序言

在一个项目中，需要输出osg仿真的图像结果，但是直接借用源码中的ScreenCaptureHandler无法实现咋指定目录下输出，且输出图像名称无法修改，默认使用按键的响应方式无法满足项目需求，在参考相关源码和帖子的基础上，以及方方的大力帮助下，有了下面的内容。
与现有网上大量内容相比，其只给出了代码，没有给出如何使用，让和我一样的超级菜鸟一头雾水。所以有了下面的内容。

a.h文件定义如下：

#pragma once#ifndef A_H
#define A_H#include <string>
#include <osgDB/WriteFile>
#include <osgViewer/ViewerEventHandlers>class CScreenCapture : public osgViewer::ScreenCaptureHandler
{
public:int il;class  WriteToImageFile : public osgViewer::ScreenCaptureHandler::CaptureOperation{public:enum SavePolicy{OVERWRITE,SEQUENTIAL_NUMBER};WriteToImageFile(const std::string& filename, const std::string& extension, SavePolicy savePolicy = SEQUENTIAL_NUMBER) {_filename = filename;_extension = extension;_savePolicy = savePolicy;ik = 0;}virtual void operator()(const osg::Image& image, const unsigned int context_id)//仿函数实现图片保存{if (!_filename.empty()){std::string patch = _filename+"_"+std::to_string(ik)+"." + _extension;osgDB::writeImageFile(image, patch); ik++;}}void setFileName(const std::string &filename){_filename = filename;}void setSavePolicy(SavePolicy savePolicy) { _savePolicy = savePolicy; }SavePolicy getSavePolicy() const { return _savePolicy; }protected:WriteToImageFile& operator = (const WriteToImageFile&) { return *this; }std::string _filename;std::string _extension;SavePolicy _savePolicy;std::vector<unsigned int> _contextSaveCounter;int ik;};CScreenCapture(CaptureOperation* defaultOperation = 0, int numFrames = 1);virtual bool handle(const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa);//void setFileName();
};#endif
//https://blog.csdn.net/xjujun/article/details/38986301

a.cpp如下：

/****************************************************************************
*
*
*
****************************************************************************///#include "stdafx.h"
#include "a.h"CScreenCapture::CScreenCapture(CaptureOperation* defaultOperation /*= 0*/, int numFrames/* = 1*/):
ScreenCaptureHandler( defaultOperation, numFrames )
{il = 0;
}bool CScreenCapture::handle( const osgGA::GUIEventAdapter& ea, osgGA::GUIActionAdapter& aa )
{osgViewer::ViewerBase* viewer = dynamic_cast<osgViewer::View*>(&aa)->getViewerBase();if (!viewer) return false;switch(ea.getEventType()){case (osgGA::GUIEventAdapter::FRAME):{  addCallbackToViewer(*viewer);if (getFramesToCapture() == 0){setFramesToCapture(1);}break;}default:break;}return false;
}//void CScreenCapture::setFileName()
//{
//  CScreenCapture::WriteToImageFile* wtf =  dynamic_cast<CScreenCapture::WriteToImageFile*>(getCaptureOperation());
//  //wtf->setFileName("11111111.jpg");
//  //wtf->setSavePolicy(wtf->SEQUENTIAL_NUMBER);
//  wtf->setFileName(std::to_string(il) + ".jpg");
//}

用法：

....std::string path = "./1/IR123456789.jpg";osg::ref_ptr<CScreenCapture::WriteToImageFile> wfi = new CScreenCapture::WriteToImageFile(osgDB::getNameLessExtension(path),osgDB::getFileExtension(path)); osg::ref_ptr<CScreenCapture >cs = new CScreenCapture(wfi.get());viewer.addEventHandler(cs.get());
//外部控制时，使用  viewer.removeEventHandler(cs.get());//此处未测试
....

参考资料：

1. https://blog.csdn.net/xjujun/article/details/38986301
2. osg源码: D:\OSG\OSG_3.4.0\src\applications\present3D\present3D.cpp [line624]

// add the screen capture handlerstd::string screenCaptureFilename = "screen_shot.jpg";while(arguments.read("--screenshot", screenCaptureFilename)) {}osg::ref_ptr<osgViewer::ScreenCaptureHandler::WriteToFile> writeFile = new osgViewer::ScreenCaptureHandler::WriteToFile(osgDB::getNameLessExtension(screenCaptureFilename),osgDB::getFileExtension(screenCaptureFilename) );osg::ref_ptr<osgViewer::ScreenCaptureHandler> screenCaptureHandler = new osgViewer::ScreenCaptureHandler(writeFile.get());screenCaptureHandler->setKeyEventTakeScreenShot('m');//osgGA::GUIEventAdapter::KEY_Print);screenCaptureHandler->setKeyEventToggleContinuousCapture('M');viewer.addEventHandler(screenCaptureHandler.get());