rockorager.dev
an experimental irc client
ui: draw scrollbar
+40
-9
src/Scrollbar.zig
+40
-9
src/Scrollbar.zig
···
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const std = @import("std");
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const vaxis = @import("vaxis");
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+
const vxfw = vaxis.vxfw;
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const Scrollbar = @This();
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···
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style: vaxis.Style = .{},
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/// The index of the bottom-most item, with 0 being "at the bottom"
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bottom: usize = 0,
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bottom: u16 = 0,
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/// total items in the list
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total: usize,
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total: u16,
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/// total items that fit within the view area
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view_size: usize,
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view_size: u16,
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+
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fn widget(self: *Scrollbar) vxfw.Widget {
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return .{
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.userdata = self,
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.drawFn = drawFn,
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};
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}
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+
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fn drawFn(ptr: *anyopaque, ctx: vxfw.DrawContext) std.mem.Allocator.Error!vxfw.Surface {
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const self: *Scrollbar = @ptrCast(@alignCast(ptr));
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return self.draw(ctx);
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}
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+
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pub fn draw(self: *Scrollbar, ctx: vxfw.DrawContext) std.mem.Allocator.Error!vxfw.Surface {
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const max = ctx.max.size();
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if (max.width == 0 or max.height == 0) {
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return .{
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.size = .{ .width = 0, .height = 0 },
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.widget = self.widget(),
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.buffer = &.{},
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.children = &.{},
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};
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}
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pub fn draw(self: Scrollbar, win: vaxis.Window) void {
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const surface = try vxfw.Surface.init(
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ctx.arena,
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self.widget(),
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.{ .width = 2, .height = max.height },
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);
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+
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// don't draw when 0 items
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if (self.total < 1) return;
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if (self.total < 1) return surface;
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// don't draw when all items can be shown
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if (self.view_size >= self.total) return;
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if (self.view_size >= self.total) return surface;
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// (view_size / total) * window height = size of the scroll bar
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const bar_height = @max(std.math.divCeil(usize, self.view_size * win.height, self.total) catch unreachable, 1);
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const bar_height = @max(std.math.divCeil(usize, self.view_size * max.height, self.total) catch unreachable, 1);
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// The row of the last cell of the bottom of the bar
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const bar_bottom = (win.height - 1) -| (std.math.divCeil(usize, self.bottom * win.height, self.total) catch unreachable);
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const bar_bottom = (max.height - 1) -| (std.math.divCeil(usize, self.bottom * max.height, self.total) catch unreachable);
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var i: usize = 0;
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while (i <= bar_height) : (i += 1)
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win.writeCell(0, bar_bottom -| i, .{ .char = self.character, .style = self.style });
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surface.writeCell(0, @intCast(bar_bottom -| i), .{ .char = self.character, .style = self.style });
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return surface;
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}
+20
-1
src/irc.zig
+20
-1
src/irc.zig
···
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const zeit = @import("zeit");
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const bytepool = @import("pool.zig");
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const Scrollbar = @import("Scrollbar.zig");
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const testing = std.testing;
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const mem = std.mem;
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const vxfw = vaxis.vxfw;
···
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const msg_view_ctx = ctx.withConstraints(.{ .height = 0, .width = 0 }, .{
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.height = max.height - 4,
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.width = max.width,
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.width = max.width - 1,
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});
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const message_view = try self.drawMessageView(msg_view_ctx);
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try children.append(.{
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.origin = .{ .row = 2, .col = 0 },
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.surface = message_view,
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});
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const scrollbar_ctx = ctx.withConstraints(
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ctx.min,
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.{ .width = 1, .height = max.height - 4 },
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);
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+
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var scrollbars: Scrollbar = .{
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// Estimate number of lines per message
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.total = @intCast(self.messages.items.len * 3),
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.view_size = max.height - 4,
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.bottom = self.scroll.offset,
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};
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const scrollbar_surface = try scrollbars.draw(scrollbar_ctx);
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// Draw the text field
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try children.append(.{
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.origin = .{ .col = max.width - 1, .row = 2 },
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.surface = scrollbar_surface,
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});
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// Draw the text field