解决图片旋转后越界，根据旋转点，旋转图片并保持图片不越界,程序为qt工程

#include <QApplication> #include <QWidget> #include <QPainter> #include <QPixmap> #include <QTransform> #include <QPushButton> #include <QVBoxLayout> #include <QResizeEvent> #include <QDebug> #include <QComboBox> #include <iostream> #include <cmath> #include <string> #include <algorithm> #include <QtDebug> #ifndef M_PI #define M_PI (3.14159265358979323846) #endif struct Rect { double x, y; // 左上角坐标 double w, h; // 宽度和高度 }; enum class RotationPoint { TOP_LEFT, TOP_CENTER, TOP_RIGHT, CENTER_LEFT, CENTER, CENTER_RIGHT, BOTTOM_LEFT, BOTTOM_CENTER, BOTTOM_RIGHT }; // 计算旋转后的矩形 Rect rotateRect(const Rect& rect, RotationPoint point, double angle) { // 将角度转换为弧度 double radians = angle * M_PI / 180.0; // 计算矩形的宽度和高度 double width = rect.w; double height = rect.h; // 计算旋转点的坐标 double centerX, centerY; switch (point) { case RotationPoint::TOP_LEFT: centerX = rect.x; centerY = rect.y; break; case RotationPoint::TOP_CENTER: centerX = rect.x + width / 2; centerY = rect.y; break; case RotationPoint::TOP_RIGHT: centerX = rect.x + width; centerY = rect.y; break; case RotationPoint::CENTER_LEFT: centerX = rect.x; centerY = rect.y + height / 2; break; case RotationPoint::CENTER: centerX = rect.x + width / 2; centerY = rect.y + height / 2; break; case RotationPoint::CENTER_RIGHT: centerX = rect.x + width; centerY = rect.y + height / 2; break; case RotationPoint::BOTTOM_LEFT: centerX = rect.x; centerY = rect.y + height; break; case RotationPoint::BOTTOM_CENTER: centerX = rect.x + width / 2; centerY = rect.y + height; break; case RotationPoint::BOTTOM_RIGHT: centerX = rect.x + width; centerY = rect.y + height; break; } // 计算旋转后的四个角的坐标 double cosTheta = cos(radians); double sinTheta = sin(radians); // 左上角 double x1_rot = centerX + (rect.x - centerX) * cosTheta - (rect.y - centerY) * sinTheta; double y1_rot = centerY + (rect.x - centerX) * sinTheta + (rect.y - centerY) * cosTheta; // 右上角 double x2_rot = centerX + (rect.x + width - centerX) * cosTheta - (rect.y - centerY) * sinTheta; double y2_rot = centerY + (rect.x + width - centerX) * sinTheta + (rect.y - centerY) * cosTheta; // 左下角 double x3_rot = centerX + (rect.x - centerX) * cosTheta - (rect.y + height - centerY) * sinTheta; double y3_rot = centerY + (rect.x - centerX) * sinTheta + (rect.y + height - centerY) * cosTheta; // 右下角 double x4_rot = centerX + (rect.x + width - centerX) * cosTheta - (rect.y + height - centerY) * sinTheta; double y4_rot = centerY + (rect.x + width - centerX) * sinTheta + (rect.y + height - centerY) * cosTheta; // 计算旋转后的矩形的边界 double minX = std::min({x1_rot, x2_rot, x3_rot, x4_rot}); double maxX = std::max({x1_rot, x2_rot, x3_rot, x4_rot}); double minY = std::min({y1_rot, y2_rot, y3_rot, y4_rot}); double maxY = std::max({y1_rot, y2_rot, y3_rot, y4_rot}); // 返回旋转后的矩形 return {minX, minY, maxX - minX, maxY - minY}; } void GetRoteDiff(RotationPoint point, int w, int h, int &x_diff, int &y_diff) { switch (point) { case RotationPoint::TOP_LEFT: x_diff = 0 ; y_diff = 0;break; case RotationPoint::TOP_CENTER: x_diff = w / 2 ; y_diff = 0;break; case RotationPoint::TOP_RIGHT: x_diff = w ; y_diff = 0;break; case RotationPoint::CENTER_LEFT: x_diff = 0 ; y_diff = h/2;break; case RotationPoint::CENTER: x_diff = w/2 ; y_diff = h/2;break; case RotationPoint::CENTER_RIGHT: x_diff = w ; y_diff = h/2;break; case RotationPoint::BOTTOM_LEFT: x_diff = 0 ; y_diff = h;break; case RotationPoint::BOTTOM_CENTER: x_diff = w/2 ; y_diff = h;break; case RotationPoint::BOTTOM_RIGHT: x_diff = w ; y_diff = h;break; } } class ImageWidget : public QWidget { public: ImageWidget(const QString& imagePath, QWidget* parent = nullptr) : QWidget(parent), rotationAngle(0) { // 加载图像并缩放为 320x320 pixmap = QPixmap(imagePath).scaled(320, 320, Qt::IgnoreAspectRatio, Qt::SmoothTransformation); orgPt = QPoint(340, 340); orgRc = rect(); orgRc.setWidth(320); orgRc.setHeight(320); // 初始化窗口大小 updateBoundingRect(RotationPoint::TOP_CENTER); QPalette palette; palette.setColor(QPalette::Window, Qt::green); // 设置背景颜色为蓝色 // 将 QPalette 应用到窗口 setPalette(palette); // 设置窗口的背景模式为窗口背景 setAutoFillBackground(true); } protected: void paintEvent(QPaintEvent* event) override { Q_UNUSED(event); QPainter painter(this); painter.setRenderHint(QPainter::Antialiasing); // 平移到窗口中心 painter.translate(-rc.x + x_diff, -rc.y + y_diff); // 旋转指定角度 painter.rotate(rotationAngle); // 绘制图像 painter.drawPixmap(-x_diff, -y_diff, pixmap); } void resizeEvent(QResizeEvent* event) override { Q_UNUSED(event); // 确保图像在窗口中居中 update(); } private: void updateBoundingRect(RotationPoint rt) { this->rt = rt; Rect rect = {0, 0, 320, 320}; // 原始矩形 RotationPoint point = rt; // 旋转点为中心 double angle = rotationAngle; // 旋转角度 Rect rotatedRect = rotateRect(rect, point, angle); //qDebug() << "rotatedRect" << rotatedRect; // 调整窗口大小 setGeometry(orgPt.x() + rotatedRect.x, orgPt.y() + rotatedRect.y, rotatedRect.w, rotatedRect.h); rc = rotatedRect; GetRoteDiff(rt, orgRc.width(), orgRc.height(), x_diff, y_diff); } void rotateImage(RotationPoint rt) { rotationAngle += 30; if (rotationAngle >= 360) { rotationAngle -= 360; } updateBoundingRect(rt); update(); // 触发重绘 } friend class ControlWidget; private: QPixmap pixmap; int rotationAngle; QPoint orgPt; QRect orgRc; Rect rc; RotationPoint rt; int x_diff; int y_diff; }; class ControlWidget : public QWidget { public: ControlWidget(QWidget* parent = nullptr) : QWidget(parent){ // 修改图像路径为 C:\\Users\\zzu\\Desktop\\1.jpg imageWidget = new ImageWidget("C:\\Users\\zzu\\Desktop\\1.jpg", this); imageWidget->move(340,340); imageWidget->resize(320,320); // 创建按钮 QPushButton* rotateButton = new QPushButton("Rotate", this); connect(rotateButton, &QPushButton::clicked, this, &ControlWidget::rotateImage); combo = new QComboBox(this); combo->addItem("TOP_LEFT"); combo->addItem("TOP_CENTER"); combo->addItem("TOP_RIGHT"); combo->addItem("CENTER_LEFT"); combo->addItem("CENTER"); combo->addItem("CENTER_RIGHT"); combo->addItem("BOTTOM_LEFT"); combo->addItem("BOTTOM_CENTER"); combo->addItem("BOTTOM_RIGHT"); combo->setCurrentIndex(0); // 设置布局 QHBoxLayout* layout = new QHBoxLayout(this); layout->addWidget(combo); layout->addWidget(rotateButton); setLayout(layout); QPalette palette; palette.setColor(QPalette::Window, Qt::blue); // 设置背景