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Archived:Rotate picture in Qt

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Archived.pngArchived: This article is archived because it is not considered relevant for third-party developers creating commercial solutions today. If you think this article is still relevant, let us know by adding the template {{ReviewForRemovalFromArchive|user=~~~~|write your reason here}}.

Qt Quick should be used for all UI development on mobile devices. The approach described in this article (using C++ for the Qt app UI) is deprecated.

Article Metadata
Tested with
Devices(s): Nokia 5800 XpressMusic, Nokia N900
Compatibility
Platform(s): Qt
Symbian
Article
Keywords: QPixmap, QPainter
Created: tepaa (20 Oct 2009)
Last edited: hamishwillee (11 Oct 2012)

Contents

Overview

This example shows how to rotate a QPixmap picture using the QPainter class.


Preconditions

  • Qt is installed on your platform.


Header

private:
// Original pixmap that will be rotated
QPixmap pixmap;


Source

// Create new rotatedPixmap that size is same as original
QPixmap rotatedPixmap(pixmap.size());
 
// Create a QPainter for it
QPainter p(&rotatedPixmap);
 
// Set rotation origo into pixmap center
QSize size = pixmap.size();
p.translate(size.height()/2,size.height()/2);
 
// Rotate the painter 90 degrees
p.rotate(90);
 
// Set origo back to upper left corner
p.translate(-size.height()/2,-size.height()/2);
 
// Draw your original pixmap on it
p.drawPixmap(0, 0, pixmap);
p.end();
 
// Change original pixmap reference into new rotated pixmap
pixmap = rotatedPixmap;


Postconditions

The picture is rotated 90 degrees.


See also

This page was last modified on 11 October 2012, at 01:14.
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