Exploring Alternatives to QTextFrameFormat::border() in Qt

Purpose

• Text frames group blocks of text, providing a way to structure content beyond paragraphs.
• In Qt, QTextFrameFormat::border() is a function used to retrieve the width (thickness) of the border surrounding a text frame within a QTextDocument.

Functionality

• Positive values specify the desired border thickness.
• A value of 0 indicates no border.
• It returns a qreal value representing the border width in pixels.

Usage

1. #include <QtGui>
   

2. Create a QTextFrameFormat object
   

   QTextFrameFormat frameFormat;
   

3. Set the border width (optional)
   

   • Use frameFormat.setBorder(borderWidth) to define the border width.

   frameFormat.setBorder(5); // Sets a 5-pixel wide border
   

4. Get the current border width (if not previously set)
   

   qreal currentBorderWidth = frameFormat.border();
   

Example

#include <QApplication>
#include <QTextEdit>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QTextEdit textEdit;

    // Create a text frame format with a 3-pixel wide solid border
    QTextFrameFormat frameFormat;
    frameFormat.setBorder(3);
    frameFormat.setBorderStyle(QTextFrameFormat::BorderStyle::Solid);

    // Apply the format to a specific text range
    QTextCursor cursor = textEdit.textCursor();
    cursor.movePosition(QTextCursor::StartOfLine);
    cursor.movePosition(QTextCursor::EndOfLine, QTextCursor::KeepAnchor);
    textEdit.setCurrentCursor(cursor);
    textEdit.textCursor().setBlockFormat(frameFormat);

    textEdit.show();

    return app.exec();
}

In this example, the first line of text in the QTextEdit will have a 3-pixel solid border.

Additional Considerations

• To customize the border appearance further, use frameFormat.setBorderBrush() and frameFormat.setBorderStyle().
  • setBorderBrush() sets the color or pattern of the border.
  • setBorderStyle() specifies the style (e.g., solid, dashed, dotted).

---

Setting Border Color

#include <QApplication>
#include <QTextEdit>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QTextEdit textEdit;

    // Create a text frame format with a blue solid border
    QTextFrameFormat frameFormat;
    frameFormat.setBorder(3); // 3-pixel width
    frameFormat.setBorderStyle(QTextFrameFormat::BorderStyle::Solid);
    frameFormat.setBorderBrush(Qt::blue); // Set border color to blue

    // Apply the format to a specific text range
    QTextCursor cursor = textEdit.textCursor();
    cursor.movePosition(QTextCursor::StartOfLine);
    cursor.movePosition(QTextCursor::EndOfLine, QTextCursor::KeepAnchor);
    textEdit.setCurrentCursor(cursor);
    textEdit.textCursor().setBlockFormat(frameFormat);

    textEdit.show();

    return app.exec();
}

Setting Border Style (Dashed)

#include <QApplication>
#include <QTextEdit>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QTextEdit textEdit;

    // Create a text frame format with a dashed border (default color is black)
    QTextFrameFormat frameFormat;
    frameFormat.setBorder(2); // 2-pixel width
    frameFormat.setBorderStyle(QTextFrameFormat::BorderStyle::Dashed);

    // Apply the format to a paragraph
    QTextCursor cursor = textEdit.textCursor();
    cursor.movePosition(QTextCursor::StartOfBlock, QTextCursor::MoveAnchor);
    cursor.movePosition(QTextCursor::EndOfBlock, QTextCursor::KeepAnchor);
    textEdit.setCurrentCursor(cursor);
    textEdit.textCursor().setBlockFormat(frameFormat);

    textEdit.show();

    return app.exec();
}

#include <QApplication>
#include <QTextEdit>
#include <QDebug>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QTextEdit textEdit;
    textEdit.setPlainText("This is some text.");

    // Get the current text frame format for the first line
    QTextCursor cursor = textEdit.textCursor();
    cursor.movePosition(QTextCursor::StartOfLine);
    QTextFrameFormat frameFormat = cursor.blockFormat();

    // Check border width and style (assuming you haven't set them previously)
    qreal currentBorderWidth = frameFormat.border();
    QTextFrameFormat::BorderStyle borderStyle = frameFormat.borderStyle();

    qDebug() << "Current border width:" << currentBorderWidth;
    qDebug() << "Current border style:";
    if (borderStyle == QTextFrameFormat::BorderStyle::Solid) {
        qDebug() << "Solid";
    } else if (borderStyle == QTextFrameFormat::BorderStyle::Dashed) {
        qDebug() << "Dashed";
    } else {
        qDebug() << "No border or other style";
    }

    textEdit.show();

    return app.exec();
}

---

Using Qt Style Sheets

• This approach can be more efficient for managing styles across multiple widgets.
• You can define border properties for a text frame using properties like border, border-width, border-style, and border-color.
• Style sheets offer a declarative way to style Qt widgets, including text frames.

Example

QTextFrame {
  border: 2px solid blue;
  /* Adjust border properties as needed */
}

Custom Painting with QPainter

• Within paint(), use QPainter methods to draw the desired border around the text frame content.
• Override the paint() event of your custom widget that displays the text frame.
• If you require more granular control over the border appearance or interactivity, you can implement custom painting using the QPainter class.

void YourWidget::paintEvent(QPaintEvent *event) {
  QPainter painter(this);
  // ... (your drawing code for the text frame)

  // Draw border using QPainter methods
  painter.setPen(QPen(Qt::blue, 2, Qt::SolidLine));
  painter.drawRect(textFrameRect); // Replace with your text frame geometry
}

• For highly customized border appearance or interactivity, explore custom painting with QPainter.
• If you need consistent styling across multiple widgets, consider Qt Style Sheets.
• Use QTextFrameFormat::border() for simple border styles applied to text frames.