in a formal manner (this is what QML uses for it's state[s] property and transition system).
You could also implement your own QLayout as others have suggested. Though the scope of the question itself suggests you may not need to. The question is quite general IMHO. The two examples provided have massive differences in terms of complexity.
For this answer, I will use Qt-equivalent terms, not the official MS Ribbon terminology.
An Overview
You are actually looking at a number of layouts, in a pattern like so:
QToolbar
| (Layout)
+--> QGroupBox/QToolButton
| | (Layout)
| +----->Button
| +----->Button
+--> QGroupBox/QToolButton
The Pattern
Let's start with just the QGroupBox that populates helps sort our buttons into groups.
Consider that our group box may hold both our dynamic QToolButton and regular widgets. When the available space shrinks, the layout:
Calculates the minimum space required for fixed-sized widgets and the minimumSizeHint() values of the widgets without fixed size policies.
Apportions the remaining space based on the growth policy of each widget.
However, our dynamic tool button may or may not change size depending on available space.
Now we have to start checking if the children of the layout are dynamic or not, using qobject_cast.
When we find a dynamic button, we have to determine if it can shrink or not. If it does, we cache this and its preferred, smaller size.
If it's going to shrink, we have to recalculate our minimum size.
And then we have to keep going, hoping that shrinking the buttons during resize doesn't cause any tricky tie-breakers.
Tie breakers: if two buttons can collapse to a smaller size, which one goess first? We have to account for that, too. Also, MS uses rows of three buttons. We can't collapse one from Qt::ToolButtonTextBesideIcon to Qt::ToolButtonIconOnly, we have to collapse a set of three.
Three horizontal buttons can collapse to three vertical buttons. This, too, needs to be calculated and cached.
There is hope.
We can simplify by making each container only able to hold dynamic tool buttons. Then we don't have to deal with tricky issues like fixed sized widgets and we only need to deal with one type of widget.
Microsoft has also helpfully implemented this behavior for us. You can learn a lot about the behavioral constraints of your layout and child widgets by empirical observation. When do groups collapse? If a group collapses, do other groups expand to take up the space? (The answer to that is no, by the way.) How do buttons group together as they collapse? Are some special in how they collapse and expand (constraints on their expansion and collapsing behavior)?
Qt has also implemented several layouts for us to study and get an idea of how they work and how they are different. QGridLayout is a promising basis, particularly if you do some math to change the row span of widgets on the fly (this is for grouping buttons as they collapse from vertical layout to sets of three horizontal buttons).
In Summary
Completely answering your question is far too broad to be on-topic on SO, but I hope this info guides you where you need to go.
I am designing a GUI in Qt that has placeholders for a number of images (images will be set and updated at run time) along with some input fields (QLineEdits with QLabels grouped into QGroupBoxes). I am using a technique similar to the answer here:
How do I make an image resize to scale in Qt?
for the image display widgets. Some are a class that inherits from QWidget that can draw an aspect-scaled image, others are a class that inherits from QLabel that can do the same and also display text. These are custom C++ classes.
The problem I am having is with the layout and getting things spaced correctly. I am using Qt Designer to layout the GUI. Since the image widgets are "empty" they don't exert a lot of "force" on the other widgets and the other widgets tend to dominate even though I don't need the other widgets to be that big. The QLineEdits especially like to be as wide as they can be. I want to GUI to be adaptable for different sizes (to accommodate different screen resolutions) so I don't really want to set a lot of sizes manually if I can help it.
I do not have a lot of experience in Qt and managing layouts. What I know I have mostly learned from playing around with it. I have tried searching for similar situations without much success. I can't figure out the terms to use for my specific situation. Does anyone have any suggestions for what I can do to better control the layout? Alternatively, are there any good resources for learning how to manage Qt's layouts? The Qt documentation I have looked at is fairly basic. There are a lot of options, most of which I am unsure exactly how they should work, and the trial-and-error approach is getting to be too cumbersome for more complex layouts.
I am using Qt 4.8.
Sorry to be vague. This is a work project and I would rather not post exactly what I have. And coming up with a generic example will take time. I think my questions are generic enough that it shouldn't matter. If a more specific example is needed, I can try to throw something together.
Edit:
Here is what the layout looks like in Designer right now. The black boxes are redacted labels. The orange boxes are where images will go. The one in the top-left corner is a particular problem. I currently have the top and bottom halves on the left in a splitter in an effort to make things fit better. I think that may be making it worse.
http://i.stack.imgur.com/nRRg3.png (long-time reader, first-time poster :-/)
Making the "What I want it to look like" picture is going to take a bit longer. It may be easy to see what I don't like. The input fields need to be much smaller to make room for the images.
Edit2:
And here's something closer to what I would like. The upper-left and right-hand images are larger and actually visible. I might like the boxes in the lower-middle to be even bigger, but there's only so much room. If I can get the layout right, I'm hoping that will optimize the size of everything for a given window size.
http://i.stack.imgur.com/yvLvi.png
I was wondering how Qt does all its styling. I need to create a custom control and I'd like for it to meet the standards such that my control won't feel out of place on different platforms and styles.
For example, I'm going to need a cursor that's used in text, does Qt provide a method for drawing it? And how would I go about implementing it such that I don't redraw the entire widget for the blinking of the cursor?
What you typically do to create custom widgets is two-folded:
combine existing widgets
derive from existing widgets
That means, e.g., if you want to create a custom text input widget, use an existing one and only change the parts you need to change in overloads. Or maybe your customization does not need to change the text input part at all, but just plug it in at the right place. The widget I am talking about right now is QLineEdit. It is actually very basic and customizable.
There actually exist two methods (at least) on how to combine widgets to form your custom one. The first is to create a .ui file and use it in your custom class (or create widgets in code). The second one is to use a QGraphicsScene. There you can combine freehand painting (QPainter), with customly positioned objects and fully-fledged widgets.
If it is too hard to solve your problem by combining widgets and/or deriving from them, the last resort is always to take an existing widget with the desired functionality (e.g. QLineEdit that has a text-edit cursor) and read/copy the code (Note: license issues may arise).
To give a better answer to your question we would need more details on what exactly you want to achieve.
I'm having all sorts of size problems with Qt. I am creating my own widgets and using different layouts (generally, I need my own to make them work properly without spending hours on the "powerful" default layouts... which don't lay things out as intended.)
Once I'm done with a widget and its layout though, it doesn't work right. The size is never getting set properly unless I call widget->resize(1, 1); which finally forces a "resize" and makes the widget look correct (i.e. recompute the geometry.) Even the updateGeometry() call has no effect.
This is a dreadful problem when the resize() needs to be called on the parent widget (yuck!) and from what I'm reading should not be necessary were the layouts properly programmed.
Is there a sample that works and is not several thousand of lines long, or does Qt require several thousand lines to make anything work perfectly, even the simplest widget?
What are the minimal functions to be called to make a widget & its layout work at once?
Thank you.
Alexis
P.S. I tried to implement the sizeHint(), minimumSize(), maximumSize(), others that I'm missing? I was hoping that would be enough. Obviously, I also implement the setGeometry() on the layout to resize the children appropriately.
--- addition 1
There is a sample image with a layout that clearly isn't available as is in Qt. The positioning, functions, and colors of the different keys is XML driven and works for any keyboard in the world.
(note, this sample doesn't show the Enter key displayed on two rows and wider below than at the top; more or less, not doable at all with the regular layouts; of course, it works with my version.)
--- clarification
I'm not too sure how to describe the problem better. I was thinking to write a test widget next to see how I can reproduce the problem and then post that and eventually fix it. 8-)
The default layout function that the internal Qt layouts make use of require a lot of coding. I would like to avoid having to copy/paste all of that because for maintenance, it makes it close to impossible.
--- today's findings
As I needed to tweak one of the widgets, I decided to add a VBoxLayout and make it work.
I actually found the problem... One of the widgets in my tree is a QScrollArea and that sizeHint() returns (-1, -1). Not exactly what I'd expect but... whatever you put inside that widget has better know how to compute its width and height or else... it fails.
Looking at the code closely, I could actually compute the width by using the widest width found. Once I used that, the widget would appear (and it actually resizes itself as things change in the list, kinda cool.)
This being said, my earlier comment about having a tree of widgets that auto-resize themselves stands. From the root up to the parents of the leaves in your tree, all of those widgets will need a valid layout. Once I added one in the top widget it resized itself and its children properly (well... in my case up to the QScrollArea, the rest required a bottom to top resizing. Funny how that works!)
--- ah! ha! moment (or: what you find reading the implementation code!)
Today I bumped in another problem which just needed the correct call... I just couldn't find anything worth it in the documentation.
All the objects have a layout now, but a certain parent would not resize properly. Plain simple.
I had a call to the parent as following:
// changes to the children are changing the geometry
parentWidget()->updateGeometry();
Yeah. The docs says that's what you have to do. Nothing happens at all with that call. No idea what it's supposed to do, I did not look at that function. It never did anything for me anyway.
So... I looked at the layout to try to understand how it would send the info up/down. I did not see much except for one interesting comment:
// will trigger resize
This is said of the SetFixedSize mode. To reach that function you need to make the layout for update. Ah! Yes... the layout, not the parent widget... let's try that instead:
parentWidget()->layout()->update();
And voila! It resizes correctly in all cases I have. Quite incredible that the widget updateGeometry() doesn't trigger the same effect...
Although it's possible to do what you want it sounds like the problems you are having are because you're using Qt in a way that it's not meant to be used. Why do you need separate widgets for each key represented on the keyboard?
I see two options, both of which are better in some way:
Use QGraphicsScene and QGraphicsView.
A single custom widget that uses custom drawing to display the keyboard (and likely uses hover for hints).
The first option is probably better. Your keys could then be represented by QGraphicsSimpleTextItem's or even a QGraphicsSvgItem. It also provides a number of standard layouts or you could choose to write your own layout. By default you can use the keyPressEvent or mouseReleaseEvent to respond to user interactions.
I'd highly recommend you take a look at the QGraphicsView examples to get an idea what you can do.
If you go the second route you'll need to record the different key locations so you can respond accordingly as the user moves the mouse around, clicks, etc.
This won't help you with your immediate issue but I wanted to show you a keyboard I made using standard layouts and buttons. It's not perfect and it still won't help you with an enter key that spans two rows but it's not bad. It's resizable too by resizing the window, although I'm not sure if that will be apparent from the images below as SO may be scaling them. (you can view the actual images by opening them in their own tab)
Anyway, this was done using only Qt Designer with no manual coding. It consists of a top level vertical layout with 5 horizontal layouts in it. The buttons are then inserted into one of the 5 horizontal layouts. The size of the keys can be controlled by setting the horizontal and vertical size policies to "ignored" for most of the buttons and then horizontal "minimum" for buttons that you want to be wider. Things can be tweaked by setting min and max size restrictions to buttons. When resized, the buttons will not maintain their relative proportions though, that would probably take some custom programming.
The styling in your example could be approximated pretty well using css style sheets and background images. Still not a minor effort but you should be able to get most of the way there without custom layouts and buttons.