Use a system icon in the setIcon method of QWidget - c++

I would like cross-platform a way to get a system icon, for example the folder icon in the setIcon method of QWidget. Something like this:
QWidget *myWidget = new QWidget;
myWidget->setIcon(/*something to get a system icon*/);
Is this possible? If it is, how to do it?

Use QFileIconProvider::icon(IconType) to get an icon of a particular kind, from a small selection of types.
In your particular case, you'd want icon(QFileIconProvider::Folder).
Use QFileIconProvider::icon(const QFileInfo &) to get an icon for a particular directory entry.
Use QIcon::fromTheme(const QString &, const QIcon & = QIcon()) to get a theme icon on Linux/X11.

I think you're looking for QIcon::fromTheme method.
Example:
QIcon undoicon = QIcon::fromTheme("edit-undo");
Note: By default, only X11 will support themed icons. In order to use themed icons on Mac and Windows, you will have to bundle a compliant theme in one of your themeSearchPaths() and set the appropriate themeName().

For linux/X11, maybe you are looking for QMimeDatabase::mimeTypesForFileName and QIcon::fromTheme.
Refer to https://stackoverflow.com/a/45739529/5785726 for a example

Related

Disable file name box in QFileDialog

I used a QFileDialog to open a browser.
Here is my code:
QString filePath = QFileDialog::getSaveFileName(this,
"Export Xml", "PluginPythonQt",
"Xml files (*.xml)");
When excute it will show a dialog like this:
I want to disable the "File name:" box in the picture or prevent user to enter a new name. How can i do that ? Thanks.
I believe you can't achieve this — save dialog is about choosing name besides the choosing where to save it. Of course, you might just ignore what user typed and force your name when he hits OK but it will just make the user angry.
Better way, in my opinion, is to use QFileDialog::getExistingDirectory which will allow the user to choose where to save the file but won't allow him to choose the file name. It will be fair, at least.
Similar question was answered in https://forum.qt.io/topic/73973/qfiledialog-with-no-edit-box.
In general, you can hide any element in any widget if you dig a bit into widget's source code to find element's name, when you have a name, you can find the corresponding element via findChild<QWidget *>(elementName).
Usually if you check QSomeWidget.h (Qt is open source!) you can find element names very easily as they are typically listed as the widgets members.
To hide both labels, fileEdit, ComboBox and even buttons, you can use this code:
QFileDialog fileDialog = new QFileDialog;
QWidget * fileNameEdit = fileDialog->findChild<QWidget *>("fileNameEdit");
Q_ASSERT(fileNameEdit);
fileNameEdit->setVisible(false);
QWidget * fileNameLabel = fileDialog->findChild<QWidget *>("fileNameLabel");
fileNameLabel->setVisible(false);
QWidget * fileTypeCombo = fileDialog->findChild<QWidget *>("fileTypeCombo");
Q_ASSERT(fileTypeCombo);
fileTypeCombo->setVisible(false);
QWidget * fileTypeLabel = fileDialog->findChild<QWidget *>("fileTypeLabel");
fileTypeLabel->setVisible(false);
QWidget * fileButtonBox = fileDialog->findChild<QWidget *>("buttonBox");
fileButtonBox->setVisible(false);
Note that even though buttons are hidden, typing Enter on keyboard (or double clicking) would trigger Open button, and dialog might disappear if you haven't done anything in Accept method. So it would also be a good idea to handle state of that button as well if you really wish buttons to be hidden as well.

QT QIcon properties for custom widget in designer

I have been working for a little while now on creating a QT custom designer widget for GUI menus. The idea being that you simply drag it into the designer, select the number of frames you'd like, how many buttons per frame, etc. and it generates and sizes everything for you.
The way the widget is structured there are properties to configure each button for the frame you are in. For example, you would use the button0Text field to enter text under Button0 while editing in frame 0, then use it again to edit Button0 which is in frame 1. Both buttons would retain the individual changes for each frame.
The Problem
Normally when I switch frames all of my properties are updated to reflect the status of the frame. The exception being QIcon. The correct icon is retained in the actual graphical representation and builds correctly, however the file path in the property list is always of the last edited for that property. I think this will be extremely confusing to an end user and I have found no way to fix it. So for example, if I set text and icons in frame 0 then switch to frame 1 the text in the property list will update to reflect the state of frame 1 but the icon path names will still show my last edit in frame 0 and not the actual icon in frame 1.
I have tried things as simple as:
setProperty("button0Icon", getButton0Icon());
That code works on properties like text, but not for the icon. I try executing it immediately after changing frames.
I have also tried:
#ifndef Q_WS_QWS
QDesignerFormWindowInterface *form = QDesignerFormWindowInterface::findFormWindow(this);
if(form){
QDesignerFormEditorInterface *editor = form->core();
QExtensionManager *manager = editor->extensionManager();
QDesignerPropertySheetExtension *sheet;
sheet = qt_extension<QDesignerPropertySheetExtension*>(manager, this);
int propertyIndex = sheet->indexOf("button0Icon");
sheet->setChanged(propertyIndex, true);
sheet->setProperty(propertyIndex, getButton0Icon());
}
#endif
And:
int propertyIndex = this->metaObject()->indexOfProperty("button0Icon");
QMetaProperty property = this->metaObject()->property(propertyIndex);
property.write(this, QIcon());
Nothing seems to update the property list in the designer.
I have all properties, including all QIcon properties properly declared in the header file with Q_PROPERTY and assigned getter and setter functions.
To be clear, the icon values are indeed retained through each frame when compiled. So it is functioning, just unclear for most users.
If anyone has any experience with this or any ideas please let me know. Thanks.
I have discovered that QIcon does not store file names/paths. The file names are only used for the creation of the QIcon. I think this is most likely the reason I do not get any feedback in the Property Browser for my QIcon properties.
Instead I have chosen to hide this property in the designer and add three new ones. Three QUrl properties, each of which is used to supply an image file. I use three because I want to construct a QIcon that contains Modes/States for normal, disabled, and pressed operations.
I take each of these QUrls and save them in QStringLists behind the scenes so their values are stored. I then construct my QIcon using the file names provided from the QUrls.
I would much prefer to be using the native QIcon in the designer for this, any thoughts or feedback are appreciated.

How to draw a custom control in QTableView?

I have to draw a custom control in QTableView. This control must looks like FileChooser.
FileChooser http://www.vision.ee.ethz.ch/computing/sepp-irix/qt-3.0-mo/filechooser.png
QStyleOptionButton button_option;
button_option.state |= QStyle::State_Enabled | QStyle::State_Off;
button_option.rect = PushButtonRect(option); //calculate button rect
button_option.text = "...";
QApplication::style()->drawControl(
QStyle::CE_PushButton,
&button_option,
painter);
The code above draws QStyle::CE_PushButton - that looks like QButton, - but there is no QStyle::CE_LineEdit in Qt library. How can I draw QLineEdit?
In order to draw custom widgets in a Table View, you need to create a custom QItemDelegate subclass and override at least the createEditor method, where you can create any kind of widget which is displayed when double-clicking into the table cell. This item delegate can be assigned to the respective column in your table view.
You would then need to create a separate class e.g. CustomFileChooser which inherits from QWidget and consists of a Line Edit and Button.
Your createEditor method would then return such an object.
You may also have to override setEditorData (which shall assign the current model value to the editor widget which was created) and setModelData (which is called when the changes are committed).
This way, the line edit and button would only be visible after double-clicking into the table cell. If you want it to be always visible, you will have to override drawDisplay() as well.
I found an answer by myself. You may display a custom editor (ordinary widget) permanently using:
void QAbstractItemView::openPersistentEditor ( const QModelIndex & index )
First you need to understand that a button is a control Element and thus you can find it under CE but when you need a lineEdit it is not a control element.
In order to paint a lineEdit, I shall quote from the qt documentation,
"QStyleOptionFrameV2 inherits QStyleOptionFrame which is used for drawing several built-in Qt widgets, including QFrame, QGroupBox, QLineEdit, and QMenu."
Yes, only a sample code that might work will help you understand it clearly!
The code should somehow look like this
QStyleOptionFrameV2 *panelFrame = new QStyleOptionFrameV2;
QLineEdit *search = new QLineEdit;
panelFrame->initFrom(search);
panelFrame->rect = QRect(x,y,w,h);//Indeed the location and the size
panelFrame->lineWidth = QApplication::style->pixelMetric(QStyle::PM_DefaultFrameWidth, panelFrame, search);
panelFrame->state |= QStyle::State_Sunken;
QApplication::style()->drawPrimitive(QStyle::PE_PanelLineEdit, panelFrame, painter);

QT Breadcrumb Navigation

I would like to add a breadcrumb navigation bar to a QT application. In KDE there is KUrlNavigator which is used by dolphin. Is there a native QT widget?
qxtcrumbview in libqxt.org
Not documented, you need to download the source code in order to find this one.
This may be achieved with QLabel: There may be multiple links in a single QLabel, see QLabel::openExternalLinks() and Qt::TextInteractionFlags.
Or in more detail:
auto label = new QLabel();
label->setText(
"<a href=\"https://doc.qt.io/qt-5/qlabel.html\">"
"QLabel</a>::"
"<a href=\"https://doc.qt.io/qt-5/qlabel.html#textInteractionFlags-prop\">"
"textInteractionFlags</a>");
label->setTextFormat(Qt::RichText);
label->setTextInteractionFlags(Qt::TextBrowserInteraction);
label->setOpenExternalLinks(true);

An "About" message box for a GUI with Qt

QMessageBox::about( this, "About Application",
"<h4>Application is a one-paragraph blurb</h4>\n\n"
"Copyright 1991-2003 Such-and-such. "
"For technical support, call 1234-56789 or see\n"
"http://www.such-and-such.com" );
This code is creating the About message box which I wanted to have with two exceptions:
1) I would like to change the icon in the message box with an aaa.png file
2) And I would like to have the link clickable. It looks like hyperlink (it is blue and underlined) but mouse click does not work
Any ideas?
I think you should create a custom QWidget for your about widget. By this way, you can put on the widget all you want. By example, you can place QLabel using the openExternalLinks property for clickable link.
To display a custom image on the QWidget, this example may help.
For the icon, you need to just set the application icon. Something like this:
QApplication::setWindowIcon(QIcon(":/aaa.png")); // from a resource file
As for making the links clickable, I don't think it can be done with the QMessageBox::about API directly.
QMessageBox msgBox;
msgBox.setTextFormat(Qt::RichText); // this does the magic trick and allows you to click the link
msgBox.setText("Text<br />http://www.such-and-such.com");
msgBox.setIcon(yourIcon);
msgBox.exec();
For future reference, the docs state that the default type for textFormat is Qt::AutoText. The docs further state that Qt::AutoText is interpreted as Qt::RichText if Qt::mightBeRichText() returns true, otherwise as Qt::PlainText. Finally, mightBeRichText uses a fast and therefore simple heuristic. It mainly checks whether there is something that looks like a tag before the first line break. So, since you dont have a tag in your first line, it assumes that it is plain text. Set it to RichText explicitely with msgBox.setTextFormat(Qt::RichText); to make it act accordingly.
there's a message in the qtcenter about it:
http://www.qtcentre.org/threads/17365-Clickable-URL-in-QMessageBox
Use http://doc.qt.nokia.com/latest/qlabel.html#setOpenExternalLinks
main.cpp
QApplication app(argc, argv);
app.setWindowIcon(QIcon(":/images/your_icon.png"));
mainwindow.cpp (into your slot if you have one)
void MainWindow::on_aboutAction_triggered()
{
QMessageBox::about(0, "window title", "<a href='http://www.jeffersonpalheta.com'>jeffersonpalheta.com</a>");
}