1 mod common {
2 pub mod image;
3 pub mod text;
4 }
5 use common::image::{image_measure_function, ImageContext};
6 use common::text::{text_measure_function, FontMetrics, TextContext, WritingMode, LOREM_IPSUM};
7 use taffy::prelude::*;
8
9 enum NodeContext {
10 Text(TextContext),
11 Image(ImageContext),
12 }
13
measure_function( known_dimensions: taffy::geometry::Size<Option<f32>>, available_space: taffy::geometry::Size<taffy::style::AvailableSpace>, node_context: Option<&mut NodeContext>, font_metrics: &FontMetrics, ) -> Size<f32>14 fn measure_function(
15 known_dimensions: taffy::geometry::Size<Option<f32>>,
16 available_space: taffy::geometry::Size<taffy::style::AvailableSpace>,
17 node_context: Option<&mut NodeContext>,
18 font_metrics: &FontMetrics,
19 ) -> Size<f32> {
20 if let Size { width: Some(width), height: Some(height) } = known_dimensions {
21 return Size { width, height };
22 }
23
24 match node_context {
25 None => Size::ZERO,
26 Some(NodeContext::Text(text_context)) => {
27 text_measure_function(known_dimensions, available_space, &*text_context, font_metrics)
28 }
29 Some(NodeContext::Image(image_context)) => image_measure_function(known_dimensions, image_context),
30 }
31 }
32
main() -> Result<(), taffy::TaffyError>33 fn main() -> Result<(), taffy::TaffyError> {
34 let mut taffy: TaffyTree<NodeContext> = TaffyTree::new();
35
36 let font_metrics = FontMetrics { char_width: 10.0, char_height: 10.0 };
37
38 let text_node = taffy.new_leaf_with_context(
39 Style::default(),
40 NodeContext::Text(TextContext { text_content: LOREM_IPSUM.into(), writing_mode: WritingMode::Horizontal }),
41 )?;
42
43 let image_node = taffy
44 .new_leaf_with_context(Style::default(), NodeContext::Image(ImageContext { width: 400.0, height: 300.0 }))?;
45
46 let root = taffy.new_with_children(
47 Style {
48 display: Display::Flex,
49 flex_direction: FlexDirection::Column,
50 size: Size { width: length(200.0), height: auto() },
51 ..Default::default()
52 },
53 &[text_node, image_node],
54 )?;
55
56 // Compute layout and print result
57 taffy.compute_layout_with_measure(
58 root,
59 Size::MAX_CONTENT,
60 // Note: this closure is a FnMut closure and can be used to borrow external context for the duration of layout
61 // For example, you may wish to borrow a global font registry and pass it into your text measuring function
62 |known_dimensions, available_space, _node_id, node_context, _style| {
63 measure_function(known_dimensions, available_space, node_context, &font_metrics)
64 },
65 )?;
66 taffy.print_tree(root);
67
68 Ok(())
69 }
70