[cairo] [PATCH] Contribution to line join and end caps

[horakm at centrum.cz]

Hello,
I tried several times to post my contribution to forum at cairo at cairographics.org first, 
but for last two days I didn't receive any reply and therefore I thought that my address is blocked.
So I add my contribution to the web interface at http://bugs.freedesktop.org/ (Bug #16954)
But two hours ago I got info about successfull reception of the previous posts. 
I am deeply sorry for flooding mailing list. Is it possible to delete them?

Martin
______________________________________________________________
> Od: horakm at centrum.cz
> Komu: <cairo at cairographics.org>
> Datum: 03.08.2008 11:53
> Předmět: [cairo] [PATCH] Contribution to line join and end caps
>
>Hello,
>
>I am working on a project which uses the cairo library for primary
graphics rendering.
>Because I quickly needed a special (not currently available in the
version 1.6.4) join and end 
>caps for lines, I implemented them myself. I added new two options to
type cairo_line_join_t 
>(CAIRO_LINE_JOIN_TRIANGLE, CAIRO_LINE_JOIN_NONE) and one option to type
cairo_line_cap_t
>(CAIRO_LINE_CAP_TRIANGLE)
>The patches for cairo.h and cairo-path-stroke.c files are attached. I
hope they will be useful.
>
>Martin Horak
>
>
>--- cairo.h 2008-04-08 00:30:32.000000000 +0200 
>+++ new\cairo.h 2008-08-01 10:19:34.343750000 +0200 
>@@ -495,6 +495,7 @@ 
>* @CAIRO_LINE_CAP_BUTT: start(stop) the line exactly at the start(end)
point 
>* @CAIRO_LINE_CAP_ROUND: use a round ending, the center of the circle is
the end point 
>* @CAIRO_LINE_CAP_SQUARE: use squared ending, the center of the square is
the end point 
>+ * @CAIRO_LINE_CAP_TRIANGLE: use triangle ending, the triangle vertex is
half of line width from the end point 
>* 
>* Specifies how to render the endpoints of the path when stroking. 
>* 
>@@ -503,7 +504,8 @@ 
>typedef enum _cairo_line_cap { 
>CAIRO_LINE_CAP_BUTT, 
>CAIRO_LINE_CAP_ROUND, 
>- CAIRO_LINE_CAP_SQUARE 
>+ CAIRO_LINE_CAP_SQUARE, 
>+ CAIRO_LINE_CAP_TRIANGLE 
>} cairo_line_cap_t; 
>
>cairo_public void 
>@@ -517,6 +519,9 @@ 
>* joint point 
>* @CAIRO_LINE_JOIN_BEVEL: use a cut-off join, the join is cut off at half

>* the line width from the joint point 
>+ * @CAIRO_LINE_JOIN_TRIANGLE: use a triangle join, the triangle vertex
is at half 
>+ * of line width from the join point 
>+ * @CAIRO_LINE_JOIN_NONE: no line join 
>* 
>* Specifies how to render the junction of two lines when stroking. 
>* 
>@@ -525,7 +530,9 @@ 
>typedef enum _cairo_line_join { 
>CAIRO_LINE_JOIN_MITER, 
>CAIRO_LINE_JOIN_ROUND, 
>- CAIRO_LINE_JOIN_BEVEL 
>+ CAIRO_LINE_JOIN_BEVEL, 
>+ CAIRO_LINE_JOIN_TRIANGLE, 
>+ CAIRO_LINE_JOIN_NONE 
>} cairo_line_join_t; 
>
>cairo_public void 
>
>
>--- cairo-path-stroke.c 2008-04-05 00:45:22.000000000 +0200 
>+++ new\cairo-path-stroke.c 2008-08-01 14:40:48.421875000 +0200 
>@@ -278,6 +278,10 @@ 
>} 
>
>switch (stroker->style->line_join) { 
>+ case CAIRO_LINE_JOIN_NONE: 
>+ { 
>+ return CAIRO_STATUS_SUCCESS; 
>+ } 
>case CAIRO_LINE_JOIN_ROUND: { 
>int i; 
>int start, step, stop; 
>@@ -477,7 +481,59 @@ 
>
>return _cairo_traps_tessellate_triangle (stroker->traps, tri); 
>} 
>- } 
>+ case CAIRO_LINE_JOIN_TRIANGLE: { 
>+ double x1, y1, x2, y2, x3, y3; 
>+ double d, douter; 
>+ double centerx, centery; 
>+ 
>+ x1 = _cairo_fixed_to_double (inpt->x); 
>+ y1 = _cairo_fixed_to_double (inpt->y); 
>+ x2 = _cairo_fixed_to_double (outpt->x); 
>+ y2 = _cairo_fixed_to_double (outpt->y); 
>+ x3 = _cairo_fixed_to_double (in->point.x); 
>+ y3 = _cairo_fixed_to_double (in->point.y); 
>+ 
>+ /* center point between inpt and outpt points */ 
>+ centerx = ( x1 + x2 ) / 2.0; 
>+ centery = ( y1 + y2 ) / 2.0; 
>+ 
>+ /* distance between inpt and in points */ 
>+ douter = sqrt( ( x1 - x3 ) * ( x1 - x3 ) + ( y1 - y3 ) * ( y1 - y3 ) );

>+ 
>+ /* distance between center and in points */ 
>+ d = sqrt( ( centerx - x3 ) * ( centerx - x3 ) + ( centery - y3 ) * (
centery - y3 ) ); 
>+ 
>+ if ( d ) 
>+ { 
>+ double dx, dy; 
>+ cairo_point_t quad[4]; 
>+ cairo_point_t outer; 
>+ 
>+ /* extrapolate distance between in and center to outer point in
cartesian space */ 
>+ dx = ( x3 - centerx ) * douter / d; 
>+ dy = ( y3 - centery ) * douter / d; 
>+ 
>+ outer.x = _cairo_fixed_from_double ( x3 - dx ); 
>+ outer.y = _cairo_fixed_from_double ( y3 - dy ); 
>+ 
>+ quad[0] = in->point; 
>+ quad[1] = *inpt; 
>+ quad[2] = outer; 
>+ quad[3] = *outpt; 
>+ 
>+ return _cairo_traps_tessellate_convex_quad (stroker->traps, quad); 
>+ } 
>+ else 
>+ { 
>+ /* bevel */ 
>+ cairo_point_t tri[3]; 
>+ tri[0] = in->point; 
>+ tri[1] = *inpt; 
>+ tri[2] = *outpt; 
>+ return _cairo_traps_tessellate_triangle (stroker->traps, tri); 
>+ } 
>+ } 
>+ } 
>} 
>
>static cairo_status_t 
>@@ -516,6 +572,29 @@ 
>
>return _cairo_traps_tessellate_triangle (stroker->traps, tri); 
>} 
>+ case CAIRO_LINE_CAP_TRIANGLE: { 
>+ double dx, dy, x1, y1; 
>+ cairo_point_t outer; 
>+ cairo_point_t tri[3]; 
>+ 
>+ dx = f->usr_vector.x; 
>+ dy = f->usr_vector.y; 
>+ dx *= stroker->style->line_width / 2.0; 
>+ dy *= stroker->style->line_width / 2.0; 
>+ cairo_matrix_transform_distance (stroker->ctm, &dx, &dy); 
>+ 
>+ x1 = _cairo_fixed_to_double( f->ccw.x + f->cw.x ) / 2.0 + dx; 
>+ y1 = _cairo_fixed_to_double( f->ccw.y + f->cw.y ) / 2.0 + dy; 
>+ 
>+ outer.x = _cairo_fixed_from_double( x1 ); 
>+ outer.y = _cairo_fixed_from_double( y1 ); 
>+ 
>+ tri[0] = outer; 
>+ tri[1] = f->cw; 
>+ tri[2] = f->ccw; 
>+ 
>+ return _cairo_traps_tessellate_triangle (stroker->traps, tri); 
>+ } 
>case CAIRO_LINE_CAP_SQUARE: { 
>double dx, dy; 
>cairo_slope_t fvector;
>
>_______________________________________________
>cairo mailing list
>cairo at cairographics.org
>http://lists.cairographics.org/mailman/listinfo/cairo
>