How to change qml's SystemPalette globally in linux - qt

I'm using systemPalette (Qt5.15) in several qml-based applications in Linux, I need one of these applications to change systemPalette of qml system-wide (globally) so that other applications can detect this change at runtime.
what I need is similar to what happens in KDE, for example, I have the following qml code:
import QtQuick 2.15
import QtQuick.Window 2.15
Window {
width: 640
height: 480
visible: true
title: qsTr("Hello World")
SystemPalette {
id: palette
colorGroup: SystemPalette.Active
}
Rectangle{
anchors.centerIn: parent
width: 200
height: width
color: palette.base
}
}
when I run the above code in my KDE plasma, if I change the system's theme from breeze to breeze-dark, the rectangle's color will change at runtime, I can even select a custom color in
Appearance->globalTheme->colors.
In my case, regardless of Linux's distro, my application needs to change systemPalette globally and set its custom values for colors, how can I do that? where does qt read those color values from? (for systemPallete)
Thanks.
P.S: I can create my own style/plugin for qt and set different colors in my custom style, but still I have no idea how to change OS style globally so that all applications can detect this at runtime.

Related

QML FontLoader.name confusion

I downloaded from Google Fonts two .ttf files on my project folder:
Montserrat-ExtraLight.ttf
Montserrat-Black.ttf
I set propperly the .qrc file in order to contain both of them.
Suppose I have the next .qml file:
import QtQuick 2.7
import QtQuick.Layouts 1.2
import QtQuick.Controls.Universal 2.0
Rectangle{
id: rectangle
height: 500
width: 700
Column{
FontLoader { id: myCustomFont1; source: "../Fonts/Montserrat/Montserrat-ExtraLight.ttf" }
FontLoader { id: myCustomFont2; source: "../Fonts/Montserrat/Montserrat-Black.ttf" }
Text{
...
text: "Qt for python"
font.family: myCustomFont1.name
...
}
Text{
...
text: "Qt for c++"
font.family: myCustomFont2.name
...
}
}
}
The problem is that the myCustomFont1.name and the myCustomFont2.name are the same, namely "Montserrat" and I don't have any solution to make distinction between them.
Therefore even if I specified the correct FontLoader-s id-s, the second text will have the same font.family like the first text.
Could be possible to solve this problem somehow?
This is not an ideal solution, but a workaround that should work. There's an open-source font editor called FontForge that you can use to change the names that Qt reads. Open the font files in question and then open the menu Element->Font Info. That opens a dialog with multiple tabs on the left. The first tab should be PS Names. This should list several fields including Fontname and Family Name. You should be able to edit those to whatever you want. Then close that dialog and use File->Generate Fonts to regenerate the .ttf files.
This is perplexing and a common source of frustration. It turns out that the name property actually specifies the family, which as you've discovered, is the same for these font files.
What distinguishes them is actually the styleName.
Try opening the font file in a font viewer like "Font Book" or "FontForge" to get the exact styleName - you'll need to specify it with a string.
Then specify the additional property:
Text{
...
text: "Qt for python"
font.family: myCustomFont1.name //or myCustomFont2.name, it doesn't matter.
font.styleName: "Extra Light"
...
}
Text{
...
text: "Qt for c++"
font.family: myCustomFont2.name
font.styleName: "Black"
...
}
I've found styleName far more predictable than combinations of weight or style or bold. And that way you can work with fonts that follow the canonical naming conventions rather than hacking their Family Name to suit QML.

What can't Qml's DropArea be used?

Qml Source code
import QtQuick 2.0
import QtQuick.Window 2.0
Window {
visible: true
width: 640
height: 480
title: qsTr("Hello World")
DropArea {
anchors.fill: parent
}
}
I use the admin rights to open the program and I can't drag and drop. However, normal opening (normal permissions) can achieve drag and drop.
Why are they doing this, this problem has been bothering me for a long time? How should I solve it.
If you try it, will it be the same?
Environmental:
Qt 5.12.2
Compiler: MSVC 2017 64bit

QML Image Element > Retina/HiDPI support for network based images

Image element of the QtQuick supports HiDPI images automatically as you know. For example it can loads #2x images in the iOS and MacOS platforms. Same code works OK on the Android platform.
There is a section in the official documentation that talked about network transparency.
But the Image element doesn't loads HiDPI version images from my server.
Is this a bug?
How can I handle this problem to load high dpi images? Is there any official suggested way?
import QtQuick 2.9
import QtQuick.Window 2.3
import QtQuick.Layouts 1.3
Window {
visible: true
width: 900
height: 520
Image {
id: img
z: 10000
source: "http://127.0.0.1:8080/images/banner-1.jpg" //<-- not loads #2x version automatically
width: 320; height: 205 //<-- also I need to specify a size otherwise it will be so big
}
}
Thank you

Two toolbar in header QtQuickCOntrols 2

I start on Qt Quick and I want to develop an application that will be deployed on an embedded system. I'm using Qt Quick Controls 2. I'm trying to create two toolbars in my header: a toolbar consisting of icons (battery level, network connection, ...) and a toolbar allowing to navigate in a StackView (as in the example Gallery provided by Qt). I would like to have two different background colors for each toolbarenter image description here. For now I have a header that have a toolbar and do the levels get organized with a ColumnLayout and two RowLayout.
How could I go about it?
You can use the Material.primary attached property to specify the Material style ToolBar color. For example:
import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Controls.Material 2.0
ApplicationWindow {
header: Column {
ToolBar {
Material.primary: Material.Red
}
ToolBar {
Material.primary: Material.Blue
}
}
}

SpinBoxStyle unable to access button state

SpinBoxStyle from QtQuick.Controls.Styles allows you to change the appearance of a SpinBox, and a part of that is the ability to redesign the up/down arrow buttons. However neither SpinBox nor the style gives you the ability to query the up/down arrow button state, so you can't check if it is pressed or hovered over.
This seems like too much of an oversight, so what part of the API docs have I missed?
I've tried adding a MouseArea to the control delegate itself, but some reason it never receives any events - the controls still work though which suggests that they are 'stealing' the events first.
SpinBox {
style: SpinBoxStyle {
incrementControl: Rectangle {
implicitHeight: 10
implicitWidth: 10
color: "blue"
MouseArea {
anchors.fill: parent
hoverEnabled: true
onEntered: console.log( "Hello" ) // Never printed
}
}
}
}
Apparently you're supposed to use the styleData properties to detect hovered and pressed states, but they aren't documented. Please create a bug report for that.
import QtQuick 2.3
import QtQuick.Controls 1.2
import QtQuick.Controls.Styles 1.2
SpinBox {
style: SpinBoxStyle {
incrementControl: Rectangle {
implicitHeight: 10
implicitWidth: 10
color: styleData.upHovered && !styleData.upPressed
? Qt.lighter("blue") : (styleData.upPressed ? Qt.darker("blue") : "blue")
}
}
}
I'm not sure why the style was implemented this way, but if you look further into the source code, you can see that there are always MouseAreas for the up and down controls. This is very confusing to me; if you're not supposed to provide an interactive control because there will always be MouseAreas shadowing them, why call it incrementControl and decrementControl? Names like increment and decrement might suffice, given that they're not able to receive almost any interaction (clicking works at least, for some reason). If you find this a bit confusing, you may also want to file a separate bug report for the API.
git log --follow -p shows that this code hasn't changed much since the introduction of styles, so I'd say the current implementation (and API) is just outdated, and hopefully there are opportunities for improving this in the future.

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