Qt-widget画坐标系以及一些功能

窗口：

mywidget.h:

#ifndef MYWIDGET_H
#define MYWIDGET_H

#include <QWidget>
#include "ui_mywidget.h"
#include <QPaintEvent>
#include <QtGui>

class MyWidget : public QWidget
{
    Q_OBJECT

public:
    MyWidget(QWidget *parent = 0);
    ~MyWidget();
    QPointF ObjectPtoDisplayP(QPointF objPoint);
    QPointF DisplayPtoObjectP(QPointF disPoint);
    QPointF WidgetPtoObjectP(QPointF wigPoint);
    QPointF ObjectPtoWidgetP(QPointF objPoint);
    QPointF ValuePtoObjectP(QPointF valPoint);
    QPointF ObjectPtoValueP(QPointF objPoint);
    QPointF scaleIn(QPointF pos_before, QPointF scale_center, double scale_value);
    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;

    QPointF paint_org;              //widget坐标系
    QSize paint_size_first;
    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;           //display坐标系
    QPointF rect_topl;             //display坐标系
    QPointF rect_bottomr;          //display坐标系

    double scale_value;

    QPointF mousepress_org;        //display坐标系

    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

mywidget.cpp:

#include "mywidget.h"

MyWidget::MyWidget(QWidget *parent)
    : QWidget(parent)
{
    ui.setupUi(this);

    margin_size = 35;

    paint_org = QPointF(margin_size + 20, margin_size - 20);      
    paint_size_first = QSize(this->width() - margin_size * 2, this->height() - margin_size * 2);
    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);   
    paint_center_new = paint_center_old;

    offset_x = 0;
    offset_y = paint_size_new.height();

    rect_center = QPointF(paint_size_new.width() / 2, paint_size_new.height() / 2);   
    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));

    scale_value = 1.05;

    mousepress_org = QPointF(0, 0);

    axis_x_old = QPointF(rect_center.rx(), 0);
    axis_y_old = QPointF(0, rect_center.ry());

    axis_scale = 20.0;

    offsetv_x = rect_center.rx();
    offsetv_y = rect_bottomr.ry();
    pixel_per_mm = (double)(rect_bottomr.rx() - rect_topl.rx()) / 600;

    mouse_current_pos = QPointF(rect_center.rx(), rect_center.ry());
    this->setMouseTracking(true);

    //this->resize(880, 640);
}

MyWidget::~MyWidget()
{

}

void MyWidget::paintEvent(QPaintEvent *event)
{
    paint_size_new = QSize(this->width() - margin_size * 2, this->height() - margin_size * 2);

    QImage image = QImage(paint_size_new, QImage::Format_RGB32);
    QColor backColor = qRgb(255, 255, 255);
    image.fill(backColor);

    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);
        rect_center = paint_center_new - paint_center_old + rect_center;
        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_bottomr.ry();
    pixel_per_mm = (double)(rect_bottomr.rx() - rect_topl.rx()) / 600;

    QPainter painter2(&image);
    QRectF rec(DisplayPtoObjectP(rect_topl), DisplayPtoObjectP(rect_bottomr));
    painter2.drawRect(rec);
     painter2.drawPoint(DisplayPtoObjectP(rect_center));
    painter2.drawText(QPointF(mouse_current_pos.rx(), mouse_current_pos.ry()), "(" + QString::number(ObjectPtoValueP(mouse_current_pos).rx(), 'f', 1) + "mm, " + QString::number(ObjectPtoValueP(mouse_current_pos).ry(), 'f', 1) + "mm)");
    //painter2.drawPoint(ValuePtoObjectP(QPointF(-150.0, 150.0)));            //(-150mm, 150mm)

    QPainter painter(this);
     //painter.setRenderHint(QPainter::Antialiasing, true);
    painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, 0))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(image.width(), 0))));
    painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-0.01, 0))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-0.01, image.height()))));

    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()))));
    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));
    painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(image.width() / 2, -35))), QString(tr("X [mm]")));
    painter.rotate(-90);
    painter.drawText(QPointF(- (image.height() / 2 + 20), 15), QString(tr("Z [mm]")));
    painter.rotate(90);

    if (rect_center.rx() > 0 && rect_center.rx() < image.width())
    {
        painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(rect_center.rx(), 0))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(rect_center.rx(), -10))));
        painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(rect_center.rx(), -20))), QString::number((double)(rect_center.rx() - offsetv_x) / pixel_per_mm, 'f', 1));
    }
    
    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));
    }

    if (axis_scale >= 35.0)
    {
        axis_scale = axis_scale / 2;
    }
    else if (axis_scale <= 15.0)
    {
        axis_scale = axis_scale * 2;
    }

    axis_x_old = QPointF(rect_center.rx(),0);
    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())
        {
            if (i % 5 == 0)
            {
                painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(axis_x_old.rx(), 0))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(axis_x_old.rx(), -10))));
                painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(axis_x_old.rx(), -20))), QString::number((double)(axis_x_old.rx() - offsetv_x) / pixel_per_mm, 'f', 1));
            }
            else
            {
                painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(axis_x_old.rx(), 0))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(axis_x_old.rx(), -5))));
            }
        }
    }
    axis_x_old = QPointF(rect_center.rx(), 0);
    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(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(axis_x_old.rx(), 0))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(axis_x_old.rx(), -10))));
                painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(axis_x_old.rx(), -20))), QString::number((double)(axis_x_old.rx() - offsetv_x) / pixel_per_mm, 'f', 1));
            }
            else
            {
                painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(axis_x_old.rx(), 0))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(axis_x_old.rx(), -5))));
            }
        }
    }

    axis_y_old = QPointF(0, 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(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, axis_y_old.ry()))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-10, axis_y_old.ry()))));
                painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-30, axis_y_old.ry()))), QString::number((double)(axis_y_old.ry() - offsetv_y) / pixel_per_mm, 'f', 1));
            }
            else
            {
                painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, axis_y_old.ry()))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-5, axis_y_old.ry()))));
            }
        }
    }
    axis_y_old = QPointF(0, 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(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, axis_y_old.ry()))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-10, axis_y_old.ry()))));
                painter.drawText(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-30, axis_y_old.ry()))), QString::number((double)(axis_y_old.ry() - offsetv_y) / pixel_per_mm, 'f', 1));
            }
            else
            {
                painter.drawLine(ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(0, axis_y_old.ry()))), ObjectPtoWidgetP(DisplayPtoObjectP(QPointF(-5, axis_y_old.ry()))));
            }
        }
    }

    painter.drawImage(paint_org, image);
}

void MyWidget::wheelEvent(QWheelEvent *event)
{
     QPointF mousepos = WidgetPtoObjectP(event->pos());
     if (event->delta() > 0)    
     {
        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);
        axis_scale = axis_scale * scale_value;
     }
     else
     {
        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);
        axis_scale = axis_scale / scale_value;
      }
      
       repaint();
}

void MyWidget::mouseMoveEvent(QMouseEvent *event)
{
    mouse_current_pos = WidgetPtoObjectP(event->pos());

    if (event->buttons() & Qt::LeftButton)
    {
        QPointF mousepos_move = ObjectPtoDisplayP(WidgetPtoObjectP(event->pos()));
        
        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()));
    }
}

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);
}

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;
}

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;
}

QPointF MyWidget::WidgetPtoObjectP(QPointF wigPoint)
{
    return QPointF(wigPoint - paint_org);
}

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);
}

代码搞得有点复杂，用于显示三维轮廓测量的深度轮廓。

特点：
1、显示鼠标点坐标值

2、矩形框坐标值固定

　　①以鼠标点为中心滚轮等比例缩放，矩形框随之缩放，坐标轴跟着缩放（减少和插入中间值）

　　②鼠标左击拖动白板视窗，矩形框随之移动，坐标值跟着移动

 3、窗口缩放，坐标系整体不缩放

有一个问题，Z轴的0.0值在缩放之后会变成-0.0，暂时未找到原因。

因为是第一次写，思路可能不是很好，有更好的方法的话，可以探讨。