How to use SVG

Saviz

One question, I have done everything to the best of my abilities but I still get the error:
"undefined reference to _imp_ZN10QSvgWidgetC1EP7QWidget"
"undefined reference to _imp_ZN10QSvgWidget4loadERK7QString"

Here is my code:

qmake .pro:

QT       += core gui
QT       += sql


greaterThan(QT_MAJOR_VERSION, 4): QT += widgets svg

CONFIG += c++11

# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    main.cpp \
    mainwindow.cpp

HEADERS += \
    mainwindow.h

FORMS += \
    mainwindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

RESOURCES += \
   Resources.qrc

mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QtSvgWidgets/QSvgWidget>
#include <QtSvg>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QSvgWidget* svg = new QSvgWidget(this);
    svg->load(QString(":/images/images/Dollar.svg"));


    ui->verticalLayout_3->addWidget(svg);
}

MainWindow::~MainWindow()
{
    delete ui;
}

mainwindow.h:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
};
#endif

main.cpp:

#include "mainwindow.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

(PS: I tried to add [include<QtSvgWidget>] but it doesn't exist by it's own. It is rather inside the "QtSvgWidgtes/QtSvgWidget")

jsulm

@Saviz Where is "QT += svg" in your pro file?

Saviz

@jsulm

In the qmake .pro file that @mrjj kindly shared, in front of the "greaterThan(QT_MAJOR_VERSION, 4):" there was "QT += widgets svg" and that is what I did. I also tried adding the "QT += svg" to the top, but that did not do the trick.

SGaist

Which version of Qt are you currently using ?

mrjj

@Saviz

Hi
it should work unless really old Qt.

Could you try in build menu to use Clean all, run qmake and then press the run ?

Saviz

@SGaist

Qt version 4.14.2 (That is what it says in the "About")

I don't understand something, I just recently downloaded Qt. When I downloaded Qt I selected the Qt 6 version but now as you told me to look at the version it says 4.14,2. What is going on I am very confused. Did I make a mistake in the download process?

SGaist

No that's the Qt Creator version. There's no Qt 4.14.

You have to take a look at the kit you are using.

Saviz

@SGaist

I took a look at the kit as you instructed.

The kit version is: Qt 6.0.3 64bit

JoeCFD

It was introduced from 4.1.
https://doc.qt.io/qt-5/qsvgwidget.html
QT += core gui widgets svg <=== you need widgets as well for qsvgwidget

If you simply need a QPixmap from a svg source for other widgets, use QSvgRenderer to paint one.

Saviz

@mrjj

I tried doing what you suggested. Unfortunately it didn't work.

I first cleaned the project and then ran qmake but I still get the same errors.
Maybe I am doing something else wrong? (Like not including something?)

JoeCFD

@Saviz CONFIG += c++17 you also need 17 for Qt 6.
Show this line of your Makefile:
LIBS = $(SUBLIBS)
it should have -lQt5Svg

SGaist

Drop the C++ CONFIG, you do not need that currently.

You should also consider updating to the latest Qt 6.1.

JoeCFD

@Saviz Another possibility is svg is not installed. Run MaintenaceTool to add it. I just installed Qt 6.1.2 in which svg is included. If you can find it in the Qt lib dir, check the path settings for Qt.

Saviz

@JoeCFD

I don't see this line in my qmake file. Maybe that is the reason it doesn't work. Should I add it?

Saviz

@JoeCFD said in How to use SVG:

MaintenaceTool

If I want to only install the SVG components, then what component do I have to select in the MaintenaceTool to install?

mrjj

@Saviz

Hi

It should be included in any of the installer options. Its not a standalone option.

I don't have Qt6 to test with.

So the project I linked cannot run under Qt6 ?

complains about svg ?

Try install the Qt 6.1.2 as @JoeCFD suggests

Saviz

@mrjj

I will give it a try. But my speed is not the best. It may take a while to download the new version. But I will report back how it went. Thank you all for your help

mrjj

@Saviz

Hi
Else a sure bet is installing Qt5.15.
While v6 does offer new things
https://wiki.qt.io/New_Features_in_Qt_6.0
Its mostly if you are using QML and it still has lots of features missing planned
for some later releases.

Saviz

@mrjj

Okay, I will try it. By the way I have one last question. Why isn't there a widget for SVG in QT Designer by default?

mrjj

@Saviz

Why isn't there a widget for SVG in QT Designer by default?

Too much work I would guess. To allow a Widget to be used in design time, a plugin must be made and maintained across many Designers.
And QSvgWidget doesn't have any properties to set at Design time. (besides the svg file) so I gues sit was
not worth the effort.

You can use the Producer Promote feature to allow a Qwidget as a place holder in Designer and then app is run its
the SVG one.