QCPPainter Class Reference
Author: Emanuel Eichhammer

· · · ·
Public Types | Public Functions
QCPPainter Class Reference

QPainter subclass used internally. More...

## Public Types
enum | PainterMode

## Public Functions
| QCPPainter ()
| QCPPainter (QPaintDevice *device)
bool | antialiasing () const
PainterModes | modes () const
void | setAntialiasing (bool enabled)
void | setMode (PainterMode mode, bool enabled=true)
void | setModes (PainterModes modes)
bool | begin (QPaintDevice *device)
void | setPen (const QPen &pen)
void | setPen (const QColor &color)
void | setPen (Qt::PenStyle penStyle)
void | drawLine (const QLineF &line)
void | drawLine (const QPointF &p1, const QPointF &p2)
void | save ()
void | restore ()
void | makeNonCosmetic ()

## Detailed Description

QPainter subclass used internally.

This QPainter subclass is used to provide some extended functionality e.g. for tweaking position consistency between antialiased and non-antialiased painting. Further it provides workarounds for QPainter quirks.

Warning
  This class intentionally hides non-virtual functions of QPainter, e.g. setPen, save and restore. So while it is possible to pass a QCPPainter instance to a function that expects a QPainter pointer, some of the workarounds and tweaks will be unavailable to the function (because it will call the base class implementations of the functions actually hidden by QCPPainter).

## Member Enumeration Documentation

## ◆ PainterMode

enum QCPPainter::PainterMode

Defines special modes the painter can operate in. They disable or enable certain subsets of features/fixes/workarounds, depending on whether they are wanted on the respective output device.

Enumerator
pmDefault | 0x00 Default mode for painting on screen devices
pmVectorized | 0x01 Mode for vectorized painting (e.g. PDF export). For example, this prevents some antialiasing fixes.
pmNoCaching | 0x02 Mode for all sorts of exports (e.g. PNG, PDF,...). For example, this prevents using cached pixmap labels
pmNonCosmetic | 0x04 Turns pen widths 0 to 1, i.e. disables cosmetic pens. (A cosmetic pen is always drawn with width 1 pixel in the vector image/pdf viewer, independent of zoom.)

## Constructor & Destructor Documentation

## ◆ QCPPainter() [1/2]

QCPPainter::QCPPainter | ( |  | ) |

Creates a new QCPPainter instance and sets default values

## ◆ QCPPainter() [2/2]

QCPPainter::QCPPainter | ( | QPaintDevice * | device | ) |
| explicit

Creates a new QCPPainter instance on the specified paint device and sets default values. Just like the analogous QPainter constructor, begins painting on device immediately.

Like begin, this method sets QPainter::NonCosmeticDefaultPen in Qt versions before Qt5.

## Member Function Documentation

## ◆ setAntialiasing()

void QCPPainter::setAntialiasing | ( | bool | enabled | ) |

Sets whether painting uses antialiasing or not. Use this method instead of using setRenderHint with QPainter::Antialiasing directly, as it allows QCPPainter to regain pixel exactness between antialiased and non-antialiased painting (Since Qt < 5.0 uses slightly different coordinate systems for AA/Non-AA painting).

## ◆ setMode()

void QCPPainter::setMode | ( | QCPPainter::PainterMode | mode,
|  | bool | enabled = true )

This is an overloaded function.
Sets the mode of the painter. This controls whether the painter shall adjust its fixes/workarounds optimized for certain output devices.

## ◆ setModes()

void QCPPainter::setModes | ( | PainterModes | modes | ) |

Sets the mode of the painter. This controls whether the painter shall adjust its fixes/workarounds optimized for certain output devices.

## ◆ begin()

bool QCPPainter::begin | ( | QPaintDevice * | device | ) |

Sets the QPainter::NonCosmeticDefaultPen in Qt versions before Qt5 after beginning painting on device. This is necessary to get cosmetic pen consistency across Qt versions, because since Qt5, all pens are non-cosmetic by default, and in Qt4 this render hint must be set to get that behaviour.

The Constructor QCPPainter(QPaintDevice *device) which directly starts painting also sets the render hint as appropriate.

Note
  this function hides the non-virtual base class implementation.

## ◆ setPen() [1/3]

void QCPPainter::setPen | ( | const QPen & | pen | ) |

Sets the pen of the painter and applies certain fixes to it, depending on the mode of this QCPPainter.

Note
  this function hides the non-virtual base class implementation.

## ◆ setPen() [2/3]

void QCPPainter::setPen | ( | const QColor & | color | ) |

This is an overloaded function.
Sets the pen (by color) of the painter and applies certain fixes to it, depending on the mode of this QCPPainter.

Note
  this function hides the non-virtual base class implementation.

## ◆ setPen() [3/3]

void QCPPainter::setPen | ( | Qt::PenStyle | penStyle | ) |

This is an overloaded function.
Sets the pen (by style) of the painter and applies certain fixes to it, depending on the mode of this QCPPainter.

Note
  this function hides the non-virtual base class implementation.

## ◆ drawLine()

void QCPPainter::drawLine | ( | const QLineF & | line | ) |

This is an overloaded function.
Works around a Qt bug introduced with Qt 4.8 which makes drawing QLineF unpredictable when antialiasing is disabled. Thus when antialiasing is disabled, it rounds the line to integer coordinates and then passes it to the original drawLine.

Note
  this function hides the non-virtual base class implementation.

## ◆ save()

void QCPPainter::save | ( |  | ) |

Saves the painter (see QPainter::save). Since QCPPainter adds some new internal state to QPainter, the save/restore functions are reimplemented to also save/restore those members.

Note
  this function hides the non-virtual base class implementation.

See also
  restore

## ◆ restore()

void QCPPainter::restore | ( |  | ) |

Restores the painter (see QPainter::restore). Since QCPPainter adds some new internal state to QPainter, the save/restore functions are reimplemented to also save/restore those members.

Note
  this function hides the non-virtual base class implementation.

See also
  save

## ◆ makeNonCosmetic()

void QCPPainter::makeNonCosmetic | ( |  | ) |

Changes the pen width to 1 if it currently is 0. This function is called in the setPen overrides when the pmNonCosmetic mode is set.

The documentation for this class was generated from the following files:

- src/painter.h
- src/painter.cpp