Bug 82 - sub-pixel line width always results in 0 twip line width

[netsweng]

Philip de Nier 2009-03-14 11:02:01 EDT

Created an attachment (id=19) [details]
fix truncation of sub-pixel line widths

The functions to set the line width (in pixel units) in ming.h uses the
"unsigned short" type. The value is then multiplied by Ming_scale internally.
This means that a line width of < 1 pixel is stored as as a line width of 0
twips and flash renders this as a line with the minimum width.

The ming.h API should be changed to accept pixel unit line widths as a float so
that a pixel unit line width < 1 results in a twip unit line width of >= 0 and
< Ming_scale and not 0.

The attached patch file has this change.

p.s. it is a pity that 1 pixel and sub-pixel line widths look the same unless
you zoom in enough. The sub-pixel line would appear lighter in other formats.

[netsweng]

strk@keybit.net 2009-05-20 05:39:17 EDT

This is a known problem. Can't remember now if a new interface was added.
The aim is not breaking ABI nor API, so I'd rather add a new interface
for correct behaving one.

Klaus ?

[netsweng]

Index: src/ming.h.in

RCS file: /cvsroot/ming/ming/src/ming.h.in,v
retrieving revision 1.104
diff -u -8 -p -r1.104 ming.h.in
--- src/ming.h.in 16 Feb 2009 18:04:34 -0000 1.104
+++ src/ming.h.in 14 Mar 2009 14:38:59 -0000
@@ -937,24 +937,24 @@ void SWFFill_move(SWFFill fill, float x,
void SWFFill_moveTo(SWFFill fill, float x, float y);

void SWFFill_setMatrix(SWFFill fill, float a, float b,
float c, float d, float x, float y);

/***** shape_util.h *****/

-void SWFShape_setLine(SWFShape shape, unsigned short width,
+void SWFShape_setLine(SWFShape shape, float width,
byte r, byte g, byte b, byte a);

-void SWFShape_setLine2Filled(SWFShape shape, unsigned short width,
+void SWFShape_setLine2Filled(SWFShape shape, float width,
SWFFillStyle fill,
int flags, float miterLimit);

-void SWFShape_setLine2(SWFShape shape, unsigned short width,
+void SWFShape_setLine2(SWFShape shape, float width,
byte r, byte g, byte b, byte a,
int flags, float miterLimit);

SWFFill SWFShape_addSolidFill(SWFShape shape, byte r, byte g, byte b, byte a);
SWFFill SWFShape_addGradientFill(SWFShape shape, SWFGradient gradient, byte flags);
SWFFill SWFShape_addBitmapFill(SWFShape shape, SWFBitmap bitmap, byte flags);

void SWFShape_setLeftFill(SWFShape shape, SWFFill fill);

Index: src/shape_util.c

RCS file: /cvsroot/ming/ming/src/shape_util.c,v
retrieving revision 1.26
diff -u -8 -p -r1.26 shape_util.c
--- src/shape_util.c 31 May 2008 14:26:09 -0000 1.26
+++ src/shape_util.c 14 Mar 2009 14:38:59 -0000
@@ -57,20 +57,20 @@ float SWFCharacter_getHeight(SWFCharacte

/*

• set line width and line color
  *

• set line width in px

• set line color as {r, g, b, a}
  *
  */
  -void SWFShape_setLine(SWFShape shape, unsigned short width,
  +void SWFShape_setLine(SWFShape shape, float width,
  byte r, byte g, byte b, byte a)
  {

  • SWFShape_setLineStyle_internal(shape, width * Ming_scale, r, g, b, a);
  • SWFShape_setLineStyle_internal(shape, (unsigned short)(width * Ming_scale), r, g, b, a);
    }

  /*

• set Linestyle2 introduce with SWF 8.
  *

• set line width in pixel

• set color {r, g, b, a}
  *
  @@ -103,21 +103,21 @@ void SWFShape_setLine(SWFShape shape, un

• SWF_LINESTYLE_FLAG_ENDCAP_NONE

• SWF_LINESTYLE_FLAG_ENDCAP_SQUARE
  *

• If join style is SWF_LINESTYLE_JOIN_MITER a miter limit factor

• must be set. Miter max length is then calculated as:

• max miter len = miter limit * width.

• If join style is not miter, this value will be ignored.
  */
  -void SWFShape_setLine2(SWFShape shape, unsigned short width,
  +void SWFShape_setLine2(SWFShape shape, float width,
  byte r, byte g, byte b, byte a,
  int flags, float miterLimit)
  {

  • SWFShape_setLineStyle2_internal(shape, width * Ming_scale,
  • SWFShape_setLineStyle2_internal(shape, (unsigned short)(width * Ming_scale),
    r, g, b, a, flags, miterLimit);
    }

  /*

• set filled Linestyle2 introduce with SWF 8.

• set line width in pixel
  *
  @@ -153,21 +153,21 @@ void SWFShape_setLine2(SWFShape shape, u

• SWF_LINESTYLE_FLAG_ENDCAP_NONE

• SWF_LINESTYLE_FLAG_ENDCAP_SQUARE
  *

• If join style is SWF_LINESTYLE_JOIN_MITER a miter limit factor

• must be set. Miter max length is then calculated as:

• max miter len = miter limit * width.

• If join style is not miter, this value will be ignored.
  */
  -void SWFShape_setLine2Filled(SWFShape shape, unsigned short width,
  +void SWFShape_setLine2Filled(SWFShape shape, float width,
  SWFFillStyle fill,
  int flags, float miterLimit)
  {

  • SWFShape_setLineStyle2filled_internal(shape, width * Ming_scale,
  • SWFShape_setLineStyle2filled_internal(shape, (unsigned short)(width * Ming_scale),
    fill, flags, miterLimit);
    }

  SWFFill SWFShape_addSolidFill(SWFShape shape, byte r, byte g, byte b, byte a)
  {
  return newSWFFill(SWFShape_addSolidFillStyle(shape, r, g, b, a));
  }