QT_滚轮缩放_坐标轴
作者：互联网
实现功能：滚轮缩放，鼠标左键按住移动，缩放时刻度线跟着一起移动，缩放时以鼠标的位置为中心
效果图：
工程文件：
mywidget.h
#ifndef MYWIDGET_H
#define MYWIDGET_H
#include <QWidget>
#include "ui_mywidget.h"
#include <QPaintEvent>
#include <QtGui>
QT_BEGIN_NAMESPACE
namespace Ui { class MyWidget; }
QT_END_NAMESPACE
class MyWidget : public QWidget
{
Q_OBJECT
public:
MyWidget(QWidget *parent = nullptr);
~MyWidget();
QPointF ObjectPtoDisplayP(QPointF objPoint);
QPointF DisplayPtoObjectP(QPointF disPoint);
QPointF WidgetPtoObjectP(QPointF wigPoint);//把相对于widget的坐标，转化为以画布的坐标
QPointF ObjectPtoWidgetP(QPointF objPoint);//把相对于以画布的坐标，转化为widget的坐标
QPointF ValuePtoObjectP(QPointF valPoint);
QPointF ObjectPtoValueP(QPointF objPoint);
//放大，以放缩的中心scale_center为准点，按照放缩比例scale_value，对点pos_before的x、y坐标进行放大
QPointF scaleIn(QPointF pos_before, QPointF scale_center, double scale_value);
//缩小，以放缩的中心scale_center为准点，按照放缩比例scale_value，对点pos_before的x、y坐标进行缩小
QPointF scaleOut(QPointF pos_before, QPointF scale_center, double scale_value);
protected:
void paintEvent(QPaintEvent *event);
void wheelEvent(QWheelEvent *event);
void mousePressEvent(QMouseEvent *event);
void mouseMoveEvent(QMouseEvent *event);
private:
Ui::MyWidget *ui;
int margin_size;
// QImage image;
QPointF paint_org; //widget坐标系，是整体显示区域的左上角起点
QSize paint_size_first; //画布的大小
QSize paint_size_old;
QSize paint_size_new;
QPointF paint_center_old; //display坐标系
QPointF paint_center_new; //display坐标系
double offset_x;
double offset_y;
QPointF rect_center; //以画布为坐标系
QPointF rect_topl; //矩形框的左上角，display坐标系
QPointF rect_bottomr; //矩形框的右下角，display坐标系
double scale_value; //缩放的比例
QPointF mousepress_org; //display坐标系，储存鼠标移动中的过程值或释放左键时的位置点坐标
QPointF axis_x_old; //display坐标系
QPointF axis_y_old; //display坐标系
double axis_scale;
double offsetv_x;
double offsetv_y;
double pixel_per_mm;
QPointF mouse_current_pos; //object坐标系
};
#endif // MYWIDGET_H
main.cpp：
#include "mywidget.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MyWidget w;
w.show();
return a.exec();
}
mywidget.cpp：
#include "mywidget.h"
#include "ui_mywidget.h"
MyWidget::MyWidget(QWidget *parent)
: QWidget(parent)
, ui(new Ui::MyWidget)
{
ui->setupUi(this);
margin_size =35;//空白边距
paint_org = QPointF(margin_size + 20, margin_size - 20); //确定绘画image的左上角
paint_size_first = QSize(this->width() - margin_size * 2, this->height() - margin_size * 2);//QSize 类代表一个矩形区域的大小，宽度和高度，计算画布的大小
paint_size_old = paint_size_first;
paint_size_new = paint_size_first;
paint_center_old = QPointF(paint_size_first.width() / 2, paint_size_first.height() / 2);//以画布左上角为原点，确定画布的中心点坐标，是在display的坐标
paint_center_new = paint_center_old;
offset_x = 0;
offset_y = paint_size_new.height();
//矩形框的中心以画布的中心为中心，以画布左上角为原点，确定画矩形框的中心点坐标
rect_center = QPointF(paint_size_new.width() / 2, paint_size_new.height() / 2);
//15指的是矩形框跟画布之间的间隙
rect_topl = QPointF(rect_center.rx() - (paint_size_new.height() / 2 -15 ), rect_center.ry() + (paint_size_new.height() / 2 -15 ));
rect_bottomr = QPointF(rect_center.rx() + (paint_size_new.height() / 2-15 ), rect_center.ry() - (paint_size_new.height() / 2-15 ));
//缩放比例初始化
scale_value = 1.05;
//储存鼠标移动中的过程值或释放左键时的位置点坐标，这里初始化
mousepress_org = QPointF(0,0);
//把画布的中心赋值给x、y轴的原点
axis_x_old = axis_y_old = QPointF(rect_center.rx(), rect_center.ry());
axis_scale = 20.0;
offsetv_x = rect_center.rx();
offsetv_y = rect_center.ry();
pixel_per_mm = (double)(rect_bottomr.rx() - rect_topl.rx()) / 600;
mouse_current_pos = QPointF(rect_center.rx(), rect_center.ry());//鼠标当前位置显示点，初始化为显示矩形中心位置坐标
//此属性保存是否为小部件启用鼠标跟踪
//如果禁用了鼠标跟踪（默认设置），则当移动鼠标时，窗口小部件仅在至少按下一个鼠标按钮时接收鼠标移动事件
//如果启用了鼠标跟踪，即使没有按下任何按钮，小部件也会接收鼠标移动事件
this->setMouseTracking(true);
this->resize(800,800);
}
MyWidget::~MyWidget()
{
delete ui;
}
void MyWidget::paintEvent(QPaintEvent *event)
{
//当窗口刷新时，按照当前窗口的大小，刷新paint_size_new画布的大小
paint_size_new = QSize(this->width() - margin_size * 2, this->height() - margin_size * 2);
paint_org = QPointF(margin_size + 20, margin_size - 20); //确定绘画image的左上角
QImage image = QImage(QSize(this->width() - margin_size * 2, this->height() - margin_size * 2), QImage::Format_RGB32);//创建画布对象
QColor backColor = qRgb(255, 255, 255);//设置为白色
image.fill(backColor);//填充画布为白色，没有这一步则画布默认为黑色
//因为窗口大小改变导致画布大小发生改变
//当画布的大小发生改变时
if (paint_size_new != paint_size_old)
{
offset_x = 0;
offset_y = paint_size_new.height();
paint_center_new = QPointF(paint_size_new.width() / 2, paint_size_new.height() / 2);
//根据变化的画布大小，改变矩形框的位置
rect_center = paint_center_new - paint_center_old + rect_center;//根据画布的中心，移动矩形的中心，保持两个中心重合
rect_topl = paint_center_new - paint_center_old + rect_topl;
rect_bottomr = paint_center_new - paint_center_old + rect_bottomr;
paint_size_old = paint_size_new;
paint_center_old = paint_center_new;
}
offsetv_x = rect_center.rx();
offsetv_y = rect_center.ry();
pixel_per_mm = (double)(rect_bottomr.rx() - rect_topl.rx()) / 600;
//用于绘画画布
QPainter painterimage(this);
//用于绘画画布上的内容
//painter在画布上作画时，需要得到object的坐标才行，所以当以display为坐标进行输入时，需要转化为object才行
QPainter painter(&image);
QPen pen(Qt::black);
painter.setPen(pen);
// painter.setRenderHint(QPainter::Antialiasing, true);
QRectF rec(DisplayPtoObjectP(rect_topl), DisplayPtoObjectP(rect_bottomr));//矩形框的左上角和右下角的坐标
painter.drawRect(rec);//画矩形框
painter.drawPoint(DisplayPtoObjectP(rect_center));//画出中心点
painterimage.drawImage(paint_org, image);
//在鼠标的当前点位置，绘画当前点的坐标数值，精度为1个小数点
painter.drawText(mouse_current_pos, "(" + QString::number(ObjectPtoValueP(mouse_current_pos).rx(), 'f', 1) + "mm, " + QString::number(ObjectPtoValueP(mouse_current_pos).ry(), 'f', 1) + "mm)");
//x 轴的主直线，画在画布的最下方，跟画布重合
painter.drawLine(DisplayPtoObjectP(QPointF(0, rect_center.ry())), DisplayPtoObjectP(QPointF(image.width(), rect_center.ry())));
//Y 轴的主直线，画在画布的最左方，跟画布边缘重合，如果完全重合就看不到直线，所以竖线向左移动一点
painter.drawLine(DisplayPtoObjectP(QPointF(rect_center.rx(), 0)), DisplayPtoObjectP(QPointF(rect_center.rx(), image.height())));
//此四行是在坐标轴的端点处各画一条长刻度线，不建议添加
// painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, 0))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, -10))));
// painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, 0))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-10, 0))));
// painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(image.width(), 0))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(image.width(), -10))));
// painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, image.height()))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-10, image.height()))));
//此四行，是始终在坐标轴的端点，显示端点的坐标值，不建议添加
// painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, -20))), QString::number((double)(0 - offsetv_x) / pixel_per_mm, 'f', 1));
// painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-30, 0))), QString::number((double)(0 - offsetv_y) / pixel_per_mm, 'f', 1));
// painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(image.width(), -20))), QString::number((double)(image.width() - offsetv_x) / pixel_per_mm, 'f', 1));
// painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-30, image.height()))), QString::number((double)(image.height() - offsetv_y) / pixel_per_mm, 'f', 1));
//绘画坐标轴标题
painter.drawText(DisplayPtoObjectP(QPointF(image.width()-45, rect_center.ry()-20)), QString(tr("X[mm]")));
// painter.rotate(-90);
painter.drawText(DisplayPtoObjectP(QPointF(rect_center.rx()-50, image.height()-20)), QString(tr("Y[mm]")));
// painter.rotate(90);
//此处两个判断语句，主要保证当主窗口大小变化时，x、y轴上的0刻度位置始终保持在各自轴的中心位置
//x轴
if (rect_center.rx() > 0 && rect_center.rx() < image.width())
{
painter.drawLine(DisplayPtoObjectP(QPointF(rect_center.rx(), rect_center.ry())),DisplayPtoObjectP(QPointF(rect_center.rx(), rect_center.ry()-10)));
painter.drawText(DisplayPtoObjectP(QPointF(rect_center.rx(), rect_center.ry()-20)), QString::number((double)(rect_center.rx() - offsetv_x) / pixel_per_mm, 'f', 1));
}
//y轴
// if (rect_center.ry() > 0 && rect_center.ry() < image.height())
// {
// painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, rect_center.ry()))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-10, rect_center.ry()))));
// painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-30, rect_center.ry()))), QString::number((double)(rect_center.ry() - offsetv_y) / pixel_per_mm, 'f', 1));
// }
//保证axis_scale在（17.5至30）范围内
if (axis_scale >= 35.0)
{
axis_scale = axis_scale / 2;
}
else if (axis_scale <= 15.0)
{
axis_scale = axis_scale * 2;
}
//x轴负半轴刻度线和坐标值
axis_x_old = QPointF(rect_center.rx(),rect_center.ry());
int i = 0;
while (axis_x_old.rx() > axis_scale)
{
axis_x_old.rx() = axis_x_old.rx() - axis_scale;
i++;
if (axis_x_old.rx() > 0 && axis_x_old.rx() < image.width())
{
//每5次，画一条长刻度线，并显示刻度值
if (i % 5 == 0)
{
//长刻度线
painter.drawLine(DisplayPtoObjectP(QPointF(axis_x_old.rx(), axis_x_old.ry())), DisplayPtoObjectP(QPointF(axis_x_old.rx(), axis_x_old.ry()-10)));
painter.drawText(DisplayPtoObjectP(QPointF(axis_x_old.rx(), axis_x_old.ry()-20)), QString::number((double)(axis_x_old.rx() - offsetv_x) / pixel_per_mm, 'f', 1));
}
else
{
//短刻度线
painter.drawLine(DisplayPtoObjectP(QPointF(axis_x_old.rx(), rect_center.ry())), DisplayPtoObjectP(QPointF(axis_x_old.rx(), rect_center.ry()-5)));
}
}
}
//x正半轴刻度线和坐标值
axis_x_old = QPointF(rect_center.rx(), rect_center.ry());
i = 0;
while ((image.width() - axis_x_old.rx()) > axis_scale)
{
axis_x_old.rx() = axis_x_old.rx() + axis_scale;
i++;
if (axis_x_old.rx() > 0 && axis_x_old.rx() < image.width())
{
if (i % 5 == 0)
{
painter.drawLine(DisplayPtoObjectP(QPointF(axis_x_old.rx(), rect_center.ry())), DisplayPtoObjectP(QPointF(axis_x_old.rx(), rect_center.ry()-10)));
painter.drawText(DisplayPtoObjectP(QPointF(axis_x_old.rx(), rect_center.ry()-20)), QString::number((double)(axis_x_old.rx() - offsetv_x) / pixel_per_mm, 'f', 1));
}
else
{
painter.drawLine(DisplayPtoObjectP(QPointF(axis_x_old.rx(), rect_center.ry())), DisplayPtoObjectP(QPointF(axis_x_old.rx(), rect_center.ry()-5)));
}
}
}
//y负半轴刻度线和坐标值
axis_y_old = QPointF(rect_center.rx(), rect_center.ry());
i = 0;
while (axis_y_old.ry() > axis_scale)
{
axis_y_old.ry() = axis_y_old.ry() - axis_scale;
i++;
if (axis_y_old.ry() > 0 && axis_y_old.ry() < image.height())
{
if (i % 5 == 0)
{
painter.drawLine(DisplayPtoObjectP(QPointF(rect_center.rx(), axis_y_old.ry())), DisplayPtoObjectP(QPointF(rect_center.rx()-10, axis_y_old.ry())));
painter.drawText(DisplayPtoObjectP(QPointF(rect_center.rx()-60, axis_y_old.ry())), QString::number((double)(axis_y_old.ry() - offsetv_y) / pixel_per_mm, 'f', 1));
}
else
{
painter.drawLine(DisplayPtoObjectP(QPointF(rect_center.rx(), axis_y_old.ry())), DisplayPtoObjectP(QPointF(rect_center.rx()-5, axis_y_old.ry())));
}
}
}
//y正半轴刻度线和坐标值
axis_y_old = QPointF(rect_center.rx(), rect_center.ry());
i = 0;
while ((image.height() - axis_y_old.ry()) > axis_scale)
{
axis_y_old.ry() = axis_y_old.ry() + axis_scale;
i++;
if (axis_y_old.ry() > 0 && axis_y_old.ry() < image.height())
{
if (i % 5 == 0)
{
painter.drawLine(DisplayPtoObjectP(QPointF(rect_center.rx(), axis_y_old.ry())), DisplayPtoObjectP(QPointF(rect_center.rx()-10, axis_y_old.ry())));
painter.drawText(DisplayPtoObjectP(QPointF(rect_center.rx()-60, axis_y_old.ry())), QString::number((double)(axis_y_old.ry() - offsetv_y) / pixel_per_mm, 'f', 1));
}
else
{
painter.drawLine(DisplayPtoObjectP(QPointF(rect_center.rx(), axis_y_old.ry())), DisplayPtoObjectP(QPointF(rect_center.rx()-5, axis_y_old.ry())));
}
}
}
// painter.drawLine(DisplayPtoObjectP(QPointF(rect_center.rx()+0, rect_center.ry()+0)), DisplayPtoObjectP(QPointF((100 - offsetv_y) / pixel_per_mm, (100 - offsetv_y) / pixel_per_mm)));
painterimage.drawImage(paint_org, image);
}
void MyWidget::wheelEvent(QWheelEvent *event)
{
//在滚轮滚动时，把鼠标的当前点，转化为画布的坐标
QPointF mousepos = WidgetPtoObjectP(event->pos());
if (event->delta() > 0)
{
//以鼠标的当前点为中心，按照缩放比例scale_value，进行放大
//对矩形框进行放大
rect_center = scaleIn(rect_center, ObjectPtoDisplayP(mousepos), scale_value);
rect_topl = scaleIn(rect_topl, ObjectPtoDisplayP(mousepos), scale_value);
rect_bottomr = scaleIn(rect_bottomr, ObjectPtoDisplayP(mousepos), scale_value);
//对坐标轴的刻度进行同步缩放
axis_scale = axis_scale * scale_value;
}
else
{
//缩小
rect_center = scaleOut(rect_center, ObjectPtoDisplayP(mousepos), scale_value);
rect_topl = scaleOut(rect_topl, ObjectPtoDisplayP(mousepos), scale_value);
rect_bottomr = scaleOut(rect_bottomr, ObjectPtoDisplayP(mousepos), scale_value);
//对坐标轴的刻度进行同步缩放
axis_scale = axis_scale / scale_value;
}
// 没有这个刷新，每次进行了滚轮，绘画事件不会立即生效
repaint();
}
void MyWidget::mouseMoveEvent(QMouseEvent *event)
{
//pos():返回鼠标光标相对于接收事件的小部件的位置
mouse_current_pos = WidgetPtoObjectP(event->pos());//刷新鼠标的当前焦点
//按住左键时移动
if (event->buttons() & Qt::LeftButton)
{
QPointF mousepos_move = ObjectPtoDisplayP(WidgetPtoObjectP(event->pos()));
//mousepos_move - mousepress_org是每次移动之间的差值，代表要把矩形框移动多远
rect_center = mousepos_move - mousepress_org + rect_center;
rect_topl = mousepos_move - mousepress_org + rect_topl;
rect_bottomr = mousepos_move - mousepress_org + rect_bottomr;
mousepress_org = mousepos_move;
}
repaint();
}
void MyWidget::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton)
{
mousepress_org = ObjectPtoDisplayP(WidgetPtoObjectP(event->pos()));
}
}
//把以左上角为原点的画布坐标系，转为以左下角为原点的坐标系
QPointF MyWidget::ObjectPtoDisplayP(QPointF objPoint)
{
return QPointF(objPoint.rx() - offset_x, -objPoint.ry() + offset_y);
}
QPointF MyWidget::DisplayPtoObjectP(QPointF disPoint)
{
return QPointF(disPoint.rx() + offset_x, -disPoint.ry() + offset_y);
}
//以放缩的中心scale_center为准点，按照放缩比例scale_value，对点pos_before的x、y坐标进行放大
QPointF MyWidget::scaleIn(QPointF pos_before, QPointF scale_center, double scale_value)
{
QPointF temp;
temp.rx() = (double)(pos_before.rx() - scale_center.rx()) * scale_value + scale_center.rx();
temp.ry() = (double)(pos_before.ry() - scale_center.ry()) * scale_value + scale_center.ry();
return temp;
}
//以放缩的中心scale_center为准点，按照放缩比例scale_value，对点pos_before的x、y坐标进行缩小
QPointF MyWidget::scaleOut(QPointF pos_before, QPointF scale_center, double scale_value)
{
QPointF temp;
temp.rx() = (double)(pos_before.rx() - scale_center.rx()) / scale_value + scale_center.rx();
temp.ry() = (double)(pos_before.ry() - scale_center.ry()) / scale_value + scale_center.ry();
return temp;
}
//把相对于widget的坐标，转化为以画布的坐标
QPointF MyWidget::WidgetPtoObjectP(QPointF wigPoint)
{
return QPointF(wigPoint - paint_org);
}
//把相对于以画布的坐标，转化为widget的坐标
QPointF MyWidget::ObjectPtoWidgetP(QPointF objPoint)
{
return QPointF(objPoint + paint_org);
}
QPointF MyWidget::ValuePtoObjectP(QPointF valPoint)
{
return DisplayPtoObjectP(QPointF(valPoint.rx() * pixel_per_mm + offsetv_x, valPoint.ry() * pixel_per_mm + offsetv_y));
}
QPointF MyWidget::ObjectPtoValueP(QPointF objPoint)
{
return QPointF((double)(ObjectPtoDisplayP(objPoint).rx() - offsetv_x) / pixel_per_mm, (double)(ObjectPtoDisplayP(objPoint).ry() - offsetv_y) / pixel_per_mm);
}
标签：center,缩放,rx,ry,坐标轴,QPointF,axis,rect,QT 来源： https://www.cnblogs.com/breathcode/p/14049984.html