How to use SVG

mrjj · 2 Jul 2021, 17:30

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 · 7 Feb 2021, 16:34

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 · 2 Jul 2021, 16:50

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 · S SGaist 2 Jul 2021, 16:47

@SGaist

I took a look at the kit as you instructed.

The kit version is: Qt 6.0.3 64bit

JoeCFD · 7 Feb 2021, 17:16

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 · 7 Feb 2021, 17:30

@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 · 7 Feb 2021, 17:47

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

SGaist · wrote on 2 Jul 2021, 18:02

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

You should also consider updating to the latest Qt 6.1.

JoeCFD · 7 Feb 2021, 18:29

@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 · 7 Mar 2021, 04:31

@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 · 3 Jul 2021, 05:12

@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 · 7 Mar 2021, 05:13

@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 · 7 Mar 2021, 05:53

@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 · 3 Jul 2021, 09:01

@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 · 3 Jul 2021, 09:08

@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 · 3 Jul 2021, 11:56

@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.

Saviz · 3 Jul 2021, 12:31

@mrjj

Very interesting. Is there a documentation that I can use for the Producer Promote feature so I can learn it?

mrjj · 7 Mar 2021, 12:32

@Saviz

Hi
Its very handy.

In your use case you place a QWidget on the form, right-click and choose to promote.
Then tell it QSvgWidget for class name and it will guess on QSvgWidget.h
Then press Add (+), then then promote.

https://doc.qt.io/qt-5/designer-using-custom-widgets.html

https://stackoverflow.com/questions/33588289/what-is-promote-to-feature-in-qt-creator-and-how-does-it-work

Do note:
Accessing it via Ui-> is possible and you can call the real functions from code, just like any other widget.

Saviz · 7 Mar 2021, 12:57

@mrjj

So, if I want to create a custom widget for SVG, how can I do that? Is there an example that I can follow for promoting a widget to SVG?

(I ask this because I really want to use SVG as default and I need a solution.)
(I am also a beginner so I have no idea where to start :) )

mrjj · S Saviz 3 Jul 2021, 12:56

@Saviz
Hi
What you mean with custom widget for SVG ?

You mean your own classed based on QSvgWidget ?

Or to simply use QSvgWidget ?