Hello,

I have downloaded and installed qwt, I made a QwtThermo like this :

.pro
Capture2.PNG

Then .pro and .cpp below :
Qt Code: 
  1. #-------------------------------------------------
  2. #
  3. # Project created by QtCreator 2018-02-07T17:08:47
  4. #
  5. #-------------------------------------------------
  6. #   QWT library
  7.  
  8. QT       += core gui
  9.  
  10. INCLUDEPATH += /usr/local/qwt-6.1.2/include
  11. LIBS += -L/usr/local/qwt-6.1.2/lib  -lqwt
  12.  
  13. greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
  14.  
  15. TARGET = sans_titre
  16. TEMPLATE = app
  17.  
  18.  
  19. SOURCES += main.cpp\
  20.         widget.cpp
  21.  
  22. HEADERS  += widget.h
  23.  
  24. FORMS    += widget.ui
To copy to clipboard, switch view to plain text mode 


.cpp
Qt Code: 
  1. #include "widget.h"
  2. #include "ui_widget.h"
  3.  
  4. Widget::Widget(QWidget *parent) :
  5.     QWidget(parent),
  6.     ui(new Ui::Widget)
  7. {
  8.     ui->setupUi(this);
  9. }
  10.  
  11. Widget::~Widget()
  12. {
  13.     delete ui;
  14. }
  15.  
  16. void Widget::On_Slide_Changed(int value)
  17. {
  18. }
To copy to clipboard, switch view to plain text mode 

But I have an error :
qwt_thermo.h : no such file or directory