[ft-devel] character spacing
In order to draw my text, I currently make calls to: FT_Get_Char_IndexFT_Load_GlyphFT_Render_Glyph and then I store the bitmap of each ascii character to memory, so that once I actually render the character, I can simply call on the stored bitmap. The problem is that the character spacing is not correct. It looks like I need to use FT_Get_Kerning to correct this, however from the examples I've seen, it looks like I need to call this before FT_Load_Glyph, i.e. at the time when I am storing each of my characters. However, I have no idea what strings will be rendered, until runtime, so I don't know the 'left_glyph' and 'right_glyph' parameters in FT_Get_Kerning beforehand. Is there a way to make use of FT_Get_Kerning while drawing my bitmap (after I've already loaded the glyph and retrieved its bitmap), in order to achieve proper character spacing at runtime? Thank-you ___ Freetype-devel mailing list Freetype-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/freetype-devel
Re: [ft-devel] character spacing
Thanks for your reply - Note, however, that today many fonts contain kerning in the GPOS table which is not handled by FreeType. Instead, you have to use a higher-level library like Pango or ICU. FT_HAS_KERNING will return true for these types of fonts? When I call, FT_Get_Kerning, the akerning value always gets set to (0,0), which from the sample code on freetype.org, looks like is an error. Could this indicate that the kerning information is in the 'GPOS' table? How can I know for sure, or is there a way to debug this? Thank-you again! Date: Mon, 19 Sep 2011 07:10:24 +0200 To: lost_bits1...@hotmail.ca CC: freetype-devel@nongnu.org Subject: Re: [ft-devel] character spacing From: w...@gnu.org In order to draw my text, I currently make calls to: FT_Get_Char_Index FT_Load_Glyph FT_Render_Glyph and then I store the bitmap of each ascii character to memory, so that once I actually render the character, I can simply call on the stored bitmap. The problem is that the character spacing is not correct. It looks like I need to use FT_Get_Kerning to correct this, however from the examples I've seen, it looks like I need to call this before FT_Load_Glyph, i.e. at the time when I am storing each of my characters. However, I have no idea what strings will be rendered, until runtime, so I don't know the 'left_glyph' and 'right_glyph' parameters in FT_Get_Kerning beforehand. Is there a way to make use of FT_Get_Kerning while drawing my bitmap (after I've already loaded the glyph and retrieved its bitmap), in order to achieve proper character spacing at runtime? Have a look at the ftstring demo program to see how simple kerning works. You can call `FT_Get_Kerning' whenever you want; it is completely unrelated to `FT_Render_Glyph'. Note, however, that today many fonts contain kerning in the GPOS table which is not handled by FreeType. Instead, you have to use a higher-level library like Pango or ICU. Werner ___ Freetype-devel mailing list Freetype-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/freetype-devel
Re: [ft-devel] FT_Get_Kerning returns 0
I check if my TTF file has kerning information using FT_HAS_KERNING, and this returns true. I then use: FT_Get_Kerning(face, prev, next, FT_KERNING_DEFAULT, delta); to determine the kerning value, but delta.x returns 0. How can I debug why the kerning value is 0 even though FT_HAS_KERNING returns true? Don't assume that there is a kerning value for all glyph pairs! Use a program like `ttx' (sourceforge.net/projects/fonttools/) to get a dump of a TrueType font. Then check whether there is a kerning value between the two particular glyphs. Werner ___ Freetype-devel mailing list Freetype-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/freetype-devel
Re: [ft-devel] character spacing
Also - as I have already invested much time in Freetype I no longer have time to integrate a different library such as Pango - is there somewhere I can obtain freely distributable TTF files that contains kerning information that can be handled by Freetype? If a font doesn't contain a `GPOS' table and only `kern', you are on the safe side. This inspection can be done even manually; just search for `GPOS' inside the font (rather at the beginning, within the first few kBytes). Werner ___ Freetype-devel mailing list Freetype-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/freetype-devel
