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// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_PLAIN_TEXT_PAINTER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_PLAIN_TEXT_PAINTER_H_
#include "third_party/blink/renderer/platform/fonts/font.h"
#include "third_party/blink/renderer/platform/instrumentation/memory_pressure_listener.h"
namespace gfx {
class PointF;
class RectF;
} // namespace gfx
namespace cc {
class PaintCanvas;
class PaintFlags;
} // namespace cc
namespace blink {
class FrameShapeCache;
class PlainTextNode;
class TextRun;
// PlainTextPainter provides functionality to render plain text, excluding
// CSS and SVG.
//
// This class supports two modes: kCanvas and kShared.
// - kCanvas: Designed for use with HTML <canvas> and OffscreenCanvas.
// - kShared: Intended for purposes other than canvas rendering.
//
// The modes differ in how whitespace within the text is handled and how
// caching behaves.
//
// Instances in kCanvas mode are created one per canvas instance.
// Instances in kShared mode are created only once and accessed via
// PlainTextPainter::Shared().
class PLATFORM_EXPORT PlainTextPainter
: public GarbageCollected<PlainTextPainter>,
public MemoryPressureListener {
public:
enum Mode { kCanvas, kShared };
explicit PlainTextPainter(Mode mode);
void Trace(Visitor* visitor) const override;
PlainTextPainter(const PlainTextPainter&) = delete;
PlainTextPainter& operator=(const PlainTextPainter&) = delete;
// Return the shared instance for non-<canvas>.
static PlainTextPainter& Shared();
// Returns a PlainTextNode instance for `run` and `font`.
// This function applied Bidi reorder and word segmentation.
const PlainTextNode& SegmentAndShape(const TextRun& run, const Font& font);
// Draw the specified text. This doesn't apply BiDi reorder.
void DrawWithoutBidi(const TextRun& run,
const Font& font,
cc::PaintCanvas& canvas,
const gfx::PointF& location,
const cc::PaintFlags& flags,
Font::DrawType = Font::DrawType::kGlyphsOnly);
// Draw the specified text, from `from_index` to `to_index` (exclusive). This
// applies BiDi reorder.
// This function returns `false` if a web font `font` is not ready and
// `action` is `kDoNotPaintIfFontNotReady`.
bool DrawWithBidiReorder(const TextRun& run,
unsigned from_index,
unsigned to_index,
const Font& font,
Font::CustomFontNotReadyAction action,
cc::PaintCanvas& canvas,
const gfx::PointF& location,
const cc::PaintFlags& flags,
Font::DrawType = Font::DrawType::kGlyphsOnly);
// Glyph bounds will be the minimum rect containing all glyph strokes, in
// coordinates using (<text run x position>, <baseline position>) as the
// origin. If the pointer is not null, glyph_bounds is expected to be
// default-initialized.
float ComputeInlineSize(const TextRun& run,
const Font& font,
gfx::RectF* glyph_bounds = nullptr);
float ComputeSubInlineSize(const TextRun&,
unsigned from_index,
unsigned to_index,
const Font& font,
gfx::RectF* glyph_bounds = nullptr);
// This doesn't apply BiDi reorder for compatibility.
float ComputeInlineSizeWithoutBidi(const TextRun& run, const Font& font);
// Returns text offset in `run` for the specified pixel position.
// This doesn't apply BiDi reorder for compatibility.
int OffsetForPositionWithoutBidi(const TextRun& run,
const Font& font,
float position,
IncludePartialGlyphsOption partial_option,
BreakGlyphsOption break_option);
// Returns a bounding rectangle for a sub-range from `from_index` to
// `to_index` (exclusive) of `run`.
// This doesn't apply BiDi reorder for compatibility.
gfx::RectF SelectionRectForTextWithoutBidi(const TextRun& run,
unsigned from_index,
unsigned to_index,
const Font& font,
const gfx::PointF& left_baseline,
float height);
// This function should be called between the end of an animation frame and
// the beginning of the next animation frame. This is for <canvas>, and we
// don't need to call this for the shared instance.
void DidSwitchFrame();
private:
const PlainTextNode& CreateNode(const TextRun& text_run,
const Font& font,
bool supports_bidi = true);
FrameShapeCache* GetCacheFor(const Font& font);
// MemoryPressureListener override:
void OnPurgeMemory() override;
// A map from a FontFallbackList to a FrameShapeCache.
// We don't need to worry about Web Fonts. When a Web Font loading state is
// changed, affected FontFallbackLists are invalidated, and are disconnected
// from owner Fonts. They will be removed from `cache_map_` by GC.
HeapHashMap<WeakMember<FontFallbackList>, Member<FrameShapeCache>> cache_map_;
const Mode mode_;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_FONTS_PLAIN_TEXT_PAINTER_H_
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