This question I have asked before and just got answer that there is an open bug for this. But this is a really required feature and, I guess, each Qt programmer who programmes a more or less serious application, it is quite probable that there is used a QTextEdit and the data is inserted in QTextEdit is serialized and deserialized. Thus I consider this issue very importand and it can be useful for many Qt developers. So I have decided to discuss with good programmers how to implement operator<<(QDataStream, QTextDocument). Otherwise we should wait when Qt guys will be kind to do that by themselves :).
So say in a QTextEdit I have some pictures and text. In different fragments the text has different format. How to get the content of this kind of QTextEdit and how to serialize, in order to show then as it was?
EDIT: I know that I can get the formated text and images by using documnet() method, which returns QTextDocument. I also know that QTextDocument has no operator<<(QDataStream, QTextDocument) and there is a request for writting this operator but it is still open. So please help me to write this method.
I guess I should inherit the QTextDocument class, then to add a new member (a container) that stores all the names of resources that are present in the QTextEdit. Then I should serialize all resources by iterating on them by using the container I have defined. Is it a good solution? If yes, then could you please help me to implement? If no then please provide me with a better idea.
You already asked this question in April:
Qt - serialize/deserialaize text and picture
The answers are still the same.
Wait for Qt to fix QTBUG-9258
Perform the serialization yourself
Depending on your needs a quick and dirty way to do it would be to get the HTML representation of the contents with QTextEdit::toHtml, then base64 encode it. I'm not sure how this will work with pictures.
Please don't repost the same questions.
See here:
How to serialize and deserialize rich text in QTextEdit?
Related
In Sublime Text, if you hold control while clicking, you can add another cursor to the document, allowing you to type and edit in multiple places at once. I'm trying to recreate this with Qt's QPlainTextEdit. The logic seems pretty simple...
On Ctrl+click, create and store a new cursor at location of the click
Draw all cursors
When any key events happen, make sure the other cursors also receive them
However, it seems that in order to do these things, I have to understand exactly how QPlainTextEdit works, and while I have a loose understanding, I find the source to be very dense and difficult to navigate.
While this feature is very important to me, I can't afford to spend a month on it. I don't know how to reasonably proceed. Is there some open source text editor built with Qt that has this feature? Can I in fact implement it without thoroughly understanding how QPlainTextEdit works? Is there some other solution I have not considered? I thought this would be trivial, or at the very least someone might have solved it before, but that doesn't appear to be the case. Any advice is appreciated.
Is there some open source text editor built with Qt that has this feature?
QtCreator is open-source (source code) and has partial multiple-cursor functionality. While it does not support Ctrl+Click to add a new cursor, you can do Shift+Alt+DownArrow to add a cursor to the following line (same column), like in SublimeText, and then insert text to all the lines at once.
It seems implemented in their class TextEditorWidget, which inherits QPlainTextEdit and reimplements plenty of its virtual methods. I don't exactly know how they implemented the multi-cursor functionality, but probably looking at the code of TextEditorWidget can give hints.
However, keep in mind that QtCreator does not have full multi-cursor functionality like in Sublime Text or CLion: the mutliple cursors are necessarily in the same column, and you cannot move the multiple cursors left/right. For example something I often do in Sublime is multiple selection at the beginning of lines, followed by Ctrl+RightArrow to jump all cursors "one word to the right". You cannot do that in QtCreator as of August 2020.
There is an open feature request for having true multiple-cursor functionality in QtCreator:
https://bugreports.qt.io/browse/QTCREATORBUG-16013
However, it seems that in order to do these things, I have to
understand exactly how QPlainTextEdit works, and while I have a loose
understanding, I find the source to be very dense and difficult to
navigate.
To some extent, but not a lot. Once you get the cursor positions, you know the positions in the document where text needs to be inserted. QTextEdit already supports multiple cursor positions:
https://doc.qt.io/qt-5/richtext-cursor.html
Rich text documents can have multiple cursors associated with them,
and each of these contains information about their position in the
document and any selections that they may hold. This cursor-based
paradigm makes common operations, such as cutting and pasting text,
simple to implement programmatically, yet it also allows more complex
editing operations to be performed on the document.
and
Multiple Cursors
Multiple cursors can be used to simultaneously edit the same document,
although only one will be visible to the user in a QTextEdit widget.
The QTextDocument ensures that each cursor writes text correctly and
does not interfere with any of the others.
Since this feature already exists, it may not be as difficult as thought to read the documentation and implement the feature.
As QPlainTextEdit is implemented by using most of the tech behind QTextEdit and QTextDocument, maybe it will meet your requirements.
Well, in my current project, the records are loaded from a database directly into QStandardItemModel and then view via QTreeView(). Everything works fine too. But I thought about the ram-memory. I think that the QStandardItemModel, including records, will be loaded into ram-memory. Similar to the data structure (for instance list), right? But what happens when I have large data sets? I read in Qt Documentation: Fetch More Example that I have to add items to the model in batches and preferably only when the items are needed by the view. It sounds good, but I have no idea how to do that. Does anyone of you know a few examples in python codes? Unfortunately, I do not understand the C ++ examples. Or does anyone know a better solution?
Don't get me wrong. I don't want a ready solution because I'm too lazy. No! I want to learn and work on it.
I have an application that has some sort of log viewer, that needs to be able to render formatted log records that are inserted to it in real time.
I am writing this in Qt and so far I was using QTextEdit for rendering of the text, which was beautified using some html tags and later inserted either with setHtml or insertHtml.
The problem is however, that these functions are insanely CPU intensive and run for ages, hanging whole application.
A similar question was asked here: QTextEdit.insertHtml() is very slow
Apart it has no really useful answer, other than stating it's really slow, it actually asks a different thing. I don't need to speed up setHtml or insertHtml. I am willing to use entirely different technique if possible.
Is there any mechanism within Qt that would allow for really fast insertions of text? Or maybe even completely different component than QTextEdit?
Is there any way to append new line to QTextEdit which contains rich text (generated in any way) that is really fast?
I also noticed QTextBrowser but it seems to be just an extension of TextEdit, could it be faster?
You should give QPlainTextEdit a try. It uses the same technology as QTextEdit but is a lot faster. It is optimized for plain text handling but do not let that fool you, it still has some basic support for formatting using HTML. You can append HTML formatted text with appendHtml().
In my application, I also need to display a large log of the task, approximately 3500 lines. Some lines of the log should be colored. For this, I used HTML formatting. QTextEdit.setHtml with this amount of text, freezed my GUI.
I replaced QTextEdit with QListWidget, in which QListWidgetItem is created for each line of the log.
It began to work much faster, without friezes.
And I saved colored text, just simple by using the QListWidgetItem.setForeground.
[This post][1]
[1]: Performantly appending (rich) text to QTextEdit or QTextBrowser in Qt contains an answer to this problem. The gist: instead of simply appending an HTML snippet, manipulate the underlying document directly.
However, I suggest that if your display really is a list of single lines, you create a QAbstractListModel QAbstractTableModel derived class instead and show it in an item view.
I have a set of complex C++ classes.
After creating objects of the class, all the data can be saved on disk.
I want to load two such saved instances and tell if they are identical.
Any ideas on how to do this in a way that is maintainable?
I've tried doing sorted text reports that print all the data and compare that. The problem is fields can get added to the classes over time and its not possible to tell if the report is "complete".
Any way introspection or reflection can be used to accomplish this?
this is a complex problem which those wonderful guys at boost.org have already solved for you:
http://www.boost.org/doc/libs/1_58_0/libs/serialization/doc/index.html
I am working with QT Creator. I have a form that contains a push button and an Line Edit. I would like to print a string that i give programatically in this LineEdit.Secondly I would also like to the from the LineBox a string that I fill in and print it using QMessageBox.
How to do it? Need some help. I don't know how to access the displayText() to write and read from a LineEdit.
I would like to specify that I put the push button and the lineedit on the Form using drag and drop.
I am working in c++ under Ubuntu
Appreciate.
You use QLineEdit::setText() to change the text and QLineEdit::text() to read.
Your questions are very basic and show a clear lack of studying the documentation and experimenting thing yourself. Qt is one of the better documented frameworks out there and with lots of examples. Please take your time to go through them.