QlineEdit重写，可以设置占位文本颜色等

#include "qtlineedit.h" #include <QPainter> #include <QDebug> QtLineEdit::QtLineEdit(QWidget *parent) : QLineEdit(parent) { m_pCursorBlinksTimer = new QTimer(this); m_pCursorBlinksTimer->setInterval(500); connect(m_pCursorBlinksTimer, &QTimer::timeout, [=] { m_bDrawCursor = !m_bDrawCursor; update(); }); m_pCursorBlinksTimer->start(); } void QtLineEdit::setPlaceholderTextColor(QColor color) { m_placeholderTextColor = color; } void QtLineEdit::setTextColor(QColor color) { m_textColor = color; } void QtLineEdit::setSelectColor(QColor color) { m_selectColor = color; } void QtLineEdit::paintEvent(QPaintEvent *event) { QPainter painter(this); QFont font = this->font(); int textHeight = font.pixelSize() == -1 ? 15 : font.pixelSize(); //绘制选择背景,背景得先画，文字才看得清 QFontMetrics fontMetric = painter.fontMetrics(); //获取字体宽度 if (this->hasSelectedText()) { //获取选中文本的起点 int selectStart = this->selectionStart(); int xPos = fontMetric.boundingRect(this->displayText().mid(0, selectStart)).width() + 1; //构建绘制矩形 QRect backRect; backRect.setX(xPos); backRect.setY((this->height() - textHeight- 1) / 2); backRect.setHeight(textHeight + 2); backRect.setWidth(fontMetric.width(this->displayText().mid(selectStart, this->selectedText().length()))); //绘制 painter.fillRect(backRect, QBrush(m_selectColor)); } //绘制光标 if (hasFocus() && m_bDrawCursor) { int cursorXPos = fontMetric.boundingRect(this->displayText().left(this->cursorPosition())).width() + 1; //修正光标位置大于整个LineEdit宽度的情况 if (cursorXPos > this->width()) { cursorXPos = this->width() - 2; } int cursorYPos = (this->height() - textHeight - 1) / 2; painter.setPen(QPen(Qt::black)); painter.drawLine(QPoint(cursorXPos, cursorYPos), QPoint(cursorXPos, cursorYPos + textHeight + 1)); } //绘制文本------------------------------ //构建绘制文本的矩形 QRect textRect; //这两个参数是为了修正光标位置和增加显示文本随光标移动和而移动的功能 int textXpos = 0, textWidth; if (!this->displayText().isEmpty()) { textWidth = fontMetric.boundingRect(this->displayText().left(this->cursorPosition())).width(); if (textWidth > this->width()) { textXpos = this->width() - textWidth - 1; } else { textWidth = this->width(); } } else { textXpos = 0; textWidth = this->width(); } textRect.setX(textXpos); textRect.setY((this->height() - textHeight) / 2); textRect.setWidth(textWidth); textRect.setHeight(textHeight); //根据要绘制的内容，设置文本和颜色 QString drawText = QString(""); if (!this->displayText().isEmpty()) { painter.setPen(QPen(m_textColor)); drawText = this->displayText(); } else if (!this->placeholderText().isEmpty()) { painter.setPen(QPen(m_placeholderTextColor)); drawText = this->placeholderText(); } //绘制 painter.drawText(textRect, Qt::AlignLeft | Qt::AlignVCenter, drawText); }