michael@0: diff --git a/gfx/cairo/libpixman/src/pixman-dither.h b/gfx/cairo/libpixman/src/pixman-dither.h
michael@0: new file mode 100644
michael@0: --- /dev/null
michael@0: +++ b/gfx/cairo/libpixman/src/pixman-dither.h
michael@0: @@ -0,0 +1,51 @@
michael@0: +#define R16_BITS     5
michael@0: +#define G16_BITS     6
michael@0: +#define B16_BITS     5
michael@0: +
michael@0: +#define R16_SHIFT    (B16_BITS + G16_BITS)
michael@0: +#define G16_SHIFT    (B16_BITS)
michael@0: +#define B16_SHIFT    0
michael@0: +
michael@0: +#define MASK 0xff
michael@0: +#define ONE_HALF 0x80
michael@0: +
michael@0: +#define A_SHIFT 8 * 3
michael@0: +#define R_SHIFT 8 * 2
michael@0: +#define G_SHIFT 8
michael@0: +#define A_MASK 0xff000000
michael@0: +#define R_MASK 0xff0000
michael@0: +#define G_MASK 0xff00
michael@0: +
michael@0: +#define RB_MASK 0xff00ff
michael@0: +#define AG_MASK 0xff00ff00
michael@0: +#define RB_ONE_HALF 0x800080
michael@0: +#define RB_MASK_PLUS_ONE 0x10000100
michael@0: +
michael@0: +#define ALPHA_8(x) ((x) >> A_SHIFT)
michael@0: +#define RED_8(x) (((x) >> R_SHIFT) & MASK)
michael@0: +#define GREEN_8(x) (((x) >> G_SHIFT) & MASK)
michael@0: +#define BLUE_8(x) ((x) & MASK)
michael@0: +
michael@0: +// This uses the same dithering technique that Skia does.
michael@0: +// It is essentially preturbing the lower bit based on the
michael@0: +// high bit
michael@0: +static inline uint16_t dither_32_to_16(uint32_t c)
michael@0: +{
michael@0: +    uint8_t b = BLUE_8(c);
michael@0: +    uint8_t g = GREEN_8(c);
michael@0: +    uint8_t r = RED_8(c);
michael@0: +    r = ((r << 1) - ((r >> (8 - R16_BITS) << (8 - R16_BITS)) | (r >> R16_BITS))) >> (8 - R16_BITS);
michael@0: +    g = ((g << 1) - ((g >> (8 - G16_BITS) << (8 - G16_BITS)) | (g >> G16_BITS))) >> (8 - G16_BITS);
michael@0: +    b = ((b << 1) - ((b >> (8 - B16_BITS) << (8 - B16_BITS)) | (b >> B16_BITS))) >> (8 - B16_BITS);
michael@0: +    return ((r << R16_SHIFT) | (g << G16_SHIFT) | (b << B16_SHIFT));
michael@0: +}
michael@0: +
michael@0: +static inline uint16_t dither_8888_to_0565(uint32_t color, pixman_bool_t toggle)
michael@0: +{
michael@0: +    // alternate between a preturbed truncation and a regular truncation
michael@0: +    if (toggle) {
michael@0: +	return dither_32_to_16(color);
michael@0: +    } else {
michael@0: +	return CONVERT_8888_TO_0565(color);
michael@0: +    }
michael@0: +}
michael@0: diff --git a/gfx/cairo/libpixman/src/pixman-linear-gradient.c b/gfx/cairo/libpixman/src/pixman-linear-gradient.c
michael@0: --- a/gfx/cairo/libpixman/src/pixman-linear-gradient.c
michael@0: +++ b/gfx/cairo/libpixman/src/pixman-linear-gradient.c
michael@0: @@ -26,16 +26,18 @@
michael@0:   */
michael@0:  
michael@0:  #ifdef HAVE_CONFIG_H
michael@0:  #include <config.h>
michael@0:  #endif
michael@0:  #include <stdlib.h>
michael@0:  #include "pixman-private.h"
michael@0:  
michael@0: +#include "pixman-dither.h"
michael@0: +
michael@0:  static pixman_bool_t
michael@0:  linear_gradient_is_horizontal (pixman_image_t *image,
michael@0:  			       int             x,
michael@0:  			       int             y,
michael@0:  			       int             width,
michael@0:  			       int             height)
michael@0:  {
michael@0:      linear_gradient_t *linear = (linear_gradient_t *)image;
michael@0: @@ -222,25 +224,28 @@ linear_get_scanline_narrow (pixman_iter_
michael@0:      return iter->buffer;
michael@0:  }
michael@0:  
michael@0:  static uint16_t convert_8888_to_0565(uint32_t color)
michael@0:  {
michael@0:      return CONVERT_8888_TO_0565(color);
michael@0:  }
michael@0:  
michael@0: +
michael@0: +
michael@0:  static uint32_t *
michael@0:  linear_get_scanline_16 (pixman_iter_t  *iter,
michael@0:  			const uint32_t *mask)
michael@0:  {
michael@0:      pixman_image_t *image  = iter->image;
michael@0:      int             x      = iter->x;
michael@0:      int             y      = iter->y;
michael@0:      int             width  = iter->width;
michael@0:      uint16_t *      buffer = (uint16_t*)iter->buffer;
michael@0: +    pixman_bool_t   toggle = ((x ^ y) & 1);
michael@0:  
michael@0:      pixman_vector_t v, unit;
michael@0:      pixman_fixed_32_32_t l;
michael@0:      pixman_fixed_48_16_t dx, dy;
michael@0:      gradient_t *gradient = (gradient_t *)image;
michael@0:      linear_gradient_t *linear = (linear_gradient_t *)image;
michael@0:      uint16_t *end = buffer + width;
michael@0:      pixman_gradient_walker_t walker;
michael@0: @@ -294,34 +299,47 @@ linear_get_scanline_16 (pixman_iter_t  *
michael@0:  	    t = ((dx * v.vector[0] + dy * v.vector[1]) - 
michael@0:  		 (dx * linear->p1.x + dy * linear->p1.y) * v2) * invden;
michael@0:  	    inc = (dx * unit.vector[0] + dy * unit.vector[1]) * invden;
michael@0:  	}
michael@0:  	next_inc = 0;
michael@0:  
michael@0:  	if (((pixman_fixed_32_32_t )(inc * width)) == 0)
michael@0:  	{
michael@0: -	    register uint16_t color;
michael@0: +	    register uint32_t color;
michael@0: +	    uint16_t dither_diff;
michael@0: +	    uint16_t color16;
michael@0: +	    uint16_t color16b;
michael@0:  
michael@0: -	    color = convert_8888_to_0565(_pixman_gradient_walker_pixel (&walker, t));
michael@0: -	    while (buffer < end)
michael@0: -		*buffer++ = color;
michael@0: +	    color = _pixman_gradient_walker_pixel (&walker, t);
michael@0: +	    color16 = dither_8888_to_0565(color, toggle);
michael@0: +	    color16b = dither_8888_to_0565(color, toggle^1);
michael@0: +	    // compute the difference
michael@0: +	    dither_diff =  color16 ^ color16b;
michael@0: +	    while (buffer < end) {
michael@0: +		*buffer++ = color16;
michael@0: +		// use dither_diff to toggle between color16 and color16b
michael@0: +		color16 ^= dither_diff;
michael@0: +		toggle ^= 1;
michael@0: +	    }
michael@0:  	}
michael@0:  	else
michael@0:  	{
michael@0:  	    int i;
michael@0:  
michael@0:  	    i = 0;
michael@0:  	    while (buffer < end)
michael@0:  	    {
michael@0:  		if (!mask || *mask++)
michael@0:  		{
michael@0: -		    *buffer = convert_8888_to_0565(_pixman_gradient_walker_pixel (&walker,
michael@0: -										  t + next_inc));
michael@0: +		    *buffer = dither_8888_to_0565(_pixman_gradient_walker_pixel (&walker,
michael@0: +										 t + next_inc),
michael@0: +						  toggle);
michael@0:  		}
michael@0: +		toggle ^= 1;
michael@0:  		i++;
michael@0:  		next_inc = inc * i;
michael@0:  		buffer++;
michael@0:  	    }
michael@0:  	}
michael@0:      }
michael@0:      else
michael@0:      {
michael@0: @@ -340,18 +358,20 @@ linear_get_scanline_16 (pixman_iter_t  *
michael@0:  
michael@0:  		    invden = pixman_fixed_1 * (double) pixman_fixed_1 /
michael@0:  			(l * (double) v.vector[2]);
michael@0:  		    v2 = v.vector[2] * (1. / pixman_fixed_1);
michael@0:  		    t = ((dx * v.vector[0] + dy * v.vector[1]) - 
michael@0:  			 (dx * linear->p1.x + dy * linear->p1.y) * v2) * invden;
michael@0:  		}
michael@0:  
michael@0: -		*buffer = convert_8888_to_0565(_pixman_gradient_walker_pixel (&walker, t));
michael@0: +		*buffer = dither_8888_to_0565(_pixman_gradient_walker_pixel (&walker, t),
michael@0: +					      toggle);
michael@0:  	    }
michael@0: +	    toggle ^= 1;
michael@0:  
michael@0:  	    ++buffer;
michael@0:  
michael@0:  	    v.vector[0] += unit.vector[0];
michael@0:  	    v.vector[1] += unit.vector[1];
michael@0:  	    v.vector[2] += unit.vector[2];
michael@0:  	}
michael@0:      }
michael@0: @@ -369,17 +389,18 @@ linear_get_scanline_wide (pixman_iter_t 
michael@0:      pixman_expand ((uint64_t *)buffer, buffer, PIXMAN_a8r8g8b8, iter->width);
michael@0:  
michael@0:      return buffer;
michael@0:  }
michael@0:  
michael@0:  void
michael@0:  _pixman_linear_gradient_iter_init (pixman_image_t *image, pixman_iter_t  *iter)
michael@0:  {
michael@0: -    if (linear_gradient_is_horizontal (
michael@0: +    // XXX: we can't use this optimization when dithering
michael@0: +    if (0 && linear_gradient_is_horizontal (
michael@0:  	    iter->image, iter->x, iter->y, iter->width, iter->height))
michael@0:      {
michael@0:  	if (iter->flags & ITER_16)
michael@0:  	    linear_get_scanline_16 (iter, NULL);
michael@0:  	else if (iter->flags & ITER_NARROW)
michael@0:  	    linear_get_scanline_narrow (iter, NULL);
michael@0:  	else
michael@0:  	    linear_get_scanline_wide (iter, NULL);
michael@0: diff --git a/gfx/cairo/libpixman/src/pixman-radial-gradient.c b/gfx/cairo/libpixman/src/pixman-radial-gradient.c
michael@0: --- a/gfx/cairo/libpixman/src/pixman-radial-gradient.c
michael@0: +++ b/gfx/cairo/libpixman/src/pixman-radial-gradient.c
michael@0: @@ -29,16 +29,18 @@
michael@0:  
michael@0:  #ifdef HAVE_CONFIG_H
michael@0:  #include <config.h>
michael@0:  #endif
michael@0:  #include <stdlib.h>
michael@0:  #include <math.h>
michael@0:  #include "pixman-private.h"
michael@0:  
michael@0: +#include "pixman-dither.h"
michael@0: +
michael@0:  static inline pixman_fixed_32_32_t
michael@0:  dot (pixman_fixed_48_16_t x1,
michael@0:       pixman_fixed_48_16_t y1,
michael@0:       pixman_fixed_48_16_t z1,
michael@0:       pixman_fixed_48_16_t x2,
michael@0:       pixman_fixed_48_16_t y2,
michael@0:       pixman_fixed_48_16_t z2)
michael@0:  {
michael@0: @@ -489,16 +491,17 @@ radial_get_scanline_16 (pixman_iter_t *i
michael@0:       *   <=> for every p, the radiuses associated with the two t solutions
michael@0:       *       have opposite sign
michael@0:       */
michael@0:      pixman_image_t *image = iter->image;
michael@0:      int x = iter->x;
michael@0:      int y = iter->y;
michael@0:      int width = iter->width;
michael@0:      uint16_t *buffer = iter->buffer;
michael@0: +    pixman_bool_t toggle = ((x ^ y) & 1);
michael@0:  
michael@0:      gradient_t *gradient = (gradient_t *)image;
michael@0:      radial_gradient_t *radial = (radial_gradient_t *)image;
michael@0:      uint16_t *end = buffer + width;
michael@0:      pixman_gradient_walker_t walker;
michael@0:      pixman_vector_t v, unit;
michael@0:  
michael@0:      /* reference point is the center of the pixel */
michael@0: @@ -575,25 +578,27 @@ radial_get_scanline_16 (pixman_iter_t *i
michael@0:  		  unit.vector[0], unit.vector[1], 0);
michael@0:  	ddc = 2 * dot (unit.vector[0], unit.vector[1], 0,
michael@0:  		       unit.vector[0], unit.vector[1], 0);
michael@0:  
michael@0:  	while (buffer < end)
michael@0:  	{
michael@0:  	    if (!mask || *mask++)
michael@0:  	    {
michael@0: -		*buffer = convert_8888_to_0565(
michael@0: +		*buffer = dither_8888_to_0565(
michael@0:  			  radial_compute_color (radial->a, b, c,
michael@0:  						radial->inva,
michael@0:  						radial->delta.radius,
michael@0:  						radial->mindr,
michael@0:  						&walker,
michael@0: -						image->common.repeat));
michael@0: +						image->common.repeat),
michael@0: +			  toggle);
michael@0:  	    }
michael@0:  
michael@0: +	    toggle ^= 1;
michael@0:  	    b += db;
michael@0:  	    c += dc;
michael@0:  	    dc += ddc;
michael@0:  	    ++buffer;
michael@0:  	}
michael@0:      }
michael@0:      else
michael@0:      {
michael@0: @@ -621,31 +626,33 @@ radial_get_scanline_16 (pixman_iter_t *i
michael@0:  			      radial->delta.x, radial->delta.y,
michael@0:  			      radial->delta.radius);
michael@0:  		    /*  / pixman_fixed_1 / pixman_fixed_1 */
michael@0:  
michael@0:  		    c = fdot (pdx, pdy, -radial->c1.radius,
michael@0:  			      pdx, pdy, radial->c1.radius);
michael@0:  		    /*  / pixman_fixed_1 / pixman_fixed_1 */
michael@0:  
michael@0: -		    *buffer = convert_8888_to_0565 (
michael@0: +		    *buffer = dither_8888_to_0565 (
michael@0:  			      radial_compute_color (radial->a, b, c,
michael@0:  						    radial->inva,
michael@0:  						    radial->delta.radius,
michael@0:  						    radial->mindr,
michael@0:  						    &walker,
michael@0: -						    image->common.repeat));
michael@0: +						    image->common.repeat),
michael@0: +			      toggle);
michael@0:  		}
michael@0:  		else
michael@0:  		{
michael@0:  		    *buffer = 0;
michael@0:  		}
michael@0:  	    }
michael@0:  
michael@0:  	    ++buffer;
michael@0: +	    toggle ^= 1;
michael@0:  
michael@0:  	    v.vector[0] += unit.vector[0];
michael@0:  	    v.vector[1] += unit.vector[1];
michael@0:  	    v.vector[2] += unit.vector[2];
michael@0:  	}
michael@0:      }
michael@0:  
michael@0:      iter->y++;
michael@0: