QT5笔记：36. QGraphicsView 综合示例 （完结撒花！）
通过此示例可以比较熟悉QGraphincsView的流程以及操作
坐标关系以及获取：
- View坐标：左上角为原点，通过鼠标移动事件获取
- Scene坐标：中心为原点，横竖为X,Y轴。通过View.mapToScene(View坐标)获取
- Item坐标：Item中心为原点，由于可旋转，X,Y轴方向不定。通过item.mapFromScene(Scene坐标，View.Transform)获取
View缩放：X、Y可以不同比例
ui->graphicsView->scale(1.1, 1.1);//放大
ui->graphicsView->scale(0.9, 0.9);//缩小
ui->graphicsView->resetTransform();//恢复比例
设置item可以拖动、选中、获取焦点
item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
可以框选多个
ui->graphicsView->setDragMode(QGraphicsView::RubberBandDrag);//鼠标框选
item缩放
item->setScale(item->scale() - 0.1);//缩小
item->setScale(item->scale() + 0.1);//放大
item->setScale(1);//恢复比例
item旋转
item->setRotation(item->rotation() - 3);//逆时针转3度
item->setRotation(item->rotation() + 3);//顺时针转3度
item前置&后置
item->setZValue(item->zValue() + 1);//前置
item->setZValue(item->zValue() - 1);//后置
item组合&打散
//组合
QGraphicsItemGroup *group = new QGraphicsItemGroup();
group->addToGroup(item);
group->setFlags(QGraphicsItemGroup::ItemIsFocusable | QGraphicsItemGroup::ItemIsSelectable | QGraphicsItemGroup::ItemIsMovable);
scene->addItem(group); //打散
QGraphicsItem *item = scene->selectedItems().at(i);
if (item->type() == QGraphicsItemGroup::Type) {
QGraphicsItemGroup *group = qgraphicsitem_cast<QGraphicsItemGroup *>(item);
scene->destroyItemGroup(group);
}
item删除
scene->removeItem(item);//删除
例子：
GraphicsView.h重写的 QGraphicsView，重写鼠标、键盘事件
#ifndef GRAPHICSVIEW_H
#define GRAPHICSVIEW_H
#include <QGraphicsView>
class GraphicsView : public QGraphicsView
{
Q_OBJECT
public:
explicit GraphicsView(QWidget *parent = nullptr);
signals:
void keyPress(QKeyEvent *event);
void mouseDoubleClick(QPoint point);
void mousePress(QPoint point);
void mouseMove(QPoint point);
// QWidget interface
protected:
void mouseDoubleClickEvent(QMouseEvent *event) override;
void mousePressEvent(QMouseEvent *event) override;
void mouseMoveEvent(QMouseEvent *event) override;
void keyPressEvent(QKeyEvent *event) override;
};
#endif // GRAPHICSVIEW_H
GraphicsView.cpp
#include "GraphicsView.h"
#include <QMouseEvent>
GraphicsView::GraphicsView(QWidget *parent) : QGraphicsView(parent)
{
}
void GraphicsView::mouseDoubleClickEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton) {
emit(mouseDoubleClick(event->pos()));
}
QGraphicsView::mouseDoubleClickEvent(event);//交还事件给父类处理
}
void GraphicsView::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton) {
emit(mousePress(event->pos()));
}
QGraphicsView::mousePressEvent(event);
}
void GraphicsView::mouseMoveEvent(QMouseEvent *event)
{
emit(mouseMove(event->pos()));
QGraphicsView::mouseMoveEvent(event);
}
void GraphicsView::keyPressEvent(QKeyEvent *event)
{
emit(keyPress(event));
QGraphicsView::keyPressEvent(event);
}
MainWindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QGraphicsScene>
#include <QLabel>
#include <QMainWindow>
#include <QMouseEvent>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();
private:
Ui::MainWindow *ui;
QGraphicsScene *scene;
static const int itemID = 1;
static const int description = 2;
int seqNum = 0;//item的ID序列
QLabel *labView = new QLabel("View坐标：", this);
QLabel *labViewCoord = new QLabel("(000 , 000)\t", this);
QLabel *labScene = new QLabel("Scene坐标：", this);
QLabel *labSceneCoord = new QLabel("(000 , 000)\t", this);
QLabel *labItem = new QLabel("Item坐标：", this);
QLabel *labItemCoord = new QLabel("(000 , 000)\t", this);
QLabel *labItemID = new QLabel("ItemID：", this);
QLabel *labItemInfo = new QLabel("", this);
private slots:
void onKeyPress(QKeyEvent *event);
void onMouseDoubleClick(QPoint point);
void onMousePress(QPoint point);
void onMouseMove(QPoint point);
void on_actItem_Rect_triggered();
void on_actItem_Polygon_triggered();
void on_actItem_Triangle_triggered();
void on_actItem_Circle_triggered();
void on_actItem_Ellipse_triggered();
void on_actItem_Line_triggered();
void on_actItem_Text_triggered();
void on_actZoomIn_triggered();
void on_actZoomOut_triggered();
void on_actRestore_triggered();
void on_actRotateLeft_triggered();
void on_actRotateRight_triggered();
void on_actEdit_Front_triggered();
void on_actEdit_Back_triggered();
void on_actGroup_triggered();
void on_actGroupBreak_triggered();
void on_actEdit_Delete_triggered();
};
#endif // MAINWINDOW_H
MainWindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QColorDialog>
#include <QFontDialog>
#include <QGraphicsRectItem>
#include <QInputDialog>
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);
scene = new QGraphicsScene(-300, -100, 600, 200);
ui->graphicsView->setScene(scene);
ui->graphicsView->setCursor(Qt::CrossCursor);
ui->graphicsView->setMouseTracking(true);
ui->graphicsView->setDragMode(QGraphicsView::RubberBandDrag);//鼠标框选
ui->statusbar->addWidget(this->labView);
ui->statusbar->addWidget(this->labViewCoord);
ui->statusbar->addWidget(this->labScene);
ui->statusbar->addWidget(this->labSceneCoord);
ui->statusbar->addWidget(this->labItem);
ui->statusbar->addWidget(this->labItemCoord);
ui->statusbar->addWidget(this->labItemID);
ui->statusbar->addWidget(this->labItemInfo);
connect(ui->graphicsView, SIGNAL(keyPress(QKeyEvent *)), this, SLOT(onKeyPress(QKeyEvent *)));
connect(ui->graphicsView, SIGNAL(mouseDoubleClick(QPoint)), this, SLOT(onMouseDoubleClick(QPoint)));
connect(ui->graphicsView, SIGNAL(mousePress(QPoint)), this, SLOT(onMousePress(QPoint)));
connect(ui->graphicsView, SIGNAL(mouseMove(QPoint)), this, SLOT(onMouseMove(QPoint)));
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_actItem_Rect_triggered()//矩形
{
QBrush brush;
brush.setColor(QColor(169, 134, 49, 200));
brush.setStyle(Qt::SolidPattern);
QGraphicsRectItem *item = new QGraphicsRectItem(-50, -30, 100, 60);
item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
item->setBrush(brush);
item->setData(itemID, seqNum++);
item->setData(description, "矩形");
scene->addItem(item);
scene->clearSelection();
item->setSelected(true);
}
void MainWindow::on_actItem_Polygon_triggered()//梯形/多边形
{
QBrush brush;
brush.setColor(QColor(255, 78, 55));
brush.setStyle(Qt::Dense4Pattern);
QVector<QPointF> points;
points << QPointF(-50, -70) << QPointF(50, -70) << QPointF(70, -30) << QPointF(-70, -30);
QPolygonF polygon = QPolygonF(points);
QGraphicsPolygonItem *item = new QGraphicsPolygonItem(points);
item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
item->setBrush(brush);
item->setData(itemID, seqNum++);
item->setData(description, "梯形");
scene->addItem(item);
scene->clearSelection();
item->setSelected(true);
}
void MainWindow::on_actItem_Triangle_triggered()//三角形
{
QBrush brush;
brush.setColor(QColor(81, 181, 110));
brush.setStyle(Qt::Dense4Pattern);
QVector<QPointF> points;
points << QPointF(0, -30) << QPointF(-30, 0) << QPointF(30, 0);
QPolygonF polygon = QPolygonF(points);
QGraphicsPolygonItem *item = new QGraphicsPolygonItem(points);
item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
item->setBrush(brush);
item->setData(itemID, seqNum++);
item->setData(description, "三角形");
scene->addItem(item);
scene->clearSelection();
item->setSelected(true);
}
void MainWindow::on_actItem_Circle_triggered()
{
QBrush brush;
brush.setColor(QColor(151, 151, 151));
brush.setStyle(Qt::SolidPattern);
QGraphicsEllipseItem *item = new QGraphicsEllipseItem(0, 0, 10, 10);
item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
item->setBrush(brush);
item->setData(itemID, seqNum++);
item->setData(description, "圆形");
scene->addItem(item);
scene->clearSelection();
item->setSelected(true);
}
void MainWindow::on_actItem_Ellipse_triggered()
{
QBrush brush;
brush.setColor(QColor(195, 195, 195));
brush.setStyle(Qt::Dense4Pattern);
QGraphicsEllipseItem *item = new QGraphicsEllipseItem(0, 0, 15, 10);
item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
item->setBrush(brush);
item->setData(itemID, seqNum++);
item->setData(description, "椭圆形");
scene->addItem(item);
scene->clearSelection();
item->setSelected(true);
}
void MainWindow::on_actItem_Line_triggered()
{
QPen pen;
pen.setWidth(2);
QGraphicsLineItem *item = new QGraphicsLineItem(-100, 0, 100, 0);
item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
item->setPen(pen);
item->setData(itemID, seqNum++);
item->setData(description, "直线");
scene->addItem(item);
scene->clearSelection();
item->setSelected(true);
}
void MainWindow::on_actItem_Text_triggered()
{
QFont font;
font.setPointSize(12);
font.setFamily("MiSans");
QString text = QInputDialog::getText(this, "", "文本内容");
QGraphicsTextItem *item = new QGraphicsTextItem(text);
item->setFlags(QGraphicsItem::ItemIsSelectable | QGraphicsItem::ItemIsFocusable | QGraphicsItem::ItemIsMovable);
item->setFont(font);
item->setData(itemID, seqNum++);
item->setData(description, "文本");
scene->addItem(item);
scene->clearSelection();
item->setSelected(true);
}
void MainWindow::on_actZoomIn_triggered()//放大
{
int count = scene->selectedItems().count();
if (count != 0) {
for (int i = 0; i < count; i++) {
QGraphicsItem *item = scene->selectedItems().at(i);
item->setScale(item->scale() + 0.1);
}
} else {
ui->graphicsView->scale(1.1, 1.1);
}
}
void MainWindow::on_actZoomOut_triggered()//缩小
{
int count = scene->selectedItems().count();
if (count != 0) {
for (int i = 0; i < count; i++) {
QGraphicsItem *item = scene->selectedItems().at(i);
item->setScale(item->scale() - 0.1);
}
} else {
ui->graphicsView->scale(0.9, 0.9);
}
}
void MainWindow::on_actRestore_triggered()//恢复比例
{
int count = scene->selectedItems().count();
if (count != 0) {
for (int i = 0; i < count; i++) {
QGraphicsItem *item = scene->selectedItems().at(i);
item->setScale(1);
}
} else {
ui->graphicsView->resetTransform();//恢复比例
}
}
void MainWindow::on_actRotateLeft_triggered()//左旋转
{
int count = scene->selectedItems().count();
if (count != 0) {
for (int i = 0; i < count; i++) {
QGraphicsItem *item = scene->selectedItems().at(i);
item->setRotation(item->rotation() - 3);
}
}
}
void MainWindow::on_actRotateRight_triggered()//右旋转
{
int count = scene->selectedItems().count();
if (count != 0) {
for (int i = 0; i < count; i++) {
QGraphicsItem *item = scene->selectedItems().at(i);
item->setRotation(item->rotation() + 3);
}
}
}
void MainWindow::on_actEdit_Front_triggered()//前置
{
int count = scene->selectedItems().count();
if (count != 0) {
for (int i = 0; i < count; i++) {
QGraphicsItem *item = scene->selectedItems().at(i);
item->setZValue(item->zValue() + 1);
}
}
}
void MainWindow::on_actEdit_Back_triggered()//后置
{
int count = scene->selectedItems().count();
if (count != 0) {
for (int i = 0; i < count; i++) {
QGraphicsItem *item = scene->selectedItems().at(i);
item->setZValue(item->zValue() - 1);
}
}
}
void MainWindow::on_actGroup_triggered()//组合
{
int count = scene->selectedItems().count();
if (count > 0) {
QGraphicsItemGroup *group = new QGraphicsItemGroup();
for (int i = count - 1; i >= 0; i--) {
QGraphicsItem *item = scene->selectedItems().at(i);
item->setSelected(false);
group->addToGroup(item);
}
group->setFlags(QGraphicsItemGroup::ItemIsFocusable | QGraphicsItemGroup::ItemIsSelectable | QGraphicsItemGroup::ItemIsMovable);
scene->addItem(group);
group->setSelected(true);
}
}
void MainWindow::on_actGroupBreak_triggered()//打散
{
int count = scene->selectedItems().count();
if (count > 0) {
for (int i = count - 1; i >= 0; i--) {
QGraphicsItem *item = scene->selectedItems().at(i);
if (item->type() == QGraphicsItemGroup::Type) {
QGraphicsItemGroup *group = qgraphicsitem_cast<QGraphicsItemGroup *>(item);
scene->destroyItemGroup(group);
}
}
}
}
void MainWindow::on_actEdit_Delete_triggered()//删除
{
int count = scene->selectedItems().count();
if (count != 0) {
for (int i = count - 1; i >= 0; i--) {
QGraphicsItem *item = scene->selectedItems().at(i);
scene->removeItem(item);
}
}
}
void MainWindow::onMouseDoubleClick(QPoint point)//双击修改颜色或字体
{
QPointF pointScene = ui->graphicsView->mapToScene(point);
QGraphicsItem *item = scene->itemAt(pointScene, ui->graphicsView->transform());
if (item != nullptr) {
switch (item->type()) {
case QGraphicsRectItem::Type: {//矩形
QGraphicsRectItem *itemRect = qgraphicsitem_cast<QGraphicsRectItem *>(item);
QBrush brush = itemRect->brush();
QColor color = QColorDialog::getColor(brush.color(), this, "选择一个颜色");
if (color.isValid()) {
brush.setColor(color);
itemRect->setBrush(brush);
}
break;
}
case QGraphicsPolygonItem::Type: {//多边形：梯形、三角形
QGraphicsPolygonItem *itemPolygon = qgraphicsitem_cast<QGraphicsPolygonItem *>(item);
QBrush brush = itemPolygon->brush();
QColor color = QColorDialog::getColor(brush.color(), this, "选择一个颜色");
if (color.isValid()) {
brush.setColor(color);
itemPolygon->setBrush(brush);
}
break;
}
case QGraphicsEllipseItem::Type: {//椭圆 & 圆
QGraphicsEllipseItem *itemEllipse = qgraphicsitem_cast<QGraphicsEllipseItem *>(item);
QBrush brush = itemEllipse->brush();
QColor color = QColorDialog::getColor(brush.color(), this, "选择一个颜色");
if (color.isValid()) {
brush.setColor(color);
itemEllipse->setBrush(brush);
}
break;
}
case QGraphicsTextItem::Type: {//文本
QGraphicsTextItem *itemText = qgraphicsitem_cast<QGraphicsTextItem *>(item);
bool ok = false;
QFont font = QFontDialog::getFont(&ok, itemText->font(), this, "选择字体", QFontDialog::DontUseNativeDialog);
if (ok) {
itemText->setFont(font);
}
QColor color = QColorDialog::getColor(itemText->defaultTextColor(), this, "选择一个颜色", QColorDialog::DontUseNativeDialog);//使用Qt的标准颜色对话框而不是操作系统的本机颜色对话框。
if (color.isValid()) {
itemText->setDefaultTextColor(color);
}
break;
}
case QGraphicsLineItem::Type: {//直线
QGraphicsLineItem *itemLine = qgraphicsitem_cast<QGraphicsLineItem *>(item);
QPen pen = itemLine->pen();
QColor color = QColorDialog::getColor(pen.color(), this, "选择一个颜色");
if (color.isValid()) {
pen.setColor(color);
itemLine->setPen(pen);
}
break;
}
default: break;
}
}
}
void MainWindow::onKeyPress(QKeyEvent *event)
{
QList<QGraphicsItem *> items = scene->selectedItems();
int count = items.count();
if (count > 0) {
switch (event->key()) {
case Qt::Key_Delete://刪除
case Qt::Key_Backspace://退格键
on_actEdit_Delete_triggered();
break;
case Qt::Key_Left://左
for (int i = 0; i < count; i++) {
QGraphicsItem *item = items.at(i);
item->setX(item->x() - 1);
}
break;
case Qt::Key_Right://右
for (int i = 0; i < count; i++) {
QGraphicsItem *item = items.at(i);
item->setX(item->x() + 1);
}
break;
case Qt::Key_Up://上
for (int i = 0; i < count; i++) {
QGraphicsItem *item = items.at(i);
item->setY(item->y() - 1);
}
break;
case Qt::Key_Down://下
for (int i = 0; i < count; i++) {
QGraphicsItem *item = items.at(i);
item->setY(item->y() + 1);
}
break;
case Qt::Key_Space: on_actRotateRight_triggered(); break;//往右转
case Qt::Key_PageUp: on_actZoomIn_triggered(); break;//放大
case Qt::Key_PageDown: on_actZoomOut_triggered(); break;//缩小
}
}
}
void MainWindow::onMousePress(QPoint point)//将鼠标点击的itemID显示在状态栏
{
QPointF pointScene = ui->graphicsView->mapToScene(point);
QGraphicsItem *item = scene->itemAt(pointScene, ui->graphicsView->transform());
if (item != nullptr) {
labItemInfo->setText(item->data(itemID).toString());
}
}
void MainWindow::onMouseMove(QPoint point)//鼠标移动事件
{
this->labViewCoord->setText(QString::asprintf("(%4d , %4d)\t", point.x(), point.y()));//View 坐標
QPointF pointScene = ui->graphicsView->mapToScene(point);
this->labSceneCoord->setText(QString::asprintf("(%4.0f , %4.0f)\t", pointScene.x(), pointScene.y()));//Scene 坐標
QGraphicsItem *item = scene->itemAt(pointScene, ui->graphicsView->transform());
if (item != nullptr) {
QPointF itemPoint = item->mapFromScene(pointScene);//item坐标
this->labItemCoord->setText(QString::asprintf("(%4.0f , %4.0f)\t", itemPoint.x(), itemPoint.x()));
this->labItemInfo->setText(item->data(itemID).toString());
} else {
this->labItemCoord->setText("(0000 , 0000)");
this->labItemInfo->setText("");
}
}
界面
Qt5 完结撒花，感谢陪伴！！！
reference:
NOTICE
- 参考视频到此还没有结束，但是我忘记写笔记了，emmmm，大家想看的，可以去B站看
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