[PATCH] xfree86: Fix rotation of 2-color non-interleaved cursor images

Aaron Plattner aplattner at nvidia.com
Mon Nov 29 18:03:53 PST 2010


Does anyone else want to review this, or are Robert's (@nvidia.com)
Reviewed-by and Cyril's Tested-by sufficient?

On Tue, Nov 16, 2010 at 12:17:33PM -0800, Aaron Plattner wrote:
> When RandR 1.2's transformation code is enabled, it rotates the cursor
> image so that it appears upright on a rotated screen.  This code
> completely mangles 2-color cursors on hardware where the the mask and
> source images are not interleaved due to two problems:
> 
> 1. stride is calculated as (width / 4) rather than (width / 8), so the
>    expression (y * stride) skips two lines instead of one for every
>    time y is incremented.
> 2. cursor_bitpos ignores the 'mask' parameter if the hardware doesn't
>    specify any of the HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_* flags.
> 
> To fix this, refactor the code to pass the whole xf86CursorInfoPtr
> through to cursor_bitpos and compute the correct stride there based on
> the flags.  If none of the SOURCE_MASK_INTERLEAVE flags are set, use
> the total cursor size to move the 'image' variable into the mask part
> of the image before computing the desired byte pointer.
> 
> Signed-off-by: Aaron Plattner <aplattner at nvidia.com>
> Reviewed-by: Robert Morell <rmorell at nvidia.com>
> ---
> Could somebody with hardware that sets SOURCE_MASK_INTERLEAVE (e.g.
> Intel) please give this patch a try and verify that it doesn't break
> rotated cursors?
> 
>  hw/xfree86/modes/xf86Cursors.c |   62 +++++++++++++++++++++++++++------------
>  1 files changed, 43 insertions(+), 19 deletions(-)
> 
> diff --git a/hw/xfree86/modes/xf86Cursors.c b/hw/xfree86/modes/xf86Cursors.c
> index ab07b60..0667447 100644
> --- a/hw/xfree86/modes/xf86Cursors.c
> +++ b/hw/xfree86/modes/xf86Cursors.c
> @@ -1,5 +1,6 @@
>  /*
>   * Copyright © 2007 Keith Packard
> + * Copyright © 2010 Aaron Plattner
>   *
>   * Permission to use, copy, modify, distribute, and sell this software and its
>   * documentation for any purpose is hereby granted without fee, provided that
> @@ -126,12 +127,33 @@ xf86_crtc_rotate_coord_back (Rotation    rotation,
>      *y_src = y_dst;
>  }
>  
> +struct cursor_bit {
> +    CARD8 *byte;
> +    char bitpos;
> +};
> +
>  /*
>   * Convert an x coordinate to a position within the cursor bitmap
>   */
> -static int
> -cursor_bitpos (int flags, int x, Bool mask)
> +static struct cursor_bit
> +cursor_bitpos (CARD8 *image, xf86CursorInfoPtr cursor_info, int x, int y,
> +	       Bool mask)
>  {
> +    const int flags = cursor_info->Flags;
> +    const Bool interleaved =
> +	!!(flags & (HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_1 |
> +		    HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_8 |
> +		    HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_16 |
> +		    HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_32 |
> +		    HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_64));
> +    const int width = cursor_info->MaxWidth;
> +    const int height = cursor_info->MaxHeight;
> +    const int stride = interleaved ? width / 4 : width / 8;
> +
> +    struct cursor_bit ret;
> +
> +    image += y * stride;
> +
>      if (flags & HARDWARE_CURSOR_SWAP_SOURCE_AND_MASK)
>  	mask = !mask;
>      if (flags & HARDWARE_CURSOR_NIBBLE_SWAPPED)
> @@ -149,29 +171,33 @@ cursor_bitpos (int flags, int x, Bool mask)
>  	x = ((x & ~31) << 1) | (mask << 5) | (x & 31);
>      else if (flags & HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_64)
>  	x = ((x & ~63) << 1) | (mask << 6) | (x & 63);
> -    return x;
> +    else if (mask)
> +	image += stride * height;
> +
> +    ret.byte = image + (x / 8);
> +    ret.bitpos = x & 7;
> +
> +    return ret;
>  }
>  
>  /*
>   * Fetch one bit from a cursor bitmap
>   */
>  static CARD8
> -get_bit (CARD8 *image, int stride, int flags, int x, int y, Bool mask)
> +get_bit (CARD8 *image, xf86CursorInfoPtr cursor_info, int x, int y, Bool mask)
>  {
> -    x = cursor_bitpos (flags, x, mask);
> -    image += y * stride;
> -    return (image[(x >> 3)] >> (x & 7)) & 1;
> +    struct cursor_bit bit = cursor_bitpos(image, cursor_info, x, y, mask);
> +    return (*bit.byte >> bit.bitpos) & 1;
>  }
>  
>  /*
>   * Set one bit in a cursor bitmap
>   */
>  static void
> -set_bit (CARD8 *image, int stride, int flags, int x, int y, Bool mask)
> +set_bit (CARD8 *image, xf86CursorInfoPtr cursor_info, int x, int y, Bool mask)
>  {
> -    x = cursor_bitpos (flags, x, mask);
> -    image += y * stride;
> -    image[(x >> 3)] |= 1 << (x & 7);
> +    struct cursor_bit bit = cursor_bitpos(image, cursor_info, x, y, mask);
> +    *bit.byte |= 1 << bit.bitpos;
>  }
>      
>  /*
> @@ -186,7 +212,6 @@ xf86_crtc_convert_cursor_to_argb (xf86CrtcPtr crtc, unsigned char *src)
>      CARD32		*cursor_image = (CARD32 *) xf86_config->cursor_image;
>      int			x, y;
>      int			xin, yin;
> -    int			stride = cursor_info->MaxWidth >> 2;
>      int			flags = cursor_info->Flags;
>      CARD32		bits;
>  
> @@ -201,10 +226,10 @@ xf86_crtc_convert_cursor_to_argb (xf86CrtcPtr crtc, unsigned char *src)
>  				    cursor_info->MaxWidth,
>  				    cursor_info->MaxHeight,
>  				    x, y, &xin, &yin);
> -	    if (get_bit (src, stride, flags, xin, yin, TRUE) ==
> +	    if (get_bit (src, cursor_info, xin, yin, TRUE) ==
>  		((flags & HARDWARE_CURSOR_INVERT_MASK) == 0))
>  	    {
> -		if (get_bit (src, stride, flags, xin, yin, FALSE))
> +		if (get_bit (src, cursor_info, xin, yin, FALSE))
>  		    bits = xf86_config->cursor_fg;
>  		else
>  		    bits = xf86_config->cursor_bg;
> @@ -407,7 +432,6 @@ xf86_crtc_load_cursor_image (xf86CrtcPtr crtc, CARD8 *src)
>          int x, y;
>      	int xin, yin;
>  	int stride = cursor_info->MaxWidth >> 2;
> -	int flags = cursor_info->Flags;
>  	
>  	cursor_image = xf86_config->cursor_image;
>  	memset(cursor_image, 0, cursor_info->MaxHeight * stride);
> @@ -419,10 +443,10 @@ xf86_crtc_load_cursor_image (xf86CrtcPtr crtc, CARD8 *src)
>  					cursor_info->MaxWidth,
>  					cursor_info->MaxHeight,
>  					x, y, &xin, &yin);
> -		if (get_bit(src, stride, flags, xin, yin, FALSE))
> -		    set_bit(cursor_image, stride, flags, x, y, FALSE);
> -		if (get_bit(src, stride, flags, xin, yin, TRUE))
> -		    set_bit(cursor_image, stride, flags, x, y, TRUE);
> +		if (get_bit(src, cursor_info, xin, yin, FALSE))
> +		    set_bit(cursor_image, cursor_info, x, y, FALSE);
> +		if (get_bit(src, cursor_info, xin, yin, TRUE))
> +		    set_bit(cursor_image, cursor_info, x, y, TRUE);
>  	    }
>      }
>      crtc->funcs->load_cursor_image (crtc, cursor_image);
> -- 
> 1.7.1
> 
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