QML:GridView 在 C++ 中更改其模型后不更新 [英] QML: GridView does not update after change its model in C++

问题描述

我的出发点是以下 QML 源代码，其中 GridView 显示 ListModel 并带有漂亮的项目交换动画:

My starting point is the following QML source, where GridView is showing ListModel with nice animation of item swaps:

import QtQuick 1.1
GridView {
    id: mainGrid
    width: 825; height: 400; cellWidth: 165; cellHeight: 95
    model: myModel
    delegate: myButton
    ListModel {
        id: myModel
        function createModel() {
            for (var i=1; i<=20; i++) {
                append({"display":i})
            }
        }
        function listItems() {
            console.log("LIST OF ITEMS")
            for (var i=0; i<=19; i++) {
                console.log("model["+i+"]="+get(i).display)
            }
        }
        function moveItem(inx1,inx2) {
            move(inx1,inx2,1)
        }
        Component.onCompleted: {
            createModel()
            listItems()
        }
    }
    Component {
        id: myButton
        Item {
            id: item
            width: 160; height: 90
            Rectangle {
                id: box
                parent: mainGrid
                x: item.x; y: item.y; width: item.width; height: item.height; border.width: 1
                Behavior on x {NumberAnimation { duration: 1000;} }
                Behavior on y {NumberAnimation { duration: 1000;} }
                Text {
                    anchors.centerIn: parent
                    text: display
                }
                MouseArea {
                    anchors.fill: parent
                    onClicked: {
                        mainGrid.model.moveItem(index,0)
                        mainGrid.model.listItems()
                    }
                }
            }
        }
    }
}

我想使用从 QStandardItemModel 派生的 C++ 模型，而不是 QML ListModel:

Instead of QML ListModel I want to use a C++ model which is derived from QStandardItemModel:

#include <QStandardItemModel>
class MyTable : public QStandardItemModel
{
private:
    Q_OBJECT
    int table[20];
public:
    explicit MyTable(QObject *parent = 0) : QStandardItemModel(parent) {}
    Q_INVOKABLE void createModel();
    Q_INVOKABLE void moveItem(int inx1, int inx2);
};

这个模型通过 qmlRegisterType<MyTable,1>("MyTable",1,0,"MyTable") 暴露给 QML.问题是，我没有得到很好的动画效果，我也不确定交换后模型是否正确更新.

This model is exposed to QML via qmlRegisterType<MyTable,1>("MyTable",1,0,"MyTable"). The problem is, that I do not get the nice animation effect and I am also not sure if after the swap the model is correctly updated.

相关的(有问题的)C++ 函数在这里:

The related (problematic) C++ functions are here:

void MyTable::createModel()
{
    for (unsigned int i=0; i<20; i++) {
        table[i]=i;
        QStandardItem* item = new QStandardItem(QString("%1").arg(table[i]));
        appendRow(item);
    }
}

void MyTable::moveItem(int inx1, int inx2) {
    //SOME MATH, IT WORKS
    int tmp = table[inx1];
    if (inx1<inx2) {
        for (int i=inx1; i<inx2; i++) table[i] = table[i+1];
        table[inx2] = tmp;
    } else if (inx2<inx1) {
        for (int i=inx1; i>inx2; i--) table[i] = table[i-1];
        table[inx2] = tmp;
    }
    //UPDATE MODEL - IS SOMETHING MISSING HERE?
    for (unsigned int i=0; i<20; i++) {
        QStandardItem* item = new QStandardItem(QString("%1").arg(table[i]));
        setItem(i,0,item);
    }
}

推荐答案

我找到了解决方案.这是工作代码(感谢 Borut123 的建议).

I found the solution. Here is the working code (thanks Borut123 for suggestions).

class MyTable : public QStandardItemModel
{
private:
    Q_OBJECT
public:
    explicit MyTable(QObject *parent = 0) : QStandardItemModel(parent) {}
    Q_INVOKABLE void createModel();
    Q_INVOKABLE void moveItem(int inx1, int inx2);
    Q_INVOKABLE void listItems();
};

void MyTable::createModel()
{
    for (unsigned int i=0; i<20; i++) {
        QStandardItem* item = new QStandardItem(QString("%1").arg(i));
        appendRow(item);
    }
}

void MyTable::moveItem(int inx1, int inx2) {
    bool ok = false;
    if (inx1 < inx2) ok = beginMoveRows(QModelIndex(),inx1,inx1,QModelIndex(),inx2+1);
    if (inx1 > inx2) ok = beginMoveRows(QModelIndex(),inx1,inx1,QModelIndex(),inx2);
    if (!ok) return;
    QStandardItem* tmp1 = takeItem(inx1);
    if (inx1<inx2) {
        for (int i=inx1; i<inx2; i++) {
            QStandardItem* tmp2 = takeItem(i+1);
            setItem(i,tmp2);
        }
    } else if (inx2<inx1) {
        for (int i=inx1; i>inx2; i--) {
            QStandardItem* tmp2 = takeItem(i-1);
            setItem(i,tmp2);
        }
    }
    setItem(inx2,tmp1);
    endMoveRows();
}

void MyTable::listItems() {
    qDebug() << "LIST OF ITEMS";
    for (unsigned int i=0; i<20; i++) {
        qDebug() << QString("table[%1]=%2").arg(i).arg(item(i)->text()).toAscii().data();
    }
}

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