[libGD] #210 [Task opened] gdImageStringFT(..., "Times-12",...) fails with gdFTUseFontConfig(1) for non-TTF

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User who did this - Michael McTernan (MichaelMcTernan) 

Attached to Project - libGD
Summary - gdImageStringFT(..., "Times-12",...) fails with gdFTUseFontConfig(1) for non-TTF
Task Type - Bug Report
Category - General
Status - Unconfirmed
Assigned To - 
Operating System - Windows
Severity - Medium
Priority - Normal
Reported Version - 2.0.35
Due in Version - Undecided
Due Date - Undecided
Details - Hi,

I call gdFTUseFontConfig(1) and then gdImageStringFT() with a font name such as "Times-12" and the point size as 12.  I consistently get the error message "Could not set character size" back.

Tracking this into the lib, FT_Set_Char_Size is failing with FT_Err_Invalid_Pixel_Size.  Following it further, it looks like fontconfig picks something like /usr/share/fonts/75dpi/timR12.pcf.gz, which seems reasonable.  The problem is that freetype is then called by GD as follows:

FT_Set_Char_Size (face, 0, (FT_F26Dot6)(ptsize*64), METRIC_RES, METRIC_RES)

METRIC_RES = 300, and the FreeType PCF driver then does the following calculation in PCF_Size_Request(): FT_REQUEST_HEIGHT:

height = (req)->height * (req)->vertResolution + 36 ) / 72;

So the request to gdImageStringFT() ends up requiring the font to be (12 * 300 + 36) / 72 = 50 points high to give the requested 12 points at 300dpi.

At this point, since a PCF for 12-point was selected, PCF_Size_Request() fails since the font face doesn't match the required dpi height.

I think that gdImageStringFTEx() needs changing such that the passed width is compensated for the 300dpi requested, or the 300 is changed to 72 (by setting 0 and 0).  Then this function call can pass and rendering can work without requiring TTFs in every case.

More information can be found at the following URL:
http://bugs.libgd.org/?do=details&task_id=210

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