Reproducing OS Minimize Behaviour in a Custom Titlle Bar done in QML - qt

Question

I'm being tasked with creating a customized title bar for our application. It needs to have rounded corners and a settings button, amongst other things. It will run exclusively on windows.
Our application uses Qt and QML for the front end.
So the only way I could find how to do this is by making the application window frameless and creating the title bar from scratch.
This is my test code:
import QtQuick 2.12
import QtQuick.Window 2.12
import QtQuick.Controls 2.0
ApplicationWindow {
id: mainWindow
visible: true
visibility: Window.Maximized
title: qsTr("Hello World")
flags: Qt.FramelessWindowHint | Qt.Window | Qt.WA_TranslucentBackground
//flags: Qt.Window | Qt.WA_TranslucentBackground
color: "#00000000"
TitleBar {
id: mainTitleBar
width: mainWindow.width;
height: mainWindow.height*0.018
color: "#aaaaaa"
onCloseApplication: {
Qt.quit();
}
onMinimizeApplication: {
mainWindow.visibility = Window.Minimized
}
}
Component.onCompleted: {
console.log("Size: " + mainWindow.width + "x" + mainWindow.height)
mainTitleBar.width = mainWindow.width
mainTitleBar.height = mainWindow.height*0.023;
}
Rectangle {
id: content
width: mainWindow.width
height: mainWindow.height - mainTitleBar.height
anchors.top: mainTitleBar.bottom
anchors.left: mainTitleBar.left
color: "#00ff00"
}
}
And
Here is the title bar code (TitleBar.js file):
import QtQuick 2.0
import QtQuick.Controls 2.0
Rectangle {
/*
* Requires setting up of
* -> width
* -> height
* -> title text
* -> icon path.
* -> Background color.
*/
id: vmWindowTitleBar
border.width: 0
x: 0
y: 0
radius: 20
signal closeApplication();
signal minimizeApplication();
// The purpose of this rectangle is to erase the bottom rounded corners
Rectangle {
width: parent.width
height: parent.height/2;
anchors.bottom: parent.bottom
anchors.left: parent.left
border.width: 0
color: parent.color
}
Text {
id: titleBarText
text: "This is The Title Bar"
anchors.verticalCenter: parent.verticalCenter
anchors.leftMargin: parent.width*0.018
}
Button {
id: minimizeButton
width: height
height: vmWindowTitleBar.height*0.8
anchors.right: closeButton.right
anchors.verticalCenter: parent.verticalCenter
anchors.rightMargin: parent.width*0.018
background: Rectangle {
id: btnMinimizeRect
color: vmWindowTitleBar.color
anchors.fill: parent
}
onPressed:{
minimizeApplication()
}
scale: pressed? 0.8:1;
contentItem: Canvas {
id: btnMinimizeCanvas
contextType: "2d"
anchors.fill: parent
onPaint: {
var ctx = btnMinimizeCanvas.getContext("2d");
var h = minimizeButton.height;
var w = minimizeButton.width;
ctx.reset();
ctx.strokeStyle = minimizeButton.pressed? "#58595b": "#757575";
ctx.lineWidth = 6;
ctx.lineCap = "round"
ctx.moveTo(0,h);
ctx.lineTo(w,h);
ctx.closePath();
ctx.stroke();
}
}
}
Button {
id: closeButton
//hoverEnabled: false
width: height
height: vmWindowTitleBar.height*0.8
anchors.right: parent.right
anchors.verticalCenter: parent.verticalCenter
anchors.rightMargin: parent.width*0.018
background: Rectangle {
id: btnCloseRect
color: vmWindowTitleBar.color
anchors.fill: parent
}
onPressed:{
closeApplication()
}
scale: pressed? 0.8:1;
Behavior on scale{
NumberAnimation {
duration: 10
}
}
contentItem: Canvas {
id: btnCloseCanvas
contextType: "2d"
anchors.fill: parent
onPaint: {
var ctx = btnCloseCanvas.getContext("2d");
var h = closeButton.height;
var w = closeButton.width;
ctx.reset();
ctx.strokeStyle = closeButton.pressed? "#58595b": "#757575";
ctx.lineWidth = 2;
ctx.lineCap = "round"
ctx.moveTo(0,0);
ctx.lineTo(w,h);
ctx.moveTo(w,0);
ctx.lineTo(0,h);
ctx.closePath();
ctx.stroke();
}
}
}
}
Now the problem comes with minimizing the application. The first thing I realize is that when using the Qt.FramelessWindowHint flag, the icon does not appear in the Windows Taskbar. Furthermore if I minimize it this happens:
And If I click on it, it doesn't restore.
So my question is, is there a way to reproduce regular minimize behavior when pressing the minimize button?
Or alternatively, is there a way I can completely customize the title bar of the application so that I can achieve the look and feel set by our UI designer?
NOTE: The current look is just a quick test. I have not set the gradient, font, or the aforementioned settings button.

Answer 1

As for me, playing with frameless windows and transparent background is kind of workaround. As I know, the only way to apply a custom shape to the window is QWindow::setMask. Sinse Window is derived from QWindow you can do that in this way.
For example, in the main.cpp:
QWindow *wnd = qobject_cast<QWindow *>(engine.rootObjects().at(0));
auto f = [wnd]() {
QPainterPath path;
path.addRoundedRect(QRectF(0, 0, wnd->geometry().width(), wnd->geometry().height()), 30, 30);
QRegion region(path.toFillPolygon().toPolygon());
wnd->setMask(region);
};
QObject::connect(wnd, &QWindow::widthChanged, f);
QObject::connect(wnd, &QWindow::heightChanged, f);
f();
Since you 'cut' the shape from the window itself, excluding title bar and frames you can leave the window flags as is.

Answer 2

Look at this way, I try to create something that you do but change completely your code.
the problem that makes change in your window size after you minimize the window is that you didn't set the initial width and height for the window so when you minimize the app it shows in the minimum width and height.
so you need to add just this in main.qml and set the initial width and height to the maximum.
width: maximumWidth
height:maximumHeight
but In the code below I change something else too.
For example, you didn't need to emit signals and then catch them in main.qml
you have access to mainWindow in TitleBar.qml.
in TitleBar.qml :
import QtQuick 2.0
import QtQuick.Controls 2.0
Rectangle {
anchors.fill: parent
height: 30
Row {
id: row
anchors.fill: parent
Label {
id: label
text: qsTr("Title ")
}
Button {
id: button
x: parent.width -80
text: qsTr("close")
onClicked:
{
mainWindow.close()
}
}
Button {
id: button1
x: parent.width -160
width: 90
text: qsTr("Minimized")
onClicked:
{
mainWindow.showMinimized()
}
}
}
}
and in main.qml :
import QtQuick 2.12
import QtQuick.Window 2.12
import QtQuick.Controls 2.0
import "."
Window {
id: mainWindow
visible: true
visibility: Window.FullScreen
title: qsTr("Hello World")
flags: Qt.FramelessWindowHint | Qt.Window | Qt.WA_TranslucentBackground
width: maximumWidth
height:maximumHeight
Rectangle {
id: content
anchors.fill: parent
x: 0
y: 20
width: mainWindow.width
height: mainWindow.height - mainTitleBar.height
anchors.top: mainTitleBar.bottom
anchors.left: mainTitleBar.left
color: "#00ff00"
}
TitleBar {
id: mainTitleBar
color: "#aaaaaa"
anchors.bottomMargin: parent.height -40
anchors.fill: parent
}
}