[PATCH 1/2] fbsplash: limit progress bar flicker

[Peter Korsgaard]

Progress bar updates flicker quite a bit on slow hw / high resolutions
as the background is completely cleared before the new progress bar
position is drawn on top.

Improve it by first drawing the progress bar and then only fill the
remaining rows with the background.

function                                             old     new   delta
fb_drawprogressbar                                   492     516     +24
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/0 up/down: 24/0)               Total: 24 bytes

Signed-off-by: Peter Korsgaard <jacmet at sunsite.dk>
---
 miscutils/fbsplash.c |   20 ++++++++++++--------
 1 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/miscutils/fbsplash.c b/miscutils/fbsplash.c
index 51ba472..937c6a4 100644
--- a/miscutils/fbsplash.c
+++ b/miscutils/fbsplash.c
@@ -213,7 +213,7 @@ static void fb_drawfullrectangle(int nx1pos, int ny1pos, int nx2pos, int ny2pos,
  */
 static void fb_drawprogressbar(unsigned percent)
 {
-	int i, left_x, top_y, width, height;
+	int i, y, left_x, top_y, pos, width, height;
 
 	// outer box
 	left_x = G.nbar_posx;
@@ -232,14 +232,13 @@ static void fb_drawprogressbar(unsigned percent)
 	height -= 2;
 	if ((height | width) < 0)
 		return;
-	fb_drawfullrectangle(
-			left_x,	top_y,
-					left_x + width, top_y + height,
-			G.nbar_colr, G.nbar_colg, G.nbar_colb);
 
+	pos = left_x;
 	if (percent > 0) {
 		// actual progress bar
-		width = width * percent / 100;
+		pos += width * percent / 100;
+
+		y = top_y;
 		i = height;
 		if (height == 0)
 			height++; // divide by 0 is bad
@@ -248,12 +247,17 @@ static void fb_drawprogressbar(unsigned percent)
 			// top line will have gray lvl 200, bottom one 100
 			unsigned gray_level = 100 + i*100/height;
 			fb_drawfullrectangle(
-					left_x, top_y, left_x + width, top_y,
+					left_x, y, pos, y,
 					gray_level, gray_level, gray_level);
-			top_y++;
+			y++;
 			i--;
 		}
 	}
+
+	fb_drawfullrectangle(
+			pos,	top_y,
+			left_x + width, top_y + height,
+			G.nbar_colr, G.nbar_colg, G.nbar_colb);
 }
 
 
-- 
1.7.6.3