pluginlib_bmp: fix bug that bitmap isn't saved correctly if width is not a multiple of 4. optimize a bit.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@22346 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 5 insertions, 5 deletions

diff --git a/apps/plugins/lib/pluginlib_bmp.c b/apps/plugins/lib/pluginlib_bmp.c
index 00c8cbbec0..8520a8b17f 100644
--- a/apps/plugins/lib/pluginlib_bmp.c
+++ b/apps/plugins/lib/pluginlib_bmp.c
@@ -35,8 +35,8 @@
  */
 int save_bmp_file( char* filename, struct bitmap *bm )
 {
-    /* I'm not really sure about this one :) */
-    int line_width = bm->width*3+((bm->width*3)%4?4-((bm->width*3)%4):0);
+    int line_width = (bm->width*3+3) & ~3;
+    int padsize = line_width - bm->width*3;
 
     const unsigned char header[] =
     {
@@ -77,10 +77,10 @@ int save_bmp_file( char* filename, struct bitmap *bm )
             };
             rb->write( fh, c, 3 );
         }
-        for( x = 0; x < 3*bm->width - line_width; x++ )
+        if(padsize != 0)
         {
-            unsigned char c = 0;
-            rb->write( fh, &c, 1 );
+            unsigned int c = 0; /* padsize is at most 3. */
+            rb->write( fh, &c, padsize );
         }
     }
     rb->close( fh );