QML Camera - take a Square photo

[guidupas]

I am trying to implement it with QQuickImageProvider but I am not understanding why it is not working. My code is below. If you could help me.

.h

#ifndef MANIPULAIMAGEM_H
#define MANIPULAIMAGEM_H
 
#include <QObject>
#include <QImage>
#include <QQuickImageProvider>
#include <QQmlEngine>
#include <QQmlContext>
 
class manipulaImagem : public QObject, public QQuickImageProvider
{
    Q_OBJECT
 
public slots:
    QString recortarFotoPerfil(const QString &imagem, QRect rectRecorte);
 
public:
    manipulaImagem(QObject *parent = 0);
 
    QImage requestImage(const QString &id, QSize *size, const QSize &requestedSize);
 
private:
    void alocaImagem(const QString &imagem, QRect rectRecorte);
 
    QImage imagemEditada;
};
 
#endif // MANIPULAIMAGEM_H

#ifndef MANIPULAIMAGEM_H
#define MANIPULAIMAGEM_H

#include <QObject>
#include <QImage>
#include <QQuickImageProvider>
#include <QQmlEngine>
#include <QQmlContext>

class manipulaImagem : public QObject, public QQuickImageProvider
{
    Q_OBJECT

public slots:
    QString recortarFotoPerfil(const QString &imagem, QRect rectRecorte);

public:
    manipulaImagem(QObject *parent = 0);

    QImage requestImage(const QString &id, QSize *size, const QSize &requestedSize);

private:
    void alocaImagem(const QString &imagem, QRect rectRecorte);

    QImage imagemEditada;
};

#endif // MANIPULAIMAGEM_H

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.cpp

#include "manipulaimagem.h"
 
#include <QDebug>
 
manipulaImagem::manipulaImagem(QObject *parent) : QQuickImageProvider(QQmlImageProviderBase::Image)
{
 
}
 
QImage manipulaImagem::requestImage(const QString &id, QSize *size, const QSize &requestedSize)
{
    if(imagemEditada.isNull())
    {
        qDebug() << "Request image: (image is null)";
    }
    else
    {
        qDebug() << "Request image: image is OK";
    }
 
    return imagemEditada;
}
 
void manipulaImagem::alocaImagem(const QString &imagem, QRect rectRecorte)
{
    QUrl caminhoImagem(imagem);
    QQmlEngine *engine = QQmlEngine::contextForObject(this)->engine();
    QQmlImageProviderBase *imageProviderBase = engine->imageProvider(caminhoImagem.host());
    QQuickImageProvider *imageProvider = static_cast<QQuickImageProvider*>(imageProviderBase);
 
    QSize imageSize;
    QString imageId = caminhoImagem.path().remove(0, 1);
imagemEditada = imageProvider->requestImage(imageId, &imageSize, imageSize);
 
    if(imagemEditada.isNull())
    {
        qDebug() << "Loading image failed";
    }
    else
    {
        qDebug() << "Loading image OK";
    }
}
 
QString manipulaImagem::recortarFotoPerfil(const QString &imagem, QRect rectRecorte)
{
    this->alocaImagem(imagem, rectRecorte);
 
    QString a = "image://ProvedorImagens/imagemEditada";
 
    if(imagemEditada.isNull())
    {
        qDebug() << "Imagem is null";
    }
    else
    {
        qDebug() << "Imagem is loaded";
    }
 
    return a;
}

#include "manipulaimagem.h"

#include <QDebug>

manipulaImagem::manipulaImagem(QObject *parent) : QQuickImageProvider(QQmlImageProviderBase::Image)
{

}

QImage manipulaImagem::requestImage(const QString &id, QSize *size, const QSize &requestedSize)
{
    if(imagemEditada.isNull())
    {
        qDebug() << "Request image: (image is null)";
    }
    else
    {
        qDebug() << "Request image: image is OK";
    }

    return imagemEditada;
}

void manipulaImagem::alocaImagem(const QString &imagem, QRect rectRecorte)
{
    QUrl caminhoImagem(imagem);
    QQmlEngine *engine = QQmlEngine::contextForObject(this)->engine();
    QQmlImageProviderBase *imageProviderBase = engine->imageProvider(caminhoImagem.host());
    QQuickImageProvider *imageProvider = static_cast<QQuickImageProvider*>(imageProviderBase);

    QSize imageSize;
    QString imageId = caminhoImagem.path().remove(0, 1);
imagemEditada = imageProvider->requestImage(imageId, &imageSize, imageSize);

    if(imagemEditada.isNull())
    {
        qDebug() << "Loading image failed";
    }
    else
    {
        qDebug() << "Loading image OK";
    }
}

QString manipulaImagem::recortarFotoPerfil(const QString &imagem, QRect rectRecorte)
{
    this->alocaImagem(imagem, rectRecorte);

    QString a = "image://ProvedorImagens/imagemEditada";

    if(imagemEditada.isNull())
    {
        qDebug() << "Imagem is null";
    }
    else
    {
        qDebug() << "Imagem is loaded";
    }

    return a;
}

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.qml

ManipulaImagem {
    id: manipulaImagem
}
 
Camera {
            id: camera
 
            captureMode: Camera.CaptureStillImage
 
            imageCapture {
                onImageCaptured: {
                    previewImage.source = manipulaImagem.recortarFotoPerfil(preview, viewfinder.mapRectToSource(Qt.rect(viewfinder.x, viewfinder.y, viewfinder.width, viewfinder.height)));
                }
            }
        }
 
Rectangle {
    id: previewRectangle
 
    visible: false
 
    anchors.fill: parent
 
    Image {
        id: previewImage
 
        fillMode: Image.PreserveAspectFit
 
        anchors.top: parent.top
 
        width: parent.width
        height: parent.width
    }

ManipulaImagem {
    id: manipulaImagem
}

Camera {
            id: camera

            captureMode: Camera.CaptureStillImage

            imageCapture {
                onImageCaptured: {
                    previewImage.source = manipulaImagem.recortarFotoPerfil(preview, viewfinder.mapRectToSource(Qt.rect(viewfinder.x, viewfinder.y, viewfinder.width, viewfinder.height)));
                }
            }
        }

Rectangle {
    id: previewRectangle

    visible: false

    anchors.fill: parent

    Image {
        id: previewImage

        fillMode: Image.PreserveAspectFit

        anchors.top: parent.top

        width: parent.width
        height: parent.width
    }

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The output of this code is:

Loading image OK

Imagem is loaded

Request image: (image is null)

QML Image: Failed to get image from provider: image://provedorimagens/imagemEditada

What happens is that when I call the functions the image is not null, but when I try to return the QImage using the provider it cant return the image. I dont know why but for the image provider the image is null.

How could I solve that?

[anda_skoa]

Where did you register your image provider instance?
Maybe you create one instance in C++ and registered this one, instead of registering the instance you created in QML?

Cheers,
_

[guidupas]

Hello anda_skoa

That is right. I am targeting to the wrong pointer.

Thank you very much.