利用QPixmap实现图片缩放、平移等操作.zip

#include "widget.h" #include<QApplication> #include<QMouseEvent> #include<QFileDialog> #include<QGridLayout> Widget::Widget(QWidget *parent) : QWidget(parent), BiBtn("放大",this), LeBtn("缩小",this), LBtn("向左",this), RBtn("向右",this), UBtn("向上",this), DBtn("向下",this), ResetBtn("还原",this), OpenBtn("打开文件",this), Alloffset(0,0), label("100%",this) { ratio= 1.0; //初始化图片缩放比例 action = Widget::None; //新建栅格布局 QGridLayout *layout=new QGridLayout; //设置按钮尺寸 BiBtn.setMaximumSize(100,40); LeBtn.setMaximumSize(100,40); LBtn.setMaximumSize(100,40); RBtn.setMaximumSize(100,40); UBtn.setMaximumSize(100,40); DBtn.setMaximumSize(100,40); ResetBtn.setMaximumSize(100,40); OpenBtn.setMaximumSize(100,40); Paint.setMinimumSize(700,600); label.setMaximumSize(100,40); //设置按钮尺寸 BiBtn.setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); LeBtn.setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); LBtn.setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); RBtn.setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); UBtn.setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); DBtn.setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); ResetBtn.setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); OpenBtn.setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding); //向布局管理器添加组件 layout->addWidget(&Paint,0,0,-1,1); layout->addWidget(&BiBtn,0,1,1,1); layout->addWidget(&LeBtn,1,1,1,1); layout->addWidget(&LBtn,2,1,1,1); layout->addWidget(&RBtn,3,1,1,1); layout->addWidget(&UBtn,4,1,1,1); layout->addWidget(&DBtn,5,1,1,1); layout->addWidget(&ResetBtn,6,1,1,1); layout->addWidget(&OpenBtn,7,1,1,1); layout->addWidget(&label,8,1,1,1); setLayout(layout); //为部件设置布局管理器 // BiBtn.setGeometry(822,10,60,25); connect(&BiBtn,SIGNAL(clicked()),this,SLOT(onBigClicked())); // LeBtn.setGeometry(822,40,60,25); connect(&LeBtn,SIGNAL(clicked()),this,SLOT(onLittleClicked())); // LBtn.setGeometry(822,70,60,25); connect(&LBtn,SIGNAL(clicked()),this,SLOT(OnLeftClicked())); // RBtn.setGeometry(822,100,60,25); connect(&RBtn,SIGNAL(clicked()),this,SLOT(OnRightClicked())); // UBtn.setGeometry(822,130,60,25); connect(&UBtn,SIGNAL(clicked()),this,SLOT(onUpClicked())); // DBtn.setGeometry(822,160,60,25); connect(&DBtn,SIGNAL(clicked()),this,SLOT(onDownClicked())); // ResetBtn.setGeometry(822,190,60,25); connect(&ResetBtn,SIGNAL(clicked()),this,SLOT(onResetClicked())); // OpenBtn.setGeometry(822,220,60,25); connect(&OpenBtn,SIGNAL(clicked()),this,SLOT(onOpenClicked())); // label.move(840,260); resize(800,600); //调整窗口大小 this->setWindowTitle("图片浏览器(请打开文件)");//设置窗口标题 } //鼠标按下拖动事件 bool Widget::event(QEvent * event) { static bool press=false; static QPoint PreDot; //检测鼠标按下 if(event->type() == QEvent::MouseButtonPress) { QMouseEvent *mouse = dynamic_cast<QMouseEvent* >(event); //判断鼠标是否是左键按下,且鼠标位置是否在绘画区域 //if(mouse->button()==Qt::LeftButton &&Paint.contains(mouse->pos())) if(mouse->button()==Qt::LeftButton) { press=true; QApplication::setOverrideCursor(Qt::OpenHandCursor); //设置鼠标样式 PreDot = mouse->pos(); } } //检测鼠标松开 else if(event->type() == QEvent::MouseButtonRelease) { QMouseEvent *mouse = dynamic_cast<QMouseEvent* >(event); //判断鼠标是否是左键释放,且之前是在绘画区域 if(mouse->button()==Qt::LeftButton && press ) { QApplication::setOverrideCursor(Qt::ArrowCursor); //改回鼠标样式 press=false; } } //检测鼠标移动 if(event->type() == QEvent::MouseMove) //移动图片 { if(press) { QMouseEvent *mouse = dynamic_cast<QMouseEvent* >(event); offset.setX(mouse->x() - PreDot.x()); offset.setY(mouse->y() - PreDot.y()); PreDot = mouse->pos(); action = Widget::Move; this->update(); } } return QWidget::event(event); } //鼠标滑轮事件 void Widget::wheelEvent(QWheelEvent* event) { if (event->angleDelta().y()>0) { //上滑,缩小 action=Widget::Shrink; this->update(); } else { //下滑,放大 action=Widget::Amplification; this->update(); } event->accept(); } //重写绘图事件 void Widget::paintEvent(QPaintEvent *event) { QPainter painter(this); //设置渲染方式 painter.setRenderHints(QPainter::SmoothPixmapTransform|QPainter::Antialiasing|QPainter::TextAntialiasing); painter.drawRect(Paint.x()-1,Paint.y()-1,Paint.width()+1,Paint.height()+1); //画框 if(image.isNull()) { return; } int NowW = ratio *pixW; int NowH = ratio *pixH; if(action==Widget::Shrink) //缩小 { ratio-=0.05*ratio; if(ratio<0.018) ratio = 0.01; /*显示比例*/ QString str; str=str.setNum(ratio*100)+"%"; //str.sprintf("%.0f%",ratio*100); label.setText(str) ; qDebug()<<"缩小:"<<ratio; } else if(action==Widget::Amplification) //放大 { ratio+=0.05*ratio; if(ratio>4.5) ratio = 5.000; /*显示比例*/ QString str; str=str.setNum(ratio*100)+"%";; //str.sprintf("%.0f%",ratio*100); label.setText(str); qDebug()<<"放大:"<<ratio; } if(action==Widget::Amplification || action==Widget::Shrink || action==Widget::Reset) //更新图片 { NowW = ratio *pixW; NowH = ratio *pixH; crtPix= pix.scaled(NowW, NowH,Qt::KeepAspectRatio,Qt::SmoothTransformation); //重新装载 action=Widget::None; } if(action==Widget::Move) //移动 { int offsetx=Alloffset.x()+offset.x(); Alloffset.setX(offsetx); int offsety=Alloffset.y()+offset.y(); Alloffset.setY(offsety); action=Widget::None; } if(abs(Alloffset.x())>=(Paint.width()/2 + NowW/2 -10)) //限制X偏移值 { if(Alloffset.x()>0) Alloffset.setX(Paint.width()/2 + NowW/2 -10); else Alloffset.setX(-Paint.width()/2 + -NowW/2 +10); } if(abs(Alloffset.y())>=(Paint.height()/2 + NowH/2 -10)) //限制Y偏移值 { if(Alloffset.y()>0) Alloffset.setY(Paint.height()/2 + NowH/2 -10); else Alloffset.setY(-Paint.height()/2 + -NowH/2 +10); } int x = Paint.width()/2 + Alloffset.x() -NowW/2; if(x<0) x=0; int y = Paint.height()/2 + Alloffset.y() -NowH/2; if(y<0) y=0; int sx = NowW/2 - Paint.width()/2 - Alloffset.x(); if(sx<0) sx=0; int sy = NowH/2 - Paint.height()/2 - Alloffset.y(); if(sy<0) sy=0; int w =(NowW - sx)>Paint.width()? Paint.width() : (NowW - sx); if(w>(Paint.width()-x)) w = Paint.width()-x; int h =(NowH - sy)>Paint.height()? Paint.height() : (NowH - sy); if(h>(Paint.