Qt 带有定位功能的图片控件

原标题：Qt 自定义图片控件

20180328更新:
我编写了一个可以用来选点的程序, Windows和主要Linux发行版均可使用. 下载地址:https://gitee.com/Mannix1994/x-y

这个控件的核心部分是基于liyuanbhu大神写的图片控件，我在他的基础之上，加入坐标追踪功能，在控件上左键点击时，在该位置画一个十字，同时将该位置记录下来，右键点击时，删除上一个坐标。在鼠标移动时，有一个十字跟着鼠标走。

头文件picturebox.h
#ifndef PICTUREBOX_H
#define PICTUREBOX_H

#include <QWidget>
#include <QImage>
#include <QPixmap>
#include <QMouseEvent>
#include <QEvent>
#include <QPoint>
#include <QLine>
#include <QVector>
#include <QStack>
#include <QStringList>
#include <QDebug>

class PictureBox : public QWidget
{
Q_OBJECT
public:
enum PB_MODE {FIXED_SIZE, FIX_SIZE_CENTRED, AUTO_ZOOM, AUTO_SIZE}; //图像显示模式
explicit PictureBox(QWidget *parent = 0);
void setMode(PB_MODE mode); //设置显示模式
~PictureBox();

private:
QPixmap m_pixmap; //当前绘制的图像
double m_scale; //缩放因子
PB_MODE m_mode; //显示模式
QBrush m_brush; //
int x,y; //当前被鼠标点击的点的x,y坐标
typedef enum {Border,TrackingCross,LocationCross} PaintMode; //绘图模式：边框、追踪十字、位置十字
PaintMode paintMode; //绘图模式
QStack<QPixmap> images; //存储历次绘制的图像
QStringList points; //存储历次被点击的坐标
QString getPointsString();//返回以","分割的店坐标

protected:
void paintEvent(QPaintEvent * event); //绘制事件

signals:
void clicked(QString points); //图片被点击的信号，发送的是被点击的点的坐标

public slots:
bool setImage(QImage &image, double scale = 1.0); //设置要显示的图像
void setBackground(QBrush brush); //设置背景

protected:
void mousePressEvent(QMouseEvent *event); //鼠标点击事件
void mouseMoveEvent(QMouseEvent *event); //鼠标移动事件
void enterEvent(QEvent *event); //鼠标进入窗口事件
void leaveEvent(QEvent *event); //鼠标离开窗口事件
};

#endif // PICTUREBOX_H

源文件picturebox.cpp

#include "picturebox.h"
#include <QPainter>
#include <QDebug>
static const int IMAGE_WIDTH = 160;
static const int IMAGE_HEIGHT = 120;
static const QSize IMAGE_SIZE = QSize(IMAGE_WIDTH, IMAGE_HEIGHT);

PictureBox::PictureBox(QWidget *parent) : QWidget(parent)
{
m_pixmap = QPixmap(IMAGE_SIZE);
m_pixmap.fill();
m_scale = 1.0;
m_mode = FIXED_SIZE;
m_brush = QBrush(Qt::white);
paintMode = Border;
}

/**
* @brief PictureBox::setBackground 设置背景
* @param brush
*/
void PictureBox::setBackground(QBrush brush)
{
m_brush = brush;
update();
}

/**
* @brief PictureBox::setMode 设置显示模式
* @param mode
*/
void PictureBox::setMode(PB_MODE mode)
{
m_mode = mode;
if(m_mode == AUTO_SIZE)
{
setFixedSize(m_pixmap.size() * m_scale);
}
else
{
setMaximumSize(QWIDGETSIZE_MAX, QWIDGETSIZE_MAX);
setMinimumSize(0, 0);
}
update();
}

/**
* @brief PictureBox::setImage 设置图片
* @param image 图片
* @param scale 缩放因子
* @return
*/
bool PictureBox::setImage(QImage &image, double scale)
{
if(image.isNull())
{
return false;
}
m_pixmap = QPixmap::fromImage(image);
m_scale = qBound(0.01, scale, 100.0);
if(m_mode == AUTO_SIZE)
{
setFixedSize(m_pixmap.size() * m_scale);
}
update();
images.push(this->grab(this->rect()));
m_pixmap = images.top();
this->update();
return true;
}

/**
* @brief PictureBox::paintEvent 调用update()以后引发的paintEvent事件
* @param event
*/
void PictureBox::paintEvent(QPaintEvent * event)
{
Q_UNUSED(event);
QPainter painter(this);
painter.setBackground(m_brush);
painter.eraseRect(rect());

double window_width, window_height;
double image_width, image_height;
double r1, r2, r;
int offset_x, offset_y;
switch (m_mode)
{
case FIXED_SIZE:
case AUTO_SIZE:
painter.scale(m_scale, m_scale);
painter.drawPixmap(0, 0, m_pixmap);
break;
case FIX_SIZE_CENTRED:
window_width = width();
window_height = height();
image_width = m_pixmap.width();
image_height = m_pixmap.height();
offset_x = (window_width - m_scale * image_width) / 2;
offset_y = (window_height - m_scale * image_height) / 2;
painter.translate(offset_x, offset_y);
painter.scale(m_scale, m_scale);
painter.drawPixmap(0, 0, m_pixmap);
break;
case AUTO_ZOOM:
window_width = width();
window_height = height();
image_width = m_pixmap.width();
image_height = m_pixmap.height();
r1 = window_width / image_width;
r2 = window_height / image_height;
r = qMin(r1, r2);
offset_x = (window_width - r * image_width) / 2;
offset_y = (window_height - r * image_height) / 2;
painter.translate(offset_x, offset_y);
painter.scale(r, r);
painter.drawPixmap(0, 0, m_pixmap);
break;
}

//绘制指定线段
int xMax = painter.window().width()-1;
int yMax = painter.window().height()-1;
QVector<QLine> lines;
if(paintMode == Border){ //绘制边框
QPoint p1(0,0),p2(xMax,0),p3(xMax,yMax),p4(0,yMax);
QLine line1(p1,p2);
QLine line2(p2,p3);
QLine line3(p3,p4);
QLine line4(p4,p1);
lines.append(line1);
lines.append(line2);
lines.append(line3);
lines.append(line4);
}
else if(paintMode == TrackingCross){ //绘制追踪十字
QPoint p1(x,0),p2(x,yMax),p3(0,y),p4(xMax,y);
QLine line1(p1,p2);
QLine line2(p3,p4);
lines.append(line1);
lines.append(line2);
}
else if(paintMode == LocationCross){ //绘制定位十字
int xMinP = (x-10)>0 ? (x-10):0;
int xMaxP = (x+10)<xMax ? (x+10):xMax;
int yMinP = (y-10)>0 ? (y-10):0;
int yMaxP = (y+10)<yMax ? (y+10):yMax;
QPoint p1(x,yMinP),p2(x,yMaxP),p3(xMinP,y),p4(xMaxP,y);
QLine line1(p1,p2);
QLine line2(p3,p4);
lines.append(line1);
lines.append(line2);
}
painter.drawLines(lines);
}

/**
* @brief PictureBox::mousePressEvent 鼠标点击，左键在图片上添加一个定位十字，右键在图片上删除一个定位十字
* @param event
*/
void PictureBox::mousePressEvent(QMouseEvent *event){
this->setMouseTracking(false); //关闭鼠标追踪
if(event->button() == Qt::LeftButton){ //鼠标左键被点击
x = event->x();
y = event->y();
//存储当被点击的点
points.append(QString("(%1,%2)").arg(x).arg(y));
//绘制定位十字
paintMode = LocationCross;
this->update();
//存储绘制后的图像
images.push(this->grab(this->rect())); //抓取当前图像并存储
//更新图像
m_pixmap = images.top();
this->update();
paintMode = TrackingCross;
}
else if(event->button() == Qt::RightButton){ //右键，弹出顶层图像
//退回上一张图像
if(images.count()>1){
images.pop();
m_pixmap = images.top();
this->update();
}
//删除最后一个点击的点
if(points.count()>0){
points.removeLast();
}
}
this->setMouseTracking(true);
emit clicked(this->getPointsString()); //发送被点击的信号
}

/**
* @brief PictureBox::mouseMoveEvent 鼠标移动事件，绘制追踪十字
* @param event
*/
void PictureBox::mouseMoveEvent(QMouseEvent *event){
4000
x = event->x();
y = event->y();
paintMode = TrackingCross;
this->update();
}

/**
* @brief PictureBox::enterEvent 进入此控件时设置鼠标追踪，通过mouseMoveEvent绘制追踪十字
* @param event
*/
void PictureBox::enterEvent(QEvent *event)
{
Q_UNUSED(event);
this->setMouseTracking(true);
}

/**
* @brief PictureBox::leaveEvent 离开此控件时关闭追踪，并将绘制模式paintMode设置边框(Border)，清除会绘制的追踪十字
* @param event
*/
void PictureBox::leaveEvent(QEvent *event)
{
Q_UNUSED(event);
this->setMouseTracking(false);
paintMode = Border;
this->update();
}

/**
* @brief PictureBox::getPointsString 返回以","分割的坐标字符串
* @return
*/
QString PictureBox::getPointsString(){
if(points.isEmpty())
return "";
QString data = points.first();
for(int i=1;i<points.count();i++){
data += ","+points.at(i);
}
return data;
}

PictureBox::~PictureBox()
{

}

调用方法
pictureBox = new PictureBox();
this->connect(pictureBox,SIGNAL(clicked(QString)),this,SLOT(onPictureClicked(QString)));
this->ui->vLayout->addWidget(pictureBox);
QImage image("1.jpg");
ui->verticalLayoutWidget->setFixedSize(image.size());
pictureBox->setImage(image);