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-rw-r--r--desktop/plot_style.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/desktop/plot_style.h b/desktop/plot_style.h
index 8f57915a9..b4e7ab8f9 100644
--- a/desktop/plot_style.h
+++ b/desktop/plot_style.h
@@ -64,6 +64,14 @@
(((((c0 >> 8) & 0xff) + ((c1 >> 8) & 0xff)) >> 1) << 8) | \
(((( c0 & 0xff) + ( c1 & 0xff)) >> 1) << 0)
+/* Choose either black or white, depending on which is furthest from the
+ * percieved lightness of the supplied colour, c0. */
+#define colour_to_bw_furthest(c0) \
+ ((((((c0 & 0x0000ff) * 77) >> 8) + \
+ (((c0 & 0x00ff00) * 151) >> 16) + \
+ (((c0 & 0xff0000) * 28) >> 24)) > \
+ (0xff / 2)) ? 0x000000 : 0xffffff)
+
/* get a bitmap pixel (image/bitmap.h) into a plot colour */
#define pixel_to_colour(b) \
b[0] | (b[1] << 8) | (b[2] << 16) | (b[3] << 24)