Qt-Qt实现高斯模糊效果

相关资料：

https://qa.1r1g.com/sf/ask/1044059061/

实例代码：

.pro

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++11

# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    main.cpp \
    mainwindow.cpp

HEADERS += \
    mainwindow.h

FORMS += \
    mainwindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

RESOURCES += \
    aa.qrc

main.cpp

#include "mainwindow.h"

#include <QApplication>
#include <QtCore>
#include <QtGui>
#include <QLabel>
#include <QBitmap>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_horizontalSlider_valueChanged(int value);
    void on_horizontalSlider_2_valueChanged(int value);

private:
    Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGraphicsDropShadowEffect>
#include <QGraphicsScene>
#include <QPainter>
#include <QGraphicsPixmapItem>

// 源作者地址：https://qa.1r1g.com/sf/ask/1044059061/
QImage applyEffectToImage(QImage src, QGraphicsEffect *effect, int extent=0)
{
    if(src.isNull()) return QImage();   //No need to do anything else!
    if(!effect) return src;             //No need to do anything else!
    QGraphicsScene scene;
    QGraphicsPixmapItem item;
    item.setPixmap(QPixmap::fromImage(src));
    item.setGraphicsEffect(effect);
    scene.addItem(&item);
    QImage res(src.size()+QSize(extent*2, extent*2), QImage::Format_ARGB32);
    res.fill(Qt::transparent);
    QPainter ptr(&res);
    scene.render(&ptr, QRectF(), QRectF( -extent, -extent, src.width()+extent*2, src.height()+extent*2 ) );
    return res;
}

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    setWindowTitle(QStringLiteral("Qt实现高斯模糊效果"));
}

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

void MainWindow::on_horizontalSlider_valueChanged(int value)
{
    QGraphicsBlurEffect *blur = new QGraphicsBlurEffect;
    blur->setBlurRadius(ui->horizontalSlider->value());
    QImage source(":/new/prefix1/a.jpeg");
    QImage result = applyEffectToImage(source, blur);

    ui->label_2->setPixmap(QPixmap::fromImage(result));
//    result.save("d:\\2.bmp");
//    ui->widget->grab(QRect(0,0,400,200)).save("d:\\1.bmp");
}

void MainWindow::on_horizontalSlider_2_valueChanged(int value)
{
    QGraphicsBlurEffect *e0 = new QGraphicsBlurEffect(this);
    e0->setBlurRadius(value);
    ui->widget->setGraphicsEffect(e0);
}

mainwindow.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>831</width>
    <height>376</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QWidget" name="widget" native="true">
    <property name="geometry">
     <rect>
      <x>0</x>
      <y>10</y>
      <width>400</width>
      <height>300</height>
     </rect>
    </property>
    <layout class="QHBoxLayout" name="horizontalLayout">
     <property name="spacing">
      <number>0</number>
     </property>
     <property name="leftMargin">
      <number>0</number>
     </property>
     <property name="topMargin">
      <number>0</number>
     </property>
     <property name="rightMargin">
      <number>0</number>
     </property>
     <property name="bottomMargin">
      <number>0</number>
     </property>
     <item>
      <widget class="QLabel" name="label">
       <property name="text">
        <string/>
       </property>
       <property name="pixmap">
        <pixmap resource="aa.qrc">:/new/prefix1/a.jpeg</pixmap>
       </property>
       <property name="scaledContents">
        <bool>true</bool>
       </property>
       <property name="wordWrap">
        <bool>false</bool>
       </property>
      </widget>
     </item>
    </layout>
   </widget>
   <widget class="QSlider" name="horizontalSlider">
    <property name="geometry">
     <rect>
      <x>110</x>
      <y>330</y>
      <width>701</width>
      <height>20</height>
     </rect>
    </property>
    <property name="minimum">
     <number>1</number>
    </property>
    <property name="maximum">
     <number>200</number>
    </property>
    <property name="orientation">
     <enum>Qt::Horizontal</enum>
    </property>
   </widget>
   <widget class="QLabel" name="label_2">
    <property name="geometry">
     <rect>
      <x>410</x>
      <y>10</y>
      <width>400</width>
      <height>300</height>
     </rect>
    </property>
    <property name="text">
     <string>TextLabel</string>
    </property>
   </widget>
   <widget class="QLabel" name="label_3">
    <property name="geometry">
     <rect>
      <x>10</x>
      <y>330</y>
      <width>91</width>
      <height>16</height>
     </rect>
    </property>
    <property name="text">
     <string>截取显示图片</string>
    </property>
   </widget>
   <widget class="QLabel" name="label_4">
    <property name="geometry">
     <rect>
      <x>10</x>
      <y>350</y>
      <width>91</width>
      <height>16</height>
     </rect>
    </property>
    <property name="text">
     <string>直接使用模糊</string>
    </property>
   </widget>
   <widget class="QSlider" name="horizontalSlider_2">
    <property name="geometry">
     <rect>
      <x>110</x>
      <y>350</y>
      <width>701</width>
      <height>20</height>
     </rect>
    </property>
    <property name="minimum">
     <number>1</number>
    </property>
    <property name="maximum">
     <number>200</number>
    </property>
    <property name="orientation">
     <enum>Qt::Horizontal</enum>
    </property>
   </widget>
  </widget>
 </widget>
 <resources>
  <include location="aa.qrc"/>
 </resources>
 <connections/>
</ui>

 

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