Cannot include QDeclarative Item

[p3c0]

So donot use QDeclarative* classes. Use Qt5 supported one.

bq. i want to change the image source in the Qml by invoking a c++ functiion that will edit the current image

To do this Qt5 way, first go through "Interacting with QML Objects from C++":http://doc.qt.io/qt-5/qtqml-cppintegration-interactqmlfromcpp.html and "Integrating QML and C++":http://doc.qt.io/qt-5/qtqml-cppintegration-topic.html.

[JKSH]

To clarify p3c0's words:

• Classes named QDeclarative[X] are obsolete. You should use them with Qt 4, but you should not use them with Qt 5.
• For Qt 5, use classes named QQml[X] and QQuick[X].

[quote author="Javeria" date="1424320806"]i m trying to initialize QtDEclarative objects, i was following this link:
Link: http://qt-project.org/doc/qt-4.8/qtbinding.html
[/quote]That link is for Qt 4. Do not follow it.

Use p3c0's links instead.

[Javeria]

Thanks a lot for the guidance but i dont have a lot of time and i have like an hour to complete this so if you guys could help in the setting of context property that i cant seem to set context propert its giving me this: error: C2227: left of '->setContextProperty' must point to class/struct/union/generic type
when i declare this:
@ QQmlEngine eng;
DetectSquares m;
eng.rootContext()->setContextProperty("m",&m);
QQmlComponent component(&engine, QUrl::fromLocalFile("main.qml"));
component.create();
@

[JKSH]

[quote author="Javeria" date="1424331653"]error: C2227: left of '- >setContextProperty' must point to class/struct/union/generic type[/quote]That means your compiler doesn't recognize the item on the left of '->setContextProperty'. Did you #include <QQmlContext>?

[Javeria]

Okay done!!, but i have to now call DetectSquares objects function iside QML file, but its givng me syntax error and i dont know how should i set the signal its really confusing :
Here s is the DetectSqaure.h
@#ifndef DETECTSQUARES_H
#define DETECTSQUARES_H
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/imgproc/imgproc.hpp"

#include <iostream>

using namespace cv;
using namespace std;

#include <QObject>

class DetectSquares: public QObject
{
Q_OBJECT
public:
double angle(Point pt1, Point pt2, Point pt0);
void findSquares(Mat image);
static void drawSquares(Mat& image, const vector<vector<Point> >& squares);
void Detect(Mat image);
bool proximity(Size rect1, Size rect2);
Rect proximity_rect(Rect rect1, Rect rect2);
Rect is_a_box(Point cp);
vector<vector<Point>> squares;
Mat image;
Point prev_pointer;
vector<Rect> Detected;
int y;

};

#endif // DETECTSQUARES_H
@
Hers the Qml Code:
@import QtQuick 2.4
import QtQuick.Controls 1.3
import QtQuick.Window 2.2
import QtQuick.Dialogs 1.2
import QtQuick 2.0
ApplicationWindow {
title: qsTr("Sketch_it")
width: 1500
height: 1000
visible: true
property var imagesListModel: ["file:/original.jpg","file:/11.jpg","file:/test (1).jpg","file:/test (2).jpg","file:/test (3).jpg","file:/test (4).jpg","file:/test (5).jpg"]
ListView {
id: imagesList
anchors.fill:parent
spacing:25
orientation: Qt.Vertical
model: imagesListModel
delegate: Image {
objectName: "Displayimage"
width: 75
height: 100
source: imagesListModel[index]
Text{
text:"Sketch"+(index+1)
}

         MouseArea {
             anchors.fill: parent

             onClicked: {
                main.source=imagesListModel[index]
                Component.OnCompleted:{
                 m.Detect();
                 }
               // console.log("User select '"+"' image");
             }
         }
    }
}
Image{
    id:main
    width: 700
    height: 600

   // source:"file:/test (6).jpg"
    anchors.centerIn: parent
    MouseArea{
      anchors.fill:parent
       onClicked: {


           console.log(mouseX+" "+mouseY);
     }
    }
}

}
@

[p3c0]

You will need to make those methods "Q_INVOKABLE":http://doc.qt.io/qt-5/qobject.html#Q_INVOKABLE. An example of how to access them is "here":http://doc.qt.io/qt-5/qtqml-cppintegration-exposecppattributes.html#exposing-methods-including-qt-slots.
But beware that QML recognizes only the "following":http://doc.qt.io/qt-5/qtqml-cppintegration-data.html#basic-qt-data-types data types. So it wont recongnize those OpenCV's user defined data types.

[Javeria]

I ve kinda follwoed it, i dnt have enough time , i have 5 min, heres the code, its giving me syntax error when i use Component.onCompleted:
@import QtQuick 2.4
import QtQuick.Controls 1.3
import QtQuick.Window 2.2
import QtQuick.Dialogs 1.2
import QtQuick 2.0
ApplicationWindow {
title: qsTr("Sketch_it")
width: 1500
height: 1000
visible: true
property var imagesListModel: ["file:/original.jpg","file:/11.jpg","file:/test (1).jpg","file:/test (2).jpg","file:/test (3).jpg","file:/test (4).jpg","file:/test (5).jpg"]
ListView {
id: imagesList
anchors.fill:parent
spacing:25
orientation: Qt.Vertical
model: imagesListModel
delegate: Image {
objectName: "Displayimage"
width: 75
height: 100
source: imagesListModel[index]
Text{
text:"Sketch"+(index+1)
}

         MouseArea {
             anchors.fill: parent

             onClicked: {
                main.source=imagesListModel[index]
                Component.OnCompleted:
                 {
                     m.Detect();
                 }
               // console.log("User select '"+"' image");
             }
         }
    }
}
Image{
    id:main
    width: 700
    height: 600

   // source:"file:/test (6).jpg"
    anchors.centerIn: parent
    MouseArea{
      anchors.fill:parent
       onClicked: {


           console.log(mouseX+" "+mouseY);
     }
    }
}

}
@

[p3c0]

Ofcourse it will.
@
void Detect(Mat image);
@

Takes an argument and you are not supplying it. Plus it takes an argument not recognized by QML. You will need to find another way to pass the data from QML to C++ and which is recognized by both.

[Javeria]

Okay but there is still syntax error in this
@Component.OnCompleted:
{

  }@

[JKSH]

• Component.onCompleted is a signal handler.
• onClicked is a signal handler.

You cannot put a signal handler inside another signal handler. You need to move Component.onCompleted up one level, at least.

[p3c0]

[quote author="JKSH" date="1424387370"]* Component.onCompleted is a signal handler.

• onClicked is a signal handler.

You cannot put a signal handler inside another signal handler. You need to move Component.onCompleted up one level, at least.
[/quote]

Right. I missed that one.

[Javeria]

Okay but i have two call two c++ functions, and one should be called when the user clicks on the main image so i cant use component.oncompleted thn?

[p3c0]

Call that function in onClicked event handler. Component.onCompleted is called after the object has been instantiated. You can call the function inside it also but since you need to do it on click, call it inside onClicked.

[JKSH]

[quote author="Javeria" date="1424418592"]Okay but i have two call two c++ functions, and one should be called when the user clicks on the main image so i cant use component.oncompleted thn?[/quote]As the name implies, Component.onCompleted runs when the component has finished loading.

Do you want your function to be called when the component finishes loading?

[Javeria]

And also i have changed my detectsquare function's parameters to Qimage
so that i could use the current selected image in that function but i dont understand how i should do that in QML? As i cant use Qimage object in QML

[p3c0]

Since you already have paths, you can just send the path string from QML to C++ and then there access that image.

[Javeria]

But I want to edit that image and send it back to qml so that it displays it in the ui

[p3c0]

Do you have paths for the Images in QML ?

If yes, then as said earlier, send the path string from QML to C++, open the image, process it, on C++ side(or whatever operations), then signal QML to display that image.

[JKSH]

Read the blog post and the comments at http://pusling.com/blog/?p=369

[Javeria]

I have decided to use Qstring and i have followed this link to assign path:
Link: http://doc.qt.io/qt-5/qtqml-cppintegration-exposecppattributes.html (The properties part)
But im getting this error
Invalid attached object assignment

QQmlComponent: Component is not ready