I'm working on a C++/Qt simulator which integrates a parameter's page. At the end of the parameters, a QLabel notifies the user whether the entered data is valid or not.
This text should appear with a custom color, so I implemented this:
ParametersDialog.h
#include <iostream>
#include <QtWidgets>
using namespace std;
class ParametersDialog: public QDialog {
Q_OBJECT
public:
ParametersDialog(QWidget *parent = nullptr);
~ParametersDialog();
...
private:
QLabel *notificationLabel = new QLabel;
...
void notify(string message, string color);
};
ParametersDialog.cpp
#include "<<src_path>>/ParametersDialog.h"
ParametersDialog::ParametersDialog(QWidget *parent): QDialog(parent) {
...
notify("TEST TEST 1 2 1 2", "green");
}
...
void ParametersDialog::notify(string message, string color = "red") {
notificationLabel->setText("<font color=" + color + ">" + message + "</font>");
}
I don't understand why it gives me this error:
D:\dev\_MyCode\SM_Streamer\<<src_path>>\ParametersDialog.cpp:65:79: error: no matching function for call to 'QLabel::setText(std::__cxx11::basic_string<char>)'
notificationLabel->setText("<font color=" + color + ">" + message + "</font>");
^
I understand that my string concatenation has created a basic_string<char> element that cannot be set as a QLabel text.
What could be the simplest implementation of my notify method?
the problem is that std::string and QString are not straight forward concatenable...
a trick can be done:
QString mx = "<font color=%1>%2</font>";
notificationLabel->setText(mx.arg(color.c_str(), message.c_str()));
Related
I recently ran into a weird issue where my QPlainTextEdit::selectionChanged handler function terminates prematurely whenever QTextCursor::mergeCharFormat/setCharFormat/setBlockCharFormat is called. Additionally, after terminating it gets called again and runs into the same issue, leading to an infinite loop.
I'm trying to replicate a feature present in many text editors (such as Notepad++) where upon selecting a word, all similar words in the entire document are highlighted. My TextEditor class is overloaded from QPlainTextEdit.
The minimal reproducible example is as follows:
main.cpp:
#include "mainWindow.h"
#include <QtWidgets/QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
mainWindow w;
w.show();
return a.exec();
}
MainWindow.h:
#pragma once
#include <QtWidgets/QMainWindow>
#include "ui_mainWindow.h"
#include "TextEditor.h"
class mainWindow : public QMainWindow
{
Q_OBJECT
public:
mainWindow(QWidget *parent = Q_NULLPTR) : QMainWindow(parent)
{
ui.setupUi(this);
auto textEdit = new TextEditor(this);
textEdit->setPlainText("test lorem ipsum test\n dolor sit test");
ui.tabWidget->addTab(textEdit, "Editor"); //Or any other way of adding the widget to the window
}
private:
Ui::mainWindowClass ui;
};
TextEditor.h:
The regex highlighter part is based on this SO answer.
#pragma once
#include <QPlainTextEdit>
class TextEditor : public QPlainTextEdit
{
Q_OBJECT
public:
TextEditor(QWidget* parent) : QPlainTextEdit(parent)
{
connect(this, &QPlainTextEdit::selectionChanged, this, &TextEditor::selectChangeHandler);
}
private:
void selectChangeHandler()
{
//Ignore empty selections
if (textCursor().selectionStart() >= textCursor().selectionEnd())
return;
//We only care about fully selected words (nonalphanumerical characters on either side of selection)
auto plaintext = toPlainText();
auto prevChar = plaintext.mid(textCursor().selectionStart() - 1, 1).toStdString()[0];
auto nextChar = plaintext.mid(textCursor().selectionEnd(), 1).toStdString()[0];
if (isalnum(prevChar) || isalnum(nextChar))
return;
auto qselection = textCursor().selectedText();
auto selection = qselection.toStdString();
//We also only care about selections that do not themselves contain nonalphanumerical characters
if (std::find_if(selection.begin(), selection.end(), [](char c) { return !isalnum(c); }) != selection.end())
return;
//Prepare text format
QTextCharFormat format;
format.setBackground(Qt::green);
//Find all words in our document that match the selected word and apply the background format to them
size_t pos = 0;
auto reg = QRegExp(qselection);
auto cur = textCursor();
auto index = reg.indexIn(plaintext, pos);
while (index >= 0)
{
//Select matched text and apply format
cur.setPosition(index);
cur.movePosition(QTextCursor::EndOfWord, QTextCursor::KeepAnchor, 1);
cur.mergeCharFormat(format); //This causes the selectChangeHandler function to terminate and then execute again, causing an infinite loop leading to a stack overflow
//Move to next match
pos = index + (size_t)reg.matchedLength();
index = reg.indexIn(plaintext, pos);
}
}
};
I suspect the format fails to apply for some reason, possibly causing an exception that gets caught inside Qt and terminates the parent function. I tried adding my own try-catch handler around the problematic area, but it did nothing (as expected).
I'm not sure whether this is my fault or a bug inside Qt. Does anybody know what I'm doing wrong or how to work around this issue?
An infinite loop is being generated because it seems that getting the text changes also changes the selection. One possible solution is to block the signals using QSignalBlocker:
void selectChangeHandler()
{
const QSignalBlocker blocker(this); // <--- this line
//Ignore empty selections
if (textCursor().selectionStart() >= textCursor().selectionEnd())
return;
// ...
Is there a property in Q(Double)SpinBox that allows the user to override digits that are right of the curser, just by typing?
For example: If the spinbox shows 12.52 I click between 1 and 2. Now I type 3.45 to get 13.45
Just checked it out - even activating Insert mode on keyboard doesn't help.
Apparently, you'll have to subclass QSPinBox and override some QAbstractSpinBox functions - at least, keyPressEvent.
QAbstractSpinBox has a pointer to underlying QLineEdit - which has a cursor position property.
There is no property, you can go with your own implementation like this:
Header:
#include <QObject>
#include <QDoubleSpinBox>
class CustomSpinBox : public QDoubleSpinBox
{
Q_OBJECT
public:
explicit CustomSpinBox(QWidget *parent = nullptr);
void keyPressEvent(QKeyEvent *event) override;
private:
void updateTextField(const QString &text);
};
Source:
#include "CustomSpinBox.h"
#include <QKeyEvent>
#include <QLineEdit>
CustomSpinBox::CustomSpinBox(QWidget *parent)
: QDoubleSpinBox(parent)
{}
void CustomSpinBox::keyPressEvent(QKeyEvent *event)
{
auto isInt = false;
event->text().toInt(&isInt);
if (isInt)
{
updateTextField(event->text());
}
else
{
QDoubleSpinBox::keyPressEvent(event);
}
}
void CustomSpinBox::updateTextField(const QString &text)
{
auto lineEdit = this->lineEdit();
auto cursorPosition = lineEdit->cursorPosition();
auto lineEditText = lineEdit->text();
QChar currentChar;
if (cursorPosition < lineEditText.size())
{
currentChar = lineEditText.at(cursorPosition);
if (currentChar.isPunct())
{
lineEdit->cursorForward(false);
}
}
lineEdit->del();
lineEdit->insert(text);
}
But please note that the behaviour can be counter-intuitive. What if the value is 1,23? With that approach, you cannot enter any value bigger than 9,(9). Maybe it is what is expected, maybe it should not jump over the dot/comma unless the value before the punctuation mark has size length bigger than 2 digits (or 3 or any other number).
How can I initialize a static list of QColors. I'm using Qt 5.11.1
In my header file i have this:
QList<QColor> *colorList;
not sure if it's more appropriate for me to use this
QColor *colorList[15];
Then in what would i write in the CPP file... something like this?:
colorList = {
QColor(220,0,0),
QColor(250,140,0),
QColor(255,255,0),
QColor(145,210,80),
QColor(0,180,20),
...
};
I'll be eventually looping through this list of colors using the color.
Update
I'm getting an error when looping through the colors. Which I'm using the colors to define the visual color of a QPushButton I subclassed.
Here are the import bits of the code.
.h
#include <QWidget>
#include <colorswatch.h>
#include <QColorDialog>
#include <QMenu>
#include <QList>
class ColorSwatchPicker : public ColorSwatch
{
Q_OBJECT
...
private:
void init();
...
QList<QColor> *colorList;
};
.cpp
void ColorSwatchPicker::createButtons()
{
//! create color swatch menu
QWidget *colorWidget = new QWidget(this);
QGridLayout *layout = new QGridLayout(colorWidget);
layout->setSpacing(4);
layout->setContentsMargins(0,0,0,0);
// create color swatches
colorList = new QList<QColor>({
QColor(255,70,50),
QColor(230,30,100),
QColor(155,40,175),
QColor(105,60,185),
QColor(65,80,180),
...
});
// Create the pushbutton control
foreach (const QColor &c, colorList) {
auto *cs = new ColorSwatch(c, this);
cs->setFixedSize(18,18);
};
}
Define an alias (optional)
using ColorList = QList<QColor>;
Initialize the list
auto *colorList = new ColorList({
QColor(220,0,0),
QColor(250,140,0),
QColor(255,255,0),
// ...
});
Iterate over the colors in colorList
foreach (const QColor &c, *colorList) {
// do something with c
}
Note (thanks to #drescherjm and #AlbertoMiola): Alternatively you can use a ranged for instead of foreach:
for (const auto &c : *colorList) {
// do something with c
}
I want to read the size and the values of my matrix from a text file.
an example of a text file
graphe.txt
4 (the size of the matrix)
1 0 1 0
1 1 1 1
0 1 1 1
0 0 0 1
I tried a code but unfortunately it didn't work .I got this errors:
error: 'class MainWindow' has no member named 'display' this->display->setText(val);
error: cannot convert 'QString' to 'int' in assignment
matrice[ligne][i]=val;
void MainWindow::remplir_matrice(int taille_mat,int matrice[][50] )
{
QFile file("/home/yosra/degré/degré/graphe.txt");
if (file.open(QIODevice::ReadOnly))
{
QTextStream in(&file);
int i=1;
int ligne=1;
while ((!in.atEnd())&&(ligne<=taille_mat))
{
ligne++;
QString line = in.readLine();
QStringList list = line.split(" ");
QString val = list.at(i);
this->display->setText(val);
val.toInt();
matrice[ligne][i]=val;
i++;
}
file.close();
}
}
void MainWindow::afficher(int matrice[][50],int taille_mat)
{
qDebug()<<" les elements de matrice";
for(int i=0;i<taille_mat;i++)
{
for(int j=0;j<taille_mat;j++)
qDebug()<<"M "<<matrice[i][j]<<endl;
}
}
void MainWindow::parourir_fichier(int matrice[50][50],int taille_mat)
{
QFile file("/home/y/degré/classement/graphe.txt");
if (file.open(QIODevice::ReadOnly))
{
QTextStream in(&file);
QStringList list;
QString line = in.readLine();
QString val = list.at(0);
this->display->setText(val);
val.toInt();
taille_mat=val;
qDebug() << "taille_mat=" << taille_mat<<endl;
file.close();
}
remplir_matrice(taille_mat,matrice);
afficher(matrice,taille_mat);
}
this is my MainWindow's header
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
void remplir_matrice(int taille_mat,int matrice[][50] );
void parourir_fichier(int matrice[][50],int taille_mat);
void afficher(int matrice[][50],int taille_mat);
private:
Ui::MainWindow *ui;
int matrice[50][50];
int taille_mat;
};
Could it be that you mean:
ui->display->setText(val);
The MainWindow class does not have a pointer to the display object. Perhaps the display object was created with Qt Creator editor as a TextEdit field?
Update
If you just want to see a value while you are still developing your code, you are probably better off using qDebug() (documentation here). You will need to include to make this work. The output will be shown in the output pane when you run the application from Qt Creator.
#include <QDebug>
// ...further down in your code:
qDebug() << "Output of val:" << val;
The second error message is pretty clear, isn't it? A QString cannot be automatically converted to an int. I don't really know Qt, but a quick Google search reveals the existence of a toInt member function, so the following probably works:
matrice[ligne][i]=val.toInt();
As for the first error message, this->display supposes the existence of a member variable in MainWindow. If display is a member function (it certainly sounds like one), then you need parentheses: this->display(). If there is no member function of that name either, then we cannot help you much with the code that you have posted.
I create own widget based on QTableView. It's something like file dialog (list). I want to act intuitively.
a) working with whole rows
b) indicator also worked with whole rows
c) using switched enter the lower level (subdirectory)
d) after run program or moving to a lower level cursor must be on the first row of the table (row 0)
And there is problem. I can not force the program to place the cursor on the first line.
I tried several methods, but none succeeded. setCurrentIndex. selectRow etc. Cursor is always somewhere else. Not highlighted, not on first line, but once it's on 10 position second on 4 position etc. It behaves unpredictably.
How can I do it?
Here my code is:
mFileBoxWidget::mFileBoxWidget(QWidget *parent) :
QTableView(parent)
,model(new QFileSystemModel())
{
this->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
this->setShowGrid(false);
this->verticalHeader()->setVisible(false);
this->installEventFilter(this);
model->setReadOnly(true);
this->setModel(model);
this->horizontalHeader()->setSectionResizeMode(0, QHeaderView::Stretch );
this->setColumnWidth(1,70);
this->setColumnWidth(2,70);
this->setColumnWidth(3,110);
this->setRootIndex(model->setRootPath("C://"));
this->setSelectionMode(QAbstractItemView::SingleSelection);
this->setSelectionBehavior(QAbstractItemView::SelectRows);
//this->selectRow(0); //Does not work - goto first row
//this->setCurrentIndes(Index); //Does not work - goto index x=0 y=0
}
Thank you with advance for all your responses.
Solved!
The problem is that the model is asynchronous. So reads the data in another thread. When I tried to set the index to the first line, still basically did not exist. The solution is, of course, to wait for loading the thread. At this point signal directoryLoaded(QString) is send. As a result, it is necessary to wait for the signal, and only then set index.
connect(myModel, SIGNAL(directoryLoaded(QString)), this, SLOT(onLoaded()));
void mFileBoxWidget::onLoaded()
{
QModelIndex index = myModel->index(myModel->rootPath());
this->setCurrentIndex(index.child(0, index.column()));
}
You shouldn't name your member variable model. QTableView has function model(), the compiler thinks this->model is meant to be this->model(), therefore you get the error you mentioned.
This is untested code, but I think something like this should work:
QModelIndex firstRow = QTableView::model()->index(0, 0);
QTableView::selectionModel()->select(firstRow,
QItemSelectionModel::ClearAndSelect |
QItemSelectionModel::Rows );
EDIT: (2013-06-19 06:12:58 UTC)
A simple (and ugly) workaround that worked so far for me is triggering a call to m_tableView->selectRow(0); from a QTimer.
Here's the sample code:
Header:
#ifndef MAINWIDGET_H
#define MAINWIDGET_H
#include <QWidget>
class QTableView;
class QFileSystemModel;
class MainWidget : public QWidget
{
Q_OBJECT
public:
MainWidget(QWidget *parent = 0);
~MainWidget();
private:
void layoutWidgets();
QFileSystemModel *m_model;
QTableView *m_tableView;
private slots:
void selectFirstRow();
// for debugging only
void selectionChanged();
};
#endif // MAINWIDGET_H
Implementation:
#include "mainwidget.h"
#include <QTableView>
#include <QHBoxLayout>
#include <QFileSystemModel>
#include <QHeaderView>
#include <QTimer>
MainWidget::MainWidget(QWidget *parent)
: QWidget(parent)
{
m_tableView = new QTableView(this);
m_model = new QFileSystemModel(this);
m_model->setReadOnly(true);
m_tableView->setModel(m_model);
m_tableView->setRootIndex(m_model->setRootPath(QDir::homePath()));
m_tableView->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
m_tableView->setShowGrid(false);
m_tableView->verticalHeader()->setVisible(false);
m_tableView->setColumnWidth(1,70);
m_tableView->setColumnWidth(2,70);
m_tableView-> setColumnWidth(3,110);
m_tableView->setSelectionMode(QAbstractItemView::SingleSelection);
m_tableView->setSelectionBehavior(QAbstractItemView::SelectRows);
//m_tableView->->setSectionResizeMode(0, QHeaderView::Stretch ); // Qt 5?
layoutWidgets();
connect(m_tableView->selectionModel(), SIGNAL(selectionChanged(QItemSelection,QItemSelection)), this, SLOT(selectionChanged()) );
// This works
QTimer::singleShot(1000, this, SLOT(selectFirstRow()));
// Direct invocation - doesn't works
// selectFirstRow();
}
void MainWidget::layoutWidgets()
{
QHBoxLayout *mainLayout = new QHBoxLayout;
mainLayout->addWidget(m_tableView);
setLayout(mainLayout);
setFixedSize(500,500);
}
void MainWidget::selectFirstRow()
{
m_tableView->selectRow(0);
}
void MainWidget::selectionChanged()
{
qDebug("Selection changed");
}
MainWidget::~MainWidget()
{}
The weird thing is, if QTimer::singleShot() needs to be triggered with a delay of at least ~25 ms., otherwise it wouldn't work in my system.
Here's the alternative, subclassing QTableView:
#include "mytableview.h"
#include <QFileSystemModel>
#include <QHeaderView>
#include <QTimer>
MyTableView::MyTableView(QWidget *parent) : QTableView(parent)
{
QFileSystemModel *myModel = new QFileSystemModel;
setModel(myModel);
setRootIndex(myModel->setRootPath(QDir::homePath()));
setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
setShowGrid(false);
verticalHeader()->setVisible(false);
//installEventFilter(this);
myModel->setReadOnly(true);
//setSectionResizeMode(0, QHeaderView::Stretch ); // Qt 5
setColumnWidth(1,70);
setColumnWidth(2,70);
setColumnWidth(3,110);
setSelectionMode(QAbstractItemView::SingleSelection);
setSelectionBehavior(QAbstractItemView::SelectRows);
QTimer::singleShot(100, this, SLOT(selectFirstRow()));
connect(selectionModel(), SIGNAL(selectionChanged(QItemSelection,QItemSelection)), this, SLOT(selectionChanged()));
}
void MyTableView::selectFirstRow()
{
// qDebug("Selecting first row");
// QModelIndex firstRow = QTableView::model()->index(0,0);
// if(firstRow.isValid()){
// selectionModel()->select(firstRow, QItemSelectionModel::ClearAndSelect | QItemSelectionModel::Rows );
// }else{
// qDebug("Invalid index");
// }
selectRow(0);
}
void MyTableView::selectionChanged()
{
qDebug("Selection changed.");
}