michael@0: summary:     Bug 689707. Use lower precision bilinear interpolation. r=joe
michael@0: 
michael@0: diff --git a/gfx/cairo/libpixman/src/pixman-bits-image.c b/gfx/cairo/libpixman/src/pixman-bits-image.c
michael@0: --- a/gfx/cairo/libpixman/src/pixman-bits-image.c
michael@0: +++ b/gfx/cairo/libpixman/src/pixman-bits-image.c
michael@0: @@ -124,18 +124,18 @@ bits_image_fetch_pixel_bilinear (bits_im
michael@0:      int height = image->height;
michael@0:      int x1, y1, x2, y2;
michael@0:      uint32_t tl, tr, bl, br;
michael@0:      int32_t distx, disty;
michael@0:  
michael@0:      x1 = x - pixman_fixed_1 / 2;
michael@0:      y1 = y - pixman_fixed_1 / 2;
michael@0:  
michael@0: -    distx = (x1 >> 8) & 0xff;
michael@0: -    disty = (y1 >> 8) & 0xff;
michael@0: +    distx = interpolation_coord(x1);
michael@0: +    disty = interpolation_coord(y1);
michael@0:  
michael@0:      x1 = pixman_fixed_to_int (x1);
michael@0:      y1 = pixman_fixed_to_int (y1);
michael@0:      x2 = x1 + 1;
michael@0:      y2 = y1 + 1;
michael@0:  
michael@0:      if (repeat_mode != PIXMAN_REPEAT_NONE)
michael@0:      {
michael@0: @@ -190,17 +190,17 @@ bits_image_fetch_bilinear_no_repeat_8888
michael@0:  
michael@0:      if (!pixman_transform_point_3d (bits->common.transform, &v))
michael@0:  	return;
michael@0:  
michael@0:      ux = ux_top = ux_bottom = bits->common.transform->matrix[0][0];
michael@0:      x = x_top = x_bottom = v.vector[0] - pixman_fixed_1/2;
michael@0:  
michael@0:      y = v.vector[1] - pixman_fixed_1/2;
michael@0: -    disty = (y >> 8) & 0xff;
michael@0: +    disty = interpolation_coord(y);
michael@0:  
michael@0:      /* Load the pointers to the first and second lines from the source
michael@0:       * image that bilinear code must read.
michael@0:       *
michael@0:       * The main trick in this code is about the check if any line are
michael@0:       * outside of the image;
michael@0:       *
michael@0:       * When I realize that a line (any one) is outside, I change
michael@0: @@ -299,17 +299,17 @@ bits_image_fetch_bilinear_no_repeat_8888
michael@0:      while (buffer < end && x < 0)
michael@0:      {
michael@0:  	uint32_t tr, br;
michael@0:  	int32_t distx;
michael@0:  
michael@0:  	tr = top_row[pixman_fixed_to_int (x_top) + 1] | top_mask;
michael@0:  	br = bottom_row[pixman_fixed_to_int (x_bottom) + 1] | bottom_mask;
michael@0:  
michael@0: -	distx = (x >> 8) & 0xff;
michael@0: +	distx = interpolation_coord(x);
michael@0:  
michael@0:  	*buffer++ = bilinear_interpolation (0, tr, 0, br, distx, disty);
michael@0:  
michael@0:  	x += ux;
michael@0:  	x_top += ux_top;
michael@0:  	x_bottom += ux_bottom;
michael@0:  	mask += mask_inc;
michael@0:      }
michael@0: @@ -324,17 +324,17 @@ bits_image_fetch_bilinear_no_repeat_8888
michael@0:  	    uint32_t tl, tr, bl, br;
michael@0:  	    int32_t distx;
michael@0:  
michael@0:  	    tl = top_row [pixman_fixed_to_int (x_top)] | top_mask;
michael@0:  	    tr = top_row [pixman_fixed_to_int (x_top) + 1] | top_mask;
michael@0:  	    bl = bottom_row [pixman_fixed_to_int (x_bottom)] | bottom_mask;
michael@0:  	    br = bottom_row [pixman_fixed_to_int (x_bottom) + 1] | bottom_mask;
michael@0:  
michael@0: -	    distx = (x >> 8) & 0xff;
michael@0: +	    distx = interpolation_coord(x);
michael@0:  
michael@0:  	    *buffer = bilinear_interpolation (tl, tr, bl, br, distx, disty);
michael@0:  	}
michael@0:  
michael@0:  	buffer++;
michael@0:  	x += ux;
michael@0:  	x_top += ux_top;
michael@0:  	x_bottom += ux_bottom;
michael@0: @@ -348,17 +348,17 @@ bits_image_fetch_bilinear_no_repeat_8888
michael@0:  	if (*mask)
michael@0:  	{
michael@0:  	    uint32_t tl, bl;
michael@0:  	    int32_t distx;
michael@0:  
michael@0:  	    tl = top_row [pixman_fixed_to_int (x_top)] | top_mask;
michael@0:  	    bl = bottom_row [pixman_fixed_to_int (x_bottom)] | bottom_mask;
michael@0:  
michael@0: -	    distx = (x >> 8) & 0xff;
michael@0: +	    distx = interpolation_coord(x);
michael@0:  
michael@0:  	    *buffer = bilinear_interpolation (tl, 0, bl, 0, distx, disty);
michael@0:  	}
michael@0:  
michael@0:  	buffer++;
michael@0:  	x += ux;
michael@0:  	x_top += ux_top;
michael@0:  	x_bottom += ux_bottom;
michael@0: @@ -675,18 +675,18 @@ bits_image_fetch_bilinear_affine (pixman
michael@0:  	const uint8_t *row2;
michael@0:  
michael@0:  	if (mask && !mask[i])
michael@0:  	    goto next;
michael@0:  
michael@0:  	x1 = x - pixman_fixed_1 / 2;
michael@0:  	y1 = y - pixman_fixed_1 / 2;
michael@0:  
michael@0: -	distx = (x1 >> 8) & 0xff;
michael@0: -	disty = (y1 >> 8) & 0xff;
michael@0: +	distx = interpolation_coord(x1);
michael@0: +	disty = interpolation_coord(y1);
michael@0:  
michael@0:  	y1 = pixman_fixed_to_int (y1);
michael@0:  	y2 = y1 + 1;
michael@0:  	x1 = pixman_fixed_to_int (x1);
michael@0:  	x2 = x1 + 1;
michael@0:  
michael@0:  	if (repeat_mode != PIXMAN_REPEAT_NONE)
michael@0:  	{
michael@0: diff --git a/gfx/cairo/libpixman/src/pixman-inlines.h b/gfx/cairo/libpixman/src/pixman-inlines.h
michael@0: --- a/gfx/cairo/libpixman/src/pixman-inlines.h
michael@0: +++ b/gfx/cairo/libpixman/src/pixman-inlines.h
michael@0: @@ -76,16 +76,31 @@ repeat (pixman_repeat_t repeat, int *c, 
michael@0:      {
michael@0:  	*c = MOD (*c, size * 2);
michael@0:  	if (*c >= size)
michael@0:  	    *c = size * 2 - *c - 1;
michael@0:      }
michael@0:      return TRUE;
michael@0:  }
michael@0:  
michael@0: +#ifdef MOZ_GFX_OPTIMIZE_MOBILE
michael@0: +#define LOW_QUALITY_INTERPOLATION
michael@0: +#endif
michael@0: +
michael@0: +static force_inline int32_t
michael@0: +interpolation_coord(pixman_fixed_t t)
michael@0: +{
michael@0: +#ifdef LOW_QUALITY_INTERPOLATION
michael@0: +    return (t >> 12) & 0xf;
michael@0: +#else
michael@0: +    return (t >> 8) & 0xff;
michael@0: +#endif
michael@0: +}
michael@0: +
michael@0: +
michael@0:  #if SIZEOF_LONG > 4
michael@0:  
michael@0:  static force_inline uint32_t
michael@0:  bilinear_interpolation (uint32_t tl, uint32_t tr,
michael@0:  			uint32_t bl, uint32_t br,
michael@0:  			int distx, int disty)
michael@0:  {
michael@0:      uint64_t distxy, distxiy, distixy, distixiy;
michael@0: @@ -122,16 +137,44 @@ bilinear_interpolation (uint32_t tl, uin
michael@0:      f = tl64 * distixiy + tr64 * distxiy + bl64 * distixy + br64 * distxy;
michael@0:      r |= ((f >> 16) & 0x000000ff00000000ull) | (f & 0xff000000ull);
michael@0:  
michael@0:      return (uint32_t)(r >> 16);
michael@0:  }
michael@0:  
michael@0:  #else
michael@0:  
michael@0: +#ifdef LOW_QUALITY_INTERPOLATION
michael@0: +/* Based on Filter_32_opaque_portable from Skia */
michael@0: +static force_inline uint32_t
michael@0: +bilinear_interpolation(uint32_t a00, uint32_t a01,
michael@0: +		       uint32_t a10, uint32_t a11,
michael@0: +		       int x, int y)
michael@0: +{
michael@0: +    int xy = x * y;
michael@0: +    static const uint32_t mask = 0xff00ff;
michael@0: +
michael@0: +    int scale = 256 - 16*y - 16*x + xy;
michael@0: +    uint32_t lo = (a00 & mask) * scale;
michael@0: +    uint32_t hi = ((a00 >> 8) & mask) * scale;
michael@0: +
michael@0: +    scale = 16*x - xy;
michael@0: +    lo += (a01 & mask) * scale;
michael@0: +    hi += ((a01 >> 8) & mask) * scale;
michael@0: +
michael@0: +    scale = 16*y - xy;
michael@0: +    lo += (a10 & mask) * scale;
michael@0: +    hi += ((a10 >> 8) & mask) * scale;
michael@0: +
michael@0: +    lo += (a11 & mask) * xy;
michael@0: +    hi += ((a11 >> 8) & mask) * xy;
michael@0: +
michael@0: +    return ((lo >> 8) & mask) | (hi & ~mask);
michael@0: +}
michael@0: +#else
michael@0:  static force_inline uint32_t
michael@0:  bilinear_interpolation (uint32_t tl, uint32_t tr,
michael@0:  			uint32_t bl, uint32_t br,
michael@0:  			int distx, int disty)
michael@0:  {
michael@0:      int distxy, distxiy, distixy, distixiy;
michael@0:      uint32_t f, r;
michael@0:  
michael@0: @@ -164,17 +207,17 @@ bilinear_interpolation (uint32_t tl, uin
michael@0:  
michael@0:      /* Alpha */
michael@0:      f = (tl & 0x0000ff00) * distixiy + (tr & 0x0000ff00) * distxiy
michael@0:        + (bl & 0x0000ff00) * distixy  + (br & 0x0000ff00) * distxy;
michael@0:      r |= f & 0xff000000;
michael@0:  
michael@0:      return r;
michael@0:  }
michael@0: -
michael@0: +#endif
michael@0:  #endif
michael@0:  
michael@0:  /*
michael@0:   * For each scanline fetched from source image with PAD repeat:
michael@0:   * - calculate how many pixels need to be padded on the left side
michael@0:   * - calculate how many pixels need to be padded on the right side
michael@0:   * - update width to only count pixels which are fetched from the image
michael@0:   * All this information is returned via 'width', 'left_pad', 'right_pad'