Re: [ft] Outline decompose scaling

[Michael IV]

I do completely understand what you are saying but it just doesn't work.

So you say to get an outline by font size of 20px for DPI = 72 I have to do this:

   err = FT_Set_Char_Size( faceHandle,64 * 20, 64 * 20, 72, 72 );

But it changes nothing.The text  remains the same size no matter what I put for width/height.

The only way I found to resize the outline points to real-world font size is to calc scale factor  by this formula : pixelFontSize = fontSize / EMunit  and then multiply the outline points with it.

Here is my full code :

const char* fontFile ="fonts/Verdana.ttf";
	std::string chars("& \n");
 
	char charcode = chars[0];
	//ParseGlyphsToPath(testPath , fontFile ,chars);
 
 
	FT_Library defLibHandle;
	FT_Error err = FT_Init_FreeType(&defLibHandle);
	if(err){
		printf(ft_errors[err].err_msg);
		throw;
	}
	FT_Face faceHandle;
	err = FT_New_Face(defLibHandle,fontFile,0,&faceHandle);
 
 
	if(err){
		printf(ft_errors[err].err_msg);
		throw;
	}
	float fontSize = 10.0f;
	 FT_F26Dot6 sz = ftFloatTo266( fontSize );
	//  FT_Set_Pixel_Sizes(faceHandle, 0, 16);
      err = FT_Set_Char_Size( faceHandle,64 * 100, 64 * 100, 72, 72 );
	FT_Glyph glyph;
 
	// load glyph
	FT_UInt glyphIndex =    FT_Get_Char_Index(faceHandle, (FT_ULong)charcode);
    err = FT_Load_Glyph(faceHandle,
                        glyphIndex,
                           FT_LOAD_NO_BITMAP | FT_LOAD_NO_SCALE);
    if (err) {
        std::cout << "FT_Load_Glyph: error\n";
    }
	
	//FT_Get_Glyph(faceHandle->glyph, &glyph);
    FT_Outline  outline = faceHandle->glyph->outline;
	
	if (faceHandle->glyph->format != ft_glyph_format_outline) {
        std::cout << "not an outline font\n";
    }
 
 
	FT_Outline_Funcs funcs;
	funcs.move_to =  (FT_Outline_MoveTo_Func)&moveTo;
	funcs.line_to =  (FT_Outline_LineTo_Func)&lineTo;
	funcs.conic_to = (FT_Outline_ConicTo_Func)&conicTo;
	funcs.cubic_to = (FT_Outline_CubicTo_Func)&cubicTo;
	funcs.shift = 0;
	funcs.delta = 0;
	// trace outline of the glyph
    err = FT_Outline_Decompose(&outline,
                                 &funcs, nullptr);

On Thu, Jun 19, 2014 at 7:55 AM, Werner LEMBERG <address@hidden> wrote:

> Yeah!I finally figured it out. shift and delta were not set. But now
> I don't understand why in the examples number 64 is used to
> downscale the coordinates?

FreeType normally returns coordinates to be multiples if 1/64th
pixels, called `26.6 fractional points'.

> I mean how do I set my text to be of size 20px when using the

> outlines?  Given that the resolution is 72 dpi.  Should I divide 72

> by 2048 and use that product to scale down the path points?

For `FT_Set_Char_Size', the horizontal and vertical resolution
parameters are integers (72 for your example), and the width and
height parameters must be given in 1/64th pixels (20*64).

If you really need integer coordinates, you have to divide all
coordinate values by 64 in the returned `FT_Outline' structure.

Maybe you can point out where the documentation fails to explain
this...


    Werner

--

Michael Ivanov

Graphics Software
onlygraphix.com
Tel:+972 54 4962254