[PATCH 2/2] Fix for full and semi-transparency under negative image.

[walter harms]

Am 19.04.2014 19:55, schrieb Mattias Andrée:
> ---
>  hw/xfree86/modes/xf86Cursors.c | 49 +++++++++++++++++++++++++++++++-----------
>  1 file changed, 37 insertions(+), 12 deletions(-)
> 
> diff --git a/hw/xfree86/modes/xf86Cursors.c b/hw/xfree86/modes/xf86Cursors.c
> index 3cb499f..5afd740 100644
> --- a/hw/xfree86/modes/xf86Cursors.c
> +++ b/hw/xfree86/modes/xf86Cursors.c
> @@ -209,6 +209,41 @@ set_bit(CARD8 *image, xf86CursorInfoPtr cursor_info, int x, int y, Bool mask)
>  }
>  
>  /*
> + * Remap a cursor pixel according to the gamma ramps
> + */
> +static CARD32
> +cursor_gamma_correct(xf86CrtcPtr crtc, CARD32 bits)
> +{
> +    float  alpha;
> +    CARD32 old_red,   new_red;
> +    CARD32 old_green, new_green;
> +    CARD32 old_blue,  new_blue;
> +
> +    if (!(crtc->gamma_red && crtc->gamma_size == 256))
> +        return bits;
> +
> +    alpha = (float)((bits >> 24) & 255) / 255.f;
> +
> +    old_red   = (bits >> 16) & 255;
> +    old_green = (bits >>  8) & 255;
> +    old_blue  = (bits >>  0) & 255;
> +
> +    new_red   = (crtc->gamma_red  [old_red  ]) >> 8;
> +    new_green = (crtc->gamma_green[old_green]) >> 8;
> +    new_blue  = (crtc->gamma_blue [old_blue ]) >> 8;
> +
> +    new_red   = new_red   * alpha + old_red   * (1 - alpha);
> +    new_green = new_green * alpha + old_green * (1 - alpha);
> +    new_blue  = new_blue  * alpha + old_blue  * (1 - alpha);
> +
> +    new_red   = new_red   < 0 ? 0 : new_red   > 255 ? 255 : new_red;
> +    new_green = new_green < 0 ? 0 : new_green > 255 ? 255 : new_green;
> +    new_blue  = new_blue  < 0 ? 0 : new_blue  > 255 ? 255 : new_blue;
> +

ok, i know that i valid C, but do you think that a more readable version
is so much slower ?
	if (val < 0 ) val=0;
	if (val >255) val=255;
that will give everyone the opprotunity to understand what is going on.

just my two cents.

re,
 wh



> +    return (bits & 0xFF000000) | (new_red << 16) | (new_green << 8) | (new_blue << 0);
> +}
> +
> +/*
>   * Load a two color cursor into a driver that supports only ARGB cursors
>   */
>  static void
> @@ -242,12 +277,7 @@ xf86_crtc_convert_cursor_to_argb(xf86CrtcPtr crtc, unsigned char *src)
>              }
>              else
>                  bits = 0;
> -            if (crtc->gamma_red && crtc->gamma_size == 256) {
> -                bits = (bits & 0xFF000000) |
> -                       ((crtc->gamma_red[(bits >> 16) & 255] >> 8) << 16) |
> -                       (crtc->gamma_green[(bits >> 8) & 255] & 0xFF00) |
> -                       (crtc->gamma_blue[bits & 255] >> 8);
> -            }
> +            bits = cursor_gamma_correct(crtc, bits);
>              cursor_image[y * cursor_info->MaxWidth + x] = bits;
>          }
>      crtc->funcs->load_cursor_argb(crtc, cursor_image);
> @@ -547,12 +577,7 @@ xf86_crtc_load_cursor_argb(xf86CrtcPtr crtc, CursorPtr cursor)
>                  bits = cursor_source[yin * source_width + xin];
>              else
>                  bits = 0;
> -            if (crtc->gamma_red && crtc->gamma_size == 256) {
> -                bits = (bits & 0xFF000000) |
> -                       ((crtc->gamma_red[(bits >> 16) & 255] >> 8) << 16) |
> -                       (crtc->gamma_green[(bits >> 8) & 255] & 0xFF00) |
> -                       (crtc->gamma_blue[bits & 255] >> 8);
> -            }
> +            bits = cursor_gamma_correct(crtc, bits);
>              cursor_image[y * image_width + x] = bits;
>          }
>