QT实现图片自定义截取功能类似QQ上传头像截取功能

#include "cutdialog.h" #include <QDebug> CutDialog::CutDialog(QWidget *parent) :m_isMoving(false), m_mouse_down(false), QFrame(parent), m_left(false), m_right(false), m_top(false), m_bottom(false) { setWindowFlags(Qt::FramelessWindowHint); setMouseTracking(true); setGeometry(0,0,200,200); cutpic.load(":/images/z_45_78.png"); label = new QLabel(this); if(!cutpic.isNull()){ label->setPixmap(cutpic.scaled(label->width(),label->height())); } else{ label->setText("is NULL"); } QGridLayout *layout = new QGridLayout(this); layout->addWidget(label); layout->setMargin(0); setLayout(layout); label->setMouseTracking(true); } CutDialog::~CutDialog() { } void CutDialog::resizeEvent(QResizeEvent *event) { label->setPixmap(cutpic.scaled(label->width(),label->height())); } void CutDialog::mousePressEvent(QMouseEvent * event) { m_startPoint = event->pos(); m_mouse_down = event->button() == Qt::LeftButton; } //画白色虚线 void CutDialog::paintEvent(QPaintEvent *event) { QPainter paint(this); QPen pen; QVector<qreal> dashes; qreal space = 3; dashes << 5 << space << 5 <<space; pen.setDashPattern(dashes); pen.setColor(Qt::white); paint.setPen(QColor(54,158,254,120)); paint.drawRect(1,1,width()-3,height()-3); paint.setPen(pen); int x_pos = (int) width()/3.0; int y_pos = (int) height()/3.0; paint.drawLine(x_pos, 1, x_pos, height()); paint.drawLine(2*x_pos, 1, 2*x_pos, height()); paint.drawLine(1, y_pos, width(), y_pos); paint.drawLine(1, 2*y_pos, width(), 2*y_pos); } QRect CutDialog::getResizeGem(QRect oldgeo, QPoint mousePoint) { QRect g = oldgeo; bool lorr = m_left | m_right; bool torb = m_top | m_bottom; int dx = mousePoint.x() - m_startPoint.x(); int dy = mousePoint.y() - m_startPoint.y(); if(lorr && torb) { int maxLen = qMin(qAbs(dx),qAbs(dy)); if(m_left && m_top && dx*dy >0) { g.setLeft(dx >0 ?g.left() + maxLen : g.left() - maxLen); g.setTop(dy >0? g.top() + maxLen : g.top() - maxLen); } if(m_right && m_top && dx*dy < 0) { g.setRight(dx>0 ? g.right() + maxLen:g.right() - maxLen); g.setTop(dy >0? g.top() + maxLen : g.top() - maxLen); } if(m_right && m_bottom && dx*dy > 0) { g.setRight(dx>0 ? g.right() + maxLen:g.right() - maxLen); g.setBottom(dy >0? g.bottom() + maxLen : g.bottom() - maxLen); } if(m_left && m_bottom && dx*dy < 0) { g.setLeft(dx >0 ?g.left() + maxLen : g.left() - maxLen); g.setBottom(dy >0? g.bottom() + maxLen : g.bottom() - maxLen); } return g; } else if(lorr) { if(m_left) g.setLeft(g.left() + dx); if(m_right) g.setRight(g.right() + dx); int len = g.width() - oldgeo.width(); int intHight = (int) len/2.0; g.setTop(g.top() - intHight); g.setBottom(g.bottom() + len - intHight); } else if(torb) { if(m_bottom) g.setBottom(g.bottom() + dy); if(m_top) g.setTop(g.top() + dy); int dheigt = g.height() - oldgeo.height(); int intWidth = (int) dheigt/2.0; g.setLeft(g.left() - intWidth); g.setRight(g.right() + dheigt - intWidth); } return g; } void CutDialog::mouseMoveEvent(QMouseEvent * event) { QPoint dragPoint = event->pos(); int x = event->x(); int y = event->y(); if(m_mouse_down) { QRect g = getResizeGem(geometry(), dragPoint); if(parentWidget()->rect().contains(g)) setGeometry(g); m_startPoint = QPoint(!m_right? m_startPoint.x():event->x(),!m_bottom? m_startPoint.y():event->y()); if(!m_left && !m_right && !m_bottom && !m_top) { QPoint p = QPoint((pos().x()+dragPoint.x() - m_startPoint.x()), (pos().y()+dragPoint.y() - m_startPoint.y())); QPoint dragEndge = p; dragEndge.setX(dragEndge.x() + rect().width()); dragEndge.setY(dragEndge.y() + rect().height()); p.setX(p.x() < 0? 0 : p.x()); p.setX(dragEndge.x() > parentWidget()->width()?parentWidget()->width()-rect().width():p.x()); p.setY(p.y() < 0? 0 : p.y()); p.setY(dragEndge.y() > parentWidget()->height()?parentWidget()->height()-rect().height():p.y()); move(p); } } else { QRect r = rect(); m_left = qAbs(x - r.left()) < 5; m_right = qAbs(x - r.right()) < 5; m_bottom = qAbs(y - r.bottom()) < 5; m_top = qAbs(y - r.top()) < 5; bool lorr = m_left | m_right; bool torb = m_top | m_bottom; if(lorr && torb) { if((m_left && m_top) || (m_right && m_bottom)){ setCursor(Qt::SizeFDiagCursor); } else setCursor(Qt::SizeBDiagCursor); } else if(lorr) setCursor(Qt::SizeHorCursor); else if(torb) setCursor(Qt::SizeVerCursor); else { setCursor(Qt::SizeAllCursor); m_bottom = m_left = m_right = m_top = false; } } } void CutDialog::mouseReleaseEvent(QMouseEvent * event) { m_mouse_down = false; }