QT在场景中利用freetype实现独立的文字绘制子类QxFreeTypeTextItem,继上一章节讲过qt中如何编译freetype
Qt编译和使用freetype矢量字库方法https://blog.csdn.net/wangningyu/article/details/138927379#QT利用freetype提取字库图片_qt freetype-CSDN博客文章浏览阅读1.2k次。这是某个项目中要用到的片段,结合上一篇文章#QT从字体名获取字库文件路径使用// 保存位图int SaveBitmapToFile(HBITMAP hBitmap, LPSTR lpFileName){HDC hDC;int iBits;WORD wBitCount; DWORD dwPaletteSize=0,dwBmBitsSize,dwDIBSize_qt freetypehttps://blog.csdn.net/wangningyu/article/details/109743104MFC/QT利用COM组件接口从字体名称、粗体、斜体获取到字体文件路径的方法-CSDN博客文章浏览阅读239次。【代码】MFC/QT利用COM组件接口从字体名称、粗体、斜体获取到字体文件路径的方法。https://blog.csdn.net/wangningyu/article/details/138802620
这里将不使用qt默认的QGraphicsSimpleTextItem与QGraphicsTextItem实现一下自定义的文字图形类:
cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGridLayout>
#include <QPushButton>
#include <QGraphicsScene>
#include <QGraphicsItem>
#include <QDebug>
#include <QPainter>
#include <QFont>
#include <QString>
#include <QColor>
#include <QTextDocument>
#include <ft2build.h>
#include FT_FREETYPE_H
class QxFreeTypeTextItem : public QGraphicsItem
{
public:
QxFreeTypeTextItem(const QString& text, int fontSize, const QString& ttfFile, const QColor& textColor, QGraphicsItem* parent = nullptr)
: QGraphicsItem(parent), m_strText(text), m_iFontSize(fontSize), m_strTtfFile(ttfFile), m_textColor(textColor)
{
m_ftLibrary = NULL;
m_ftFace = NULL;
if (FT_Init_FreeType(&m_ftLibrary))
{
qDebug() << "FT_Init_FreeType failed.";
return;
}
if (FT_New_Face(m_ftLibrary, m_strTtfFile.toStdString().c_str(), 0, &m_ftFace))
{
qDebug() << "FT_New_Face failed: " << m_strTtfFile;
return;
}
FT_Set_Pixel_Sizes(m_ftFace, 0, m_iFontSize);
}
~QxFreeTypeTextItem()
{
if(m_ftFace)
{
FT_Done_Face(m_ftFace);
m_ftFace = NULL;
}
if(m_ftLibrary)
{
FT_Done_FreeType(m_ftLibrary);
m_ftLibrary = NULL;
}
}
QRectF boundingRect() const override
{
return m_rect;
}
void setRect(qreal left, qreal top, qreal width, qreal height)
{
m_rect = QRectF(left, top, width, height);
update();
}
void paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget = nullptr) override
{
int x = m_rect.left();
int y = m_rect.top();
Q_UNUSED(option);
Q_UNUSED(widget);
// 开始利用freetype绘制文字
painter->setRenderHint(QPainter::Antialiasing);
painter->setPen(m_textColor);
for (int i = 0; i < m_strText.length(); ++i)
{
QChar ucode = m_strText.at(i);
ushort unicode = ucode.unicode();
if (FT_Load_Char(m_ftFace, unicode, FT_LOAD_RENDER))
{
continue;
}
FT_GlyphSlot glyph = m_ftFace->glyph;
QImage glyphImage(glyph->bitmap.width, glyph->bitmap.rows, QImage::Format_ARGB32);
glyphImage.fill(Qt::transparent);
for (unsigned int j = 0; j < glyph->bitmap.rows; ++j)
{
for (unsigned int k = 0; k < glyph->bitmap.width; ++k)
{
int alpha = glyph->bitmap.buffer[j * glyph->bitmap.width + k];
glyphImage.setPixel(k, j, qRgba(m_textColor.red(), m_textColor.green(), m_textColor.blue(), alpha));
}
}
painter->drawImage(QPointF(x + glyph->bitmap_left, y - glyph->bitmap_top), glyphImage);
x += (glyph->advance.x >> 6);
}
}
private:
QString m_strText;
int m_iFontSize;
QString m_strTtfFile;
QColor m_textColor;
FT_Library m_ftLibrary;
FT_Face m_ftFace;
QRectF m_rect;
};
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
QGraphicsScene *pScene = new QGraphicsScene(this);
pScene->setSceneRect(QRect(0, 0, 800, 500));
ui->graphicsView->setScene(pScene);
ui->graphicsView->setRenderHint(QPainter::Antialiasing);
//ui->graphicsView->setCacheMode(QGraphicsView::CacheBackground);
//ui->graphicsView->setViewportUpdateMode(QGraphicsView::BoundingRectViewportUpdate);
ui->graphicsView->setAlignment(Qt::AlignVCenter | Qt::AlignHCenter);
ui->graphicsView->setMouseTracking(true);
ui->graphicsView->setStyleSheet(QString("background:%1").arg(QColor(255, 255, 176).name()));
QColor clr(0, 0, 255);
QxFreeTypeTextItem *pItem = new QxFreeTypeTextItem("FreeType: Hello-Normal by wangningyu", 32, "C:/ArialUMS.TTF", clr);
pItem->setRect(10, 10, 300, 100);
pItem->setFlag(QGraphicsItem::ItemIsMovable, true);
pItem->setFlag(QGraphicsItem::ItemIsSelectable, true);
pScene->addItem(pItem);
pItem = new QxFreeTypeTextItem("FreeType: Hello-Bold by wangningyu", 32, "C:/Windows/Fonts/Arialbd.ttf", clr);
pItem->setRect(10, 50, 300, 100);
pItem->setFlag(QGraphicsItem::ItemIsMovable, true);
pItem->setFlag(QGraphicsItem::ItemIsSelectable, true);
pScene->addItem(pItem);
pItem = new QxFreeTypeTextItem("FreeType: Hello-Italic by wangningyu", 32, "C:/Windows/Fonts/Ariali.ttf", clr);
pItem->setRect(10, 90, 300, 100);
pItem->setFlag(QGraphicsItem::ItemIsMovable, true);
pItem->setFlag(QGraphicsItem::ItemIsSelectable, true);
pScene->addItem(pItem);
pItem = new QxFreeTypeTextItem("FreeType: Hello-Bold-Italic by wangningyu", 32, "C:/Windows/Fonts/Arialbi.ttf", clr);
pItem->setRect(10, 130, 300, 100);
pItem->setFlag(QGraphicsItem::ItemIsMovable, true);
pItem->setFlag(QGraphicsItem::ItemIsSelectable, true);
pScene->addItem(pItem);
}
MainWindow::~MainWindow()
{
delete ui;
}
测试效果: