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clutter/utils: Remove magic numbers from fixed point calculations

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Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2587>
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Daniel van Vugt 2022-08-18 18:16:40 +08:00 committed by Marge Bot
parent 3c50a9f8aa
commit f94189d4eb
1 changed files with 9 additions and 6 deletions
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15
src/compositor/clutter-utils.c
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@ -25,6 +25,9 @@
#include <math.h> #include <math.h>
#define FIXED_SHIFT 8
#define FIXED_ONE (1 << FIXED_SHIFT)
/* This file uses pixel-aligned region computation to determine what /* This file uses pixel-aligned region computation to determine what
* can be clipped out. This only really works if everything is aligned * can be clipped out. This only really works if everything is aligned
* to the pixel grid - not scaled or rotated and at integer offsets. * to the pixel grid - not scaled or rotated and at integer offsets.
@ -46,12 +49,12 @@
*/ */
/* The definition of "close enough" to integral pixel values is /* The definition of "close enough" to integral pixel values is
* equality when we convert to 24.8 fixed-point. * equality when we convert to fixed-point.
*/ */
static inline int static inline int
round_to_fixed (float x) round_to_fixed (float x)
{ {
return roundf (x * 256); return roundf (x * FIXED_ONE);
} }
/* Help macros to scale from OpenGL <-1,1> coordinates system to /* Help macros to scale from OpenGL <-1,1> coordinates system to
@ -84,10 +87,10 @@ meta_actor_vertices_are_untransformed (graphene_point3d_t *verts,
v3x = round_to_fixed (verts[3].x); v3y = round_to_fixed (verts[3].y); v3x = round_to_fixed (verts[3].x); v3y = round_to_fixed (verts[3].y);
/* Using shifting for converting fixed => int, gets things right for /* Using shifting for converting fixed => int, gets things right for
* negative values. / 256. wouldn't do the same * negative values. / FIXED_ONE wouldn't do the same
*/ */
x = v0x >> 8; x = v0x >> FIXED_SHIFT;
y = v0y >> 8; y = v0y >> FIXED_SHIFT;
if (out_transforms) if (out_transforms)
{ {
@ -98,7 +101,7 @@ meta_actor_vertices_are_untransformed (graphene_point3d_t *verts,
} }
/* At integral coordinates? */ /* At integral coordinates? */
if (x * 256 != v0x || y * 256 != v0y) if (x * FIXED_ONE != v0x || y * FIXED_ONE != v0y)
return FALSE; return FALSE;
/* Not scaled? */ /* Not scaled? */