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66378471a0
PDF 1.7 spec, p231, 4.4.2 Path-Painting Operators, Stroking: "If a subpath is degenerate (consists of a single-point closed path or of two or more points at the same coordinates), the S operator paints it only if round line caps have been specified, producing a filled circle centered at the single point. If butt or projecting square line caps have been specified, S produces no output, because the orientation of the caps would be indeterminate. (This rule applies only to zero-length subpaths of the path being stroked, and not to zero-length dashes in a dash pattern. In the latter case, the line caps are always painted, since their orientation is determined by the direction of the underlying path.) A single-point open subpath (specified by a trailing m operator) produces no output." In practice, Chrome, Firefox, and Preview all also draw a square for square line endings (Preview a square rotated 45 degrees). Chrome even draws something weird-looking for butt caps. (Acrobat only draws the round cap, per spec.) https://html.spec.whatwg.org/multipage/canvas.html#trace-a-path sounds like zero-lengths paths should be ignored for canvas, but in practice Chrome and Firefox do draw them. (Safari doesn't.) We don't do linecaps in SVGs yet, but https://www.w3.org/TR/SVG/paths.html#ZeroLengthSegments says: "As mentioned in Stroke Properties, linecaps must be painted for zero-length subpaths when stroke-linecap has a value of round or square." With this commit, we now draw round and square linecaps for zero-lengths paths, which is what's apparently desired most of the time. Maybe we can add a setting to pick different behavior for PDF (only draw round caps), canvas (don't draw caps on zero-length paths), and SVG (draw round and square caps) in the future.
113 lines
3.1 KiB
C++
113 lines
3.1 KiB
C++
/*
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* Copyright (c) 2024, Nico Weber <thakis@chromium.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibTest/TestCase.h>
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#include <LibGfx/Path.h>
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TEST_CASE(path_to_fill_short_wide_line_with_butt_linecap)
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{
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// Test drawing a horizontal rect by stroking a vertical short wide line.
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{
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int width = 100;
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int height = 1;
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Gfx::Path path;
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path.move_to({ width / 2, 0 });
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path.line_to({ width / 2, height });
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auto fill = path.stroke_to_fill(width, Gfx::Path::CapStyle::Butt);
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EXPECT_EQ(fill.bounding_box(), Gfx::FloatRect({ 0, 0 }, { width, height }));
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}
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// Test drawing a vertical rect by stroking a horizontal short wide line.
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{
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int width = 1;
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int height = 100;
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Gfx::Path path;
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path.move_to({ 0, height / 2 });
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path.line_to({ width, height / 2 });
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auto fill = path.stroke_to_fill(height, Gfx::Path::CapStyle::Butt);
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EXPECT_EQ(fill.bounding_box(), Gfx::FloatRect({ 0, 0 }, { width, height }));
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}
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}
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TEST_CASE(path_to_fill_square_linecap)
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{
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int line_width = 10;
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int width = 100;
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Gfx::Path path;
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path.move_to({ line_width / 2, line_width / 2 });
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path.line_to({ width - line_width / 2, line_width / 2 });
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auto fill = path.stroke_to_fill(line_width, Gfx::Path::CapStyle::Square);
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EXPECT_EQ(fill.bounding_box(), Gfx::FloatRect({ 0, 0 }, { width, line_width }));
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}
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TEST_CASE(path_to_fill_single_point)
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{
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Gfx::Path path;
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path.move_to({ 10, 10 });
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path.line_to({ 10, 10 });
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{
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auto fill = path.stroke_to_fill(8, Gfx::Path::CapStyle::Butt);
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EXPECT(fill.is_empty());
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}
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{
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auto fill = path.stroke_to_fill(8, Gfx::Path::CapStyle::Round);
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EXPECT(!fill.is_empty());
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}
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{
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auto fill = path.stroke_to_fill(8, Gfx::Path::CapStyle::Square);
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EXPECT_EQ(fill.bounding_box(), Gfx::FloatRect({ 6, 6 }, { 8, 8 }));
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}
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}
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TEST_CASE(path_to_fill_two_single_points)
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{
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Gfx::Path path;
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path.move_to({ 10, 10 });
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path.line_to({ 10, 10 });
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path.move_to({ 20, 20 });
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path.line_to({ 20, 20 });
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{
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auto fill = path.stroke_to_fill(8, Gfx::Path::CapStyle::Butt);
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EXPECT(fill.is_empty());
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}
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{
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auto fill = path.stroke_to_fill(8, Gfx::Path::CapStyle::Round);
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EXPECT(!fill.is_empty());
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}
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{
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auto fill = path.stroke_to_fill(8, Gfx::Path::CapStyle::Square);
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EXPECT(!fill.is_empty());
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}
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}
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TEST_CASE(path_to_string)
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{
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{
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Gfx::Path path;
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path.move_to({ 10, 10 });
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path.line_to({ 20, 20 });
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path.quadratic_bezier_curve_to({ 30, 30 }, { 40, 40 });
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path.cubic_bezier_curve_to({ 50, 50 }, { 60, 60 }, { 10, 10 });
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path.close();
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EXPECT_EQ(path.to_byte_string(), "M 10,10 L 20,20 Q 30,30 40,40 C 50,50 60,60 10,10 Z");
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}
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{
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Gfx::Path path;
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path.move_to({ 10, 10 });
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path.line_to({ 20, 20 });
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path.quadratic_bezier_curve_to({ 30, 30 }, { 40, 40 });
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path.cubic_bezier_curve_to({ 50, 50 }, { 60, 60 }, { 10, 10 });
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EXPECT_EQ(path.to_byte_string(), "M 10,10 L 20,20 Q 30,30 40,40 C 50,50 60,60 10,10");
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}
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}
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