QwtThermo.qt5 - Man Page


#include <qwt_thermo.h>

Inherits QwtAbstractScale.

Public Types

enum ScalePos { NoScale, LeftScale, RightScale, TopScale, BottomScale }

Public Slots

void setValue (double val)

Public Member Functions

QwtThermo (QWidget *parent=NULL)
virtual ~QwtThermo ()
const QBrush & alarmBrush () const
const QColor & alarmColor () const
bool alarmEnabled () const
double alarmLevel () const
int borderWidth () const
const QBrush & fillBrush () const
const QColor & fillColor () const
double maxValue () const
virtual QSize minimumSizeHint () const
double minValue () const
int pipeWidth () const
const QwtScaleDraw * scaleDraw () const
ScalePos scalePosition () const
void setAlarmBrush (const QBrush &b)
void setAlarmColor (const QColor &c)
void setAlarmEnabled (bool tf)
void setAlarmLevel (double v)
void setBorderWidth (int w)
void setFillBrush (const QBrush &b)
void setFillColor (const QColor &c)
void setMargin (int m)
void setMaxValue (double v)
void setMinValue (double v)
void setOrientation (Qt::Orientation o, ScalePos s)
void setPipeWidth (int w)
void setRange (double vmin, double vmax, bool lg=false)
void setScaleDraw (QwtScaleDraw *)
void setScalePosition (ScalePos s)
virtual QSize sizeHint () const
double value () const

Protected Member Functions

void draw (QPainter *p, const QRect &update_rect)
void drawThermo (QPainter *p)
virtual void fontChange (const QFont &oldFont)
void layoutThermo (bool update=true)
virtual void paintEvent (QPaintEvent *e)
virtual void resizeEvent (QResizeEvent *e)
virtual void scaleChange ()
QwtScaleDraw * scaleDraw ()

Detailed Description

The Thermometer Widget.

QwtThermo is a widget which displays a value in an interval. It supports:

By default, the scale and range run over the same interval of values. QwtAbstractScale::setScale() changes the interval of the scale and allows easy conversion between physical units.

The example shows how to make the scale indicate in degrees Fahrenheit and to set the value in degrees Kelvin:

#include <qapplication.h>
#include <qwt_thermo.h>

double Kelvin2Fahrenheit(double kelvin)
    // see http://en.wikipedia.org/wiki/Kelvin
    return 1.8*kelvin - 459.67;

int main(int argc, char **argv)
    const double minKelvin = 0.0;
    const double maxKelvin = 500.0;

    QApplication a(argc, argv);
    QwtThermo t;
    t.setRange(minKelvin, maxKelvin);
    t.setScale(Kelvin2Fahrenheit(minKelvin), Kelvin2Fahrenheit(maxKelvin));
    // set the value in Kelvin but the scale displays in Fahrenheit
    // 273.15 Kelvin = 0 Celsius = 32 Fahrenheit
    return a.exec();

Constructor & Destructor Documentation

QwtThermo::QwtThermo (QWidget *parent = NULL) [explicit]



parent Parent widget

Member Function Documentation

const QBrush & QwtThermo::alarmBrush () const

Return the liquid brush above the alarm threshold.

See also:


double QwtThermo::alarmLevel () const

Return the alarm threshold.

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int QwtThermo::borderWidth () const

Return the border width of the thermometer pipe.

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void QwtThermo::draw (QPainter *painter, const QRect &rect) [protected]

Draw the whole QwtThermo.


painter Painter
rect Update rectangle

void QwtThermo::drawThermo (QPainter *painter) [protected]

Redraw the liquid in thermometer pipe.


painter Painter

const QBrush & QwtThermo::fillBrush () const

Return the liquid brush.

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const QColor & QwtThermo::fillColor () const

Return the liquid color.

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void QwtThermo::layoutThermo (boolupdate_geometry = true) [protected]

Recalculate the QwtThermo geometry and layout based on the QwtThermo::rect() and the fonts.


update_geometry notify the layout system and call update to redraw the scale

QSize QwtThermo::minimumSizeHint () const [virtual]

Return a minimum size hint. Warning:

The return value depends on the font and the scale.

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void QwtThermo::paintEvent (QPaintEvent *event) [protected], [virtual]

Qt paint event. event Paint event

int QwtThermo::pipeWidth () const

Return the width of the pipe.

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const QwtScaleDraw * QwtThermo::scaleDraw () const


the scale draw of the thermo

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QwtScaleDraw * QwtThermo::scaleDraw () [protected]


the scale draw of the thermo

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QwtThermo::ScalePos QwtThermo::scalePosition () const

Return the scale position.

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void QwtThermo::setAlarmBrush (const QBrush &brush)

Specify the liquid brush above the alarm threshold. Parameters:

brush New brush. The default is solid white.

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void QwtThermo::setAlarmColor (const QColor &c)

Specify the liquid color above the alarm threshold. Parameters:

c New color. The default is white.

void QwtThermo::setAlarmEnabled (booltf)

Enable or disable the alarm threshold. Parameters:

tf true (disabled) or false (enabled)

void QwtThermo::setAlarmLevel (doublelevel)

Specify the alarm threshold.


level Alarm threshold

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void QwtThermo::setBorderWidth (intwidth)

Set the border width of the pipe.


width Border width

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void QwtThermo::setFillBrush (const QBrush &brush)

Change the brush of the liquid. Parameters:

brush New brush. The default brush is solid black.

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void QwtThermo::setFillColor (const QColor &c)

Change the color of the liquid. Parameters:

c New color. The default color is black.

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void QwtThermo::setMargin (intm)

Specify the distance between the pipe's endpoints and the widget's border. The margin is used to leave some space for the scale labels. If a large font is used, it is advisable to adjust the margins.


m New Margin. The default values are 10 for horizontal orientation and 20 for vertical orientation.


The margin has no effect if the scale is disabled.

This function is a NOOP because margins are determined automatically.

void QwtThermo::setMaxValue (doublemax)

Set the maximum value.


max Maximum value

See also:

maxValue(), setMinValue()

void QwtThermo::setMinValue (doublemin)

Set the minimum value.


min Minimum value

See also:

minValue(), setMaxValue()

void QwtThermo::setOrientation (Qt::Orientationo, ScalePoss)

Set the thermometer orientation and the scale position. The scale position NoScale disables the scale.


o orientation. Possible values are Qt::Horizontal and Qt::Vertical. The default value is Qt::Vertical.
s Position of the scale. The default value is NoScale.

A valid combination of scale position and orientation is enforced:

  • a horizontal thermometer can have the scale positions TopScale, BottomScale or NoScale;
  • a vertical thermometer can have the scale positions LeftScale, RightScale or NoScale;
  • an invalid scale position will default to NoScale.

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void QwtThermo::setPipeWidth (intwidth)

Change the width of the pipe.


width Width of the pipe

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void QwtThermo::setRange (doublevmin, doublevmax, boollogarithmic = false)

Set the range. Parameters:

vmin value corresponding lower or left end of the thermometer
vmax value corresponding to the upper or right end of the thermometer
logarithmic logarithmic mapping, true or false

void QwtThermo::setScaleDraw (QwtScaleDraw *scaleDraw)

Set a scale draw. For changing the labels of the scales, it is necessary to derive from QwtScaleDraw and overload QwtScaleDraw::label().


scaleDraw ScaleDraw object, that has to be created with new and will be deleted in ~QwtThermo or the next call of setScaleDraw().

void QwtThermo::setScalePosition (ScalePosscalePos)

Change the scale position (and thermometer orientation). Parameters:

scalePos Position of the scale.

A valid combination of scale position and orientation is enforced:

  • if the new scale position is LeftScale or RightScale, the scale orientation will become Qt::Vertical;
  • if the new scale position is BottomScale or TopScale, the scale orientation will become Qt::Horizontal;
  • if the new scale position is NoScale, the scale orientation will not change.

See also:

setOrientation(), scalePosition()

void QwtThermo::setValue (doublevalue) [slot]

Set the current value.


value New Value

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QSize QwtThermo::sizeHint () const [virtual]


the minimum size hint

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Generated automatically by Doxygen for Qwt User's Guide from the source code.


Tue Nov 20 2012 Version 5.2.3 Qwt User's Guide