laser_pdf/elements/
force_break.rs

1use crate::*;
2
3/// Forces a break after it. Breaking mostly means page breaking, but the same mechanism could be
4/// used for columns or other advanced layout usecases.
5///
6/// This element takes up no space but causes the layout to continue on the next page or column when
7/// used in a breakable context.
8pub struct ForceBreak;
9
10impl Element for ForceBreak {
11    fn first_location_usage(&self, _ctx: FirstLocationUsageCtx) -> FirstLocationUsage {
12        FirstLocationUsage::WillUse
13    }
14
15    fn measure(&self, ctx: MeasureCtx) -> ElementSize {
16        if let Some(breakable) = ctx.breakable {
17            *breakable.break_count = 1;
18        }
19
20        ElementSize {
21            width: None,
22            height: None,
23        }
24    }
25
26    fn draw(&self, ctx: DrawCtx) -> ElementSize {
27        if let Some(breakable) = ctx.breakable {
28            // Note: This passes None as the height even though it always returns WillUse from
29            // first_location_usage. Just because the first location has None height doesn't mean
30            // it was skipped. In fact it would be incorrect if this element were to return
31            // WillSkip. WillSkip implies that if the element is drawn with a full first height it
32            // has to then look the same.
33            (breakable.do_break)(ctx.pdf, 0, None);
34        }
35
36        ElementSize {
37            width: None,
38            height: None,
39        }
40    }
41}
42
43#[cfg(test)]
44mod tests {
45    use super::*;
46    use crate::test_utils::*;
47
48    #[test]
49    fn test_force_break() {
50        for output in ElementTestParams::default().run(&ForceBreak) {
51            output.assert_size(ElementSize {
52                width: None,
53                height: None,
54            });
55
56            if let Some(b) = output.breakable {
57                b.assert_break_count(1);
58                b.assert_extra_location_min_height(None);
59            }
60        }
61    }
62}
laser_pdf/elements/force_break.rs

laser_pdf/elements/
force_break.rs
