QT 从ttf文件中读取图标

最近在做项目时，遇到需要显示一些特殊字符的需求，这些特殊字符无法从键盘敲出来，于是乎，发现可以从字体库文件ttf中读取显示。

参考博客：QT 图标字体类IconHelper封装支持Font Awesome 5-CSDN博客

该博客封装的很不错，值得一看！

一、下载ttf文件

Font Awesome，一套绝佳的图标字体库和CSS框架

解压出来后，通过如下网站可以在线查看键值对照关系

Iconfont Previewiconfont preview for web, Momo's Blog, LuckyMomohttps://blog.luckly-mjw.cn/tool-show/iconfont-preview/index.html很好玩的一个网站!

就可以看到该字体库解析出来的很多图标了。

这里请看图片中红色圆圈全中的 bug 图标，如果需要读取他，那么请记住他的编码：&#xf188

注意，在代码中，我们用的是16进制方式，即：0xf188

在windows环境，右键字体，选择预览，即可看到字体名称！

字体名称 和 字体文件名 是必须要知道的！

二、编码

1.初始化字体后，就可以使用这个字体了

QFontDatabase::addApplicationFont("字体文件名");    // fontawesome-webfont.ttf
QFont iconFont = QFont("字体名称");    // FontAwesome

2.从字体库中获取图标，返回QPixmap

QPixmap IconHelper::getPixmap(const QColor &color, const QChar &str,quint32 size, quint32 pixWidth, quint32 pixHeight, int flags)
{QPixmap pix(pixWidth, pixHeight);pix.fill(Qt::transparent);QPainter painter;painter.begin(&pix);painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);painter.setPen(color);iconFont.setPixelSize(size);painter.setFont(iconFont);painter.drawText(pix.rect(), flags, str);painter.end();return pix;
}

如果想要QImage，或者需要将图标保存为本地图片，则将QPixmap转为QImage后再保存本地即可。

IconHelper iconHelper("FontAwesome", "fontawesome-webfont.ttf");
QPixmap pixmap = iconHelper.getPixmap(QColor(0, 0, 0), QChar(0xf188), 300, 300, 300);
QImage iamge = pixmap.toImage();     // 转为 QImage
iamge.save("文件路径/文件名字.png");    // 保存为本地图片 

3.可以直接给部件设置背景图

void IconHelper::setIcon(QLabel *lab, const QChar &str, quint32 size)
{iconFont.setPixelSize(size);lab->setFont(iconFont);lab->setText(str);
}

4.测试1，给按钮设置背景图标为篮球，图标编码为 0xf17d

int size = 100;                                                             
int width = 100;                                                            
int height = 100;  IconHelper iconHelper("FontAwesome", "fontawesome-webfont.ttf");            
QWidget *w = new QWidget;                                                   
w->setFixedSize(width*3, height*3); QPushButton *btn = new QPushButton(w);                                      
btn->setFixedSize(width, height);   iconHelper.setIcon(btn, QChar(0xf17d), size);  QHBoxLayout *hLayout = new QHBoxLayout(w);                                  
hLayout->addWidget(btn);                                                    
w->setLayout(hLayout);    w->show();                                                                  

5.测试2，给QLabel设置背景图标为虫子，图标编码为 0xf188

int size = 300;                                                                           
int width = 300;                                                                          
int height = 300;    IconHelper iconHelper("FontAwesome", "fontawesome-webfont.ttf");                          
QPixmap p = iconHelper.getPixmap(QColor(0, 0, 0), QChar(0xf188), size, width, height);    QWidget *w = new QWidget;                                                                 
w->setFixedSize(p.size()); QLabel label(w);                                                                          
label.setFixedSize(p.size());                                                             
label.setPixmap(p);  QHBoxLayout *hLayout = new QHBoxLayout(w);                                                
hLayout->addWidget(&label);                                                               
w->setLayout(hLayout);  w->show();                                                                                

三、代码汇总

iconhelper.h

#ifndef ICONHELPER_H
#define ICONHELPER_H#include <QtCore>
#include <QtGui>
#if (QT_VERSION > QT_VERSION_CHECK(5,0,0))#include <QtWidgets>
#endif//图形字体处理类
class IconHelper : public QObject
{Q_OBJECTpublic:explicit IconHelper(QString fontName, QString fontFileName, QObject *parent = nullptr);~IconHelper() override;void setIcon(QLabel *lab, const QChar &str, quint32 size = 12);void setIcon(QPushButton *btn, const QChar &str, quint32 size = 12);QPixmap getPixmap(const QColor &color, const QChar &str, quint32 size = 12,quint32 pixWidth = 15, quint32 pixHeight = 15, int flags = Qt::AlignCenter);private:QFont iconFont;             // 图形字体
};
#endif // ICONHELPER_H

iconhelper.cpp

#include "iconhelper.h"IconHelper::IconHelper(QString fontName, QString fontFileName, QObject *parent) : QObject(parent)
{// 判断图形字体是否存在,不存在则加入QFontDatabase fontDb;if (!fontDb.families().contains(fontName)) {// 从资源文件中读取ttf文件int fontId = QFontDatabase::addApplicationFont(QString(":/image/%1").arg(fontFileName));QStringList fontName = QFontDatabase::applicationFontFamilies(fontId);if (0 == fontName.count()) {qDebug() << QString("load fontFileName error").arg(fontFileName);}}if (fontDb.families().contains(fontName)) {iconFont = QFont(fontName);
#if (QT_VERSION >= QT_VERSION_CHECK(4, 8, 0))iconFont.setHintingPreference(QFont::PreferNoHinting);
#endif} else {    // 容错处理，如果字体加载失败，则使用默认字体QFont f;iconFont = f;}
}IconHelper::~IconHelper()
{}void IconHelper::setIcon(QLabel *lab, const QChar &str, quint32 size)
{iconFont.setPixelSize(size);lab->setFont(iconFont);lab->setText(str);
}void IconHelper::setIcon(QPushButton *btn, const QChar &str, quint32 size)
{iconFont.setPixelSize(size);btn->setFont(iconFont);btn->setText(str);
}QPixmap IconHelper::getPixmap(const QColor &color, const QChar &str,quint32 size, quint32 pixWidth, quint32 pixHeight, int flags)
{QPixmap pix(pixWidth, pixHeight);pix.fill(Qt::transparent);QPainter painter;painter.begin(&pix);painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);painter.setPen(color);iconFont.setPixelSize(size);painter.setFont(iconFont);painter.drawText(pix.rect(), flags, str);painter.end();return pix;
}

当根据大小获取到图标QPixmap后，就可以根据具体需要添加到相应的部件进行显示了！

完！