Qt 实现橡皮擦拭显示图片

1.简介

在一些游戏中看见类似解密破案的效果，使用手触摸去擦拭图片上的灰尘，然后显示最终的图片，所以也想试试Qt实现的效果。大家有自己想做的效果，都可以尝试。

以下是效果展示图。

可以控制橡皮擦的大小，进行擦拭。

2.原理

鼠标按住，然后移动，不断的给移动的圆形区域设置像素点的值，显示图片。

源码：

#include "wipewidget.h"
#include "ui_wipewidget.h"
#include <QDebug>

WipeWidget::WipeWidget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::WipeWidget)
{
    ui->setupUi(this);

    setMouseTracking(true);
}

WipeWidget::~WipeWidget()
{
    delete ui;
}

void WipeWidget::setEraserSize(int size)
{
    m_eraserSize = size;
    m_point = QPoint(this->width()/2,this->height()/2);

    update();
}

void WipeWidget::paintEvent(QPaintEvent *e)
{
    Q_UNUSED(e);
    //画圆圈
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing, true); // 启用抗锯齿
    painter.drawImage(0,0,m_image);

    QPen pen;
    pen.setWidth(2);
    pen.setColor(Qt::white);
    painter.setPen(pen);

    qDebug()<<"";
    painter.drawEllipse(m_point,m_eraserSize,m_eraserSize);

    if(m_isMousePressed)
        setImage(m_point);
}

void WipeWidget::mousePressEvent(QMouseEvent *event)
{
    m_isMousePressed = true;
}

void WipeWidget::mouseReleaseEvent(QMouseEvent *event)
{
    Q_UNUSED(event);
    m_isMousePressed = false;
}

void WipeWidget::mouseMoveEvent(QMouseEvent *event)
{
    m_point = event->pos();
    update();
}

void WipeWidget::showEvent(QShowEvent *event)
{
    Q_UNUSED(event);
    if(m_isInit)
       return;

    m_isInit = true;
    m_srcImage = QImage("./demo.jpeg").scaled(this->width(),this->height());
    m_image = QImage(m_srcImage.width(),m_srcImage.height(),m_srcImage.format());
}

void WipeWidget::setImage(QPoint point)
{
    int centerX = point.x();
    int centerY = point.y();

    if(centerX > m_srcImage.width() ||
       centerY > m_srcImage.height())
        return;

    int radius = m_eraserSize;

    for (int x = qMax(centerX - radius,0);
         x < qMin(centerX + radius,m_srcImage.width()); x++)
    {
        for (int y = qMax(centerY - radius,0);
             y < qMin(centerY + radius,m_srcImage.height()); y++)
        {
            if ((x - centerX) * (x - centerX) + (y - centerY) * (y - centerY) <= radius * radius)
            {
                if(x <= m_srcImage.width() && m_srcImage.height()-y <= m_srcImage.height())
                {
                    m_image.setPixel(x,y,m_srcImage.pixel(x, y));
                }
            }
        }
    }
}