pybootchartgui: show elapsed time for each task

Currently, finding the elapsed time of each task in buildtimes.svg
is a manual effort of checking the top axis and finding and subtracting
the end and start time of the task.

This change adds the elapsed time for each task, so that
manual effort of comparing start/end time is avoided.

(From OE-Core rev: b2678422b411ccbd19a7b198c872b92077567391)

Signed-off-by: Mauro Queiros <Mauro.Queiros@criticaltechworks.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 3efebd3404de548f0757863da237f2d18ce60013)
Signed-off-by: Jose Quaresma <jose.quaresma@foundries.io>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

scripts/pybootchartgui/pybootchartgui/draw.py

@@ -558,6 +558,11 @@ def render_processes_chart(ctx, options, trace, curr_y, w, h, sec_w):
             draw_rect(ctx, PROC_BORDER_COLOR, (x, y, w, proc_h))
 
             draw_label_in_box(ctx, PROC_TEXT_COLOR, process, x, y + proc_h - 4, w, proc_h)
+
+            # Show elapsed time for each task
+            elapsed_time = f"{trace.processes[process][1] - start}s"
+            draw_text(ctx, elapsed_time, PROC_TEXT_COLOR, x + w + 4, y + proc_h - 4)
+
             y = y + proc_h
 
     return curr_y