rockorager.dev
an experimental irc client
ui: fix scrollbar integer overflow on channels with lots of messages
Reported-by: erk on IRC
+5
-2
src/Scrollbar.zig
+5
-2
src/Scrollbar.zig
···
58
@memset(surface.buffer, empty);
59
60
// (view_size / total) * window height = size of the scroll bar
61
-
const bar_height = @max(std.math.divCeil(usize, self.view_size * max.height, self.total) catch unreachable, 1);
62
63
// The row of the last cell of the bottom of the bar
64
-
const bar_bottom = (max.height - 1) -| (std.math.divCeil(usize, self.bottom * max.height, self.total) catch unreachable);
65
66
var i: usize = 0;
67
while (i <= bar_height) : (i += 1)
···
58
@memset(surface.buffer, empty);
59
60
// (view_size / total) * window height = size of the scroll bar
61
+
const premul1 = std.math.mulWide(u16, self.view_size, max.height);
62
+
const bar_height = @max(std.math.divCeil(usize, premul1, self.total) catch unreachable, 1);
63
64
+
// Premultiply. We use mulWide to ensure we never overflow
65
+
const premul2 = std.math.mulWide(u16, self.bottom, max.height);
66
// The row of the last cell of the bottom of the bar
67
+
const bar_bottom = (max.height - 1) -| (std.math.divCeil(usize, premul2, self.total) catch unreachable);
68
69
var i: usize = 0;
70
while (i <= bar_height) : (i += 1)