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List of known FreeType 2 Bugs |
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----------------------------- |
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"Identifier" is a string to uniquely identify the bug. A more detailed |
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description of the bug is found below the table of opened bugs. |
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"Date" is the date when the bug was first reported or entered in this |
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document. Dates are in _European_ format, i.e day/month/year. |
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"Opened By" is the name of the person who first spotted the bug. Note that |
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we can use abbreviations here, like: |
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"David" for David Turner |
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"Werner" for Werner Lemberg |
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etc. |
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"Reproduceable" indicates whether the bug could be reproduced by the |
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development team or not (it can be specific to a given platform), whether it |
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always happens, or only sporadically, etc. |
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I. Open bugs |
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============ |
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Identifier Date Opened by Reproduceable |
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------------------------------------------------------------------------------ |
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NO-CID-CMAPS 13-09-2001 David always |
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BAD-TT-RENDERING 12-09-2001 Paul Pedriana ? |
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BAD-THIN-LINES 13-09-2001 David ? |
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NOT-WINDOWS-METRICS 07-10-2001 David always |
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ADVANCED-COMPOSITES 25-10-2001 George Williams always |
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--------------------END-OF-OPENED-BUGS-TABLE---------------------------------- |
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II. Closed bugs |
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=============== |
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Identifier Date Closed by Closure date |
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------------------------------------------------------------------------------ |
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BAD-TTNAMEID.H 12-09-2001 Antoine N/A |
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BAD-T1-CHARMAP 15-06-2001 David 2.0.5 |
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BAD-UNIXXXX-NAMES 30-07-2001 David 2.0.5 |
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GLYPH_TO_BITMAP-BUG 05-12-2001 David 05-12-2001 |
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AUTOHINT-NO-SBITS 13-09-2001 David 2.0.6 |
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TT-GLYPH-CRASH 01-01-2002 David 2.0.6 |
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T1-FONT-CRASH 01-01-2002 David 2.0.6 |
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BAD-ADVANCES 30-11-2001 David 2.0.6 |
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GLYPH-TO-BITMAP-BUG 15-12-2001 David 2.0.6 |
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--------------------END-OF-CLOSED-BUGS-TABLE---------------------------------- |
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III. Bug descriptions |
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===================== |
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--- START OF OPEN BUGS --- |
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NO-CID-CMAPS |
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Not exactly a bug, but the CFF font driver doesn't build a Unicode charmap |
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from the contents of font files, which prevents efficiently using fonts in |
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this format. |
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BAD-TT-RENDERING |
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According to Paul Pedriana <PPedriana@maxis.com>, there is a rather |
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important difference between the rendering of TrueType-hinted glyphs of |
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current FT2 and old betas. |
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Tests and comparisons show a _major_ discrepancy of monochrome truetype |
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bytecode-hinted glyphs! Something seems to be really broken here! |
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Some of this has been fixed in 2.0.6; there was a bug in the TrueType |
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loader that prevented it from loading composites correctly. However, |
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there are still _subtle_ differences between FT1 and FT2 when it comes to |
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monochrome TrueType-hinted glyphs (the major differences are gone though). |
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BAD-THIN-LINES |
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It seems that the anti-aliased renderer in FreeType has problems rendering |
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extremely thin straight lines correctly, at least when using the |
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FT_Outline_Render() function. |
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NOT-WINDOWS-METRICS |
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FreeType doesn't always return the same metrics as Windows for ascender, |
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descender, and text height, depending on character pixel sizes. A lot of |
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testing on Windows is needed to debug this properly. It might be due to a |
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rounding bug when computing the "x_scale" and "y_scale" values. |
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ADVANCED-COMPOSITES |
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Provided by George Williams <pfaedit@users.sourceforge.net>: |
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I notice that truetype/ttgload.c only supports Apple's definition of |
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offsets for composite glyphs. Apple and Microsoft behave differently if |
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there is a scale factor. OpenType defines some bits to disambiguate. |
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(A problem in both 2.0.4 and 2.0.5.) |
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Apple says (http://fonts.apple.com/TTRefMan/RM06/Chap6glyf.html) that if |
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flags&ARGS_ARE_XY is set then the offsets should be scaled by the scale |
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factors (as you have done), but they also say something very cryptic |
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about what happens when the component is rotated at 45<EFBFBD> (which you do |
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not support) -- See the "Important" note at the bottom. |
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The old truetype spec from Microsoft did not mention this. The OpenType |
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spec (http://www.microsoft.com/typography/otspec/glyf.htm, |
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http://partners.adobe.com/asn/developer/opentype/glyf.html) defines two |
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new bits to disambiguate: |
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SCALED_COMPONENT_OFFSET 11 |
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Composite designed to have the component offset scaled (designed for |
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Apple rasterizer) |
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UNSCALED_COMPONENT_OFFSET 12 |
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Composite designed not to have the component offset scaled (designed |
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for the Microsoft TrueType rasterizer) |
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Perhaps you could add a load_flag to allow the user to define the |
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default setting? |
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David says: |
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Wow, I was not even aware of this, it will probably take a little time |
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to implement since I don't have any font that implement these |
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"features", and also because I believe that we're running out of bits |
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for "load_flag", some other way to set preferences is probably needed. |
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--- END OF OPEN BUGS --- |
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BAD-TTNAMEID.H |
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The file "ttnameid.h" contains various constant macro definitions |
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corresponding to important values defined by the TrueType specification. |
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Joe Man <trmetal@yahoo.com.hk> reports that: |
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According to the information from TrueType v1.66: |
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Platform ID = 3 (Microsoft) |
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the Encoding ID of GB2312 = 4 |
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the Encoding ID of big5 = 3 |
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However, I have found that in ttnameid.h: |
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TT_MS_ID_GB2312 = 3 |
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TT_MS_ID_BIG_5 = 4 |
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Which one is correct? |
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Antoine replied that this was a bug in the TT 1.66 specification, and that |
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FreeType followed the most recent TrueType/OpenType specification here. |
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AUTOHINT-SBITS |
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When trying to load a glyph, with the auto-hinter activated (i.e., when |
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using FT_LOAD_FORCE_AUTOHINT, or when the font driver doesn't provide its |
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own hinter), embedded bitmaps are _never_ loaded, unlike the default |
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behaviour described by the API specification. |
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This seems to be a bug in FT_Load_Glyph(), but there is no way to solve it |
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efficiently without making a few important internal changes to the |
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library's design (more importantly, to the font driver interface). |
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This has been corrected with a hack in FT_Load_Glyph(). More important |
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internal changes should help get rid of it with a clean solution in a |
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further release like FreeType 2.1. |
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BAD-T1-CHARMAP |
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Type1 driver doesn't read "cacute" and "lslash" characters from iso8859-2 |
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charset. Those characters are mapped as MAC-one in glnames.py, so they |
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cannot be shown in Adobe Type1 fonts. |
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(This was due to a bug in the "glnames.py" script used to generate the |
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table of glyph names in 'src/psaux/pstables.h'.) |
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BAD-UNIXXXX-NAMES |
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Glyph names like uniXXXX are not recognized as they should be. It seems |
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that code in psmodule.c for uniXXXX glyph names was never tested. The |
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patch is very simple. |
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(A simple bug that was left un-noticed due to the fact that I don't have |
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any Postscript font that use this convention, unfortunately.) |
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GLYPH_TO_BITMAP-BUG |
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Calling FT_Glyph_To_Bitmap() sometimes modifies the original glyph |
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outline, creating weird alignment artefacts. |
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This subtle bug was really in the file `src/smooth/ftsmooth.c'. |
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Basically, the outline was shifted before rendering it into a new bitmap |
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buffer. However, it wasn't properly un-shifted after that operation. |
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This was only noticeable with certain glyphs or certain fonts; it crept in |
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a long time ago. |
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The same bug has been fixed in src/raster/ftrender1.c also. |
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TT-GLYPH-CRASH |
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The library crashed when trying to load certain glyphs from an |
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automatically generated TrueType file (tt1095m_.ttf submitted by Scott |
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Long). |
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It turned out that the font contained invalid glyph data (i.e. was |
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broken), but the TrueType glyph loader in FreeType wasn't paranoid enough, |
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which resulted in nasty memory overwrites all over the place. |
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T1-FONT-CRASH |
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The library crashed when trying to load the "Stalingrad Regular" face from |
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the "sadn.pfb" font file provided by Anthony Fok (and the Gnome-Print team |
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I believe). |
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This was due to the fact that the font missed a full font name entry, |
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though boasted a family name and postscript name. The Type 1 face loader |
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didn't check for these pathetic cases and seg-faulted. |
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BAD-ADVANCES |
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All scalable font drivers returned un-fitted glyph advances when |
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FT_LOAD_DEFAULT was used, which was incorrect. This problem was pretty |
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old but hadn't been spotted because all test programs actually explicitly |
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or implicitly (i.e. through the cache) rounded the advance widths of |
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glyphs. |
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This resulted in poor rendering of a number of client applications however |
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(it is strange to see they took so long to notify the FreeType team). |
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GLYPH-TO-BITMAP-BUG |
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FT_Glyph_To_Bitmap() did incorrectly modify the source glyph in certain |
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cases, which resulted in random behaviour and bad text rendering. This |
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was spotted to bugs in both the monochrome and smooth rasterizer. |
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=== end of file ===
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