Beyond insertList(): Alternative Approaches for Qt List Creation

Purpose

• Converts that block into the first item of a newly created list with the specified format.
• Inserts a new empty block at the current cursor position.

Functionality

1. • The function first calls insertBlock() to create an empty text block at the cursor's location. This block serves as the foundation for the list item.

2. List Creation and Formatting
   

   • createList() is then invoked, either with a QTextListFormat object or a QTextListFormat::Style argument.
   • The QTextListFormat allows you to define various list properties, such as indentation level, bullet or numbering style, and spacing.
   • The QTextListFormat::Style provides a simpler way to specify the basic list type (e.g., bullets, numbers).

3. List Association
   

   • The newly created list is associated with the empty block inserted earlier. This transforms the block into the first item in the list.

Return Value

• The function returns a pointer to the newly created QTextList object. This allows for further manipulation of the list's properties after insertion (if needed).

Example

#include <QGuiApplication>
#include <QTextEdit>

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    QTextEdit textEdit;

    QTextCursor cursor = textEdit.textCursor();
    cursor.insertList(QTextListFormat::ListDisc); // Insert a bulleted list

    textEdit.setText("This is the first list item.\n");

    textEdit.show();

    return app.exec();
}

In this example:

1. A QTextEdit widget is created.
2. A QTextCursor object is obtained, representing the current editing position.
3. insertList(QTextListFormat::ListDisc) is called to insert a new bulleted list at the cursor's location.
4. Text is added to the list using textEdit.setText().

Key Points

• Access and modify existing lists using QTextCursor::currentList().
• Use QTextListFormat for more granular control over list appearance.
• QTextCursor::insertList() doesn't directly add existing text to a list. It creates a new list and makes the empty block at the cursor the first item.

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Inserting a Numbered List with Custom Style

#include <QGuiApplication>
#include <QTextEdit>

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    QTextEdit textEdit;

    QTextCursor cursor = textEdit.textCursor();

    // Create a custom list format with numbering starting from 3
    QTextListFormat listFormat;
    listFormat.setStyle(QTextListFormat::NumberedList);
    listFormat.setNumberPropertyName("list-style-type"); // Use CSS-style numbering
    listFormat.setProperty("list-style-position", "inside"); // Numbers inside list items
    listFormat.setProperty("counter-reset", "2"); // Start numbering from 3

    cursor.insertList(listFormat);

    textEdit.setText("This is the first numbered item.\nAnother numbered item.");

    textEdit.show();

    return app.exec();
}

This example:

• Starts numbering from 3 by resetting the counter (counter-reset: 2).
• Positions numbers inside list items (list-style-position: inside).
• Uses CSS-style numbering (list-style-type) for a more modern look.
• Sets the numbering style to numbered (QTextListFormat::NumberedList).
• Creates a custom QTextListFormat with specific numbering properties.

Nesting Lists and Indentation Control

#include <QGuiApplication>
#include <QTextEdit>

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    QTextEdit textEdit;

    QTextCursor cursor = textEdit.textCursor();

    // Insert a bulleted list
    cursor.insertList(QTextListFormat::ListDisc);
    textEdit.setText("This is the top-level item.\n");

    // Move the cursor one position down (to the next line)
    cursor.movePosition(QTextCursor::Down, QTextCursor::LineBoundary, 1);

    // Create a nested numbered list with increased indentation
    QTextListFormat nestedListFormat;
    nestedListFormat.setStyle(QTextListFormat::NumberedList);
    nestedListFormat.setIndent(20); // Indent nested list by 20 pixels

    cursor.createList(nestedListFormat);

    textEdit.setText("This is a nested numbered item.\nAnother nested item.");

    textEdit.show();

    return app.exec();
}

This example demonstrates nesting lists:

• Creates the nested list using createList().
• Defines a nested numbered list format with indentation.
• Moves the cursor down to the next line for nested content.
• Creates a top-level bulleted list.

Modifying Existing Lists

#include <QGuiApplication>
#include <QTextEdit>

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    QTextEdit textEdit;

    textEdit.setText("This is plain text.\n");

    QTextCursor cursor = textEdit.textCursor();
    cursor.movePosition(QTextCursor::Down, QTextCursor::LineBoundary, 1);

    // Insert a bulleted list at the current position
    cursor.insertList(QTextListFormat::ListDisc);

    textEdit.setText("This becomes the first bulleted item.\n");

    // Move the cursor to the beginning of the list
    cursor.movePosition(QTextCursor::StartOfLine);
    cursor.movePosition(QTextCursor::Up, QTextCursor::LineBoundary, 1);

    // Check if the cursor is currently inside a list
    if (cursor.currentList()) {
        // Change the list style to numbered
        cursor.currentList()->setStyle(QTextListFormat::NumberedList);
    }

    textEdit.show();

    return app.exec();
}

This example shows how to modify an existing list:

• If a list exists, changes its style to numbered.
• Moves the cursor to the beginning of the list.
• Inserts a bulleted list after some plain text.

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Using HTML Formatting

• Example:
• This approach offers flexibility in styling and customization through CSS.
• If you're working with rich text and have control over the input, consider using HTML tags to define lists.

<ul> <li>Item 1</li>
  <li>Item 2</li>
</ul>
<ol> <li>Item 3</li>
  <li>Item 4</li>
</ol>

• Set this HTML content as the text of your QTextEdit widget.

Manual Formatting and Indentation

• Example:
• Adjust indentation using whitespace or tab characters.
• Use prepended characters like "-" or numbers for bullets or numbering.
• Create separate paragraphs for each list item.
• For basic lists, you can programmatically insert text and control indentation levels.

QString item1 = "- Item 1\n";
QString item2 = "  - Sub-item 1\n"; // Indented for sub-item

textEdit.insertPlainText(item1 + item2);

Third-Party Libraries

• These libraries might offer more efficient or user-friendly ways to create and manage lists.

• Consider using third-party libraries if they offer functionalities beyond what QTextCursor::insertList() provides.
• For simpler lists, manual formatting might suffice.
• If HTML formatting is already part of your workflow, using HTML tags provides flexibility.
• If you need control over list formatting and behavior, QTextCursor::insertList() remains a viable option.