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moppeeerandClaude Opus 5.5
6f47f10b4b
The renderer painted the paper, then blended page items with it: black text in Color Dodge over blank paper dodged the white to white and vanished, and other modes showed the same way. In InDesign (and in PDF, where the page group starts transparent) the paper is not a backdrop: over blank paper an object in any blend mode shows as it is, and only the objects below it are blended with. On spreads that use a blend mode the items are now drawn in their own group, laid over the paper once; other spreads render as before. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
49 lines
2.4 KiB
Rust
49 lines
2.4 KiB
Rust
//! Blend modes blend with the objects below, never with the paper: over blank paper an object in
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//! Color Dodge (or any other mode) shows as it is, as in InDesign and in the exported PDF.
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use designcraft_color::{BlendMode, Color, Swatch};
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use designcraft_compose::Cache;
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use designcraft_doc::{Document, Fill, Item, ItemId, Shape, SpreadRef, build::NewDocument};
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use designcraft_geom::{Affine, Rect, shapes};
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use designcraft_render::{Placed, RenderOptions, Renderer};
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/// A 200 x 100 page: a mid-blue rectangle on the right half, and over both halves a black
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/// rectangle in `blend`.
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fn document(blend: BlendMode) -> Document {
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let mut d = Document::new(&NewDocument { width: 200.0, height: 100.0, facing_pages: false, ..Default::default() });
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d.swatches.push(Swatch::color("Mid blue", Color::rgb(0.2, 0.4, 0.6)));
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let mut rect = |r: Rect, swatch: &str, blend: BlendMode| {
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let id = ItemId(d.alloc());
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let mut it = Item::new(id, d.default_layer(), Shape::Rectangle, shapes::rectangle(r));
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it.fill = Fill::swatch(swatch);
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it.blend = blend;
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d.insert_item(SpreadRef::Doc(0), it, None).unwrap();
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};
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rect(Rect::new(100.0, 0.0, 200.0, 100.0), "Mid blue", BlendMode::Normal);
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rect(Rect::new(20.0, 20.0, 180.0, 80.0), "[Black]", blend);
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d
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}
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fn pixel(d: &Document, x: u32, y: u32) -> [u8; 4] {
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let mut r = Renderer::new();
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r.threads = 0;
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let placed = [Placed { spread: SpreadRef::Doc(0), xf: Affine::IDENTITY }];
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let img = r.render(d, &Cache::new(), &placed, 200, 100, Affine::IDENTITY, &RenderOptions::default());
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let i = ((y * 200 + x) * 4) as usize;
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[img.pixels[i], img.pixels[i + 1], img.pixels[i + 2], img.pixels[i + 3]]
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}
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#[test]
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fn a_blend_mode_over_blank_paper_shows_the_object_as_it_is() {
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let d = document(BlendMode::ColorDodge);
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// Over the paper: black ([Black] shows as about 52 grey), as in Normal (it used to dodge the white paper to white, vanishing).
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let over_paper = pixel(&d, 50, 50);
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assert!(over_paper[0] < 80 && over_paper[1] < 80 && over_paper[2] < 80, "{over_paper:?}");
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// Over the blue rectangle it still blends: black in Color Dodge leaves the blue as it is.
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let over_blue = pixel(&d, 150, 50);
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assert!(over_blue[2] > 120 && over_blue[2] > over_blue[0], "{over_blue:?}");
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// Normal is unchanged.
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let normal = pixel(&document(BlendMode::Normal), 150, 50);
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assert!(normal[0] < 80 && normal[2] < 80, "{normal:?}");
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}
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