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WRaster: Changed equality/inequality comparison on floating point number

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The equality comparison (a == b) is known to be a dangerous trap
when floating-point arithmetics are involved. This patch changes
all the cases which try to do this to a safer check.
This commit is contained in:
Christophe CURIS
2013-05-11 00:07:16 +02:00
committed by Carlos R. Mafra
parent 80a59696e5
commit 8ef38e9910
3 changed files with 31 additions and 6 deletions
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2
wrlib/png.c
View File

@@ -140,7 +140,7 @@ RImage *RLoadPNG(RContext *context, const char *file)
sgamma = (context->attribs->rgamma + context->attribs->ggamma + context->attribs->bgamma) / 3; sgamma = (context->attribs->rgamma + context->attribs->ggamma + context->attribs->bgamma) / 3;
} else if ((tmp = getenv("DISPLAY_GAMMA")) != NULL) { } else if ((tmp = getenv("DISPLAY_GAMMA")) != NULL) {
sgamma = atof(tmp); sgamma = atof(tmp);
if (sgamma == 0) if (sgamma < 1.0E-3)
sgamma = 1; sgamma = 1;
} else { } else {
/* blah */ /* blah */

21
wrlib/rotate.c
View File

@@ -43,12 +43,23 @@ RImage *RRotateImage(RImage * image, float angle)
int x, y; int x, y;
int bpp = image->format == RRGBAFormat ? 4 : 3; int bpp = image->format == RRGBAFormat ? 4 : 3;
/*
* Angle steps below this value would represent a rotation
* of less than 1 pixel for a 4k wide image, so not worth
* bothering the difference. That makes it a perfect
* candidate for an Epsilon when trying to compare angle
* to known values
*/
static const float min_usable_angle = 0.00699;
angle = ((int)angle % 360) + (angle - (int)angle); angle = ((int)angle % 360) + (angle - (int)angle);
if (angle == 0.0) { if (angle < min_usable_angle) {
/* Rotate by 0 degree */
return RCloneImage(image); return RCloneImage(image);
} else if (angle == 90.0) { } else if ((angle > 90.0 - min_usable_angle) &&
(angle < 90.0 + min_usable_angle)) {
nwidth = image->height; nwidth = image->height;
nheight = image->width; nheight = image->width;
@@ -91,7 +102,8 @@ RImage *RRotateImage(RImage * image, float angle)
} }
} }
} }
} else if (angle == 180.0) { } else if ((angle > 180.0 - min_usable_angle) &&
(angle < 180.0 + min_usable_angle)) {
nwidth = image->width; nwidth = image->width;
nheight = image->height; nheight = image->height;
@@ -129,7 +141,8 @@ RImage *RRotateImage(RImage * image, float angle)
nptr--; nptr--;
} }
} }
} else if (angle == 270.0) { } else if ((angle > 270.0 - min_usable_angle) &&
(angle < 270.0 + min_usable_angle)) {
nwidth = image->height; nwidth = image->height;
nheight = image->width; nheight = image->width;

14
wrlib/scale.c
View File

@@ -187,8 +187,20 @@ static double B_spline_filter(double t) /* box (*) box (*) box (*) box */
static double sinc(double x) static double sinc(double x)
{ {
/*
* The original code did this:
* if (x != 0) ...
* This code is unsafe, it should be:
* if (fabs(x) > EPSILON) ...
*
* But the call to fabs is already done in the *ONLY* function
* that call sinc: 'Lanczos3_filter'
*
* The goal was to avoid a Divide-by-0 error, now we also
* avoid a +/-inf result too
*/
x *= PI; x *= PI;
if (x != 0) if (x > 1.0E-9)
return (sin(x) / x); return (sin(x) / x);
return (1.0); return (1.0);
} }