从 qml 中的 .txt 或 .csv 文件中读取一行(Qt Quick) [英] Reading a line from a .txt or .csv file in qml (Qt Quick)
问题描述
我需要在模拟屏幕上显示一个字符串.为此,我应该从现有的 Filename.txt/Filename.csv 文件中读取文本.文本参数更新,如下面的代码所示.我需要从文本文件访问字符串并在 MarqueeText 元素中使用它.Accessed 字符串应用于 MarqueeText 元素的 text 字段.
I need to display a string on a simulation screen. For that I'm supposed to read the text from an existing Filename.txt/Filename.csv file. The text parameter is updated as shown in the below piece of code. I need to access the string from a text file and use it in MarqueeText element. The Accessed string shall be used in the text field of the MarqueeText element.
MarqueeText {
id:scrolltext
width: 255
height: 48
anchors.verticalCenter: parent.horizontalCenter
text: //i need to access the string in text file to be displayed
}
请帮我解决这个问题.谢谢.
Please help me with this. Thank you.
推荐答案
按照 wiki 页面阅读有关在 QML 中访问文件的信息.诺基亚维基论坛 http://web.archive.org/web/20150227025348/http://developer.nokia.com/community/wiki/Reading_and_writing_files_in_QML
Follow the wiki page to read about accessing files in QML. Nokia Wiki Forum http://web.archive.org/web/20150227025348/http://developer.nokia.com/community/wiki/Reading_and_writing_files_in_QML
总结:
创建自定义 QML 类型 FileIO:
Create a custom QML type, FileIO:
fileio.h
#ifndef FILEIO_H
#define FILEIO_H
#include <QObject>
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 read();
Q_INVOKABLE bool write(const QString& data);
QString source() { return mSource; };
public slots:
void setSource(const QString& source) { mSource = source; };
signals:
void sourceChanged(const QString& source);
void error(const QString& msg);
private:
QString mSource;
};
#endif // FILEIO_H
fileio.cpp
#include "fileio.h"
#include <QFile>
#include <QTextStream>
FileIO::FileIO(QObject *parent) :
QObject(parent)
{
}
QString FileIO::read()
{
if (mSource.isEmpty()){
emit error("source is empty");
return QString();
}
QFile file(mSource);
QString fileContent;
if ( file.open(QIODevice::ReadOnly) ) {
QString line;
QTextStream t( &file );
do {
line = t.readLine();
fileContent += line;
} while (!line.isNull());
file.close();
} else {
emit error("Unable to open the file");
return QString();
}
return fileContent;
}
bool FileIO::write(const QString& data)
{
if (mSource.isEmpty())
return false;
QFile file(mSource);
if (!file.open(QFile::WriteOnly | QFile::Truncate))
return false;
QTextStream out(&file);
out << data;
file.close();
return true;
}
注册新的 QML 类型:
#include "fileio.h"
Q_DECL_EXPORT int main(int argc, char *argv[])
{
...
qmlRegisterType<FileIO, 1>("FileIO", 1, 0, "FileIO");
...
}
实际 QML 使用:
import QtQuick 1.1
import FileIO 1.0
Rectangle {
width: 360
height: 360
Text {
id: myText
text: "Hello World"
anchors.centerIn: parent
}
FileIO {
id: myFile
source: "my_file.txt"
onError: console.log(msg)
}
Component.onCompleted: {
console.log( "WRITE"+ myFile.write("TEST"));
myText.text = myFile.read();
}
}
这篇关于从 qml 中的 .txt 或 .csv 文件中读取一行(Qt Quick)的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!