Qt's application wide stylesheet not overwritten by local default stylesheet - css

I have an application which loads a .qss styling file and apply the stylesheet to the whole application. My problem is that it modifies the default QGroupBox styling instead of a subclass of it, and I would like a default-style QGroupBox in one place.
Here is an example of the styling applied application wide that I'm trying to replace by the default one.
QGroupBox {
border: 0px solid gray;
border-bottom: 1px solid block;
}
I have tried to reset the stylesheet by using
_ui->setupUi(this);
_ui->myGroupBox->setStylesheet("");
But this does not work. From what I've gathered, the application-wide styling should have happened duing the setupUi() phase though, and thus be overwritten by the empty (default) stylesheet. This does not seem to be the case.
I have also tried without success to set it directly from Qt Designer, or from the qss file using.
myGroupBox {
}
However, if I put border-bottom: 1px solid red; in the qss file, it is correctly registered and overrule the default style. I do not now the default parameters though, so I cannot set them all by hand if needed.
If I remove the annoying qss rule, it works fine, but it breaks the application ui in 50 other places and I sadly do not have the time to refactor it right now.
Am I missing something when it comes to resetting to the default stylesheet?
Thanks.

You seem to be mixing up the styles with stylesheets. These are different beasts. When a widget has a stylesheet, it is not styled by the style mechanism anymore, because the styles in general aren't flexible enough to be modified by stylesheets, since they e.g. depend on platform-provided images etc. The two mechanisms are exclusive of each other: either one can control the appearance of the widget, but once you use a stylesheet, it's all-or-nothing: the style mechanism is out of the picture.
Simply fix your stylesheet to apply only to the group boxes it should apply to - you can select them by name or name path.

Related

Can I disable vaadin flow theeming and apply ordinary css

Vaadin flow theming and styles confuse me. Is there a way to disable it and apply natural css. I know how to reference a css file inside vaadin, and use setClassName but I would prefer to use ordinary css style for components.
Thank you
You can override the default lumo styling by providing yours. For instance, to remove the background color from a ComboBox, I can target the input as follows in a CSS file named vaadin-combo-box.css:
[part="input-field"] {
background-color: var(--lumo-base-color);
max-width: fit-content;
}
To set the colors for a disabled button, you can target it as follows:
filename: vaadin-button.css
code:
:host([theme~='primary'][disabled]) {
background-color: red;
}
And you get the following:
To change the primary color or any other global styling, explore your styles.css file.
For a better understanding, take a look at this video https://vaadin.com/learn/training/v14-theming
Like with all other styling you need to check the states / attributes of the component while the specific state is active and check the DOM - only caveat would be that you need to add those style in the specific files like vaadin-button.css to be applied inside the shadow DOM.

Bootstrap 4 - CSS without any global styles

I'm developing a small control which is directly embedded in a parent page (without iFrame).
My control is written using react-bootstrap, so the bootstrap4 css is also embedded along with my control.
While developing my app as standalone, everything was fine.
After embedding it however, it turns out that there are some "global" bootstrap styles, such as the so called "list-styles" that don't get applied only on HTML elements having bootstrap classes, but instead on any matching HTML tag.
This causes the parent page's layout to get scrambled once my control is loaded.
Examples for bootstrap classes that are applied globally and which cause problems for me are styles like these which can be found in the bootstrap4 default css:
dl, ol, ul {
margin-top: 0;
margin-bottom: 1rem;
}
or
label {
display: inline-block;
margin-bottom: .5rem;
}
This is very unfortunate for my use case. Is there a way for getting rid of any styles in bootstrap, which are not linked to any proper css bootstrap class? I don't want any styling of HTML tags that are not explicitly linked to a bootstrap class.
Thanks for your help.
I can think of three options, though I'm not sure they will do for you:
Paste Bootstrap's styles into a local file (instead of getting them from a CDN or something) and delete what you don't want (most of the unwanted styles should be at the top of the file)
Look for another, more minimal version of Bootstrap. I don't know if such versions/customizations exist but they very well might
Don't use Bootstrap. You can just as easily write your own css lines (personally I find that Bootstrap makes you lose control over your styling, but that's my opinion)

Correct approach to override DetailsRow styling

What would be the correct way to override the styling of the Office UI Fabric DetailsRow component?
I mean, this component does not expose anything like className in its props, so it does not seem to be possible to append any custom class names to the row's root element within an onRenderRow override, well, unless one fully re-writes the row rendering code.
Of course I could fall back to a dirty hack and use something like
ms-DetailsRow: hover {
background-color: #cbcbcb !important;
}
in my own CSS file that is loaded after Office Fabric UI styles, but that does not look like a clean solution to me.

GWT - Changing CSS hover property

I'm a new user of GWT and I'm looking for some advice concerning "theme management".
I have to make a website that can handle theme changes. What I mean is that a user can make is own theme by filling a form, then the website will automatically and dynamically changes its color to display the new ones.
I thought using a CSS sheet for all the static properties and using some GWT lines (e.g. label.getElement.getStyle.setColor(...)) to change color. But I have many "hover" properties and I think creating many MouseOverHandler is not a good idea ...
Is there a way to edit CSS sheet dynamically or a magic trick to do that ?
Thanks.
You have many options - the most straight forward (to me) is to make use of the existing CSS classes that GWT introduces. If you look at javadocs for any of the widgets GWT provides, you'll notice the CSS Style Rules section. For example, Button:
.gwt-Button
the outer element
That means that every Button you add to the page has a .gwt-Button style applied to it. If you inject a CSS stylesheet with a rule that overrides this style:
.gwtButton {
background: red;
}
All your buttons will turn red. You can inject stylesheets using StyleInjector. Creating the stylesheet's content dynamically is up to you - but it's just text, it shouldn't be hard (but make sure the generated CSS rules are valid!).
To get you started, try hooking up this code to some button and see if clicking it triggers changing all the Buttons on the page red:
StyleInjector.inject(".gwt-Button { background: red; }");
If you have custom widgets that you want styled differently, just add an individual class to them (.customWidgetWhatever, like Button has .gwt-Button, etc.) that you will include in your custom stylesheet.
Make sure you understand how CSS works and what it can do for you. For example, if you want to style each button the same, you don't have to change each button's style individually, just use:
button {
background: green;
}
And all the <button>s will turn green.
The easiest way to change themes without reloading the whole application is to assign a theme class to the body element.
You'd want to prepend each CSS class in your app with a particular theme, e.g.:
.theme1 .myClass {
color: red;
}
.theme2 .myClass {
color: blue;
}
Then you'll apply a particular theme to the body element:
<body class="theme1">
When you want to change themes, you'll have to change the body class so it will become:
<body class="theme2">
this way, each element that has class myClass will have its color changed from red to blue.
You cannot edit a CSS file dynamically, but you can inject CSS style either as a new CSS file, or directly into your document.
For example, you can define all key CSS rules in your "main.css" file, and add your user-defined rules directly into the host HTML page with a style tag.

QT Stylesheet for HLine/VLine color

I'm pretty new to this Qt thing and its whole stylesheet system. My background of HTML/CSS helps a little to understand the system, but a lot of things just happens for no apparent reason....or don't happen.
Anyway, the mystery of the HLINE and the VLINE and how to change the lines' color is just a mystery for me. I learned from other questions and various fora that it's linked to the QFrame elements. And I can change the color of the line if I just use something like
QFrame
{
color: red;
}
But this of course changes the color of tons of other things that uses a QFrame as well. I could of course go into the HLINE element and put color: red; in there and that works fine, but my app requires that I put everything in a single stylesheet that gets loaded into the app. So styling individual elements is not an option.
A solution would look something like
QFrame HLine, QFrame VLine
{
color: red;
}
QFrame[frameShape="4"] /* QFrame::HLine == 0x0004 */
{
color: red;
}
QFrame[frameShape="5"] /* QFrame::VLine == 0x0005 */
{
color: green;
}
HLine and VLine are tricky to style. It's worth taking a look at the "Detailed Description" section of the documentation. For a quick fix, I found that this set of rules allows customizing the appearance of such lines via stylesheet in a reliable and relatively clean manner:
QFrame[frameShape="4"],
QFrame[frameShape="5"]
{
border: none;
background: red;
}
This works regardless of the frameShadow property, which otherwise affects their appearance and the effect of style rules. Keep in mind that the width of the lines are not 1px by default -- this can be changed using the min-width, max-width, min-height or max-height properties, as appropriate.
For a more detailed overview of my findings, read along.
Most QFrames have the QFrame::Plain frameShape by default, but HLine and VLine's default frameShape is QFrame::Sunken. This means that they are not really lines, but thin boxes that contain a mid-line that's used to provide the 3D effect. From the documentation:
The mid-line width specifies the width of an extra line in the middle of the frame, which uses a third color to obtain a special 3D effect. Notice that a mid-line is only drawn for Box, HLine and VLine frames that are raised or sunken.
If you set the frameShape to Plain, this midline is still visible, and can be styled with the color property (note: that's not a background-color or border-color!)
But this doesn't work for a HLine/VLine that's left with the default Sunken appearance. One way to fix this could be to set separate styles for Plain and Sunken QFrames by using attribute selectors with the decimal values of the property enums (which are described in the documentation in hehadecimal), like so:
/* Reference (from doc.qt.io/qt-5/qframe.html#types):
* - frameShape[4] --> QFrame::HLine = 0x0004
* - frameShape[5] --> QFrame::VLine = 0x0005
* - frameShadow[16] --> QFrame::Plain = 0x0010 (default for most widgets)
* - frameShadow[48] --> QFrame::Sunken = 0x0030 (default for HLine/VLine)
*/
QFrame[frameShape="4"][frameShadow="16"],
QFrame[frameShape="5"][frameShadow="16"]
{
...
}
QFrame[frameShape="4"][frameShadow="48"],
QFrame[frameShape="5"][frameShadow="48"]
{
...
}
but since the styles that work for HLine/VLine with QFrame::Sunken also work for those with QFrame::Plain, it's usually a waste to do so. I show them above for educational value only about how to use attribute selectors.
The best approach is to treat the QFrame as the box that it is, and either (1) set border-top or border-right coupled with a max-height: 0px (or max-width for a VLine), to ensure the inside of the box doesn't take up space in the layout; or (2) use a background color coupled with border: none (in which case, max-height/width should be 1 or larger, otherwise the QFrame is invisible). The latter is the solution I'd recommend, as shown in the first code block above.
Hope this helps!
According to QDarkStyleSheet issue, You could use:
QFrame[width="3"], QFrame[height="3]
These selectors, they seem to work cross-platform, and they are unlikely to change.
Probably better than using enum values as ints, as they are likely to change with Qt versions, and line styling are not, as they fulfill certain requirements.
but my app requires that i put everything in a single stylesheet that
gets loaded into the app.
You can use Conflict Resolution. Suppose that you have a QMainWindow object with lots of widgets on it . Set these style sheets for the maindionw style sheet :
QLabel#label{
background-color: rgb(255, 170, 255);
}
QPushButton#pushButton{
color: rgb(0, 0, 255);
}
QFrame#line{
background-color: rgb(0, 170, 255);
}
The first css just changes a QLabel name label on your mainwindow and set its back color to rgb(255, 170, 255). The next will change text color of a QPushButton named pushButton to (0,0,255);. The third one change property of a line.Lines are just a QFrame.
So the solution that I can offer is to place your css in a file and then load this file using QFile and QTextStream and then set the contents of the file for css of your main winodw or main widget using setStyleSheet ( const QString & styleSheet ) function. or If you are using creator just right click on your main window and select change stylesheet and then paste your css. But bear in mind that you should use conflict resolution.
You can leave Qt's hlines and build up your own very easy. For frames you want looks like hline add property "class" as "HLine" (for example), in designer or in c++ code:
frame->setProperty("class", "HLine")
.
Then, you can define in main view's or in global app stylesheet something like this:
QFrame.HLine {
border: none;
border-bottom: 2px solid red;
}
and you will get horizontal two pixels red line.

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