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<p>This is essentially a duplicate of the recent patch by Maarten
Lankhorst (which spurred me into finally posting these, which laid
on my laptop for a couple months), with a slightly different
approach. It is mostly included as it is a prerequisite for the
subsequent patches, but they should work just as well with
Maarten's patch.</p>
<p>This series of patches is driven by a discussion with Marc
Jeanmougin and the need of having dithering in pixman for
inkscape, and tries to implement the recommendations given by
Soren in previous threads on the topic.<br>
</p>
<p>- Basile<br>
<b></b><b></b></p>
<div class="moz-cite-prefix">On 12/3/18 3:55 PM, Basile Clement
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:20181203145530.9649-1-basile-pixman@clement.pm">
<pre class="moz-quote-pre" wrap="">This patch modifies the gradient walker to be able to generate floating
point values directly in addition to a8r8g8b8 32 bit values. This is
then used by the various gradient implementations to render in floating
point when asked to do so, instead of rendering to a8r8g8b8 and then
expanding to floating point as they were doing previously.
---
pixman/pixman-conical-gradient.c | 36 ++++++----
pixman/pixman-gradient-walker.c | 92 ++++++++++++++++++-------
pixman/pixman-linear-gradient.c | 49 ++++++++------
pixman/pixman-private.h | 65 ++++++++++++++----
pixman/pixman-radial-gradient.c | 112 ++++++++++++++++++-------------
5 files changed, 234 insertions(+), 120 deletions(-)
diff --git a/pixman/pixman-conical-gradient.c b/pixman/pixman-conical-gradient.c
index 8bb46ae..a39e20c 100644
--- a/pixman/pixman-conical-gradient.c
+++ b/pixman/pixman-conical-gradient.c
@@ -51,7 +51,10 @@ coordinates_to_parameter (double x, double y, double angle)
}
static uint32_t *
-conical_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
+conical_get_scanline (pixman_iter_t *iter,
+ const uint32_t *mask,
+ int Bpp,
+ pixman_gradient_walker_write_t write_pixel)
{
pixman_image_t *image = iter->image;
int x = iter->x;
@@ -61,7 +64,7 @@ conical_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
gradient_t *gradient = (gradient_t *)image;
conical_gradient_t *conical = (conical_gradient_t *)image;
- uint32_t *end = buffer + width;
+ uint32_t *end = buffer + width * (Bpp / 4);
pixman_gradient_walker_t walker;
pixman_bool_t affine = TRUE;
double cx = 1.;
@@ -109,11 +112,12 @@ conical_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
{
double t = coordinates_to_parameter (rx, ry, conical->angle);
- *buffer = _pixman_gradient_walker_pixel (
- &walker, (pixman_fixed_48_16_t)pixman_double_to_fixed (t));
+ write_pixel (&walker,
+ (pixman_fixed_48_16_t)pixman_double_to_fixed (t),
+ buffer);
}
- ++buffer;
+ buffer += (Bpp / 4);
rx += cx;
ry += cy;
@@ -144,11 +148,12 @@ conical_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
t = coordinates_to_parameter (x, y, conical->angle);
- *buffer = _pixman_gradient_walker_pixel (
- &walker, (pixman_fixed_48_16_t)pixman_double_to_fixed (t));
+ write_pixel (&walker,
+ (pixman_fixed_48_16_t)pixman_double_to_fixed (t),
+ buffer);
}
- ++buffer;
+ buffer += (Bpp / 4);
rx += cx;
ry += cy;
@@ -161,14 +166,17 @@ conical_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
}
static uint32_t *
-conical_get_scanline_wide (pixman_iter_t *iter, const uint32_t *mask)
+conical_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
{
- uint32_t *buffer = conical_get_scanline_narrow (iter, NULL);
-
- pixman_expand_to_float (
- (argb_t *)buffer, buffer, PIXMAN_a8r8g8b8, iter->width);
+ return conical_get_scanline (iter, mask, 4,
+ _pixman_gradient_walker_write_narrow);
+}
- return buffer;
+static uint32_t *
+conical_get_scanline_wide (pixman_iter_t *iter, const uint32_t *mask)
+{
+ return conical_get_scanline (iter, NULL, 16,
+ _pixman_gradient_walker_write_wide);
}
void
diff --git a/pixman/pixman-gradient-walker.c b/pixman/pixman-gradient-walker.c
index 822f8e6..9f11cf4 100644
--- a/pixman/pixman-gradient-walker.c
+++ b/pixman/pixman-gradient-walker.c
@@ -122,10 +122,10 @@ gradient_walker_reset (pixman_gradient_walker_t *walker,
left_c = right_c;
}
- /* The alpha channel is scaled to be in the [0, 255] interval,
+ /* The alpha channel is scaled to be in the [0, 1] interval,
* and the red/green/blue channels are scaled to be in [0, 1].
* This ensures that after premultiplication all channels will
- * be in the [0, 255] interval.
+ * be in the [0, 1] interval.
*/
la = (left_c->alpha * (1.0f/257.0f));
lr = (left_c->red * (1.0f/257.0f));
@@ -143,7 +143,7 @@ gradient_walker_reset (pixman_gradient_walker_t *walker,
if (FLOAT_IS_ZERO (rx - lx) || left_x == INT32_MIN || right_x == INT32_MAX)
{
walker->a_s = walker->r_s = walker->g_s = walker->b_s = 0.0f;
- walker->a_b = (la + ra) / 2.0f;
+ walker->a_b = (la + ra) / 510.0f;
walker->r_b = (lr + rr) / 510.0f;
walker->g_b = (lg + rg) / 510.0f;
walker->b_b = (lb + rb) / 510.0f;
@@ -152,12 +152,12 @@ gradient_walker_reset (pixman_gradient_walker_t *walker,
{
float w_rec = 1.0f / (rx - lx);
- walker->a_b = (la * rx - ra * lx) * w_rec;
+ walker->a_b = (la * rx - ra * lx) * w_rec * (1.0f/255.0f);
walker->r_b = (lr * rx - rr * lx) * w_rec * (1.0f/255.0f);
walker->g_b = (lg * rx - rg * lx) * w_rec * (1.0f/255.0f);
walker->b_b = (lb * rx - rb * lx) * w_rec * (1.0f/255.0f);
- walker->a_s = (ra - la) * w_rec;
+ walker->a_s = (ra - la) * w_rec * (1.0f/255.0f);
walker->r_s = (rr - lr) * w_rec * (1.0f/255.0f);
walker->g_s = (rg - lg) * w_rec * (1.0f/255.0f);
walker->b_s = (rb - lb) * w_rec * (1.0f/255.0f);
@@ -169,34 +169,78 @@ gradient_walker_reset (pixman_gradient_walker_t *walker,
walker->need_reset = FALSE;
}
-uint32_t
-_pixman_gradient_walker_pixel (pixman_gradient_walker_t *walker,
- pixman_fixed_48_16_t x)
+static argb_t
+pixman_gradient_walker_pixel_float (pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x)
{
- float a, r, g, b;
- uint8_t a8, r8, g8, b8;
- uint32_t v;
+ argb_t f;
float y;
if (walker->need_reset || x < walker->left_x || x >= walker->right_x)
- gradient_walker_reset (walker, x);
+ gradient_walker_reset (walker, x);
y = x * (1.0f / 65536.0f);
- a = walker->a_s * y + walker->a_b;
- r = a * (walker->r_s * y + walker->r_b);
- g = a * (walker->g_s * y + walker->g_b);
- b = a * (walker->b_s * y + walker->b_b);
+ f.a = walker->a_s * y + walker->a_b;
+ f.r = f.a * (walker->r_s * y + walker->r_b);
+ f.g = f.a * (walker->g_s * y + walker->g_b);
+ f.b = f.a * (walker->b_s * y + walker->b_b);
+
+ return f;
+}
- a8 = a + 0.5f;
- r8 = r + 0.5f;
- g8 = g + 0.5f;
- b8 = b + 0.5f;
+static uint32_t
+pixman_gradient_walker_pixel_32 (pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x)
+{
+ argb_t f = pixman_gradient_walker_pixel_float (walker, x);
+ uint32_t v;
- v = ((a8 << 24) & 0xff000000) |
- ((r8 << 16) & 0x00ff0000) |
- ((g8 << 8) & 0x0000ff00) |
- ((b8 >> 0) & 0x000000ff);
+ pixman_contract_from_float (&v, &f, 1);
return v;
}
+
+void
+_pixman_gradient_walker_write_narrow (pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x,
+ uint32_t *buffer)
+{
+ *buffer = pixman_gradient_walker_pixel_32 (walker, x);
+}
+
+void
+_pixman_gradient_walker_write_wide (pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x,
+ uint32_t *buffer)
+{
+ *(argb_t *)buffer = pixman_gradient_walker_pixel_float (walker, x);
+}
+
+void
+_pixman_gradient_walker_fill_narrow (pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x,
+ uint32_t *buffer,
+ uint32_t *end)
+{
+ register uint32_t color;
+
+ color = pixman_gradient_walker_pixel_32 (walker, x);
+ while (buffer < end)
+ *buffer++ = color;
+}
+
+void
+_pixman_gradient_walker_fill_wide (pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x,
+ uint32_t *buffer,
+ uint32_t *end)
+{
+ register argb_t color;
+ argb_t *buffer_wide = (argb_t *)buffer;
+ argb_t *end_wide = (argb_t *)end;
+
+ color = pixman_gradient_walker_pixel_float (walker, x);
+ while (buffer_wide < end_wide)
+ *buffer_wide++ = color;
+}
diff --git a/pixman/pixman-linear-gradient.c b/pixman/pixman-linear-gradient.c
index 40c8c9f..a5d8be9 100644
--- a/pixman/pixman-linear-gradient.c
+++ b/pixman/pixman-linear-gradient.c
@@ -89,8 +89,11 @@ linear_gradient_is_horizontal (pixman_image_t *image,
}
static uint32_t *
-linear_get_scanline_narrow (pixman_iter_t *iter,
- const uint32_t *mask)
+linear_get_scanline (pixman_iter_t *iter,
+ const uint32_t *mask,
+ int Bpp,
+ pixman_gradient_walker_write_t write_pixel,
+ pixman_gradient_walker_fill_t fill_pixel)
{
pixman_image_t *image = iter->image;
int x = iter->x;
@@ -103,10 +106,10 @@ linear_get_scanline_narrow (pixman_iter_t *iter,
pixman_fixed_48_16_t dx, dy;
gradient_t *gradient = (gradient_t *)image;
linear_gradient_t *linear = (linear_gradient_t *)image;
- uint32_t *end = buffer + width;
+ uint32_t *end = buffer + width * (Bpp / 4);
pixman_gradient_walker_t walker;
- _pixman_gradient_walker_init (&walker, gradient, image->common.repeat);
+ _pixman_gradient_walker_init (&walker,gradient, image->common.repeat);
/* reference point is the center of the pixel */
v.vector[0] = pixman_int_to_fixed (x) + pixman_fixed_1 / 2;
@@ -137,7 +140,7 @@ linear_get_scanline_narrow (pixman_iter_t *iter,
if (l == 0 || unit.vector[2] == 0)
{
/* affine transformation only */
- pixman_fixed_32_32_t t, next_inc;
+ pixman_fixed_32_32_t t, next_inc;
double inc;
if (l == 0 || v.vector[2] == 0)
@@ -152,7 +155,7 @@ linear_get_scanline_narrow (pixman_iter_t *iter,
invden = pixman_fixed_1 * (double) pixman_fixed_1 /
(l * (double) v.vector[2]);
v2 = v.vector[2] * (1. / pixman_fixed_1);
- t = ((dx * v.vector[0] + dy * v.vector[1]) -
+ t = ((dx * v.vector[0] + dy * v.vector[1]) -
(dx * linear->p1.x + dy * linear->p1.y) * v2) * invden;
inc = (dx * unit.vector[0] + dy * unit.vector[1]) * invden;
}
@@ -160,11 +163,7 @@ linear_get_scanline_narrow (pixman_iter_t *iter,
if (((pixman_fixed_32_32_t )(inc * width)) == 0)
{
- register uint32_t color;
-
- color = _pixman_gradient_walker_pixel (&walker, t);
- while (buffer < end)
- *buffer++ = color;
+ fill_pixel (&walker, t, buffer, end);
}
else
{
@@ -175,12 +174,11 @@ linear_get_scanline_narrow (pixman_iter_t *iter,
{
if (!mask || *mask++)
{
- *buffer = _pixman_gradient_walker_pixel (&walker,
- t + next_inc);
+ write_pixel (&walker, t + next_inc, buffer);
}
i++;
next_inc = inc * i;
- buffer++;
+ buffer += (Bpp / 4);
}
}
}
@@ -202,14 +200,14 @@ linear_get_scanline_narrow (pixman_iter_t *iter,
invden = pixman_fixed_1 * (double) pixman_fixed_1 /
(l * (double) v.vector[2]);
v2 = v.vector[2] * (1. / pixman_fixed_1);
- t = ((dx * v.vector[0] + dy * v.vector[1]) -
+ t = ((dx * v.vector[0] + dy * v.vector[1]) -
(dx * linear->p1.x + dy * linear->p1.y) * v2) * invden;
}
- *buffer = _pixman_gradient_walker_pixel (&walker, t);
+ write_pixel (&walker, t, buffer);
}
- ++buffer;
+ buffer += (Bpp / 4);
v.vector[0] += unit.vector[0];
v.vector[1] += unit.vector[1];
@@ -223,14 +221,21 @@ linear_get_scanline_narrow (pixman_iter_t *iter,
}
static uint32_t *
-linear_get_scanline_wide (pixman_iter_t *iter, const uint32_t *mask)
+linear_get_scanline_narrow (pixman_iter_t *iter,
+ const uint32_t *mask)
{
- uint32_t *buffer = linear_get_scanline_narrow (iter, NULL);
+ return linear_get_scanline (iter, mask, 4,
+ _pixman_gradient_walker_write_narrow,
+ _pixman_gradient_walker_fill_narrow);
+}
- pixman_expand_to_float (
- (argb_t *)buffer, buffer, PIXMAN_a8r8g8b8, iter->width);
- return buffer;
+static uint32_t *
+linear_get_scanline_wide (pixman_iter_t *iter, const uint32_t *mask)
+{
+ return linear_get_scanline (iter, NULL, 16,
+ _pixman_gradient_walker_write_wide,
+ _pixman_gradient_walker_fill_wide);
}
void
diff --git a/pixman/pixman-private.h b/pixman/pixman-private.h
index 73a5414..0a07467 100644
--- a/pixman/pixman-private.h
+++ b/pixman/pixman-private.h
@@ -340,18 +340,18 @@ _pixman_image_validate (pixman_image_t *image);
*/
typedef struct
{
- float a_s, a_b;
- float r_s, r_b;
- float g_s, g_b;
- float b_s, b_b;
- pixman_fixed_48_16_t left_x;
- pixman_fixed_48_16_t right_x;
-
- pixman_gradient_stop_t *stops;
- int num_stops;
- pixman_repeat_t repeat;
-
- pixman_bool_t need_reset;
+ float a_s, a_b;
+ float r_s, r_b;
+ float g_s, g_b;
+ float b_s, b_b;
+ pixman_fixed_48_16_t left_x;
+ pixman_fixed_48_16_t right_x;
+
+ pixman_gradient_stop_t *stops;
+ int num_stops;
+ pixman_repeat_t repeat;
+
+ pixman_bool_t need_reset;
} pixman_gradient_walker_t;
void
@@ -363,9 +363,46 @@ void
_pixman_gradient_walker_reset (pixman_gradient_walker_t *walker,
pixman_fixed_48_16_t pos);
+argb_t
+_pixman_gradient_walker_pixel_float (pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x);
+
uint32_t
-_pixman_gradient_walker_pixel (pixman_gradient_walker_t *walker,
- pixman_fixed_48_16_t x);
+_pixman_gradient_walker_pixel_32 (pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x);
+
+typedef void (*pixman_gradient_walker_write_t) (
+ pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x,
+ uint32_t *buffer);
+
+void
+_pixman_gradient_walker_write_narrow(pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x,
+ uint32_t *buffer);
+
+void
+_pixman_gradient_walker_write_wide(pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x,
+ uint32_t *buffer);
+
+typedef void (*pixman_gradient_walker_fill_t) (
+ pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x,
+ uint32_t *buffer,
+ uint32_t *end);
+
+void
+_pixman_gradient_walker_fill_narrow(pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x,
+ uint32_t *buffer,
+ uint32_t *end);
+
+void
+_pixman_gradient_walker_fill_wide(pixman_gradient_walker_t *walker,
+ pixman_fixed_48_16_t x,
+ uint32_t *buffer,
+ uint32_t *end);
/*
* Edges
diff --git a/pixman/pixman-radial-gradient.c b/pixman/pixman-radial-gradient.c
index 6a21796..0367d78 100644
--- a/pixman/pixman-radial-gradient.c
+++ b/pixman/pixman-radial-gradient.c
@@ -66,15 +66,18 @@ fdot (double x1,
return x1 * x2 + y1 * y2 + z1 * z2;
}
-static uint32_t
-radial_compute_color (double a,
- double b,
- double c,
- double inva,
- double dr,
- double mindr,
- pixman_gradient_walker_t *walker,
- pixman_repeat_t repeat)
+static void
+radial_write_color (double a,
+ double b,
+ double c,
+ double inva,
+ double dr,
+ double mindr,
+ pixman_gradient_walker_t *walker,
+ pixman_repeat_t repeat,
+ int Bpp,
+ pixman_gradient_walker_write_t write_pixel,
+ uint32_t *buffer)
{
/*
* In this function error propagation can lead to bad results:
@@ -99,21 +102,25 @@ radial_compute_color (double a,
double t;
if (b == 0)
- return 0;
+ {
+ memset (buffer, 0, Bpp);
+ return;
+ }
t = pixman_fixed_1 / 2 * c / b;
if (repeat == PIXMAN_REPEAT_NONE)
{
if (0 <= t && t <= pixman_fixed_1)
- return _pixman_gradient_walker_pixel (walker, t);
+ return write_pixel (walker, t, buffer);
}
else
{
if (t * dr >= mindr)
- return _pixman_gradient_walker_pixel (walker, t);
+ return write_pixel (walker, t, buffer);
}
- return 0;
+ memset (buffer, 0, Bpp);
+ return;
}
discr = fdot (b, a, 0, b, -c, 0);
@@ -139,24 +146,28 @@ radial_compute_color (double a,
if (repeat == PIXMAN_REPEAT_NONE)
{
if (0 <= t0 && t0 <= pixman_fixed_1)
- return _pixman_gradient_walker_pixel (walker, t0);
+ return write_pixel (walker, t0, buffer);
else if (0 <= t1 && t1 <= pixman_fixed_1)
- return _pixman_gradient_walker_pixel (walker, t1);
+ return write_pixel (walker, t1, buffer);
}
else
{
if (t0 * dr >= mindr)
- return _pixman_gradient_walker_pixel (walker, t0);
+ return write_pixel (walker, t0, buffer);
else if (t1 * dr >= mindr)
- return _pixman_gradient_walker_pixel (walker, t1);
+ return write_pixel (walker, t1, buffer);
}
}
- return 0;
+ memset (buffer, 0, Bpp);
+ return;
}
static uint32_t *
-radial_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
+radial_get_scanline (pixman_iter_t *iter,
+ const uint32_t *mask,
+ int Bpp,
+ pixman_gradient_walker_write_t write_pixel)
{
/*
* Implementation of radial gradients following the PDF specification.
@@ -247,7 +258,7 @@ radial_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
gradient_t *gradient = (gradient_t *)image;
radial_gradient_t *radial = (radial_gradient_t *)image;
- uint32_t *end = buffer + width;
+ uint32_t *end = buffer + width * (Bpp / 4);
pixman_gradient_walker_t walker;
pixman_vector_t v, unit;
@@ -330,18 +341,21 @@ radial_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
{
if (!mask || *mask++)
{
- *buffer = radial_compute_color (radial->a, b, c,
- radial->inva,
- radial->delta.radius,
- radial->mindr,
- &walker,
- image->common.repeat);
+ radial_write_color (radial->a, b, c,
+ radial->inva,
+ radial->delta.radius,
+ radial->mindr,
+ &walker,
+ image->common.repeat,
+ Bpp,
+ write_pixel,
+ buffer);
}
b += db;
c += dc;
dc += ddc;
- ++buffer;
+ buffer += (Bpp / 4);
}
}
else
@@ -375,20 +389,23 @@ radial_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
pdx, pdy, radial->c1.radius);
/* / pixman_fixed_1 / pixman_fixed_1 */
- *buffer = radial_compute_color (radial->a, b, c,
- radial->inva,
- radial->delta.radius,
- radial->mindr,
- &walker,
- image->common.repeat);
+ radial_write_color (radial->a, b, c,
+ radial->inva,
+ radial->delta.radius,
+ radial->mindr,
+ &walker,
+ image->common.repeat,
+ Bpp,
+ write_pixel,
+ buffer);
}
else
{
- *buffer = 0;
+ memset (buffer, 0, Bpp);
}
}
- ++buffer;
+ buffer += (Bpp / 4);
v.vector[0] += unit.vector[0];
v.vector[1] += unit.vector[1];
@@ -401,14 +418,17 @@ radial_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
}
static uint32_t *
-radial_get_scanline_wide (pixman_iter_t *iter, const uint32_t *mask)
+radial_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
{
- uint32_t *buffer = radial_get_scanline_narrow (iter, NULL);
-
- pixman_expand_to_float (
- (argb_t *)buffer, buffer, PIXMAN_a8r8g8b8, iter->width);
+ return radial_get_scanline (iter, mask, 4,
+ _pixman_gradient_walker_write_narrow);
+}
- return buffer;
+static uint32_t *
+radial_get_scanline_wide (pixman_iter_t *iter, const uint32_t *mask)
+{
+ return radial_get_scanline (iter, NULL, 16,
+ _pixman_gradient_walker_write_wide);
}
void
@@ -422,11 +442,11 @@ _pixman_radial_gradient_iter_init (pixman_image_t *image, pixman_iter_t *iter)
PIXMAN_EXPORT pixman_image_t *
pixman_image_create_radial_gradient (const pixman_point_fixed_t * inner,
- const pixman_point_fixed_t * outer,
- pixman_fixed_t inner_radius,
- pixman_fixed_t outer_radius,
- const pixman_gradient_stop_t *stops,
- int n_stops)
+ const pixman_point_fixed_t * outer,
+ pixman_fixed_t inner_radius,
+ pixman_fixed_t outer_radius,
+ const pixman_gradient_stop_t *stops,
+ int n_stops)
{
pixman_image_t *image;
radial_gradient_t *radial;
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