rockorager.dev
an experimental irc client
ui: anchor message view when we have scroll
+18
-4
src/irc.zig
+18
-4
src/irc.zig
···
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offset: u16 = 0,
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/// Message offset into the list of messages. We use this to lock the viewport if we have a
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/// scroll. Otherwise, when offset == 0 this is effectively ignored (and should be 0)
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msg_offset: u32 = 0,
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msg_offset: ?u16 = null,
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/// Pending scroll we have to handle while drawing. This could be up or down. By convention
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/// we say positive is a scroll up.
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pending: i17 = 0,
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pending: i16 = 0,
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} = .{},
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pub const Member = struct {
···
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/// Consumes any pending scrolls and schedules another tick if needed
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fn doScroll(self: *Channel, ctx: *vxfw.EventContext) anyerror!void {
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defer {
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// At the end of this function, we anchor our msg_offset if we have any amount of
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// scroll. This prevents new messages from automatically scrolling us
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if (self.scroll.offset > 0 and self.scroll.msg_offset == null) {
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self.scroll.msg_offset = @intCast(self.messages.items.len);
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}
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// If we have no offset, we reset our anchor
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if (self.scroll.offset == 0) {
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self.scroll.msg_offset = null;
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}
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}
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const animation_tick: u32 = 30;
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// No pending scroll. Return early
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if (self.scroll.pending == 0) return;
···
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var children = std.ArrayList(vxfw.SubSurface).init(ctx.arena);
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// Row is the row we are printing on.
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// Row is the row we are printing on. We add the offset to achieve our scroll location
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var row: i17 = max.height + self.scroll.offset;
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var iter = std.mem.reverseIterator(self.messages.items);
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const offset = self.scroll.msg_offset orelse self.messages.items.len;
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var iter = std.mem.reverseIterator(self.messages.items[0..offset]);
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const gutter_width = 6;
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while (iter.next()) |msg| {
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// Break if we have gone past the top of the screen