C++ de>index.row（）>=this->rowCount（）@MarekR，谢谢！我可以让Q_ASSERT_X在错误条件=（I>=0&&I

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de>index.row（）>=this->rowCount（）@MarekR，谢谢！我可以让Q_ASSERT_X在错误条件=（I>=0&&IASSERT failure in QList<T>::at: "index out of range", … QtCore/qlist.h, line 452 The program has unexpectedly finished.

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// Other Classes:
#include "datamodelcontroller.h"
#include "imageprovider.h"


int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QQmlApplicationEngine engine;

    // Initialize and register model:
    DataModelController model;
    QQmlContext *context = engine.rootContext();
    context->setContextProperty("DataModelFromContext", &model);

    // Register image provider for each "role" to the model:
    ImageProvider *imageProvider = new ImageProvider(&model);
    engine.addImageProvider(QLatin1String("provider"), imageProvider);

    // Get the main.qml path from a relative path:
    PathResolver pathObject("qml/DebugProject/main.qml");
    QString qmlPath = pathObject.pathResult;

    // Create Component:
    QQmlComponent *component = new QQmlComponent(&engine);
    component->loadUrl(QUrl(qmlPath));

    // Display Window:
    QObject *topLevel = component->create();
    QQuickWindow *window = qobject_cast<QQuickWindow*>(topLevel);
    QSurfaceFormat surfaceFormat = window->requestedFormat();
    window->setFormat(surfaceFormat);
    window->show();

    return app.exec();
}

class DataModelController : public QAbstractListModel
{
    Q_OBJECT
public:
    explicit DataModelController(QObject *parent = 0);

    enum DataRoles {
            FileNameRole = Qt::UserRole + 1,
            ImageRole
        };

        // QAbstractListModel:
        void addData(ImageData*& imageObj);
        int rowCount(const QModelIndex & parent = QModelIndex()) const;
        QVariant data(const QModelIndex & index, int role = Qt::DisplayRole) const;
        QHash<int, QByteArray> roleNames() const;

        // Get the Model Data:
        QList<ImageData*> getModelData();

signals:
    void imageSelectedStateChange(bool selectedImageStateValue);

public slots:
    void testLoadData();
    void removeData(int index);
    void setSelected(int index);
    bool isSelected(int index);
    void toggleSelected(int index);
    void deleteSelected();
    int count();

private:
    // Model Data here:
    QList<ImageData*> _modelData;

};

DataModelController::DataModelController(QObject *parent) : QAbstractListModel(parent)
{
}

void DataModelController::addData(ImageData*& imageObj) {
    beginInsertRows(QModelIndex(), rowCount(), rowCount());
    _modelData << imageObj; // for QList<>
    endInsertRows();
}

int DataModelController::rowCount(const QModelIndex &) const {
    return _modelData.size();
}

// Slot:
int DataModelController::count() {
    return this->rowCount();
}

QVariant DataModelController::data(const QModelIndex & index, int role) const
{
    if(!index.isValid())
        return QVariant();
    ImageData* imgObj = _modelData[index.row()];
    if (role == FileNameRole) {
        string imgFileName = imgObj->getFileName();
        QString fileName(imgFileName.c_str());
        return fileName;
    }
    if (role == ImageRole) {
        QString url = QString::number(index.row());
        return url;
    }
    return QVariant();
}

QHash<int, QByteArray> DataModelController::roleNames() const {
    QHash<int, QByteArray> roles;
    roles[FileNameRole] = "filename";
    roles[ImageRole] = "thumbnail";
    return roles;
}

QList<ImageData*> DataModelController::getModelData() {
    return _modelData;
}

void DataModelController::testLoadData()
{
    int width = 256, height = 256;
    for (int i = 0; i < 5; i++) {
        ostringstream digit;
        digit<<i;
        string imgPath("qml/DebugProject/TempImages/"+digit.str()+".jpg");
        PathResolver path(imgPath.c_str());
        QImage img(path.pathResult);

        // Initialize an Image Object:
        string fileName("file"+digit.str());
        ImageData *image = new ImageData(fileName);
        image->setData(NULL);
        image->nX = width;
        image->nY = height;
        image->setThumbnailQImage(img, width, height);
        image->setSelected(false);
        this->addData(image);
    }
}

void DataModelController::removeData(int index) {
    cout << "deleting index: " << index << endl;
    this->beginRemoveRows(QModelIndex(), index, index);
    _modelData.removeAt(index);
    // delete _modelData.takeAt(index); // tried this
    this->endRemoveRows();
    //this->beginResetModel();
    //this->endResetModel();
}

void DataModelController::setSelected(int index) {
    ImageData *imgObj = this->getModelData().at(index);
    if (!imgObj->getState()) {
        imgObj->setSelected(true);
        emit imageSelectedStateChange(imgObj->getState());
    }
}

bool DataModelController::isSelected(int index) {
    ImageData *imgObj = this->getModelData().at(index);
    return imgObj->getState();
}

void DataModelController::toggleSelected(int index) {
    ImageData *imgObj = this->getModelData().at(index);
    imgObj->setSelected(!imgObj->getState());
    emit imageSelectedStateChange(imgObj->getState());
}

void DataModelController::deleteSelected() {
    for (int i = this->rowCount()-1; i >= 0; i--) {
        if (this->isSelected(i)) {
            cout << i << ": state: " << this->isSelected(i) << endl;
            this->removeData(i);
            cout << this->rowCount();
        }
    }
}

class ImageData
{
public:
    ImageData();
    ImageData(string filename);

    long nX, nY; // image width, height

    void setFileName(string filename);
    string getFileName() const;

    void setSelected(bool state);
    bool getState() const;

    void setThumbnail(const int width, const int height);
    void setThumbnailQImage(QImage &imgStart, int width, int height);
    QImage getThumbnail() const;

    void setData(float* data);
    float* getData() const;


private:
    string _fileName;
    QImage _thumbnail;
    float* _data;
    bool _isSelected;

    void normalizeAndScaleData(float*& dataVector);
    void getMaxMinValues(float& datamax, float& datamin, float*& data, const int numPixels, bool verbose);
    unsigned char* getByteArrayFromFloatArray(int bytesPerRow, float*& dataVector);
};

import QtQuick 2.1
import QtQuick.Controls 1.0
import QtQuick.Window 2.1
import QtQuick.Controls.Styles 1.0
import QtQuick.Layouts 1.0

ApplicationWindow {
    id: mainAppWindow
    width: 1024*1.5*0.5
    height: 256
    color: "gray"
    property real imgScale: 0.5

    Window {
        id: gridViewMenu
        width: 160
        height: 128
        opacity: 0.8
        color: "black"
        visible: true
        x: 1024;
        Column {
            id: colButtons
            x: 10;
            y: 10;
            spacing: 25
            CustomButton {
                id: deleteSelectedButton; text: "Delete Selected"
                onClicked: {
                    DataModelFromContext.deleteSelected();
                }
            }
            CustomButton {
                id: testDataButton; text: "Load Test Images"
                visible: true
                onClicked: DataModelFromContext.testLoadData()
            }
        }
    }

    Rectangle {
        id: mainRect
        width: mainAppWindow.width*0.95
        height: mainAppWindow.height*0.8
        anchors.horizontalCenter: parent.horizontalCenter
        anchors.top: parent.top
        color: "transparent"

        // GRIDVIEW is here:
        Rectangle {
            id: gridContainer
            anchors.centerIn: parent
            width: parent.width
            height: parent.height*0.9
            color: "transparent"

            GridView {
                property int itemWidth: mainRect.width*imgScale;
                id: gridView
                interactive: true
                anchors.centerIn: parent
                width: parent.width;
                height: parent.height;
                cellWidth: itemWidth/3
                cellHeight: itemWidth/3
                focus: true
                model: DataModelFromContext
                delegate: gridDelegate
                Behavior on opacity {
                    NumberAnimation { duration: 500; easing.type: Easing.InOutQuad }
                }
                Keys.onPressed: {
                    if (event.key == Qt.Key_D) {
                        DataModelFromContext.deleteSelected()
                    }
                }
            } // end of gridView

            // GRIDVIEW Delegate:
            Component {
                id: gridDelegate
                Rectangle {
                    id: gridImageWrapper
                    width: gridView.cellWidth
                    height: gridView.cellHeight
                    color: "black"
                    Rectangle {
                        id: imageBorder
                        anchors.fill: parent
                        color: "transparent"
                        border.color: "green"
                        border.width: 1
                        z: 1
                    }
                    MouseArea {
                        id: selectImage
                        anchors.fill: parent
                        onClicked: {
                            // toggleSelected triggers the C++ signal: imageSelectedStateChange
                            DataModelFromContext.toggleSelected(index);
                            console.log(index + "; " + DataModelFromContext.count() )
                        }
                    }
                    Rectangle {
                        id: selectedImageBorder
                        anchors.fill: parent
                        color: "transparent"
                        border.color: "orange"
                        border.width: 2
                        opacity: 0
                        z: 2
                        Connections {
                            target: DataModelFromContext
                            onImageSelectedStateChange: {
                                selectedImageBorder.opacity = DataModelFromContext.isSelected(index);
                            }
                        }
                    }
                    Image {
                        property int itemWidth: mainRect.width*imgScale
                        id: frontIcon
                        anchors.centerIn: parent
                        source: "image://provider/" + thumbnail
                        smooth: true
                        visible: true
                        sourceSize.width: itemWidth/3;
                        sourceSize.height: itemWidth/3;
                    }

                } // end of Grid Delegate Rectangle

            } // end of Grid Delegate

        } // end of gridContainer Rectangle


    } // End: mainRect

} // End Main Application Window

#include "imagedata.h"

ImageData::ImageData()
{
}

ImageData::ImageData(string filename)
{
    _fileName = filename;
}

void ImageData::setFileName(string filename) {
    _fileName = filename;
}

string ImageData::getFileName() const {
    return _fileName;
}

void ImageData::setSelected(bool state) {
    _isSelected = state;
}

bool ImageData::getState() const {
    return _isSelected;
}

QImage ImageData::getThumbnail() const {
    return _thumbnail;
}

void ImageData::setThumbnailQImage(QImage &imgStart, int width, int height) {
    QImage img;
    //QImage *imgStart = new QImage(pix, nX, nY, bytesPerRow, QImage::Format_Indexed8);
    img = QPixmap::fromImage(imgStart).scaled(width, height, Qt::KeepAspectRatio).toImage();
    _thumbnail = img;
}

void ImageData::setData(float* data) {
    _data = data;
}

float* ImageData::getData() const {
    return _data;
}

// Function: getMaxMinValues
void ImageData::getMaxMinValues(float& datamax, float& datamin, float*& data, 
                                const int numPixels, bool verbose) {
    datamin  = 1.0E30;
    datamax  = -1.0E30;
    for (int pix = 0; pix < numPixels-1; pix++)  {
        if (data[pix] < datamin) {datamin = data[pix];}
        if (data[pix] > datamax) {datamax = data[pix];}
    }
    if (verbose) {
        std::cout << "Min and Max pixel values = " << datamin << "; " << datamax << std::endl;
    }
}


// Function: normalizeAndScaleData
void ImageData::normalizeAndScaleData(float*& dataVector)
{
    // ---- Find Max and Min Values:
    float datamin, datamax;

    this->getMaxMinValues(datamax, datamin, dataVector, nX*nY, false);

    // Get average and standard deviation:
    float avg = 0, sig = 0;
    for (int px = 0; px < nX*nY; px++) {
        avg += dataVector[px];
    }
    avg /= nX*nY;
    for (int px = 0; px<nX*nY; px++) {
        sig += powf(dataVector[px] - avg, 0.5);
        //sig += powf(dataVector[px] - avg, 2.0);
    }
    sig = pow(sig/(nX*nY), 0.5);
    int deviations = 5;
    if (datamin < avg-deviations*sig) {datamin = avg-deviations*sig;}
    if (datamax > avg+deviations*sig) {datamax = avg+deviations*sig;}

    // ---- ScaleImage Data Here (linear scaling):
    for (int px = 0; px<nX*nY; px++) {
        dataVector[px] = (dataVector[px]-datamin)/(datamax - datamin);
    }
}

unsigned char * ImageData::getByteArrayFromFloatArray(int bytesPerRow, float*& dataVector)
{
    unsigned char *pix = new unsigned char[nX*nY];
    for (int row = 0; row < nY; row++) {
        for (int col = 0; col < nX; col++)
            pix[row*bytesPerRow + col] = (unsigned char) 255*dataVector[row*nX + col];
    }
    return pix;
}

// Function: setThumbnail
void ImageData::setThumbnail(const int width, const int height) {
    QImage img;
    float *dataVector = this->getData();
    if (dataVector == NULL) {
        dataVector = new float[width*height];
    } else {
        normalizeAndScaleData(dataVector);
    }

    // Map to Byte Array (nX = cols of pixels in a row, nY = rows):
    int bytesPerPixel = 1; // = sizeof(unsigned char)
    int pixelsPerRow = nX;
    int bytesPerRow = bytesPerPixel*pixelsPerRow;
    unsigned char *pix = getByteArrayFromFloatArray(bytesPerRow, dataVector);

    // Calculate the Thumbnail Image:
    QImage *imgStart = new QImage(pix, nX, nY, bytesPerRow, QImage::Format_Indexed8);
    img = QPixmap::fromImage(*imgStart).scaled(width, height, Qt::KeepAspectRatio).toImage();

    _thumbnail = img;
}

QVariant DataModelController::data(const QModelIndex & index, int role) const
{
    cout << "model index = " << index.row() << endl; // add this to help troubleshoot
    if (!index.isValid() || index.row() > this->rowCount() || !this->modelContainsRow(index.row()) ) {
        return QVariant();
    }

Image {
    .
    .
    source: "image://provider/" + thumbnail
    .
    .
}

Image {
    .
    .
    source: "image://provider/" + index
    .
    .
}

bool ImageProvider::isValidIndex(DataModelController* model, int index) {
    int size = model->count();
    if (index >= size || index < 0)
        return false;
    return true;
}