[1/2] Implement floating point gradient computation

Submitted by Maarten Lankhorst on Jan. 3, 2019, 11:18 a.m.

Details

Message ID 20190103111847.29685-1-maarten.lankhorst@linux.intel.com
State New
Headers show
Series "Series without cover letter" ( rev: 3 2 1 ) in Pixman

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Commit Message

Maarten Lankhorst Jan. 3, 2019, 11:18 a.m.
From: Basile Clement <basile-pixman@clement.pm>

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.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
---
 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(-)

Patch hide | download patch | download mbox

diff --git a/pixman/pixman-conical-gradient.c b/pixman/pixman-conical-gradient.c
index 8bb46aecdcab..a39e20c4eb68 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 822f8e62bae7..9f11cf450e25 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 40c8c9f37dbe..a5d8be95919d 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 73a54146ddb1..0a07467c6593 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 6a217963da18..0367d78424d9 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;

Comments

On Thu, 2019-01-03 at 12:18 +0100, Maarten Lankhorst wrote:
> From: Basile Clement <basile-pixman@clement.pm>
> 
> 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.
> 
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

This series seems to be a pretty severe performance regression.
test/radial-perf-test on my machine goes from ~0.003 to ~0.006, which
is not great. At -O2 gcc doesn't seem to be smart enough to inline
radial_get_scanline (etc) into its callers or to specialize it for the
two possible pixel widths, but it does at -O3 and it doesn't fix the
performance. Likewise LTO doesn't help any.

What _does_ help is pasting in the old implementation of
_pixman_gradient_walker_pixel as the body of
pixman_gradient_walker_pixel_32. Apparently the out-of-line call to
pixman_contract_from_float is pretty punishing.

Cosmetic comments inline below...

> diff --git a/pixman/pixman-gradient-walker.c b/pixman/pixman-gradient-walker.c
> index 822f8e62bae7..9f11cf450e25 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.
>       */

This comment reads a bit funny now.

> @@ -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);

Whitespace error.

> diff --git a/pixman/pixman-private.h b/pixman/pixman-private.h
> index 73a54146ddb1..0a07467c6593 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;

This appears to just be adding another space between the type and slot
names? Seems unnecessary.

- ajax