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https://github.com/RGBCube/serenity
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9121cc7cae
This requires an implementation of the "text preparation algorithm" as specified here: html.spec.whatwg.org/multipage/canvas.html#text-preparation-algorithm However, we're missing a lot of things such as the CanvasTextDrawingStyles interface, so most of the algorithm was not implemented. Additionally, we also are not able to use a LineBox like the algorithm suggests, because our layouting infra is not up to the task yet. The prepare_text function does nothing other than figuring out the width of the given text and return glyphs with offsets at the moment.
123 lines
3.7 KiB
C++
123 lines
3.7 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/RefCounted.h>
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#include <LibGfx/AffineTransform.h>
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#include <LibGfx/Color.h>
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#include <LibGfx/Forward.h>
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#include <LibGfx/Painter.h>
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#include <LibGfx/Path.h>
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#include <LibWeb/Bindings/Wrappable.h>
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#include <LibWeb/DOM/ExceptionOr.h>
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#include <LibWeb/Layout/InlineNode.h>
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#include <LibWeb/Layout/LineBox.h>
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namespace Web::HTML {
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class CanvasRenderingContext2D
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: public RefCounted<CanvasRenderingContext2D>
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, public Bindings::Wrappable {
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AK_MAKE_NONCOPYABLE(CanvasRenderingContext2D);
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AK_MAKE_NONMOVABLE(CanvasRenderingContext2D);
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public:
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using WrapperType = Bindings::CanvasRenderingContext2DWrapper;
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static NonnullRefPtr<CanvasRenderingContext2D> create(HTMLCanvasElement& element) { return adopt_ref(*new CanvasRenderingContext2D(element)); }
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~CanvasRenderingContext2D();
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void set_fill_style(String);
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String fill_style() const;
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void set_stroke_style(String);
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String stroke_style() const;
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void fill_rect(float x, float y, float width, float height);
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void stroke_rect(float x, float y, float width, float height);
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void clear_rect(float x, float y, float width, float height);
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void draw_image(const HTMLImageElement&, float x, float y);
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void scale(float sx, float sy);
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void translate(float x, float y);
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void rotate(float degrees);
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void set_line_width(float line_width) { m_drawing_state.line_width = line_width; }
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float line_width() const { return m_drawing_state.line_width; }
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void begin_path();
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void close_path();
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void move_to(float x, float y);
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void line_to(float x, float y);
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void quadratic_curve_to(float cx, float cy, float x, float y);
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DOM::ExceptionOr<void> arc(float x, float y, float radius, float start_angle, float end_angle, bool counter_clockwise);
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DOM::ExceptionOr<void> ellipse(float x, float y, float radius_x, float radius_y, float rotation, float start_angle, float end_angle, bool counter_clockwise);
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void rect(float x, float y, float width, float height);
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void stroke();
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void fill_text(const String&, float x, float y, Optional<double> max_width);
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// FIXME: We should only have one fill(), really. Fix the wrapper generator!
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void fill(Gfx::Painter::WindingRule);
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void fill(const String& fill_rule);
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RefPtr<ImageData> create_image_data(int width, int height) const;
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void put_image_data(const ImageData&, float x, float y);
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void save();
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void restore();
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void reset();
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bool is_context_lost();
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void reset_to_default_state();
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HTMLCanvasElement* canvas() { return m_element; }
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RefPtr<TextMetrics> measure_text(String const& text);
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private:
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explicit CanvasRenderingContext2D(HTMLCanvasElement&);
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struct PreparedTextGlyph {
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unsigned int c;
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Gfx::IntPoint position;
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};
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struct PreparedText {
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Vector<PreparedTextGlyph> glyphs;
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Gfx::TextAlignment physical_alignment;
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Gfx::IntRect bounding_box;
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};
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void did_draw(const Gfx::FloatRect&);
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PreparedText prepare_text(String const& text, float max_width = INFINITY);
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OwnPtr<Gfx::Painter> painter();
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WeakPtr<HTMLCanvasElement> m_element;
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// https://html.spec.whatwg.org/multipage/canvas.html#drawing-state
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struct DrawingState {
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Gfx::AffineTransform transform;
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Gfx::Color fill_style { Gfx::Color::Black };
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Gfx::Color stroke_style { Gfx::Color::Black };
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float line_width { 1 };
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};
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DrawingState m_drawing_state;
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Vector<DrawingState> m_drawing_state_stack;
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// https://html.spec.whatwg.org/multipage/canvas.html#concept-canvas-context-lost
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bool m_context_lost { false };
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Gfx::Path m_path;
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};
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}
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