如何更改 QLineEdit 中部分文本的颜色？

Question

我想为 QLineEdit 中编写的文本添加一些语法突出显示，但它不支持富文本格式，我无法将 QlineEdit 更改为其他内容，所以我应该找到如何在此小部件中设置文本颜色。

有没有办法做到这一点？

Answer 1

刚刚找到了一个巧妙的技巧。

static void setLineEditTextFormat(QLineEdit* lineEdit, const QList<QTextLayout::FormatRange>& formats)
{
    if(!lineEdit)
        return;

    QList<QInputMethodEvent::Attribute> attributes;
    foreach(const QTextLayout::FormatRange& fr, formats)
    {
        QInputMethodEvent::AttributeType type = QInputMethodEvent::TextFormat;
        int start = fr.start - lineEdit->cursorPosition();
        int length = fr.length;
        QVariant value = fr.format;
        attributes.append(QInputMethodEvent::Attribute(type, start, length, value));
    }
    QInputMethodEvent event(QString(), attributes);
    QCoreApplication::sendEvent(lineEdit, &event);
}

static void clearLineEditTextFormat(QLineEdit* lineEdit)
{
    setLineEditTextFormat(lineEdit, QList<QTextLayout::FormatRange>());
}

// Usage example:
QLineEdit* lineEdit = new QLineEdit;
lineEdit->setText(tr("Task Tracker - Entry"));

QList<QTextLayout::FormatRange> formats;

QTextCharFormat f;

f.setFontWeight(QFont::Bold);
QTextLayout::FormatRange fr_task;
fr_task.start = 0;
fr_task.length = 4;
fr_task.format = f;

f.setFontItalic(true);
f.setBackground(Qt::darkYellow);
f.setForeground(Qt::white);
QTextLayout::FormatRange fr_tracker;
fr_tracker.start = 5;
fr_tracker.length = 7;
fr_tracker.format = f;

formats.append(fr_task);
formats.append(fr_tracker);

setLineEditTextFormat(lineEdit, formats);

Answer 2

您可以使用style sheets更改颜色。

 QLineEdit* myLineEdit = new QLineEdit("Whatever");

 //for whatever case you want to change the color
 if(syntax_needs_to_highlighted)
      myLineEdit->setStyleSheet("QLineEdit#myLineEdit{color:blue}"); 

对于这种情况，您可能需要考虑使用QTextBrowser。

Answer 3

您可以像这样更改文本的颜色：

QLineEdit *line = new QLineEdit();
line->setText("this is a test");
line->setStyleSheet("foreground-color: blue;");

如果不起作用，请将最后一行替换为以下内容：

line->setStyleSheet("color: blue;");

Answer 4

我可以通过在QLineEdit 上覆盖QLabel 然后将行的文本颜色编辑为白色来实现此目的。当textEdited 信号发出时，使用它来更新QLabel 的文本。 QLabel 接受富文本，因此您可以处理 QLineEdit 中的文本，并将关键字替换为所需的 HTML，以便以您想要的方式显示文本。我相信您可以修改代码以更改当前选择的文本颜色。

class LabelEditPair(QLineEdit):
    """
    QLineEdit that changes the color of the word 'blue' to blue and
    the changes the font weight of the word 'bold' to bold.
    """
    def __init__(self):
        super().__init__()

        self.label = QLabel("starting out")
        self.label.setParent(self)
        self.label.move(3, 0)
        self.label.setAttribute(Qt.WA_TransparentForMouseEvents)
        self.setStyleSheet("QLineEdit{color: white}")

        self.textEdited.connect(self.text_edited)

    def resizeEvent(self, event):
        self.label.setFixedHeight(self.height())
        self.label.setFixedWidth(self.width())
        super().resizeEvent(event)

    def text_edited(self, text):
        text = text.replace("blue", "<span style='color: blue'>blue</span>")
        text = text.replace("bold", "<span style='font-weight: bold'>bold</span>")
        self.label.setText(text)

编辑

上一个示例在文本从QLineEdit 小部件溢出的情况下效果不佳。这是一个更全面的小部件，它使用相同的想法，但不是创建QLineEdit 的子类，而是使用QLineEdit 和两个QLabels 的子类QFrame，一个在光标之前，一个在光标之后。该小部件将正则表达式匹配替换为 HTML 以更改这些字符的样式。

class LabelEditPair(QFrame):
    """
    QLineEdit that changes the color of the word 'blue' to blue and
    the changes the font weight of the word 'bold' to bold.
    """
    def __init__(self, initial_text: str):
        super().__init__()

        self.stylized_regex: List[Tuple[str, str]] = []

        self.setFixedHeight(22)
        self.setObjectName("frame")
        self.setStyleSheet("QFrame#frame{background-color: white; border: 1px solid gray}"
                           "QFrame:hover#frame{border: 1px solid black}"
                           "QFrame:selected#frame{border: 1px solid blue}")
        self.setFrameStyle(QFrame.Box)
        self.line_edit = QLineEdit(initial_text)
        self.line_edit.setParent(self)
        self.line_edit.move(0, 2)
        self.line_edit.setStyleSheet("border: 0px solid white; background-color:transparent")

        self.line_edit.setFixedWidth(2**16)

        self.left_label = QLabel()
        self.left_label.setParent(self.line_edit)
        self.left_label.move(1, 1)
        self.left_label.setAlignment(Qt.AlignRight)
        self.left_label.setAttribute(Qt.WA_TransparentForMouseEvents)

        self.right_label = QLabel()
        self.right_label. setParent(self.line_edit)
        self.right_label.move(5, 1)
        self.right_label.setAlignment(Qt.AlignLeft)
        self.right_label.setAttribute(Qt.WA_TransparentForMouseEvents)
        self.right_label.setFixedWidth(2**16)
        self.offset = 0

        self.line_edit.textEdited.connect(self.text_edited)
        self.line_edit.cursorPositionChanged.connect(self.apply_shift)
        self.line_edit.selectionChanged.connect(self.set_text_to_update)
        self.update_text_needed = True

        self.placeholder = ""
        self.color = (0, 0, 0)

    def text(self):
        return self.line_edit.text()

    def setReadOnly(self, read_only: bool):
        self.line_edit.setReadOnly(read_only)
        self.line_edit.setAttribute(Qt.WA_TransparentForMouseEvents, read_only)
        self.line_edit.end(False)

    def set_placeholder_text(self, text: str):
        self.placeholder = text

    def set_text_color(self, color: Tuple[int, int, int]):
        self.color = color

    def set_text_to_update(self):
        self.update_text_needed = True

    def text_edited(self, text: str):
        if len(text) == 0:
            self.left_label.setText(self.placeholder)
            self.left_label.setStyleSheet("color: gray")
            return
        self.left_label.setStyleSheet(f"color: rbg{self.color}")
        new = self.line_edit.cursorPosition()
        left_text = text[:new]
        right_text = text[new:]
        self.left_label.setText(left_text)
        self.right_label.setText(right_text)
        for style, regex in self.stylized_regex:
            matches = findall(regex, left_text)
            for match in matches:
                left_text = left_text.replace(match, f"<span style='{style}'>{match}</span>")
                self.left_label.setText(left_text)
            matches_right = findall(regex, right_text)
            for match in matches_right:
                right_text = right_text.replace(match, f"<span style='{style}'>{match}</span>")
                self.right_label.setText(right_text)
        self.update_text_needed = False

    def add_style_for_regex(self, style: str, regex: str):
        self.stylized_regex.append((style, regex))

    def apply_shift(self, old=None, new=None):
        text = self.line_edit.text()
        rect = self.line_edit.cursorRect()
        x_pos = rect.x()
        if x_pos + self.offset > self.width() - 8 and new == old + 1:
            self.offset = -1*(x_pos - (self.width()-8))
        elif new + 1 == old and x_pos + self.offset < self.width() * 1/2:
            self.offset += 5
        self.offset = min(0, self.offset)
        if len(text) == 0:
            self.offset = 0
        self.line_edit.move(self.offset, 2)
        self.left_label.setFixedWidth(x_pos + 4)
        self.right_label.move(x_pos + 5, 1)
        if self.update_text_needed:
            self.text_edited(text=text)
        self.update_text_needed = True

示例用法

self.color_edit = LabelEditPair("")
self.color_edit.add_style_for_regex("color: blue", "(?:HI|HELLO)")
main_layout.addWidget(self.color_edit)