QwtNullPaintDevice(3)

📦

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🎀 NAME 🎀

okay so this is the manual page for QwtNullPaintDevice(3), coming at you from the Library Functions Manual (Qwt User's Guide), and the NAME is literally: A null paint device doing nothing. No cap, bestie — it's a null paint device, and it is doing nothing. 💅

✨ SYNOPSIS ✨

#include <qwt_null_paintdevice.h>

Inherits QPaintDevice.
Inherited by QwtGraphic.

🌸 Public Types 🌸

enum Mode { NormalMode, PolygonPathMode, PathMode } — render mode. 🎨

🫶 Public Member Functions 🫶

QwtNullPaintDevice () — constructor.
virtual ~QwtNullPaintDevice () — destructor.
void setMode (Mode) — sets the render mode.
Mode mode () const — returns the render mode.
virtual QPaintEngine * paintEngine () const override — see QPaintDevice::paintEngine().
virtual int metric (PaintDeviceMetric) const override — it does the metric thing; see QPaintDevice::metric().
virtual void drawRects (const QRect *, int) — see QPaintEngine::drawRects().
virtual void drawRects (const QRectF *, int) — see QPaintEngine::drawRects().
virtual void drawLines (const QLine *, int) — see QPaintEngine::drawLines().
virtual void drawLines (const QLineF *, int) — see QPaintEngine::drawLines().
virtual void drawEllipse (const QRectF &) — see QPaintEngine::drawEllipse().
virtual void drawEllipse (const QRect &) — see QPaintEngine::drawEllipse().
virtual void drawPath (const QPainterPath &) — see QPaintEngine::drawPath().
virtual void drawPoints (const QPointF *, int) — see QPaintEngine::drawPoints().
virtual void drawPoints (const QPoint *, int) — see QPaintEngine::drawPoints().
virtual void drawPolygon (const QPointF *, int, QPaintEngine::PolygonDrawMode) — see QPaintEngine::drawPolygon().
virtual void drawPolygon (const QPoint *, int, QPaintEngine::PolygonDrawMode) — see QPaintEngine::drawPolygon().
virtual void drawPixmap (const QRectF &, const QPixmap &, const QRectF &) — see QPaintEngine::drawPixmap().
virtual void drawTextItem (const QPointF &, const QTextItem &) — see QPaintEngine::drawTextItem().
virtual void drawTiledPixmap (const QRectF &, const QPixmap &, const QPointF &) — see QPaintEngine::drawTiledPixmap().
virtual void drawImage (const QRectF &, const QImage &, const QRectF &, Qt::ImageConversionFlags) — see QPaintEngine::drawImage().
virtual void updateState (const QPaintEngineState &) — see QPaintEngine::updateState().

🧚 Protected Member Functions 🧚

virtual QSize sizeMetrics () const =0 — pure virtual, protected, and it returns the size needed to implement metric(). Iconic. 💅

💖 Detailed Description 💖

It's a null paint device doing nothing. Yes, that's the whole vibe. ✨

Sometimes the important layout/rendering geometries are not available or changeable from the public Qt class interface (f.e hidden in the style implementation).

QwtNullPaintDevice can be used to manipulate or filter out this information by analyzing the stream of paint primitives.

F.e. QwtNullPaintDevice is used by QwtPlotCanvas to identify styled backgrounds with rounded corners.

Definition at line 32 of file qwt_null_paintdevice.h.

🦋 Member Enumeration Documentation 🦋

`enum QwtNullPaintDevice::Mode`

Render mode. See also setMode(), mode().

Enumerator:

NormalMode — all vector graphic primitives are painted by the corresponding draw methods.
PolygonPathMode — vector graphic primitives ( beside polygons ) are mapped to a QPainterPath and are painted by drawPath. In PathMode mode only a few draw methods are called:
- drawPath()
- drawPixmap()
- drawImage()
- drawPolygon()
PathMode — vector graphic primitives are mapped to a QPainterPath and are painted by drawPath. In PathMode mode only a few draw methods are called:
- drawPath()
- drawPixmap()
- drawImage()

Definition at line 40 of file qwt_null_paintdevice.h.

🧚 Constructor & Destructor Documentation 🧚

`QwtNullPaintDevice::QwtNullPaintDevice ()`

Constructor.

Definition at line 367 of file qwt_null_paintdevice.cpp.

`QwtNullPaintDevice::~QwtNullPaintDevice () [virtual]`

Destructor.

Definition at line 374 of file qwt_null_paintdevice.cpp.

👑 Member Function Documentation 👑

`void QwtNullPaintDevice::drawEllipse (const QRect & rect) [virtual]`

See QPaintEngine::drawEllipse().

Definition at line 521 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawEllipse (const QRectF & rect) [virtual]`

See QPaintEngine::drawEllipse().

Definition at line 515 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawImage (const QRectF & rect, const QImage & image, const QRectF & subRect, Qt::ImageConversionFlags flags) [virtual]`

See QPaintEngine::drawImage().

Reimplemented in QwtGraphic.

Definition at line 596 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawLines (const QLine * lines, int lineCount) [virtual]`

See QPaintEngine::drawLines().

Definition at line 499 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawLines (const QLineF * lines, int lineCount) [virtual]`

See QPaintEngine::drawLines().

Definition at line 507 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawPath (const QPainterPath & path) [virtual]`

See QPaintEngine::drawPath().

Reimplemented in QwtGraphic.

Definition at line 527 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawPixmap (const QRectF & rect, const QPixmap & pm, const QRectF & subRect) [virtual]`

See QPaintEngine::drawPixmap().

Reimplemented in QwtGraphic.

Definition at line 569 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawPoints (const QPoint * points, int pointCount) [virtual]`

See QPaintEngine::drawPoints().

Definition at line 541 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawPoints (const QPointF * points, int pointCount) [virtual]`

See QPaintEngine::drawPoints().

Definition at line 533 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawPolygon (const QPoint * points, int pointCount, QPaintEngine::PolygonDrawMode mode) [virtual]`

See QPaintEngine::drawPolygon().

Definition at line 559 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawPolygon (const QPointF * points, int pointCount, QPaintEngine::PolygonDrawMode mode) [virtual]`

See QPaintEngine::drawPolygon().

Definition at line 549 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawRects (const QRect * rects, int rectCount) [virtual]`

See QPaintEngine::drawRects().

Definition at line 483 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawRects (const QRectF * rects, int rectCount) [virtual]`

See QPaintEngine::drawRects().

Definition at line 491 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawTextItem (const QPointF & pos, const QTextItem & textItem) [virtual]`

See QPaintEngine::drawTextItem().

Definition at line 578 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::drawTiledPixmap (const QRectF & rect, const QPixmap & pixmap, const QPointF & subRect) [virtual]`

See QPaintEngine::drawTiledPixmap().

Definition at line 586 of file qwt_null_paintdevice.cpp.

`int QwtNullPaintDevice::metric (PaintDeviceMetric deviceMetric) const [override], [virtual]`

See QPaintDevice::metric().

Parameters:

deviceMetric — type of metric.

Returns: metric information for the given paint device metric.

`QwtNullPaintDevice::Mode QwtNullPaintDevice::mode () const`

Returns: render mode.

`QPaintEngine * QwtNullPaintDevice::paintEngine () const [override], [virtual]`

See QPaintDevice::paintEngine().

Definition at line 401 of file qwt_null_paintdevice.cpp.

`void QwtNullPaintDevice::setMode (Mode mode)`

Set the render mode.

Parameters:

mode — new mode.

`virtual QSize QwtNullPaintDevice::sizeMetrics () const [protected], [pure virtual]`

Returns: size needed to implement metric().

Implemented in QwtGraphic.

`void QwtNullPaintDevice::updateState (const QPaintEngineState & state) [virtual]`

See QPaintEngine::updateState().

Reimplemented in QwtGraphic.

Definition at line 607 of file qwt_null_paintdevice.cpp.

🌈 Author 🌈

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

💖 That's the whole page, bestie — source/version: Qwt User's Guide; page: QwtNullPaintDevice(3); date: not printed in the footer, so I'm not inventing one. 🎀

📦 where this page comes from

alpine 3.24: qwt-doc 6.3.0-r0 · custom
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-04: a language model's rewrite of the original, under its terms