Qt如何实现绘制网格背景

本篇内容介绍了“Qt如何实现绘制网格背景”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！

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_OBJECTpublic:    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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