diff options
Diffstat (limited to 'draw/draw_affine.c')
| -rw-r--r-- | draw/draw_affine.c | 158 |
1 files changed, 149 insertions, 9 deletions
diff --git a/draw/draw_affine.c b/draw/draw_affine.c index 95d28bea..c1ee88f8 100644 --- a/draw/draw_affine.c +++ b/draw/draw_affine.c @@ -454,6 +454,146 @@ fz_paint_affine_color_near(byte *dp, byte *sp, int sw, int sh, int u, int v, int } } +/* RJW: The following code was originally written to be sensitive to + * FLT_EPSILON. Given the way the 'minimum representable difference' + * between 2 floats changes size as we scale, we now pick a larger + * value to ensure idempotency even with rounding problems. The + * value we pick is still far smaller than would ever show up with + * antialiasing. + */ +#define MY_EPSILON 0.001 + +void +fz_gridfit_matrix(fz_matrix *m) +{ + if (fabsf(m->b) < FLT_EPSILON && fabsf(m->c) < FLT_EPSILON) + { + if (m->a > 0) + { + float f; + /* Adjust left hand side onto pixel boundary */ + f = (float)(int)(m->e); + if (f - m->e > MY_EPSILON) + f -= 1.0; /* Ensure it moves left */ + m->a += m->e - f; /* width gets wider as f <= m->e */ + m->e = f; + /* Adjust right hand side onto pixel boundary */ + f = (float)(int)(m->a); + if (m->a - f > MY_EPSILON) + f += 1.0; /* Ensure it moves right */ + m->a = f; + } + else if (m->a < 0) + { + float f; + /* Adjust right hand side onto pixel boundary */ + f = (float)(int)(m->e); + if (m->e - f > MY_EPSILON) + f += 1.0; /* Ensure it moves right */ + m->a += m->e - f; /* width gets wider (more -ve) */ + m->e = f; + /* Adjust left hand side onto pixel boundary */ + f = (float)(int)(m->a); + if (f - m->a > MY_EPSILON) + f -= 1.0; /* Ensure it moves left */ + m->a = f; + } + if (m->d > 0) + { + float f; + /* Adjust top onto pixel boundary */ + f = (float)(int)(m->f); + if (f - m->f > MY_EPSILON) + f -= 1.0; /* Ensure it moves upwards */ + m->d += m->f - f; /* width gets wider as f <= m->f */ + m->f = f; + /* Adjust bottom onto pixel boundary */ + f = (float)(int)(m->d); + if (m->d - f > MY_EPSILON) + f += 1.0; /* Ensure it moves down */ + m->d = f; + } + else if (m->d < 0) + { + float f; + /* Adjust bottom onto pixel boundary */ + f = (float)(int)(m->f); + if (m->f - f > MY_EPSILON) + f += 1.0; /* Ensure it moves down */ + m->d += m->f - f; /* width gets wider (more -ve) */ + m->f = f; + /* Adjust top onto pixel boundary */ + f = (float)(int)(m->d); + if (f - m->d > MY_EPSILON) + f -= 1.0; /* Ensure it moves up */ + m->d = f; + } + } + else if (fabsf(m->a) < FLT_EPSILON && fabsf(m->d) < FLT_EPSILON) + { + if (m->b > 0) + { + float f; + /* Adjust left hand side onto pixel boundary */ + f = (float)(int)(m->f); + if (f - m->f > MY_EPSILON) + f -= 1.0; /* Ensure it moves left */ + m->b += m->f - f; /* width gets wider as f <= m->f */ + m->f = f; + /* Adjust right hand side onto pixel boundary */ + f = (float)(int)(m->b); + if (m->b - f > MY_EPSILON) + f += 1.0; /* Ensure it moves right */ + m->b = f; + } + else if (m->b < 0) + { + float f; + /* Adjust right hand side onto pixel boundary */ + f = (float)(int)(m->f); + if (m->f - f > MY_EPSILON) + f += 1.0; /* Ensure it moves right */ + m->b += m->f - f; /* width gets wider (more -ve) */ + m->f = f; + /* Adjust left hand side onto pixel boundary */ + f = (float)(int)(m->b); + if (f - m->b > MY_EPSILON) + f -= 1.0; /* Ensure it moves left */ + m->b = f; + } + if (m->c > 0) + { + float f; + /* Adjust top onto pixel boundary */ + f = (float)(int)(m->e); + if (f - m->e > MY_EPSILON) + f -= 1.0; /* Ensure it moves upwards */ + m->c += m->e - f; /* width gets wider as f <= m->e */ + m->e = f; + /* Adjust bottom onto pixel boundary */ + f = (float)(int)(m->c); + if (m->c - f > MY_EPSILON) + f += 1.0; /* Ensure it moves down */ + m->c = f; + } + else if (m->c < 0) + { + float f; + /* Adjust bottom onto pixel boundary */ + f = (float)(int)(m->e); + if (m->e - f > MY_EPSILON) + f += 1.0; /* Ensure it moves down */ + m->c += m->e - f; /* width gets wider (more -ve) */ + m->e = f; + /* Adjust top onto pixel boundary */ + f = (float)(int)(m->c); + if (f - m->c > MY_EPSILON) + f -= 1.0; /* Ensure it moves up */ + m->c = f; + } + } +} + /* Draw an image with an affine transform on destination */ static void @@ -469,15 +609,7 @@ fz_paint_image_imp(fz_pixmap *dst, fz_bbox scissor, fz_pixmap *shape, fz_pixmap void (*paintfn)(byte *dp, byte *sp, int sw, int sh, int u, int v, int fa, int fb, int w, int n, int alpha, byte *color, byte *hp); /* grid fit the image */ - if (fz_is_rectilinear(ctm)) - { - ctm.a = roundup(ctm.a); - ctm.b = roundup(ctm.b); - ctm.c = roundup(ctm.c); - ctm.d = roundup(ctm.d); - ctm.e = floorf(ctm.e); - ctm.f = floorf(ctm.f); - } + fz_gridfit_matrix(&ctm); /* turn on interpolation for upscaled and non-rectilinear transforms */ dolerp = 0; @@ -519,6 +651,14 @@ fz_paint_image_imp(fz_pixmap *dst, fz_bbox scissor, fz_pixmap *shape, fz_pixmap u = (fa * x) + (fc * y) + inv.e * 65536 + ((fa + fc) >> 1); v = (fb * x) + (fd * y) + inv.f * 65536 + ((fb + fd) >> 1); + /* RJW: The following is voodoo. No idea why it works, but it gives + * the best match between scaled/unscaled/interpolated/non-interpolated + * that we have found. */ + if (dolerp) { + u -= 32768; + v -= 32768; + } + dp = dst->samples + ((y - dst->y) * dst->w + (x - dst->x)) * dst->n; n = dst->n; sp = img->samples; |