From e957bba771ea200da16f4d3a02aaec7784c65168 Mon Sep 17 00:00:00 2001 From: Přemysl Janouch Date: Sat, 20 Oct 2018 04:27:35 +0200 Subject: Use a common algorithm for scrollbars Let's have reasonable behaviour with Unicode one as well. --- nncmpp.c | 42 +++++++++++++++++++----------------------- 1 file changed, 19 insertions(+), 23 deletions(-) diff --git a/nncmpp.c b/nncmpp.c index cb4f091..aff53e1 100644 --- a/nncmpp.c +++ b/nncmpp.c @@ -1172,25 +1172,30 @@ app_visible_items (void) return MAX (0, app_fitting_items ()); } +/// Figure out scrollbar appearance. @a s is the minimal slider length as well +/// as the scrollbar resolution per @a visible item. struct scrollbar { long length, start; } -app_compute_scrollbar (long top, long total, long visible) +app_compute_scrollbar (struct tab *tab, long visible, long s) { + long top = tab->item_top, total = tab->item_count; if (total < visible) return (struct scrollbar) { 0, 0 }; if (visible == 1) - return (struct scrollbar) { 1, 0 }; + return (struct scrollbar) { s, 0 }; if (visible == 2) - return (struct scrollbar) { 1, top >= total / 2 }; + return (struct scrollbar) { s, top >= total / 2 ? s : 0 }; // Only be at the top or bottom when the top or bottom item can be seen. // The algorithm isn't optimal but it's a bitch to get right. - double lenf = 1. + (visible - 2.) * visible / total, length = 0.; - long offset = 1. + (visible - 2.) * top / total + modf (lenf, &length); + double available_length = s * visible - 2 - s + 1; + + double lenf = s + available_length * visible / total, length = 0.; + long offset = 1 + available_length * top / total + modf (lenf, &length); if (top == 0) return (struct scrollbar) { length, 0 }; if (top + visible >= total) - return (struct scrollbar) { length, visible - length }; + return (struct scrollbar) { length, s * visible - length }; return (struct scrollbar) { length, offset }; } @@ -1210,8 +1215,7 @@ app_draw_scrollbar (void) hard_assert (tab->item_count != 0); if (!g.use_partial_boxes) { - struct scrollbar bar = app_compute_scrollbar - (tab->item_top, tab->item_count, visible_items); + struct scrollbar bar = app_compute_scrollbar (tab, visible_items, 1); for (int row = 0; row < visible_items; row++) { move (g.header_height + row, COLS - 1); @@ -1223,19 +1227,11 @@ app_draw_scrollbar (void) return; } - // TODO: clamp the values, make sure they follow the right order - // We subtract half a character from both the top and the bottom, hence -1 - // XXX: I'm not completely sure why we need that 0.5 constant in both - int length = (double) visible_items / tab->item_count - * (visible_items - 1) * 8 + 0.5; - int start = (double) tab->item_top / tab->item_count - * (visible_items - 1) * 8 + 0.5; - - // Then we make sure the bar is at least one character high, hence +8 - int end = start + length + 8; + struct scrollbar bar = app_compute_scrollbar (tab, visible_items, 8); + bar.length += bar.start; - int start_part = start % 8; start /= 8; - int end_part = end % 8; end /= 8; + int start_part = bar.start % 8; bar.start /= 8; + int end_part = bar.length % 8; bar.length /= 8; // Even with this, the solid part must be at least one character high static const char *partials[] = { "█", "▇", "▆", "▅", "▄", "▃", "▂", "▁" }; @@ -1243,12 +1239,12 @@ app_draw_scrollbar (void) for (int row = 0; row < visible_items; row++) { chtype attrs = APP_ATTR (SCROLLBAR); - if (row > start && row <= end) + if (row > bar.start && row <= bar.length) attrs ^= A_REVERSE; const char *c = " "; - if (row == start) c = partials[start_part]; - if (row == end) c = partials[end_part]; + if (row == bar.start) c = partials[start_part]; + if (row == bar.length) c = partials[end_part]; move (g.header_height + row, COLS - 1); -- cgit v1.2.3-70-g09d2