2008年（884）
分类： C/C++
2008-08-06 10:03:11
1、通过 CFontDialog 进行字体选择，但是正常情况下得到的字体列表示当前系统中所有支持的字体，当然也包括其它一些非 TrueType 字体，要在 CFontDialog 的列表中剔出非 TrueType 的字体很简单，只需在配置 CFontDialog 时如下设置：
CFontDialog dlg; dlg.m_cf.Flags |= CF_TTONLY; //only enum TrueType
2、要遍历所选择的字体中所包含的所有字符，这个我们不禁想到可以通过 .ttf文件的解析来完成，但是如何得到选择的字体所对应的 .ttf文件哪？同实际的操作，得知在CfontDialog中显示的字体的名称和所对应的.ttf文件不是一一对应的关系，例如：选择的字体为 Arial 那么在 System/Fonts/下却没有 Arial.ttf 的文件，在网上找了很多例子都不能百分百无误的实现，在 codeproject 中有一个例子
Sample 通过注册表的方法来查找，但是同样存在上面的问题。而且即使能够找到相对应的.ttf文件，要解析这个文件也很有困难，因为存在 ttc的问题(即：一个是一个ttf的集合，一个文件里面有可能定义几种 TrueType 字体)，这样还要根据选择的字体然后在读取ttf文件的过程中进行比较，找到描述这种这种字体的部分，后来发现选择的字体有可能和文档中定义的TrueType
字体名称不一致，因为有中文字体的存在，这一部分我并没有进行测试。因为在之后的解决过程找到了另外一种解决的方法。
DWORD CDC::GetFontData( DWORD dwTable, DWORD dwOffset, LPVOID lpData, DWORD cbData ) const; Remarks Retrieves font-metric information from a scalable font file. The information to retrieve is identified by specifying an offset into the font file and the length of the information to return. An application can sometimes use the GetFontData member function to save a TrueType font with a document. To do this, the application determines whether the font can be embedded and then retrieves the entire font file, specifying 0 for the dwTable, dwOffset, and cbData parameters.
通过上面的函数可以轻易的得到选入DC中的TrueType字体的 ttf文件中的数据，但是如果想得到整个的字体文件还是会存在ttc的问题，因为这个函数得到的数据是其中选择的那种字体的数据，但是对于各个数据段offset的定义却是针对于整个文档的，如果直接引用就会有问题，也没有找到其他更好的解决方法，但是却可以准确地得到关于其中任意一个Table的数据，刚刚好对于字符集中所包含的字符的定于存在于"cmap" Table中，问题解决了，如下：
// Macro to pack a TrueType table name into a DWORD.
#define MAKETABLENAME(ch1, ch2, ch3, ch4) (\
(((DWORD)(ch4)) << 24) | \
(((DWORD)(ch3)) << 16) | \
(((DWORD)(ch2)) << 8) | \
((DWORD)(ch1))
)
DWORD tag = MAKETABLENAME( ''c'',''m'',''a'',''p'' );
DWORD size = m_pFontDC->GetFontData(tag,0, NULL, 0);
unsigned char *pBuffer = new unsigned char[size];
m_pFontDC->GetFontData(tag,0,pBuffer,size);
//do something with pBuffer
delete[] pBuffer;
其中具体的一些操作也可以参照
msdn 中的文章。之后就是解析ttf文件了，这要参考MS发布的TrueType Font规格书了，当然即使看懂了规格书，要自己做解析程序也是短时间难以完成的，还是让我们来找找有没有其他的
已经有了的经验，在这里就要提到一个开源的项目了
fontforge 这是个日本人和台湾人维护的一个项目，可以支持多种字体进行解析和编辑，可以是个 Linux 下的程序，不过我们可以使用 Cygwin 来使这个程序在
Windows下运行起来，具体请参考 freefonts.oaka.org，但是这个程序太复杂太庞大了，我们一时半会
还不能理出头绪来，幸好在
cle.linux.org
看到 fontfoge 中有一个小工具叫做 showttf.c 可以简单的对于ttf文件进行解析，下载过来，进行编译，很有效。之后将其改进成可以只针对于“cmap”数据进行解析，并得到字体中支持字符的分段。
/*
read a short(2 bytes) from a stream
**/
static int Getushort(unsigned char **ttf) {
unsigned char ch1 = **(ttf);
(*ttf) ;
unsigned char ch2 = **(ttf);
(*ttf) ;
return( (ch1<<8)|ch2 );
}
/*
read a long(4 bytes) from a stream
**/
static int Getlong(unsigned char **ttf) {
unsigned char ch1 = **(ttf);
(*ttf) ;
unsigned char ch2 = **(ttf);
(*ttf) ;
unsigned char ch3 = **(ttf);
(*ttf) ;
unsigned char ch4 = **(ttf);
(*ttf) ;
return( (ch1<<24)|(ch2<<16)|(ch3<<8)|ch4 );
}
/*
Parse the table of "cmap"
**/
BOOL ReadttfEncodings(unsigned char *start_addr)
{
BOOL bResult = TRUE;
unsigned char *ttf = start_addr;
//local variable
int i;
int nencs, version;
int enc = 0;
int platform, specific;
int offset, encoff;
int format, len;
int segCount;
unsigned short *endchars,*startchars;
version = Getushort(&ttf);
nencs = Getushort(&ttf);
if ( version!=0 && nencs==0 )
nencs = version;/* Sometimes they are backwards */
for ( i=0; i < nencs; i )
{
platform = Getushort(&ttf);
specific = Getushort(&ttf);
offset = Getlong(&ttf);
if ( platform==3 /*&& (specific==1 || specific==5)*/)
{
enc = 1;
encoff = offset;
} else if ( platform==1 && specific==0 && enc!=1 )
{
enc = 2;
encoff = offset;
} else if ( platform==1 && specific==1 )
{
enc = 1;
encoff = offset;
} else if ( platform==0 ) {
enc = 1;
encoff = offset;
}
if ( platform==3 )
{
//MS Symbol
}
else if ( platform==1 )
{
//Mac Roman;
}
else if ( platform==0 )
{
//Unicode Default
}
else{}
}
if ( enc!=0 )
{
//reset pointer address
ttf = start_addr encoff;
format = Getushort(&ttf);
if ( format!=12 && format!=10 && format!=8 )
{
len = Getushort(&ttf);
/*Language*/ Getushort(&ttf);
}
else
{
/* padding */ Getushort(&ttf);
len = Getlong(&ttf);
/*Format*/ Getlong(&ttf);
}
if ( format==0 )
{
//can''t be supported
bResult = FALSE;
}
else if ( format==4 )
{
//Format 4 (Windows unicode),only supported Format 4
segCount = Getushort(&ttf)/2;
/* searchRange = */ Getushort(&ttf);
/* entrySelector = */ Getushort(&ttf);
/* rangeShift = */ Getushort(&ttf);
endchars = new unsigned short[segCount];
for ( i=0; i < segCount; i )
endchars[i] = Getushort(&ttf);
if ( Getushort(&ttf)!=0 )
{
//Expected 0 in true type font;
}
startchars = new unsigned short[segCount];
for ( i=0; i < segCount; i )
startchars[i] = Getushort(&ttf);
//do something with endchars & startchars
delete[] startchars;
delete[] endchars;
}
else if ( format==6 )
{
/* Apple''s unicode format */
/* Well, the docs say it''s for 2byte encodings, but Apple actually*/
/* uses it for 1 byte encodings which don''t fit into the require-*/
/* ments for a format 0 sub-table. See Zapfino.dfont */
//can''t be supported
bResult = FALSE;
}
else if ( format==2 )
{
//can''t be supported
bResult = FALSE;
}
else if ( format==12 )
{
//can''t be supported
bResult = FALSE;
}
else if ( format==8 )
{
// fprintf(stderr,"I don''t support mixed 16/32 bit
// characters (no unicode surogates), format=%d", format);
// can''t be supported
bResult = FALSE;
}
else if ( format==10 )
{
//fprintf(stderr,"I don''t support 32 bit characters format=%d", format);
//can''t be supported
bResult = FALSE;
}
else
{
//fprintf(stderr,"Eh? Unknown encoding format=%d", format);
//can''t be supported
bResult = FALSE;
}
}
return bResult;
}
3、通过选入字体的DC得到字体的点阵数据，这个处理依靠如下的函数，
DWORD GetGlyphOutline( UINT nChar,
UINT nFormat,
LPGLYPHMETRICS lpgm,
DWORD cbBuffer,
LPVOID lpBuffer,
const MAT2 FAR* lpmat2 ) const;
Remarks
Retrieves the outline curve or bitmap for an outline character in the current font.
具体请参考
msdn 可以得到 anti-alias 等多种格式的数据。
但是这个有一个问题就是如果对应一个字体的size的各个参数，这里面的麻烦很多，后来总结如下如下：
还有补充的就是 GetGlyphOutline 数据是有一定的对齐方式的，要进行一些处理，代码如下：
BOOL CreateFontMatrix(int iAA,
UINT nChar,
unsigned char **pOutPut,
int *iBytesPreLine,
int *iLine,
int *iBaseLine,
int *iBox_x,
int *iBox_y)
{
unsigned char *pBuf;
TEXTMETRIC tm;
GLYPHMETRICS glyph;
int width,height,box_x,box_y,ori_x,ori_y,size,iAdjust;
BOOL bRel = TRUE;
MAT2 mat2 =
{
{ 0, 1, },
{ 0, 0, },
{ 0, 0, },
{ 0, 1, }
};
//Get glyph outline
memset(&glyph,0,sizeof(GLYPHMETRICS));
size = m_pFontDC->GetGlyphOutline(nChar,m_nFormat,&glyph,0,NULL,&mat2);
if (size >= 0) // if char is space, the size may be zero
{
int count = 0;
int data = 0;
pBuf = new unsigned char[size];
m_pFontDC->GetTextMetrics(&tm);
m_pFontDC->GetGlyphOutline(nChar,m_nFormat,&glyph,size,pBuf,&mat2);
ori_x = glyph.gmptGlyphOrigin.x;
//if ori_x is negative,set ori_x zero
ori_x = (ori_x < 0) ? 0 : ori_x;
ori_y = tm.tmAscent - glyph.gmptGlyphOrigin.y;
box_x = glyph.gmBlackBoxX;
box_y = glyph.gmBlackBoxY;
width = glyph.gmCellIncX;
iAdjust = (box_x 3)&0xfffc; //DWORD align
if((box_x ori_x) > width)
box_x = width - ori_x;
height= m_pLf->lfHeight;
//convert
int index = 0;
if (iAA == AA_2)
{
width = (width%4 == 0)?width/4:(width/4 1); //here,to 2bits/pix
*pOutPut = new unsigned char[width*height 1];
memset(*pOutPut,0,width*height 1);
//if size == 0 all data is 0
if(size > 0)
{
for (int i = 0; i < box_y; i )
{
for (int j = 0; j < box_x; j )
{
//int k = pBuf[i*iAdjust j];
data = AA2_GRAG_MATRIX[pBuf[i*iAdjust j]];
index = (i ori_y)*width (j ori_x)/4;
switch((j ori_x)%4)
{
case 0:
(*pOutPut)[index] |= (data<<6)&0xC0;
break;
case 1:
(*pOutPut)[index] |= (data<<4)&0x30;
break;
case 2:
(*pOutPut)[index] |= (data<<2)&0x0C;
break;
case 3:
(*pOutPut)[index] |= data&0x03;
break;
default:
{}
}
}//end j
}//end i
}
}//end AA 2*2
else if (iAA == AA_4)
{
width = (width%2 == 0)?width/2:(width/2 1); //here,to 4bits/pix
*pOutPut = new unsigned char[width*height 1];
memset(*pOutPut,0,width*height 1);
//if size == 0 all data is 0
if(size > 0)
{
for (int i = 0; i < box_y; i )
{
for (int j = 0; j < box_x; j )
{
ASSERT(pBuf[i*iAdjust j] <= 17);
data = AA4_GRAG_MATRIX[pBuf[i*iAdjust j]];
index = (i ori_y)*width (j ori_x)/2;
switch((j ori_x)%2)
{
case 0:
(*pOutPut)[index] |= (data<<4)&0xF0;
break;
case 1:
(*pOutPut)[index] |= data&0x0F;
break;
default:
{}
}
}//end j
}//end i
}
}//end AA 4*4
else //start Normal
{
//Note: monochrome bitmap，the first data in pBuff is on the Left-bottom
// one bit per pix
width = (width%8 == 0)?width/8:(width/8 1); //here,to 4bits/pix
if (width == 0)
width = 1;
*pOutPut = new unsigned char[width*height 1];
memset(*pOutPut,0,width*height 1);
//if size == 0 all data is 0
if(size > 0)
{
for (int i = 0; i < box_y; i )
{
for (int j = 0; j < width; j )
{
(*pOutPut)[(i ori_y)*width j] |= data<<(8-ori_x);
data = pBuf[i*(size/box_y) j];
(*pOutPut)[(i ori_y)*width j] |= data>>ori_x;
}//end j
}//end i
}
}//end else(normal bitmap)
if(pBuf != NULL)
delete[] pBuf;
//set return result
*iBytesPreLine = width;
*iLine = height;
*iBaseLine = tm.tmAscent;
*iBox_x = glyph.gmCellIncX;//box_x;
*iBox_y = box_y;
bRel = TRUE;
}
else//if size
bRel = FALSE;
return bRel;
}
结束语