How to display Arabic notations in left-to-right direction in QLineEdit/QLabel etc.?

Question

In Qt's implementation arabic notation is shown in right-to-left direction, thus any strings that contain arabic notations will be right-aligned.

But what my application wants to do is showing all texts in left-to-right direction, whether it contains arabic notations or not. And all texts are left-aligned.

An example is shown below:

• This is what I want to implement

  

• This is how QLineEdit displays texts containing arabic notations in its default way

  

• This is how QLabel does it

  

EDIT:

Paste the test string here. ە抠门哥ە(

EDIT:

Providing an alternate solution.

Finally I can achieve my goal roughly by using QTextEdit which has a QTextDocument. The following code snippet shows how I did it. But I have no idea how Qt deals with text direction from a global perspective, so I can't achieve my goal with QLabel etc... It would be great if someone can give some detailed information about Qt's text engine.

QTextDocument *doc = ui->textEdit->document();
QTextOption textOption = doc->defaultTextOption();
textOption.setTextDirection(Qt::LeftToRight);
doc->setDefaultTextOption(textOption);
ui->textEdit->setDocument(doc);

Answer 1

Unicode provides Directional Formatting Characters,and Qt supports it well.

Thus,for QLabel and QLineEdit etc. we can insert a LRM control character
,which is define in Unicode Bidirectional Algorithm, at the beginning of a RightToLeft string to make the string left-alignment.For more information about Unicode Bidirectional Algorithm,click here.

QString(QChar(0x200E))+strText;

And for QTextEdit etc. which has a QTextDocument we can make RightToLeft string left-alignment by setting QTextDocment's textDirection to Qt::LeftToRight.

ps:
QString has a isRightToLeft member function to decide whether the string is RightToLeft or not. For example,a string that begins with a notation from Right-to-left writting language is RightToLeft.

I answered another one,which maybe helpful for finding your own solution.

Answer 2

In Qt documentation about setLayoutDirection you can read :

This method no longer affects text layout direction since Qt 4.7.

So you can not use this method. For QLineEdit you can send a Qt::Key_Direction_L keyboard event to the line edit to make it left to right event if the characters are Arabic or Persian :

QKeyEvent event(QEvent::KeyPress, Qt::Key_Direction_L, 0);
qApp->sendEvent(ui->lineEdit, &event);