Archived:Load, Resize image and set background image in Qt application/widget

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Qt Quick should be used for all UI development on mobile devices. The approach described in this article (based on QWidget) is deprecated.

Article Metadata

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Code Example

Source file: Media:QtSetBackground.zip

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Tested with

Devices(s): Nokia 5800 XpressMusic

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Compatibility

Platform(s): Qt

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Article

Keywords: QWidget::setPalette(), QPalette::setBrush, QPixmap(),QPixmap::scaled()

Created: savaj (11 Jun 2009)

Last edited: hamishwillee (11 Oct 2012)

Overview

This code snippets shows how to load image, resize image and set image in background of widget/application. The API QPixmap() will load image using file name. API QPixmap::scaled() will returns a copy of the pixmap scaled to a rectangle with the given width and height. QPalette::setBrush() sets the brush for the given color role (here background) to the specified brush (here image)for all groups in the palette. QWidget::setPalette() set a given palette for a Widget.

This snippet can be self-signed. As it does not use any API which require developer/certified signing.

Headers required

#include <QPalette>
#include <QDesktopWidget>

Source

void SetBackground::SetBackgroundImage()
{
	//Using QPalette you can set background image as follows.
	 QPalette p = palette();
 
	 //Load image to QPixmap, Give full path of image
	QPixmap pixmap1("c://01.JPG"); //For emulator C: is ..\epoc32\winscw\c so image must be at that location
 
	//resize image if it is larger than screen size.
	QDesktopWidget* desktopWidget = QApplication::desktop();
	QRect rect = desktopWidget->availableGeometry();
 
	QSize size(rect.width() , rect.height());
	//resize as per your requirement..
	QPixmap pixmap(pixmap1.scaled(size));
 
	p.setBrush(QPalette::Background,  pixmap);
	setPalette(p);
}

Postconditions

The code snippet is expected to show background image in application.

Code Example

• The Code Example will set image in background and example is tested on Nokia 5800 XpressMusic.