[ft] FT_Outline_Get_BBox() negative overflow

[Marco Wertz]

I've encountered a strange issue with FT_Outline_Get_BBox(). When getting the 
dimensions
of the following shape bbox.yMin overflows into the negative:

        setvector(v1, 28800, 9600);
        FT_Stroker_BeginSubPath(stroker, &v1, 0);
        FT_Stroker_LineTo(stroker, &v1);

        setvector(v1, 28800, 6400);
        FT_Stroker_LineTo(stroker, &v1);
                
        setvector(v1, 28800, 10666);
        setvector(v2, 22400, 10666);
        setvector(v3, 22400, 6400);     
        FT_Stroker_CubicTo(stroker, &v1, &v2, &v3);
        
        setvector(v1, 22400, 2133);
        setvector(v2, 28800, 2133);
        setvector(v3, 28800, 6399);
        FT_Stroker_CubicTo(stroker, &v1, &v2, &v3);

Here is the result returned by FT_Outline_Get_BBox():

        BBOX: 22400 -2147474048 28866 9599

Is this a bug or have I done something wrong here? 

Small demo source attached.

Marco


#include <stdio.h>
#include <math.h>

#include <ft2build.h> 
#include FT_FREETYPE_H 
#include FT_GLYPH_H 
#include FT_OUTLINE_H 
#include FT_SYNTHESIS_H 
#include FT_STROKER_H
#include FT_BBOX_H

#define setvector(pv, px, py) (pv).x = (px); (pv).y = (py);

static FT_Library freetype_library = NULL;
 
int main(int argc, char *argv[])
{
        FT_Stroker stroker;
        FT_UInt points, contours;
        FT_Outline outline;
        FT_BBox bbox;
        FT_Vector v1, v2, v3;
                        
        FT_Init_FreeType(&freetype_library);
        
        FT_Stroker_New(freetype_library, &stroker);

        setvector(v1, 28800, 9600);
        FT_Stroker_BeginSubPath(stroker, &v1, 0);
        FT_Stroker_LineTo(stroker, &v1);

        setvector(v1, 28800, 6400);
        FT_Stroker_LineTo(stroker, &v1);
                
        setvector(v1, 28800, 10666);
        setvector(v2, 22400, 10666);
        setvector(v3, 22400, 6400);     
        FT_Stroker_CubicTo(stroker, &v1, &v2, &v3);
        
        setvector(v1, 22400, 2133);
        setvector(v2, 28800, 2133);
        setvector(v3, 28800, 6399);
        FT_Stroker_CubicTo(stroker, &v1, &v2, &v3);
                                
        FT_Stroker_EndSubPath(stroker);
        
        FT_Stroker_GetBorderCounts(stroker, FT_STROKER_BORDER_LEFT, &points, 
&contours);
                
        memset(&outline, 0, sizeof(FT_Outline));
        FT_Outline_New(freetype_library, 1024, 512, &outline);

        outline.n_points = 0;
        outline.n_contours = 0;
        FT_Stroker_Export(stroker, &outline);   
                                
        FT_Stroker_Done(stroker);
                
        FT_Outline_Get_BBox(&outline, &bbox);

        printf("BBOX: %d %d %d %d\n", bbox.xMin, bbox.yMin, bbox.xMax, 
bbox.yMax);
        
        FT_Outline_Done(freetype_library, &outline);    
        FT_Done_FreeType(freetype_library);
                        
        return 0;
}
        
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