QLabel设置图像的方法+绘制文本换行显示

1、QLabel设置图像有两种方法

(1) void setPicture(const QPicture &);

(2) void setPixmap(const QPixmap &);

QPicture和QPixmap都是继承于QPaintDevice，它们都可以通过加载图片的方式获取：bool load(QIODevice *dev, const char *format = nullptr)，也可以通过QPainter上绘制。

2、QPainter绘制文本换行显示

void drawText(const QRect &r, int flags, const QString &text, QRect *br = nullptr)

在设置第二个参数flags时，使用Qt::TextWrapAnywhere 即可使文本换行显示。

3、核心代码

(1) LabelEx.h

#ifndef LABELEX_H
#define LABELEX_H#include <QLabel>const QString kText = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";class LabelEx : public QLabel
{Q_OBJECT
public:explicit LabelEx(QWidget *parent = nullptr);~LabelEx();protected:void paintEvent(QPaintEvent *event) Q_DECL_OVERRIDE;
};#endif // LABELEX_H

(2) LabelEx.cpp

#include "LabelEx.h"
#include <qpainter.h>LabelEx::LabelEx(QWidget *parent) : QLabel(parent)
{
}LabelEx::~LabelEx()
{
}void LabelEx::paintEvent(QPaintEvent *event)
{Q_UNUSED(event);QPainter painter(this);painter.setRenderHint(QPainter::TextAntialiasing);painter.fillRect(rect(), QColor(255, 160, 160));painter.drawText(rect(), Qt::AlignLeft |Qt::AlignTop |Qt::TextWrapAnywhere, kText);
}

(3) LabelTestDlg.h

#ifndef LABELTESTDLG_H
#define LABELTESTDLG_H#include <QDialog>
#include "LabelEx.h"class LabelTestDlg : public QDialog
{Q_OBJECT    
public:LabelTestDlg(QWidget *parent = nullptr);~LabelTestDlg();private:void init();private:QLabel  *m_lb1 = nullptr;QLabel  *m_lb2 = nullptr;LabelEx *m_lb3 = nullptr;
};
#endif // LABELTESTDLG_H

(4) LabelTestDlg.cpp

#include "LabelTestDlg.h"
#include <qpicture.h>
#include <qpainter.h>
#include <qboxlayout.h>LabelTestDlg::LabelTestDlg(QWidget *parent): QDialog(parent)
{init();
}LabelTestDlg::~LabelTestDlg()
{
}void LabelTestDlg::init()
{setWindowTitle("Label测试");m_lb1 = new QLabel(this);m_lb2 = new QLabel(this);m_lb3 = new LabelEx(this);m_lb1->setFixedSize(150, 300);    m_lb2->setFixedSize(150, 300);    m_lb3->setFixedSize(150, 300);QPicture pic;QPainter painter1(&pic);painter1.fillRect(m_lb1->rect(), QColor(160, 255, 160));painter1.drawText(m_lb1->rect(), Qt::AlignLeft |Qt::AlignTop |Qt::TextWrapAnywhere, kText);m_lb1->setPicture(pic);QPixmap pix(m_lb2->size());pix.fill(QColor(160, 160, 255));QPainter painter2(&pix);painter2.drawText(m_lb2->rect(), Qt::AlignLeft |Qt::AlignTop |Qt::TextWrapAnywhere, kText);m_lb2->setPixmap(pix);QHBoxLayout *lay = new QHBoxLayout(this);lay->setContentsMargins(16, 16, 16, 16);lay->setSpacing(16);lay->addWidget(m_lb1);lay->addWidget(m_lb2);lay->addWidget(m_lb3);
}

4、程序运行效果