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pjs/gfx/cairo/quartz-minimize-gradient-re...

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# HG changeset patch
# User Robert O'Callahan <robert@ocallahan.org>
# Date 1249558989 -43200
# Node ID 0bac4c903d2bb1d5c0d5426209001fc2a77cc105
# Parent 963b9451ad305924738d05d997a640698cd3af91
Bug 508730. Don't repeat a Quartz gradient more times than necessary, to avoid Quartz quality problems when there are lots of repeated color stops. r=jmuizelaar
diff --git a/gfx/cairo/cairo/src/cairo-quartz-surface.c b/gfx/cairo/cairo/src/cairo-quartz-surface.c
--- a/gfx/cairo/cairo/src/cairo-quartz-surface.c
+++ b/gfx/cairo/cairo/src/cairo-quartz-surface.c
@@ -710,82 +710,100 @@ CreateGradientFunction (const cairo_grad
return CGFunctionCreate (pat,
1,
input_value_range,
4,
gradient_output_value_ranges,
&gradient_callbacks);
}
+static void
+UpdateLinearParametersToIncludePoint(double *min_t, double *max_t, CGPoint *start,
+ double dx, double dy,
+ double x, double y)
+{
+ /* Compute a parameter t such that a line perpendicular to the (dx,dy)
+ vector, passing through (start->x + dx*t, start->y + dy*t), also
+ passes through (x,y).
+
+ Let px = x - start->x, py = y - start->y.
+ t is given by
+ (px - dx*t)*dx + (py - dy*t)*dy = 0
+
+ Solving for t we get
+ numerator = dx*px + dy*py
+ denominator = dx^2 + dy^2
+ t = numerator/denominator
+
+ In CreateRepeatingLinearGradientFunction we know the length of (dx,dy)
+ is not zero. (This is checked in _cairo_quartz_setup_linear_source.)
+ */
+ double px = x - start->x;
+ double py = y - start->y;
+ double numerator = dx*px + dy*py;
+ double denominator = dx*dx + dy*dy;
+ double t = numerator/denominator;
+
+ if (*min_t > t) {
+ *min_t = t;
+ }
+ if (*max_t < t) {
+ *max_t = t;
+ }
+}
+
static CGFunctionRef
CreateRepeatingLinearGradientFunction (cairo_quartz_surface_t *surface,
const cairo_gradient_pattern_t *gpat,
CGPoint *start, CGPoint *end,
- CGAffineTransform matrix)
+ cairo_rectangle_int_t *extents)
{
cairo_pattern_t *pat;
float input_value_range[2];
+ double t_min = 0.;
+ double t_max = 0.;
+ double dx = end->x - start->x;
+ double dy = end->y - start->y;
+ double bounds_x1, bounds_x2, bounds_y1, bounds_y2;
- CGPoint mstart, mend;
+ if (!extents) {
+ extents = &surface->extents;
+ }
+ bounds_x1 = extents->x;
+ bounds_y1 = extents->y;
+ bounds_x2 = extents->x + extents->width;
+ bounds_y2 = extents->y + extents->height;
+ _cairo_matrix_transform_bounding_box (&gpat->base.matrix,
+ &bounds_x1, &bounds_y1,
+ &bounds_x2, &bounds_y2,
+ NULL);
- double dx, dy;
- int x_rep_start = 0, x_rep_end = 0;
- int y_rep_start = 0, y_rep_end = 0;
+ UpdateLinearParametersToIncludePoint(&t_min, &t_max, start, dx, dy,
+ bounds_x1, bounds_y1);
+ UpdateLinearParametersToIncludePoint(&t_min, &t_max, start, dx, dy,
+ bounds_x2, bounds_y1);
+ UpdateLinearParametersToIncludePoint(&t_min, &t_max, start, dx, dy,
+ bounds_x2, bounds_y2);
+ UpdateLinearParametersToIncludePoint(&t_min, &t_max, start, dx, dy,
+ bounds_x1, bounds_y2);
- int rep_start, rep_end;
-
- // figure out how many times we'd need to repeat the gradient pattern
- // to cover the whole (transformed) surface area
- mstart = CGPointApplyAffineTransform (*start, matrix);
- mend = CGPointApplyAffineTransform (*end, matrix);
-
- dx = fabs (mend.x - mstart.x);
- dy = fabs (mend.y - mstart.y);
-
- if (dx > 1e-6) {
- x_rep_start = (int) ceil(MIN(mstart.x, mend.x) / dx);
- x_rep_end = (int) ceil((surface->extents.width - MAX(mstart.x, mend.x)) / dx);
-
- if (mend.x < mstart.x) {
- int swap = x_rep_end;
- x_rep_end = x_rep_start;
- x_rep_start = swap;
- }
- }
-
- if (dy > 1e-6) {
- y_rep_start = (int) ceil(MIN(mstart.y, mend.y) / dy);
- y_rep_end = (int) ceil((surface->extents.width - MAX(mstart.y, mend.y)) / dy);
-
- if (mend.y < mstart.y) {
- int swap = y_rep_end;
- y_rep_end = y_rep_start;
- y_rep_start = swap;
- }
- }
-
- rep_start = MAX(x_rep_start, y_rep_start);
- rep_end = MAX(x_rep_end, y_rep_end);
-
- // extend the line between start and end by rep_start times from the start
- // and rep_end times from the end
-
- dx = end->x - start->x;
- dy = end->y - start->y;
-
- start->x = start->x - dx * rep_start;
- start->y = start->y - dy * rep_start;
-
- end->x = end->x + dx * rep_end;
- end->y = end->y + dy * rep_end;
+ /* Move t_min and t_max to the nearest usable integer to try to avoid
+ subtle variations due to numerical instability, especially accidentally
+ cutting off a pixel. Extending the gradient repetitions is always safe. */
+ t_min = floor (t_min);
+ t_max = ceil (t_max);
+ end->x = start->x + dx*t_max;
+ end->y = start->y + dy*t_max;
+ start->x = start->x + dx*t_min;
+ start->y = start->y + dy*t_min;
// set the input range for the function -- the function knows how to
// map values outside of 0.0 .. 1.0 to that range for REPEAT/REFLECT.
- input_value_range[0] = 0.0 - 1.0 * rep_start;
- input_value_range[1] = 1.0 + 1.0 * rep_end;
+ input_value_range[0] = t_min;
+ input_value_range[1] = t_max;
if (_cairo_pattern_create_copy (&pat, &gpat->base))
/* quartz doesn't deal very well with malloc failing, so there's
* not much point in us trying either */
return NULL;
return CGFunctionCreate (pat,
1,
@@ -840,35 +858,43 @@ UpdateRadialParameterToIncludePoint(doub
}
}
/* This must only be called when one of the circles properly contains the other */
static CGFunctionRef
CreateRepeatingRadialGradientFunction (cairo_quartz_surface_t *surface,
const cairo_gradient_pattern_t *gpat,
CGPoint *start, double *start_radius,
- CGPoint *end, double *end_radius)
+ CGPoint *end, double *end_radius,
+ cairo_rectangle_int_t *extents)
{
- CGRect clip = CGContextGetClipBoundingBox (surface->cgContext);
- CGAffineTransform transform;
cairo_pattern_t *pat;
float input_value_range[2];
CGPoint *inner;
double *inner_radius;
CGPoint *outer;
double *outer_radius;
/* minimum and maximum t-parameter values that will make our gradient
cover the clipBox */
double t_min, t_max, t_temp;
/* outer minus inner */
double dr, dx, dy;
+ double bounds_x1, bounds_x2, bounds_y1, bounds_y2;
- _cairo_quartz_cairo_matrix_to_quartz (&gpat->base.matrix, &transform);
- /* clip is in cairo device coordinates; get it into cairo user space */
- clip = CGRectApplyAffineTransform (clip, transform);
+ if (!extents) {
+ extents = &surface->extents;
+ }
+ bounds_x1 = extents->x;
+ bounds_y1 = extents->y;
+ bounds_x2 = extents->x + extents->width;
+ bounds_y2 = extents->y + extents->height;
+ _cairo_matrix_transform_bounding_box (&gpat->base.matrix,
+ &bounds_x1, &bounds_y1,
+ &bounds_x2, &bounds_y2,
+ NULL);
if (*start_radius < *end_radius) {
/* end circle contains start circle */
inner = start;
outer = end;
inner_radius = start_radius;
outer_radius = end_radius;
} else {
@@ -878,36 +904,37 @@ CreateRepeatingRadialGradientFunction (c
inner_radius = end_radius;
outer_radius = start_radius;
}
dr = *outer_radius - *inner_radius;
dx = outer->x - inner->x;
dy = outer->y - inner->y;
+ /* We can't round or fudge t_min here, it has to be as accurate as possible. */
t_min = -(*inner_radius/dr);
inner->x += t_min*dx;
inner->y += t_min*dy;
*inner_radius = 0.;
t_temp = 0.;
UpdateRadialParameterToIncludePoint(&t_temp, inner, dr, dx, dy,
- clip.origin.x, clip.origin.y);
+ bounds_x1, bounds_y1);
UpdateRadialParameterToIncludePoint(&t_temp, inner, dr, dx, dy,
- clip.origin.x + clip.size.width, clip.origin.y);
+ bounds_x2, bounds_y1);
UpdateRadialParameterToIncludePoint(&t_temp, inner, dr, dx, dy,
- clip.origin.x + clip.size.width, clip.origin.y + clip.size.height);
+ bounds_x2, bounds_y2);
UpdateRadialParameterToIncludePoint(&t_temp, inner, dr, dx, dy,
- clip.origin.x, clip.origin.y + clip.size.height);
+ bounds_x1, bounds_y2);
/* UpdateRadialParameterToIncludePoint assumes t=0 means radius 0.
But for the parameter values we use with Quartz, t_min means radius 0.
- Also, add a small fudge factor to avoid rounding issues. Since the
- circles are alway expanding and containing the earlier circles, this is
- OK. */
- t_temp += 1e-6;
+ Since the circles are alway expanding and contain the earlier circles,
+ it's safe to extend t_max/t_temp as much as we want, so round t_temp up
+ to the nearest integer. This may help us give stable results. */
+ t_temp = ceil (t_temp);
t_max = t_min + t_temp;
outer->x = inner->x + t_temp*dx;
outer->y = inner->y + t_temp*dy;
*outer_radius = t_temp*dr;
/* set the input range for the function -- the function knows how to
map values outside of 0.0 .. 1.0 to that range for REPEAT/REFLECT. */
if (*start_radius < *end_radius) {
@@ -1218,33 +1245,57 @@ _cairo_quartz_setup_fallback_source (cai
surface->sourceImageRect = CGRectMake (0.0, 0.0, w, h);
surface->sourceImage = img;
surface->sourceImageSurface = fallback;
surface->sourceTransform = CGAffineTransformMakeTranslation (x0, y0);
return DO_IMAGE;
}
+/*
+Quartz does not support repeating radients. We handle repeating gradients
+by manually extending the gradient and repeating color stops. We need to
+minimize the number of repetitions since Quartz seems to sample our color
+function across the entire range, even if part of that range is not needed
+for the visible area of the gradient, and it samples with some fixed resolution,
+so if the gradient range is too large it samples with very low resolution and
+the gradient is very coarse. CreateRepeatingLinearGradientFunction and
+CreateRepeatingRadialGradientFunction compute the number of repetitions needed
+based on the extents of the object (the clip region cannot be used here since
+we don't want the rasterization of the entire gradient to depend on the
+clip region).
+*/
static cairo_quartz_action_t
_cairo_quartz_setup_linear_source (cairo_quartz_surface_t *surface,
- const cairo_linear_pattern_t *lpat)
+ const cairo_linear_pattern_t *lpat,
+ cairo_rectangle_int_t *extents)
{
const cairo_pattern_t *abspat = &lpat->base.base;
cairo_matrix_t mat;
CGPoint start, end;
CGFunctionRef gradFunc;
CGColorSpaceRef rgb;
bool extend = abspat->extend == CAIRO_EXTEND_PAD;
if (lpat->base.n_stops == 0) {
CGContextSetRGBStrokeColor (surface->cgContext, 0., 0., 0., 0.);
CGContextSetRGBFillColor (surface->cgContext, 0., 0., 0., 0.);
return DO_SOLID;
}
+ if (lpat->p1.x == lpat->p2.x &&
+ lpat->p1.y == lpat->p2.y) {
+ /* Quartz handles cases where the vector has no length very
+ * differently from pixman.
+ * Whatever the correct behaviour is, let's at least have only pixman's
+ * implementation to worry about.
+ */
+ return _cairo_quartz_setup_fallback_source (surface, abspat);
+ }
+
mat = abspat->matrix;
cairo_matrix_invert (&mat);
_cairo_quartz_cairo_matrix_to_quartz (&mat, &surface->sourceTransform);
rgb = CGColorSpaceCreateDeviceRGB();
start = CGPointMake (_cairo_fixed_to_double (lpat->p1.x),
_cairo_fixed_to_double (lpat->p1.y));
@@ -1254,33 +1305,34 @@ _cairo_quartz_setup_linear_source (cairo
if (abspat->extend == CAIRO_EXTEND_NONE ||
abspat->extend == CAIRO_EXTEND_PAD)
{
gradFunc = CreateGradientFunction (&lpat->base);
} else {
gradFunc = CreateRepeatingLinearGradientFunction (surface,
&lpat->base,
&start, &end,
- surface->sourceTransform);
+ extents);
}
surface->sourceShading = CGShadingCreateAxial (rgb,
start, end,
gradFunc,
extend, extend);
CGColorSpaceRelease(rgb);
CGFunctionRelease(gradFunc);
return DO_SHADING;
}
static cairo_quartz_action_t
_cairo_quartz_setup_radial_source (cairo_quartz_surface_t *surface,
- const cairo_radial_pattern_t *rpat)
+ const cairo_radial_pattern_t *rpat,
+ cairo_rectangle_int_t *extents)
{
const cairo_pattern_t *abspat = &rpat->base.base;
cairo_matrix_t mat;
CGPoint start, end;
CGFunctionRef gradFunc;
CGColorSpaceRef rgb;
bool extend = abspat->extend == CAIRO_EXTEND_PAD;
double c1x = _cairo_fixed_to_double (rpat->c1.x);
@@ -1322,17 +1374,18 @@ _cairo_quartz_setup_radial_source (cairo
if (abspat->extend == CAIRO_EXTEND_NONE ||
abspat->extend == CAIRO_EXTEND_PAD)
{
gradFunc = CreateGradientFunction (&rpat->base);
} else {
gradFunc = CreateRepeatingRadialGradientFunction (surface,
&rpat->base,
&start, &r1,
- &end, &r2);
+ &end, &r2,
+ extents);
}
surface->sourceShading = CGShadingCreateRadial (rgb,
start,
r1,
end,
r2,
gradFunc,
@@ -1341,17 +1394,18 @@ _cairo_quartz_setup_radial_source (cairo
CGColorSpaceRelease(rgb);
CGFunctionRelease(gradFunc);
return DO_SHADING;
}
static cairo_quartz_action_t
_cairo_quartz_setup_source (cairo_quartz_surface_t *surface,
- const cairo_pattern_t *source)
+ const cairo_pattern_t *source,
+ cairo_rectangle_int_t *extents)
{
assert (!(surface->sourceImage || surface->sourceShading || surface->sourcePattern));
surface->oldInterpolationQuality = CGContextGetInterpolationQuality (surface->cgContext);
CGContextSetInterpolationQuality (surface->cgContext, _cairo_quartz_filter_to_quartz (source->filter));
if (source->type == CAIRO_PATTERN_TYPE_SOLID) {
cairo_solid_pattern_t *solid = (cairo_solid_pattern_t *) source;
@@ -1367,24 +1421,22 @@ _cairo_quartz_setup_source (cairo_quartz
solid->color.blue,
solid->color.alpha);
return DO_SOLID;
}
if (source->type == CAIRO_PATTERN_TYPE_LINEAR) {
const cairo_linear_pattern_t *lpat = (const cairo_linear_pattern_t *)source;
- return _cairo_quartz_setup_linear_source (surface, lpat);
-
+ return _cairo_quartz_setup_linear_source (surface, lpat, extents);
}
if (source->type == CAIRO_PATTERN_TYPE_RADIAL) {
const cairo_radial_pattern_t *rpat = (const cairo_radial_pattern_t *)source;
- return _cairo_quartz_setup_radial_source (surface, rpat);
-
+ return _cairo_quartz_setup_radial_source (surface, rpat, extents);
}
if (source->type == CAIRO_PATTERN_TYPE_SURFACE &&
(source->extend == CAIRO_EXTEND_NONE || (CGContextDrawTiledImagePtr && source->extend == CAIRO_EXTEND_REPEAT)))
{
const cairo_surface_pattern_t *spat = (const cairo_surface_pattern_t *) source;
cairo_surface_t *pat_surf = spat->surface;
CGImageRef img;
@@ -1852,17 +1904,17 @@ _cairo_quartz_surface_paint (void *abstr
if (IS_EMPTY(surface))
return CAIRO_STATUS_SUCCESS;
if (op == CAIRO_OPERATOR_DEST)
return CAIRO_STATUS_SUCCESS;
CGContextSetCompositeOperation (surface->cgContext, _cairo_quartz_cairo_operator_to_quartz (op));
- action = _cairo_quartz_setup_source (surface, source);
+ action = _cairo_quartz_setup_source (surface, source, NULL);
if (action == DO_SOLID || action == DO_PATTERN) {
CGContextFillRect (surface->cgContext, CGRectMake(surface->extents.x,
surface->extents.y,
surface->extents.width,
surface->extents.height));
} else if (action == DO_SHADING) {
CGContextSaveGState (surface->cgContext);
@@ -1886,16 +1938,35 @@ _cairo_quartz_surface_paint (void *abstr
}
_cairo_quartz_teardown_source (surface, source);
ND((stderr, "-- paint\n"));
return rv;
}
+static cairo_bool_t
+_cairo_quartz_source_needs_extents (const cairo_pattern_t *source)
+{
+ /* For repeating gradients we need to manually extend the gradient and
+ repeat stops, since Quartz doesn't support repeating gradients natively.
+ We need to minimze the number of repeated stops, and since rasterization
+ depends on the number of repetitions we use (even if some of the
+ repetitions go beyond the extents of the object or outside the clip
+ region), it's important to use the same number of repetitions when
+ rendering an object no matter what the clip region is. So the
+ computation of the repetition count cannot depended on the clip region,
+ and should only depend on the object extents, so we need to compute
+ the object extents for repeating gradients. */
+ return (source->type == CAIRO_PATTERN_TYPE_LINEAR ||
+ source->type == CAIRO_PATTERN_TYPE_RADIAL) &&
+ (source->extend == CAIRO_EXTEND_REPEAT ||
+ source->extend == CAIRO_EXTEND_REFLECT);
+}
+
static cairo_int_status_t
_cairo_quartz_surface_fill (void *abstract_surface,
cairo_operator_t op,
const cairo_pattern_t *source,
cairo_path_fixed_t *path,
cairo_fill_rule_t fill_rule,
double tolerance,
cairo_antialias_t antialias,
@@ -1926,17 +1997,27 @@ _cairo_quartz_surface_fill (void *abstra
return CAIRO_STATUS_SUCCESS;
}
CGContextSaveGState (surface->cgContext);
CGContextSetShouldAntialias (surface->cgContext, (antialias != CAIRO_ANTIALIAS_NONE));
CGContextSetCompositeOperation (surface->cgContext, _cairo_quartz_cairo_operator_to_quartz (op));
- action = _cairo_quartz_setup_source (surface, source);
+ if (_cairo_quartz_source_needs_extents (source))
+ {
+ /* We don't need precise extents since these are only used to
+ compute the number of gradient reptitions needed to cover the
+ object. */
+ cairo_rectangle_int_t path_extents;
+ _cairo_path_fixed_approximate_fill_extents (path, &path_extents);
+ action = _cairo_quartz_setup_source (surface, source, &path_extents);
+ } else {
+ action = _cairo_quartz_setup_source (surface, source, NULL);
+ }
CGContextBeginPath (surface->cgContext);
stroke.cgContext = surface->cgContext;
stroke.ctm_inverse = NULL;
rv = _cairo_quartz_cairo_path_to_quartz_context (path, &stroke);
if (rv)
goto BAIL;
@@ -2059,17 +2140,24 @@ _cairo_quartz_surface_stroke (void *abst
CGContextSetLineDash (surface->cgContext, style->dash_offset, fdash, max_dashes);
if (fdash != sdash)
free (fdash);
}
CGContextSetCompositeOperation (surface->cgContext, _cairo_quartz_cairo_operator_to_quartz (op));
- action = _cairo_quartz_setup_source (surface, source);
+ if (_cairo_quartz_source_needs_extents (source))
+ {
+ cairo_rectangle_int_t path_extents;
+ _cairo_path_fixed_approximate_stroke_extents (path, style, ctm, &path_extents);
+ action = _cairo_quartz_setup_source (surface, source, &path_extents);
+ } else {
+ action = _cairo_quartz_setup_source (surface, source, NULL);
+ }
CGContextBeginPath (surface->cgContext);
stroke.cgContext = surface->cgContext;
stroke.ctm_inverse = ctm_inverse;
rv = _cairo_quartz_cairo_path_to_quartz_context (path, &stroke);
if (rv)
goto BAIL;
@@ -2180,17 +2268,26 @@ _cairo_quartz_surface_show_glyphs (void
if (op == CAIRO_OPERATOR_DEST)
return CAIRO_STATUS_SUCCESS;
if (cairo_scaled_font_get_type (scaled_font) != CAIRO_FONT_TYPE_QUARTZ)
return CAIRO_INT_STATUS_UNSUPPORTED;
CGContextSaveGState (surface->cgContext);
- action = _cairo_quartz_setup_source (surface, source);
+ if (_cairo_quartz_source_needs_extents (source))
+ {
+ cairo_rectangle_int_t glyph_extents;
+ _cairo_scaled_font_glyph_device_extents (scaled_font, glyphs, num_glyphs,
+ &glyph_extents);
+ action = _cairo_quartz_setup_source (surface, source, &glyph_extents);
+ } else {
+ action = _cairo_quartz_setup_source (surface, source, NULL);
+ }
+
if (action == DO_SOLID || action == DO_PATTERN) {
CGContextSetTextDrawingMode (surface->cgContext, kCGTextFill);
} else if (action == DO_IMAGE || action == DO_TILED_IMAGE || action == DO_SHADING) {
CGContextSetTextDrawingMode (surface->cgContext, kCGTextClip);
isClipping = TRUE;
} else {
if (action != DO_NOTHING)
rv = CAIRO_INT_STATUS_UNSUPPORTED;
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