Commit d237f719 authored by Thomas Zimmermann's avatar Thomas Zimmermann Committed by Helge Deller
Browse files

lib/fonts: Fix bit position when rotating by 180 degrees 

Fix the horizontal bit position when rotating a glyph by 180°. The
original code in rotate_ud() rounded the value in width up to a
multiple of 8, aka the bit pitch, and calculated the rotated pixel
from that value. The new code stores the glyph's pitch in bit_pitch,
but fails to update the rotated pixel's output accordingly. Simply
replacing the variable does this.

The bug can be reproduced by setting a font with an unaligned width,
such as sun12x22, like this:

 setfont sun12x22
 echo 2 > /sys/class/graphics/fbcon/rotate

Without the fix, the font looks distorted.

Fixes: a30e9e6b ("lib/fonts: Refactor glyph-rotation helpers")
Closes: https://lore.gitlab.freedesktop.org/drm-ai-reviews/review-patch7-20260407092555.58816-8-tzimmermann@suse.de/


Cc: dri-devel@lists.freedesktop.org
Cc: linux-fbdev@vger.kernel.org
Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent 0b996ae5

lib/fonts/font_rotate.c

+1 −1
Original line number Diff line number Diff line
@@ -106,7 +106,7 @@ static void __font_glyph_rotate_180(const unsigned char *glyph, 
	for (y = 0; y < height; y++) {

		for (x = 0; x < width; x++) {

			if (font_glyph_test_bit(glyph, x, y, bit_pitch)) {

				font_glyph_set_bit(out, width - (1 + x + shift), height - (1 + y),

				font_glyph_set_bit(out, bit_pitch - 1 - x - shift, height - 1 - y,

						   bit_pitch);

			}

		}