D3D中的字体绘制（1）

D3D中的字体绘制（1）

9.1 ID3DXFont

在D3DX库中提供了一个ID3DXFont接口，它能被用于在Direct3D应用程序中绘制文字。

9.1.1创建一个ID3DXFont

我们能够使用D3DXCreateFontIndirect函数来创建一个ID3DXFont接口。

Creates a font object indirectly for both a device and a font.

HRESULT D3DXCreateFontIndirect(
 LPDIRECT3DDEVICE9 pDevice,
 CONST D3DXFONT_DESC * pDesc,
 LPD3DXFONT * ppFont
);

Parameters

pDevice

[in] Pointer to an IDirect3DDevice9 interface, the device to be associated with the font object.

pDesc

[in] Pointer to a D3DXFONT_DESC structure, describing the attributes of the font object to create. If the compiler settings require Unicode, the data type D3DXFONT_DESC resolves to D3DXFONT_DESCW; otherwise, the data type resolves to D3DXFONT_DESCA. See Remarks.

ppFont

[out] Returns a pointer to an ID3DXFont interface, representing the created font object.

Return Values

If the function succeeds, the return value is D3D_OK. If the function fails, the return value can be one of the following: D3DERR_INVALIDCALL, E_OUTOFMEMORY.

Remarks

The compiler setting also determines the function version. If Unicode is defined, the function call resolves to D3DXCreateFontIndirectW. Otherwise, the function call resolves to D3DXCreateFontIndirectA because ANSI strings are being used.

Defines the attributes of a font.

typedef struct D3DXFONT_DESC {
 INT Height;
 UINT Width;
 UINT Weight;
 UINT MipLevels;
 BOOL Italic;
 BYTE CharSet;
 BYTE OutputPrecision;
 BYTE Quality;
 BYTE PitchAndFamily;
 TCHAR FaceName[LF_FACESIZE];
} D3DXFONT_DESC, *LPD3DXFONT_DESC;

Members

Height

Height, in logical units, of the font's character cell or character.

Width

Width, in logical units, of characters in the font.

Weight

Weight of the font in the range from 0 through 1000.

MipLevels

Number of mip levels requested. If this value is zero or D3DX_DEFAULT, a complete mipmap chain is created. If the value is 1, the texture space is mapped identically to the screen space.

Italic

Set to TRUE for an Italic font.

CharSet

Character set.

OutputPrecision

Output precision. The output precision defines how closely the output must match the requested font height, width, character orientation, escapement, pitch, and font type.

Quality

Output quality.

PitchAndFamily

Pitch and family of the font.

FaceName

A null-terminated string or characters that specifies the typeface name of the font. The length of the string must not exceed 32 characters, including the terminating null character. If FaceName is an empty string, the first font that matches the other specified attributes will be used. If the compiler settings require Unicode, the data type TCHAR resolves to WCHAR; otherwise, the data type resolves to CHAR. See Remarks.

Remarks

The compiler setting also determines the structure type. If Unicode is defined, the D3DXFONT_DESC structure type resolves to a D3DXFONT_DESCW; otherwise the structure type resolves to a D3DXFONT_DESCA.

Possible values of the above members are given in the GDI LOGFONT structure.

下面的代码片段显示了怎样使用这个函数：

    D3DXFONT_DESC font_desc;
    ZeroMemory( & font_desc,  sizeof (font_desc));

    font_desc.Height             =   25 ;         //  in logical units
    font_desc.Width                 =   12 ;         //  in logical units
    font_desc.Weight             =   500 ;         //  boldness, range 0(light) - 1000(bold)
    font_desc.Italic             =  FALSE;
    font_desc.CharSet             =  DEFAULT_CHARSET;
    font_desc.OutputPrecision     =   0 ;
    font_desc.Quality             =   0 ;
    font_desc.PitchAndFamily     =   0 ;

    strcpy(font_desc.FaceName,  " Times New Roman " );

     if (FAILED(D3DXCreateFontIndirect(g_d3d_device,  & font_desc,  & g_d3d_font)))
    {
        MessageBox(NULL,  " D3DXCreateFontIndirect() - FAILED " , NULL, MB_OK);
        PostQuitMessage( 0 );
    }

 

注意：你也能够使用D3DXCreateFont函数来获得一个ID3DXFont接口指针。

9.1.2绘制文本

一旦我们获得了ID3DXFont接口指针，绘制文本就是很简单的事情了，我们只要调用ID3DXFont::DrawText方法就可以实现了。

Draws formatted text. This method supports ANSI and Unicode strings.

INT DrawText(
 LPD3DXSPRITE pSprite,
 LPCTSTR pString,
 INT Count,
 LPRECT pRect,
 DWORD Format,
 D3DCOLOR Color
);

Parameters

pSprite

[in] Pointer to an ID3DXSprite object that contains the string. Can be NULL, in which case Direct3D will render the string with its own sprite object. To improve efficiency, a sprite object should be specified if ID3DXFont::DrawText is to be called more than once in a row.

pString

[in] Pointer to a string to draw.If the Count parameter is -1, the string must be null-terminated.

Count

[in] Specifies the number of characters in the string. If Count is -1, then the pString parameter is assumed to be a pointer to a null-terminated string and ID3DXFont::DrawText computes the character count automatically.

pRect

[in] Pointer to a RECT structure that contains the rectangle, in logical coordinates, in which the text is to be formatted. As with any RECT object, the coordinate value of the rectangle's right side must be greater than that of its left side. Likewise, the coordinate value of the bottom must be greater than that of the top.

Format

[in] Specifies the method of formatting the text. It can be any combination of the following values:

DT_BOTTOM

Justifies the text to the bottom of the rectangle. This value must be combined with DT_SINGLELINE.

DT_CALCRECT

Determines the width and height of the rectangle. If there are multiple lines of text, ID3DXFont::DrawText uses the width of the rectangle pointed to by the pRect parameter and extends the base of the rectangle to bound the last line of text. If there is only one line of text, ID3DXFont::DrawText modifies the right side of the rectangle so that it bounds the last character in the line. In either case, ID3DXFont::DrawText returns the height of the formatted text but does not draw the text.

DT_CENTER

Centers text horizontally in the rectangle.

DT_EXPANDTABS

Expands tab characters. The default number of characters per tab is eight.

DT_LEFT

Aligns text to the left.

DT_NOCLIP

Draws without clipping. ID3DXFont::DrawText is somewhat faster when DT_NOCLIP is used.

DT_RIGHT

Aligns text to the right.

DT_RTLREADING

Displays text in right-to-left reading order for bidirectional text when a Hebrew or Arabic font is selected. The default reading order for all text is left-to-right.

DT_SINGLELINE

Displays text on a single line only. Carriage returns and line feeds do not break the line.

DT_TOP

Top-justifies text.

DT_VCENTER

Centers text vertically (single line only).

DT_WORDBREAK

Breaks words. Lines are automatically broken between words if a word would extend past the edge of the rectangle specified by the pRect parameter. A carriage return/line feed sequence also breaks the line.

Color

[in] Color of the text. For more information, see D3DCOLOR.

Return Values

If the function succeeds, the return value is the height of the text in logical units. If DT_VCENTER or DT_BOTTOM is specified, the return value is the offset from pRect (top to the bottom) of the drawn text. If the function fails, the return value is zero.

Remarks

The parameters of this method are very similar to those of the GDI DrawText function.

This method supports both ANSI and Unicode strings.

This method must be called inside a IDirect3DDevice9::BeginScene ... IDirect3DDevice9::EndScene block. The only exception is when an application calls ID3DXFont::DrawText with DT_CALCRECT to calculate the size of a given block of text.

Unless the DT_NOCLIP format is used, this method clips the text so that it does not appear outside the specified rectangle. All formatting is assumed to have multiple lines unless the DT_SINGLELINE format is specified.

If the selected font is too large for the rectangle, this method does not attempt to substitute a smaller font.

This method supports only fonts whose escapement and orientation are both zero.

运行截图：

主程序：

/* *************************************************************************************
  Shows how to calculate the number of frames rendered per second and demonstrates 
  how to render text with the ID3DXFont interface.  
 ************************************************************************************* */

#include  < stdio.h >
#include  " d3dUtility.h "

#pragma warning(disable :  4100   4996 )

const   int  WIDTH   =   640 ;
const   int  HEIGHT  =   480 ;

IDirect3DDevice9 *         g_d3d_device;
ID3DXFont *                 g_d3d_font;

DWORD    g_frame_count;
float     g_time_elapsed;
float     g_fps;
char     g_fps_string[ 9 ];

/////////////////////////////////////////////////////////////////////////////////////////////////// /

bool  setup()
{    
    D3DXFONT_DESC font_desc;
    ZeroMemory( & font_desc,  sizeof (font_desc));

    font_desc.Height             =   25 ;         //  in logical units
    font_desc.Width                 =   12 ;         //  in logical units
    font_desc.Weight             =   500 ;         //  boldness, range 0(light) - 1000(bold)
    font_desc.Italic             =  FALSE;
    font_desc.CharSet             =  DEFAULT_CHARSET;
    font_desc.OutputPrecision     =   0 ;
    font_desc.Quality             =   0 ;
    font_desc.PitchAndFamily     =   0 ;

    strcpy(font_desc.FaceName,  " Times New Roman " );

     if (FAILED(D3DXCreateFontIndirect(g_d3d_device,  & font_desc,  & g_d3d_font)))
    {
        MessageBox(NULL,  " D3DXCreateFontIndirect() - FAILED " , NULL, MB_OK);
        PostQuitMessage( 0 );
    }
    
     return   true ;
}

////////////////////////////////////////////////////////////////////////////////////////////////////// /

void  cleanup()
{    
    safe_release < ID3DXFont *> (g_d3d_font);    
}

////////////////////////////////////////////////////////////////////////////////////////////////////// /

bool  display( float  time_delta)
{
     //  update: compute the frames per second.

    g_frame_count ++ ;
    g_time_elapsed  +=  time_delta;

     if (g_time_elapsed  >=   1.0f )
    {
        g_fps  =  g_frame_count  /  g_time_elapsed;

        sprintf(g_fps_string,  " %f " , g_fps);
        g_fps_string[ 8 ]  =   ' \0 ' ;     //  mark end of string

        g_time_elapsed  =   0.0f ;
        g_frame_count   =   0 ;
    }

     //  render

    g_d3d_device -> Clear( 0 , NULL, D3DCLEAR_TARGET  |  D3DCLEAR_ZBUFFER,  0xffffffff ,  1.0f ,  0 );

    g_d3d_device -> BeginScene();

    RECT rect  =  { 0 ,  0 , WIDTH, HEIGHT};
    g_d3d_font -> DrawText(NULL, g_fps_string,  - 1 ,  & rect, DT_TOP  |  DT_LEFT,  0xff000000 );

    g_d3d_device -> EndScene();

    g_d3d_device -> Present(NULL, NULL, NULL, NULL);

     return   true ;
}

////////////////////////////////////////////////////////////////////////////////////////////////////// /

LRESULT CALLBACK wnd_proc(HWND hwnd, UINT msg, WPARAM word_param, LPARAM long_param)
{
     switch (msg)
    {
     case  WM_DESTROY:
        PostQuitMessage( 0 );
         break ;

     case  WM_KEYDOWN:
         if (word_param  ==  VK_ESCAPE)
            DestroyWindow(hwnd);
         break ;
    }

     return  DefWindowProc(hwnd, msg, word_param, long_param);
}

////////////////////////////////////////////////////////////////////////////////////////////////////// /

int  WINAPI WinMain(HINSTANCE inst, HINSTANCE, PSTR cmd_line,  int  cmd_show)
{
     if ( !  init_d3d(inst, WIDTH, HEIGHT,  true , D3DDEVTYPE_HAL,  & g_d3d_device))
    {
        MessageBox(NULL,  " init_d3d() - failed. " ,  0 , MB_OK);
         return   0 ;
    }

     if ( !  setup())
    {
        MessageBox(NULL,  " Steup() - failed. " ,  0 , MB_OK);
         return   0 ;
    }

    enter_msg_loop(display);

    cleanup();
    g_d3d_device -> Release();

     return   0 ;
}

 

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