Qt实现绘制网格背景的示例代码
目录
- 现有功能
- 运行结果
- 源码
- window.h
- window.cpp
- main.cpp
现有功能
- 使用滚轮缩放。
- 缩放到达一定阈值后恢复网格大小。
- 窗口大小调整时网格背景也自动调整重绘。
运行结果
源码
window.h
#ifndef WINDOW_H #define WINDOW_H #include <QWidget> #include <QPen> #include <QPainter> #include <QPaintEvent> class Window : public QWidget { Q_OBJECT public: Window(QWidget *parent = nullptr); ~Window(); protected: void paintEvent(QPaintEvent *event); void wheelEvent(QWheelEvent *event); void resizeEvent(QResizeEvent *event); private: void setBackgroundColor(); // 设置窗口背景颜色 void drawRowLines(QPainter *painter); // 绘制横线 void drawColLines(QPainter *painter); // 绘制竖线 private: int minGap; // 最小线间隔 int maxGap; // 最大线间隔 float gap; // 当前线间隔 float startX; // 竖线初始x坐标(从窗口中间开始) float startY; // 横线初始y坐标(从窗口中间开始) QPen lightPen; // 细一点的画笔 QPen darkPen; // 粗一点的画笔 }; #endif // WINDOW_H
window.cpp
#include "window.h" #include <QColor> #include <QPalette> #include <QPointF> Window::Window(QWidget *parent) : QWidget(parent) { this->minGap = 4; this->maxGap = 14; this->gap = (this->minGap + this->maxGap) / 2; this->startX = this->width() / 2; this->startY = this->height() / 2; this->lightPen = QPen(QColor(222, 222, 222)); this->darkPen = QPen(QColor(222, 222, 222)); this->darkPen.setWidth(2); this->setBackgroundColor(); } Window::~Window() { } void Window::setBackgroundColor() { QPalette palette; palette.setColor(QPalette::Background, QColor(250, 250, 250)); this->setPalette(palette); this->setAutoFillBackground(true); } void Window::drawRowLines(QPainter *painter) { int lineCount = 0; float biggerY = this->startY; float smallerY = this->startY; painter->setPen(this->darkPen); while (true) { painter->drawLine(QPointF(0.0, biggerY), QPointF(this->width(), biggerY)); painter->drawLine(QPointF(0.0, smallerY), QPointF(this->width(), smallerY)); biggerY += this->gap; smallerY -= this->gap; if (smallerY <= 0 || biggerY >= this->height()) { break; } // 每间隔一定数量的线,就画一条粗一点的横线 lineCount += 1; if (lineCount == 10) { painter->setPen(this->darkPen); lineCount = 0; } else { painter->setPen(this->lightPen); } } } void Window::drawColLines(QPainter *painter) { int lineCount = 0; float biggerX = this->startX; float smallerX = this->startX; painter->setPen(this->darkPen); while (true) { painter->drawLine(QPointF(biggerX, 0.0), QPointF(biggerX, this->height())); painter->drawLine(QPointF(smallerX, 0.0), QPointF(smallerX, this->height())); biggerX += this->gap; smallerX -= this->gap; if (smallerX <= 0 || biggerX >= this->width()) { break; } // 每间隔一定数量的线,就画一条粗一点的竖线 lineCount += 1; if (lineCount == 10) { painter->setPen(this->darkPen); lineCount = 0; } else { painter->setPen(this->lightPen); } } } void Window::paintEvent(QPaintEvent *event) { QWidget::paintEvent(event); QPainter painter(this); this->drawRowLines(&painter); this->drawColLines(&painter); } void Window::wheelEvent(QWheelEvent *event) { QWidget::wheelEvent(event); if (event->angleDelta().y() > 0) { this->gap += 0.1; } else if (event->angleDelta().y() < 0) { this->gap -= 0.1; } if (this->gap >= this->maxGap) { this->gap = this->minGap; } else if (this->gap <= this->minGap) { this->gap = this->maxGap; } this->update(); } void Window::resizeEvent(QResizeEvent *event) { QWidget::resizeEvent(event); this->startX = this->width() / 2; this->startY = this->height() / 2; this->update(); }
main.cpp
#include "window.h" #include <QApplication> int main(int argc, char *argv[]) { QApplication a(argc, argv); Window w; w.show(); return a.exec(); }
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