zoom the Image Element in QML. without using QImage::scaled(), QPixmap::scaled(). - image

Question

I am trying to implement zoom in / out of a image using Image Element in QML.
I want the Pixel scale to be modified if i double click / pinch zoom.
How can i implement this without using QImage::scaled(), QPixmap::scaled().
Basically i dont want to involve Qt logic into my application.
I want Similar effect to hat is happening in the following tutorial
http://harmattan-dev.nokia.com/docs/library/html/qt4/widgets-imageviewer.html
But without Qt Logic in the app.

Answer 1

i know it's not the best answer but i cannot write a comment (i got less then 50 reps...) but zooming in/out qml is easy using PinchArea if you add a MouseArea you can also use onClicked or onDoubleClicked.... there is a useful example for pinch to zoom here(qt.git).
The ImageViewer example you posted got features like print save and so on, and you don't want to use "qt Logic", so i think you will need to use "qt Logic". I would wirte one class for each feature and implement it where i need it.
first of all i think this could help you(Extending QML Functionalities using C++).
Here a (not tested) example for saveing and reading a file:
fileio.h
#ifndef FILEIO_H
#define FILEIO_H
#include <QObject>
#include <QVariant>
class FileIO : public QObject
{
Q_OBJECT
public:
Q_PROPERTY(QString source
READ source
WRITE setSource
NOTIFY sourceChanged)
explicit FileIO(QObject *parent = 0);
Q_INVOKABLE QString source();
Q_INVOKABLE QVariant read();
Q_INVOKABLE bool write(const QVariant& data);
public slots:
void setSource(const QString& source) ;
signals:
void sourceChanged(const QString& source);
void error(const QString& msg);
private:
QString mSource;
};
#endif // FILEIO_H
and fileio.cpp
#include "fileio.h"
#include <QFile>
#include <QDataStream>
#include <QString>
#include <QDebug>
FileIO::FileIO(QObject *parent) :
QObject(parent){
}
QString FileIO::source(){
return mSource;
}
QVariant FileIO::read()
{
if (mSource.isEmpty()){
emit error("source is empty");
return QVariant();
}
QFile file(mSource);
QVariant fileContent; // i dont know if you can use QImage but i think you cann't
if ( file.open(QIODevice::ReadOnly) ) {
QDataStream t( &file );
fileContent << t //you may have to reimplement "<<" operator
file.close();
} else {
emit error("Unable to open the file");
return QVariant();
}
return fileContent;
}.....
and register that in main.cpp like
qmlRegisterType<FileIO, 1>("FileIO", 1, 0, "FileIO");
so you can import it in your qml like
import FileIO 1.0
Rectangle{
id: someId
...
FileIO{
id: yourAccessToYourFileIOclass
}
}
i've not tested that code yet, i hope it helps.
for better answers post what you want to do exacly save, print , any filters....
p.s. I also would create a model in qt and bring it to qml...
greez Matthias