CppUnit TDD之探索swf文件头(中)

这一篇，我们来看一下代码。

using System;

using System.IO;

namespace SwfheaderReader

{

/// <summary>

/// Summary description for FlashHeaderReader.

/// </summary>

public class FlashHeaderReader

{

internal int FrameRate

{

get { return mFrameRate; }

}

internal int FrameCount

{

get { return mFrameCount; }

}

internal int Width

{

get { return mWidth; }

}

internal int Height

{

get { return mHeight; }

}

internal bool Error

{

get {return mbErrorSignature;}

}

private int mFrameRate=0;

private int mFrameCount=0;

private int mVersion=0;

private bool mIsCompressed=false;

private int mWidth=0;

private int mHeight=0;

private bool mbErrorSignature;

// To Parse Header

private byte[] data;

private int currentIndex;

public FlashHeaderReader(String filename)

{

currentIndex=0;

mbErrorSignature=false;

FileStream fs = File.OpenRead(filename);

data = new byte[fs.Length];

fs.Read (data,data.Length);

fs.Close();

ParseHeader();

}

/*

*Parse the header of the swf format

*Format http://www.half-serious.com/swf/format/index.html#header

*convert from PHP : http://www.zend.com/codex.php?id=1382&single=1

*/

private void ParseHeader()

{

ReadSignature();

mVersion=GetNextByte();

ReadFileLength();

ReadFrameSize();

ReadFrameRate();

ReadFrameCount();

}

/*

* Read first caractere FWS or CWS

* File compressed are not supported

*/

private void ReadSignature()

{

Byte readingByte=GetNextByte();

if (readingByte=='C')

{

mIsCompressed=true;

// Not supported

}

if (readingByte!='F' && readingByte!='C')

{

mbErrorSignature=true;

}

if (GetNextByte()!='W') mbErrorSignature=true;

if (GetNextByte()!='S') mbErrorSignature=true;

}

/*

*Read the RECT Structure : Frame size in twips

*This retrieve from byte the size.

*the source PHP is difficult to translate I have made

*something working...

*/

private void ReadFrameSize()

{

int cByte = GetNextByte();

int NbBits=cByte>>3;

cByte&=7;

cByte<<=5;

int currentBit=2;

int currentValue;

// Must get all 4 values in the RECT

for (int numField=0;numField<4;numField++)

{

currentValue=0;

int bitcount = 0 ;

while (bitcount<NbBits)

{

if ((cByte&128)==128)

{

currentValue =currentValue + (1<<(NbBits-bitcount-1)) ;

}

cByte<<=1 ;

cByte &= 255 ;

currentBit-- ;

bitcount++ ;

// We will be needing a new byte if we run out of bits

if (currentBit<0)

{

cByte = GetNextByte() ;

currentBit = 7 ;

}

}

// TWIPS to PIXELS

currentValue/=20;

switch (numField)

{

case 0:

mWidth = currentValue ;

break ;

case 1:

mWidth = currentValue - mWidth ;

break ;

case 2:

mHeight = currentValue ;

break ;

case 3:

mHeight = currentValue - mHeight ;

break;

}

}

}

/*

* Read Frame delay in 8.8 fixed number of frames per second

*/

private void ReadFrameRate()

{

// Frame rate

bytefps_decimal,fps_int ;

fps_decimal = GetNextByte();

fps_int =GetNextByte();

mFrameRate=fps_int+(fps_decimal)/100;

}

private void ReadFrameCount()

{

for (int i=0;i<2;i++)

{

mFrameCount+= (GetNextByte()<<(8*i)) ;

}

}

/*

*ReadFileLength : Length of entire file in bytes

*Not implemented

*/

private void ReadFileLength()

{

//Read Size

GetNextByte();

GetNextByte();

GetNextByte();

GetNextByte();

}

/*

*Retrieve one caractere of the buffer.

*/

private byte GetNextByte()

{

Byte result;

result=data[currentIndex];

currentIndex++;

return(result);

}

}

}

哇塞。怎么这么写啊。

private void ParseHeader()

{

ReadSignature();

mVersion=GetNextByte();

ReadFileLength();

ReadFrameSize();

ReadFrameRate();

ReadFrameCount();

}

在C++里面，我一个File的open一下就读完所有的结构了啊。

还好我前两年看了设计模式，要不还不被人笑死。这个应该算是builder模式吧。

从重构的角度讲，小函数更具灵活性，而且更容易被重用。这点上，最后一个函数GetNextByte()也是深得重构理论真传。

好了，先写个测试读取文件大小的用例吧。

写个读取swf文件的类。

//SwfReader.h

#pragma once

typedef struct Swfheader {

DWORD mfType; // CWS,Signature 0x46,0x57,0x53 (“FWS”)

BYTE version;

DWORD fileLength;

WORD frameRate;

WORD frameCount;

} SWfheADER,*PSWfheADER;

class CSwfReader

{

public:

CSwfReader(void){};

~CSwfReader(void)

{

if (NULL != m_byData)

{

delete[] m_byData;

}

}

void ParseHeader(void)

{

ReadSignature();

swfheader.version = GetNextByte();

m_bHeader = TRUE;

ReadFileLength();

ReadFrameSize();

ReadFrameRate();

ReadFrameCount();

}

SWfheADER swfheader;

BOOL m_bOpen;

BOOL m_bHeader;

private:

BYTE* m_byData;

CFile m_file;

int currentIndex;

void ReadSignature()

{

GetNextByte();

GetNextByte();

GetNextByte();

}

void ReadFileLength()

{

swfheader.fileLength = GetNextDWord();

}

void ReadFrameSize()

{

}

void ReadFrameRate()

{

}

void ReadFrameCount()

{

}

BYTE GetNextByte()

{

BYTE result;

result=m_byData[currentIndex];

currentIndex++;

return(result);

}

WORD GetNextWord()

{

WORD result;

result=m_byData[currentIndex];

currentIndex+=2;

return(result);

}

DWORD GetNextDWord()

{

DWORD result;

int temp = 0;

result = m_byData[currentIndex];

temp = m_byData[currentIndex+1];

result += temp<<8;

temp = m_byData[currentIndex+2];

result += temp<<16;

temp = m_byData[currentIndex+3];

result += temp<<24;

currentIndex+=4;

return(result);

}

public:

CSwfReader(CString aszName)

:currentIndex(0)

,m_bOpen(FALSE)

,m_bHeader(FALSE)

{

if(!m_file.Open(aszName,CFile::modeRead))

{

m_bOpen = FALSE;

return ;

}

int dwFileSize = m_file.GetLength();

m_byData = new BYTE[dwFileSize];

memset(m_byData,0x00,dwFileSize);

m_file.Read(m_byData,dwFileSize);

m_bOpen = TRUE;

}

};

不是吧，怎么都写在h里面啊。（会写c++程序吗？）

Visual Assist 10.4里面集成了函数挪移的重构方法。所以写在哪里不重要哦。关键是，这不是发布容易嘛！

过会儿，我就（乾坤）挪移一下。（真想挪点儿面包过来。）

在CSwfReaderTest类里面添加TestSwfReader测试方法。引用需要测试的头文件过来。

void TestSwfReader(void)

{

CSwfReader swfR(_T("g:/worksource/Robot/Twins02.swf"));

swfR.ParseHeader();

BYTE version = swfR.swfheader.version;

int length = swfR.swfheader.fileLength;

CPPUNIT_ASSERT_EQUAL((int)version,5);

CPPUNIT_ASSERT_EQUAL(length,81125);

}

好了。泡一下测试吧。是不是又通过了。

这就像上学的时候，每次到大考的时候，都不慌张。为什么？

因为每月一次的模拟考试，已经让你了解了，你的考试水平。正常情况是不会有太大偏差的。

cppunit也是这样一个东西吧。可以让我们每个部分都自测一下。然后发布的时候，就不用着急了。基本上，主要的，核心的功能，都有测试代码，每次都运行着，不会出现太大偏差。

上传一下源码。让一些比较懒的朋友，舒服一下。

更多精彩部分，请看下篇。

原文地址：https://www.jb51.cc/javaschema/288067.html