Dynamically generating images in ISAPI extension using GDI+ with live demo

#pragma once
#include <math.h>

/*! \brief A GDI+ Image Renderer for MFC ISAPI Extensions

\par Description

<p>This class enables you to render GDI+ image on the server and send them directly to the client browser
without passing by temporarly files.</p>

\par Basic use
<p>The use of the class is straight forward: build a CGDIpISAPI object with all the pointers and call WriteImage:</p>
\code
void CHttpServerDerviedClass::Default( CHttpServerContext* pCtxt)
{
	using namespace Gdiplus;

	// creating bitmap
	Bitmap bitmap(320,200);
	// drawing on this bitmap
	...
	
	// sending bitmap to the browser
	CGDIpISAPI renderer( this, pCtxt, &bitmap );
		// sending image
	renderer.WriteImage();
}
\endcode

\par Output options
<p>You can choose the image code (PNG, JPEG, BMP or TIFF) and change the quality ratio for the PNG and JPEG files.
The quality must be between 0 and 100.</p>
<p>All these options can be set at the construction or by setters.</p>
\code 
// Setting bmp type
renderer.SetImageType( CGDIpISAPI::ImageBMP);
\endcode
\code 
// Changing quality
renderer.SetQuality( 98 );
\endcode

\par Initializing GDI+
<p>Do not forget to initialize and deinitialize GDI+. I'm using a helper class for that: CGDIpInitializer.</p>
\code 
class CMyExtension
{
...
	CGDIpInitializer m_GDIpInitializer;
}
\endcode
\code
BOOL CMyExtension::GetExtensionVersion(HSE_VERSION_INFO* pVer)
{
	// Appelez l'impl�mentation par d�faut pour l'initialisation
	CHttpServer::GetExtensionVersion(pVer);

	// Initialize GDI+
	m_GDIpInitializer.Initialize();
	...
\endcode
\code
BOOL CMyExtension::TerminateExtension(DWORD dwFlags)
{
	// l'extension est arr�t�e
	//TODO�: nettoyez les ressources par instance
	m_GDIpInitializer.Deinitialize();
\endcode
\par What not to do...
<ul>
<li>When writing an image, do not write anything else!</li>
</ul>

\author Jonathan de Halleux, dehalleux@auto.ucl.ac.be
*/
class CGDIpISAPI
{
public:
	//! \name Typdefs
	//@{
	//! Different supported image codecs
	static enum EImageType
	{
		//! Portable Network Graphics
		ImagePNG = 0,
		//! Famous JPEG
		ImageJPEG = 1,
		//! Bitmap
		ImageBMP=2
	};
	//@}

	//! \name Constructors
	//@{
	/*! \brief Default constructor

	  \param pServer pointer to the CHttpServer class
	  \param pCtxt pointer to the CHttpServerContext object
	  \param pImage pointer to a GDI+ image object
	  \param eImageType image type (default is PNG)
	  \param ulQuality quality. Applies to PNG and JPEG (default is 80)

	  The quality must be an integer between 0 (ugly, good compression) and 100 (nice, poor compression).
	 */
	CGDIpISAPI(CHttpServer* pServer=NULL, 
		CHttpServerContext* pCtxt=NULL,
		Gdiplus::Image* pImage=NULL, EImageType eImageType = ImagePNG, ULONG ulQuality = 80)
	: m_pServer(pServer),m_pCtxt(pCtxt), m_pImage(pImage), m_eImageType(ImagePNG)
	{	SetQuality(ulQuality);};
	~CGDIpISAPI(){};
	//@}

	//! \name Output options
	//@{
	//! Sets the image type
	void SetImageType(EImageType eImageType)	{	m_eImageType = eImageType;};
	//! return the image type
	EImageType GetImageType() const				{	return m_eImageType;};
	//! returns CGI string describing the current image type
	LPCTSTR CGDIpISAPI::GetImageTypeString() const;
	//! Sets the quality between 0 (ugly, good compression) and 100 (nice, poor compression)
	void SetQuality(ULONG ulQuality)			{	m_ulQuality=__min(100,ulQuality);};
	//! return the quality
	ULONG GetQuality() const					{	return m_ulQuality;};
	//@}

	//! \name Output functions
	//@{
	//! Send the image to the brower
	void WriteImage();
	//! Writes info about the image
	void WriteInfo(void);
	//@}

private:
	//! \name Helpers
	//@{
	void DumpError(LPCTSTR pszFormat, ...);
	void WriteContext(LPCTSTR szFormat,...);
	int GetEncoderClsid(const WCHAR* format, CLSID* pClsid);
	//@}
		
	CHttpServer* m_pServer;
	CHttpServerContext* m_pCtxt;
	Gdiplus::Image* m_pImage;
	EImageType m_eImageType;
	UINT m_ulQuality;
};