[Git][freetype/freetype-demos][master] [ftmulti] Enable overlap flag testing.

[Alexei Podtelezhnikov (@apodtele)]

Alexei Podtelezhnikov pushed to branch master at FreeType / FreeType Demo Programs

Commits:

• 46b5ae2d
  by Alexei Podtelezhnikov at 2023-02-11T18:30:39-05:00

  [ftmulti] Enable overlap flag testing.
  
  Variation fonts often relay on overlapping contours, which require
  oversampling to render properly. FreeType relies on FT_OUTLINE_OVERLAP
  to trigger the expensive mitigation algorithm. This commit enables
  tinkering with the overlap flags and, therefore, the oversampling.
  Normally, the flags should be set by the font designers sparingly.
  
  The bitmap strike toggle is no longer available, which has never
  been important for the variation font testing.
  
  * src/ftmulti.c (Process_Event): Reassign F4 to overlap toggle.
  (Render_Glyph): Tinker with the overlap flags before rendering.
  

1 changed file:

• src/ftmulti.c

Changes:

src/ftmulti.c

---

...	...	@@ -94,7 +94,7 @@
94	94	static int hinted = 1; /* is glyph hinting active? */
95	95	static int grouping = 1; /* is axis grouping active? */
96	96	static int antialias = 1; /* is anti-aliasing active? */
97		- static int use_sbits = 1; /* do we use embedded bitmaps? */
	97	+ static int overlaps = 0x0; /* flip overlap flags or not? */
98	98	static int Num; /* current first glyph index */
99	99
100	100	static int res = 72;
...	...	@@ -103,8 +103,6 @@
103	103
104	104	static int Fail;
105	105
106		- static int graph_init = 0;
107		-
108	106	static int render_mode = 1;
109	107
110	108	static FT_MM_Var *multimaster = NULL;
...	...	@@ -305,8 +303,6 @@
305	303	bit = (grBitmap*)surface;
306	304
307	305	fore_color = grFindColor( bit, 255, 255, 255, 255 ); /* white */
308		-
309		- graph_init = 1;
310	306	}
311	307
312	308
...	...	@@ -322,6 +318,10 @@
322	318	/* first, render the glyph image into a bitmap */
323	319	if ( glyph->format != FT_GLYPH_FORMAT_BITMAP )
324	320	{
	321	+ /* overlap flags mitigate AA rendering artifacts in overlaps */
	322	+ /* by oversampling, toggle the flag to test the effect */
	323	+ glyph->outline.flags ^= overlaps;
	324	+
325	325	error = FT_Render_Glyph( glyph, antialias ? FT_RENDER_MODE_NORMAL
326	326	: FT_RENDER_MODE_MONO );
327	327	if ( error )
...	...	@@ -373,14 +373,11 @@
373	373	int flags;
374	374
375	375
376		- flags = FT_LOAD_DEFAULT;
	376	+ flags = FT_LOAD_NO_BITMAP;
377	377
378	378	if ( !hint )
379	379	flags |= FT_LOAD_NO_HINTING;
380	380
381		- if ( !use_sbits )
382		- flags |= FT_LOAD_NO_BITMAP;
383		-
384	381	return FT_Load_Glyph( face, idx, flags );
385	382	}
386	383
...	...	@@ -558,7 +555,7 @@
558	555	grWriteln( "q, ESC quit ftmulti" );
559	556	grWriteln( "F2 toggle axis grouping" );
560	557	grWriteln( "F3 toggle outline hinting" );
561		- grWriteln( "F4 toggle embedded bitmaps" );
	558	+ grWriteln( "F4 toggle overlap flags" );
562	559	grWriteln( "F5 toggle anti-aliasing" );
563	560	grWriteln( "F6 cycle through hinting engines (if available)" );
564	561	grLn();
...	...	@@ -645,10 +642,10 @@
645	642	break;
646	643
647	644	case grKeyF4:
648		- use_sbits = !use_sbits;
649		- new_header = use_sbits
650		- ? "embedded bitmaps are now used if available"
651		- : "embedded bitmaps are now ignored";
	645	+ overlaps ^= FT_OUTLINE_OVERLAP;
	646	+ new_header = overlaps
	647	+ ? "overlap flags are flipped"
	648	+ : "overlap flags are unchanged";
652	649	break;
653	650
654	651	case grKEY( ',' ):

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