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typographer_context_skia.cc
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1 // Copyright 2013 The Flutter Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "impeller/typographer/backends/skia/typographer_context_skia.h"
6
7 #include <cstddef>
8 #include <cstdint>
9 #include <memory>
10 #include <numeric>
11 #include <utility>
12 #include <vector>
13
14 #include "flutter/fml/logging.h"
15 #include "flutter/fml/trace_event.h"
16 #include "fml/closure.h"
17
18 #include "impeller/base/validation.h"
19 #include "impeller/core/allocator.h"
20 #include "impeller/core/buffer_view.h"
21 #include "impeller/core/formats.h"
22 #include "impeller/core/host_buffer.h"
23 #include "impeller/core/platform.h"
24 #include "impeller/core/texture_descriptor.h"
25 #include "impeller/geometry/rect.h"
26 #include "impeller/geometry/size.h"
27 #include "impeller/renderer/command_buffer.h"
28 #include "impeller/renderer/render_pass.h"
29 #include "impeller/renderer/render_target.h"
30 #include "impeller/typographer/backends/skia/typeface_skia.h"
31 #include "impeller/typographer/font_glyph_pair.h"
32 #include "impeller/typographer/glyph.h"
33 #include "impeller/typographer/glyph_atlas.h"
34 #include "impeller/typographer/rectangle_packer.h"
35 #include "impeller/typographer/typographer_context.h"
36 #include "include/core/SkColor.h"
37 #include "include/core/SkImageInfo.h"
38 #include "include/core/SkPaint.h"
39 #include "include/core/SkSize.h"
40
41 #include "third_party/skia/include/core/SkBitmap.h"
42 #include "third_party/skia/include/core/SkBlendMode.h"
43 #include "third_party/skia/include/core/SkCanvas.h"
44 #include "third_party/skia/include/core/SkFont.h"
45 #include "third_party/skia/include/core/SkSurface.h"
46
47 namespace impeller {
48
49 constexpr auto kPadding = 2;
50
51 namespace {
52 SkPaint::Cap ToSkiaCap(Cap cap) {
53 switch (cap) {
54 case Cap::kButt:
55 return SkPaint::Cap::kButt_Cap;
56 case Cap::kRound:
57 return SkPaint::Cap::kRound_Cap;
58 case Cap::kSquare:
59 return SkPaint::Cap::kSquare_Cap;
60 }
61 FML_UNREACHABLE();
62 }
63
64 SkPaint::Join ToSkiaJoin(Join join) {
65 switch (join) {
66 case Join::kMiter:
67 return SkPaint::Join::kMiter_Join;
68 case Join::kRound:
69 return SkPaint::Join::kRound_Join;
70 case Join::kBevel:
71 return SkPaint::Join::kBevel_Join;
72 }
73 FML_UNREACHABLE();
74 }
75 } // namespace
76
77 std::shared_ptr<TypographerContext> TypographerContextSkia::Make() {
78 return std::make_shared<TypographerContextSkia>();
79 }
80
81 TypographerContextSkia::TypographerContextSkia() = default;
82
83 TypographerContextSkia::~TypographerContextSkia() = default;
84
85 std::shared_ptr<GlyphAtlasContext>
86 TypographerContextSkia::CreateGlyphAtlasContext(GlyphAtlas::Type type) const {
87 return std::make_shared<GlyphAtlasContext>(type);
88 }
89
90 static SkImageInfo GetImageInfo(const GlyphAtlas& atlas, Size size) {
91 switch (atlas.GetType()) {
92 case GlyphAtlas::Type::kAlphaBitmap:
93 return SkImageInfo::MakeA8(SkISize{static_cast<int32_t>(size.width),
94 static_cast<int32_t>(size.height)});
95 case GlyphAtlas::Type::kColorBitmap:
96 return SkImageInfo::MakeN32Premul(size.width, size.height);
97 }
98 FML_UNREACHABLE();
99 }
100
101 /// Append as many glyphs to the texture as will fit, and return the first index
102 /// of [extra_pairs] that did not fit.
103 static size_t AppendToExistingAtlas(
104 const std::shared_ptr<GlyphAtlas>& atlas,
105 const std::vector<FontGlyphPair>& extra_pairs,
106 std::vector<Rect>& glyph_positions,
107 const std::vector<Rect>& glyph_sizes,
108 ISize atlas_size,
109 int64_t height_adjustment,
110 const std::shared_ptr<RectanglePacker>& rect_packer) {
111 TRACE_EVENT0("impeller", __FUNCTION__);
112 if (!rect_packer || atlas_size.IsEmpty()) {
113 return 0;
114 }
115
116 for (size_t i = 0; i < extra_pairs.size(); i++) {
117 ISize glyph_size = ISize::Ceil(glyph_sizes[i].GetSize());
118 IPoint16 location_in_atlas;
119 if (!rect_packer->AddRect(glyph_size.width + kPadding, //
120 glyph_size.height + kPadding, //
121 &location_in_atlas //
122 )) {
123 return i;
124 }
125 // Position the glyph in the center of the 1px padding.
126 glyph_positions.push_back(Rect::MakeXYWH(
127 location_in_atlas.x() + 1, //
128 location_in_atlas.y() + height_adjustment + 1, //
129 glyph_size.width, //
130 glyph_size.height //
131 ));
132 }
133
134 return extra_pairs.size();
135 }
136
137 static size_t PairsFitInAtlasOfSize(
138 const std::vector<FontGlyphPair>& pairs,
139 const ISize& atlas_size,
140 std::vector<Rect>& glyph_positions,
141 const std::vector<Rect>& glyph_sizes,
142 int64_t height_adjustment,
143 const std::shared_ptr<RectanglePacker>& rect_packer,
144 size_t start_index) {
145 FML_DCHECK(!atlas_size.IsEmpty());
146
147 for (size_t i = start_index; i < pairs.size(); i++) {
148 ISize glyph_size = ISize::Ceil(glyph_sizes[i].GetSize());
149 IPoint16 location_in_atlas;
150 if (!rect_packer->AddRect(glyph_size.width + kPadding, //
151 glyph_size.height + kPadding, //
152 &location_in_atlas //
153 )) {
154 return i;
155 }
156 glyph_positions.push_back(Rect::MakeXYWH(
157 location_in_atlas.x() + 1, //
158 location_in_atlas.y() + height_adjustment + 1, //
159 glyph_size.width, //
160 glyph_size.height //
161 ));
162 }
163
164 return pairs.size();
165 }
166
167 static ISize ComputeNextAtlasSize(
168 const std::shared_ptr<GlyphAtlasContext>& atlas_context,
169 const std::vector<FontGlyphPair>& extra_pairs,
170 std::vector<Rect>& glyph_positions,
171 const std::vector<Rect>& glyph_sizes,
172 size_t glyph_index_start,
173 int64_t max_texture_height) {
174 // Because we can't grow the skyline packer horizontally, pick a reasonable
175 // large width for all atlases.
176 static constexpr int64_t kAtlasWidth = 4096;
177 static constexpr int64_t kMinAtlasHeight = 1024;
178
179 ISize current_size = ISize(kAtlasWidth, kMinAtlasHeight);
180 if (atlas_context->GetAtlasSize().height > current_size.height) {
181 current_size.height = atlas_context->GetAtlasSize().height * 2;
182 }
183
184 auto height_adjustment = atlas_context->GetAtlasSize().height;
185 while (current_size.height <= max_texture_height) {
186 std::shared_ptr<RectanglePacker> rect_packer;
187 if (atlas_context->GetRectPacker() || glyph_index_start) {
188 rect_packer = RectanglePacker::Factory(
189 kAtlasWidth,
190 current_size.height - atlas_context->GetAtlasSize().height);
191 } else {
192 rect_packer = RectanglePacker::Factory(kAtlasWidth, current_size.height);
193 }
194 glyph_positions.erase(glyph_positions.begin() + glyph_index_start,
195 glyph_positions.end());
196 atlas_context->UpdateRectPacker(rect_packer);
197 auto next_index = PairsFitInAtlasOfSize(
198 extra_pairs, current_size, glyph_positions, glyph_sizes,
199 height_adjustment, rect_packer, glyph_index_start);
200 if (next_index == extra_pairs.size()) {
201 return current_size;
202 }
203 current_size = ISize(current_size.width, current_size.height * 2);
204 }
205 return {};
206 }
207
208 static void DrawGlyph(SkCanvas* canvas,
209 const SkPoint position,
210 const ScaledFont& scaled_font,
211 const SubpixelGlyph& glyph,
212 const Rect& scaled_bounds,
213 const std::optional<GlyphProperties>& prop,
214 bool has_color) {
215 const auto& metrics = scaled_font.font.GetMetrics();
216 SkGlyphID glyph_id = glyph.glyph.index;
217
218 SkFont sk_font(
219 TypefaceSkia::Cast(*scaled_font.font.GetTypeface()).GetSkiaTypeface(),
220 metrics.point_size, metrics.scaleX, metrics.skewX);
221 sk_font.setEdging(SkFont::Edging::kAntiAlias);
222 sk_font.setHinting(SkFontHinting::kSlight);
223 sk_font.setEmbolden(metrics.embolden);
224 sk_font.setSubpixel(true);
225 sk_font.setSize(sk_font.getSize() * scaled_font.scale);
226
227 auto glyph_color = prop.has_value() ? prop->color.ToARGB() : SK_ColorBLACK;
228
229 SkPaint glyph_paint;
230 glyph_paint.setColor(glyph_color);
231 glyph_paint.setBlendMode(SkBlendMode::kSrc);
232 if (prop.has_value() && prop->stroke) {
233 glyph_paint.setStroke(true);
234 glyph_paint.setStrokeWidth(prop->stroke_width * scaled_font.scale);
235 glyph_paint.setStrokeCap(ToSkiaCap(prop->stroke_cap));
236 glyph_paint.setStrokeJoin(ToSkiaJoin(prop->stroke_join));
237 glyph_paint.setStrokeMiter(prop->stroke_miter);
238 }
239 canvas->save();
240 canvas->translate(glyph.subpixel_offset.x, glyph.subpixel_offset.y);
241 canvas->drawGlyphs(1u, // count
242 &glyph_id, // glyphs
243 &position, // positions
244 SkPoint::Make(-scaled_bounds.GetLeft(),
245 -scaled_bounds.GetTop()), // origin
246 sk_font, // font
247 glyph_paint // paint
248 );
249 canvas->restore();
250 }
251
252 /// @brief Batch render to a single surface.
253 ///
254 /// This is only safe for use when updating a fresh texture.
255 static bool BulkUpdateAtlasBitmap(const GlyphAtlas& atlas,
256 std::shared_ptr<BlitPass>& blit_pass,
257 HostBuffer& host_buffer,
258 const std::shared_ptr<Texture>& texture,
259 const std::vector<FontGlyphPair>& new_pairs,
260 size_t start_index,
261 size_t end_index) {
262 TRACE_EVENT0("impeller", __FUNCTION__);
263
264 bool has_color = atlas.GetType() == GlyphAtlas::Type::kColorBitmap;
265
266 SkBitmap bitmap;
267 bitmap.setInfo(GetImageInfo(atlas, Size(texture->GetSize())));
268 if (!bitmap.tryAllocPixels()) {
269 return false;
270 }
271
272 auto surface = SkSurfaces::WrapPixels(bitmap.pixmap());
273 if (!surface) {
274 return false;
275 }
276 auto canvas = surface->getCanvas();
277 if (!canvas) {
278 return false;
279 }
280
281 for (size_t i = start_index; i < end_index; i++) {
282 const FontGlyphPair& pair = new_pairs[i];
283 auto data = atlas.FindFontGlyphBounds(pair);
284 if (!data.has_value()) {
285 continue;
286 }
287 auto [pos, bounds, placeholder] = data.value();
288 FML_DCHECK(!placeholder);
289 Size size = pos.GetSize();
290 if (size.IsEmpty()) {
291 continue;
292 }
293
294 DrawGlyph(canvas, SkPoint::Make(pos.GetLeft(), pos.GetTop()),
295 pair.scaled_font, pair.glyph, bounds, pair.glyph.properties,
296 has_color);
297 }
298
299 // Writing to a malloc'd buffer and then copying to the staging buffers
300 // benchmarks as substantially faster on a number of Android devices.
301 BufferView buffer_view = host_buffer.Emplace(
302 bitmap.getAddr(0, 0),
303 texture->GetSize().Area() *
304 BytesPerPixelForPixelFormat(
305 atlas.GetTexture()->GetTextureDescriptor().format),
306 DefaultUniformAlignment());
307
308 return blit_pass->AddCopy(std::move(buffer_view), //
309 texture, //
310 IRect::MakeXYWH(0, 0, texture->GetSize().width,
311 texture->GetSize().height));
312 }
313
314 static bool UpdateAtlasBitmap(const GlyphAtlas& atlas,
315 std::shared_ptr<BlitPass>& blit_pass,
316 HostBuffer& host_buffer,
317 const std::shared_ptr<Texture>& texture,
318 const std::vector<FontGlyphPair>& new_pairs,
319 size_t start_index,
320 size_t end_index) {
321 TRACE_EVENT0("impeller", __FUNCTION__);
322
323 bool has_color = atlas.GetType() == GlyphAtlas::Type::kColorBitmap;
324
325 for (size_t i = start_index; i < end_index; i++) {
326 const FontGlyphPair& pair = new_pairs[i];
327 auto data = atlas.FindFontGlyphBounds(pair);
328 if (!data.has_value()) {
329 continue;
330 }
331 auto [pos, bounds, placeholder] = data.value();
332 FML_DCHECK(!placeholder);
333
334 Size size = pos.GetSize();
335 if (size.IsEmpty()) {
336 continue;
337 }
338 // The uploaded bitmap is expanded by 1px of padding
339 // on each side.
340 size.width += 2;
341 size.height += 2;
342
343 SkBitmap bitmap;
344 bitmap.setInfo(GetImageInfo(atlas, size));
345 if (!bitmap.tryAllocPixels()) {
346 return false;
347 }
348
349 auto surface = SkSurfaces::WrapPixels(bitmap.pixmap());
350 if (!surface) {
351 return false;
352 }
353 auto canvas = surface->getCanvas();
354 if (!canvas) {
355 return false;
356 }
357
358 DrawGlyph(canvas, SkPoint::Make(1, 1), pair.scaled_font, pair.glyph, bounds,
359 pair.glyph.properties, has_color);
360
361 // Writing to a malloc'd buffer and then copying to the staging buffers
362 // benchmarks as substantially faster on a number of Android devices.
363 BufferView buffer_view = host_buffer.Emplace(
364 bitmap.getAddr(0, 0),
365 size.Area() * BytesPerPixelForPixelFormat(
366 atlas.GetTexture()->GetTextureDescriptor().format),
367 DefaultUniformAlignment());
368
369 // convert_to_read is set to false so that the texture remains in a transfer
370 // dst layout until we finish writing to it below. This only has an impact
371 // on Vulkan where we are responsible for managing image layouts.
372 if (!blit_pass->AddCopy(std::move(buffer_view), //
373 texture, //
374 IRect::MakeXYWH(pos.GetLeft() - 1, pos.GetTop() - 1,
375 size.width, size.height), //
376 /*label=*/"", //
377 /*mip_level=*/0, //
378 /*slice=*/0, //
379 /*convert_to_read=*/false //
380 )) {
381 return false;
382 }
383 }
384 return blit_pass->ConvertTextureToShaderRead(texture);
385 }
386
387 static Rect ComputeGlyphSize(const SkFont& font,
388 const SubpixelGlyph& glyph,
389 Scalar scale) {
390 SkRect scaled_bounds;
391 SkPaint glyph_paint;
392 if (glyph.properties.has_value() && glyph.properties->stroke) {
393 glyph_paint.setStroke(true);
394 glyph_paint.setStrokeWidth(glyph.properties->stroke_width * scale);
395 glyph_paint.setStrokeCap(ToSkiaCap(glyph.properties->stroke_cap));
396 glyph_paint.setStrokeJoin(ToSkiaJoin(glyph.properties->stroke_join));
397 glyph_paint.setStrokeMiter(glyph.properties->stroke_miter);
398 }
399 font.getBounds(&glyph.glyph.index, 1, &scaled_bounds, &glyph_paint);
400
401 // Expand the bounds of glyphs at subpixel offsets by 2 in the x direction.
402 Scalar adjustment = 0.0;
403 if (glyph.subpixel_offset != Point(0, 0)) {
404 adjustment = 1.0;
405 }
406 return Rect::MakeLTRB(scaled_bounds.fLeft - adjustment, scaled_bounds.fTop,
407 scaled_bounds.fRight + adjustment,
408 scaled_bounds.fBottom);
409 };
410
411 std::pair<std::vector<FontGlyphPair>, std::vector<Rect>>
412 TypographerContextSkia::CollectNewGlyphs(
413 const std::shared_ptr<GlyphAtlas>& atlas,
414 const std::vector<std::shared_ptr<TextFrame>>& text_frames) {
415 std::vector<FontGlyphPair> new_glyphs;
416 std::vector<Rect> glyph_sizes;
417 size_t generation_id = atlas->GetAtlasGeneration();
418 intptr_t atlas_id = reinterpret_cast<intptr_t>(atlas.get());
419 for (const auto& frame : text_frames) {
420 // TODO(jonahwilliams): re-enable glyph condition once
421 // https://github.com/flutter/flutter/issues/163730 is fixed
422 #if false
423 auto [frame_generation_id, frame_atlas_id] =
424 frame->GetAtlasGenerationAndID();
425 if (atlas->IsValid() && frame->IsFrameComplete() &&
426 frame_generation_id == generation_id && frame_atlas_id == atlas_id &&
427 !frame->GetFrameBounds(0).is_placeholder) {
428 continue;
429 }
430 #endif // false
431 frame->ClearFrameBounds();
432 frame->SetAtlasGeneration(generation_id, atlas_id);
433
434 for (const auto& run : frame->GetRuns()) {
435 auto metrics = run.GetFont().GetMetrics();
436
437 auto rounded_scale = TextFrame::RoundScaledFontSize(frame->GetScale());
438 ScaledFont scaled_font{.font = run.GetFont(), .scale = rounded_scale};
439
440 FontGlyphAtlas* font_glyph_atlas =
441 atlas->GetOrCreateFontGlyphAtlas(scaled_font);
442 FML_DCHECK(!!font_glyph_atlas);
443
444 SkFont sk_font(
445 TypefaceSkia::Cast(*scaled_font.font.GetTypeface()).GetSkiaTypeface(),
446 metrics.point_size, metrics.scaleX, metrics.skewX);
447 sk_font.setEdging(SkFont::Edging::kAntiAlias);
448 sk_font.setHinting(SkFontHinting::kSlight);
449 sk_font.setEmbolden(metrics.embolden);
450 // Rather than computing the bounds at the requested point size and
451 // scaling up the bounds, we scale up the font size and request the
452 // bounds. This seems to give more accurate bounds information.
453 sk_font.setSize(sk_font.getSize() * scaled_font.scale);
454 sk_font.setSubpixel(true);
455
456 for (const auto& glyph_position : run.GetGlyphPositions()) {
457 Point subpixel = TextFrame::ComputeSubpixelPosition(
458 glyph_position, scaled_font.font.GetAxisAlignment(),
459 frame->GetOffsetTransform());
460 SubpixelGlyph subpixel_glyph(glyph_position.glyph, subpixel,
461 frame->GetProperties());
462 const auto& font_glyph_bounds =
463 font_glyph_atlas->FindGlyphBounds(subpixel_glyph);
464
465 if (!font_glyph_bounds.has_value()) {
466 new_glyphs.push_back(FontGlyphPair{scaled_font, subpixel_glyph});
467 auto glyph_bounds =
468 ComputeGlyphSize(sk_font, subpixel_glyph, scaled_font.scale);
469 glyph_sizes.push_back(glyph_bounds);
470
471 auto frame_bounds = FrameBounds{
472 Rect::MakeLTRB(0, 0, 0, 0), //
473 glyph_bounds, //
474 /*placeholder=*/true //
475 };
476
477 frame->AppendFrameBounds(frame_bounds);
478 font_glyph_atlas->AppendGlyph(subpixel_glyph, frame_bounds);
479 } else {
480 frame->AppendFrameBounds(font_glyph_bounds.value());
481 }
482 }
483 }
484 }
485 return {std::move(new_glyphs), std::move(glyph_sizes)};
486 }
487
488 std::shared_ptr<GlyphAtlas> TypographerContextSkia::CreateGlyphAtlas(
489 Context& context,
490 GlyphAtlas::Type type,
491 HostBuffer& host_buffer,
492 const std::shared_ptr<GlyphAtlasContext>& atlas_context,
493 const std::vector<std::shared_ptr<TextFrame>>& text_frames) const {
494 TRACE_EVENT0("impeller", __FUNCTION__);
495 if (!IsValid()) {
496 return nullptr;
497 }
498 std::shared_ptr<GlyphAtlas> last_atlas = atlas_context->GetGlyphAtlas();
499 FML_DCHECK(last_atlas->GetType() == type);
500
501 if (text_frames.empty()) {
502 return last_atlas;
503 }
504
505 // ---------------------------------------------------------------------------
506 // Step 1: Determine if the atlas type and font glyph pairs are compatible
507 // with the current atlas and reuse if possible. For each new font and
508 // glyph pair, compute the glyph size at scale.
509 // ---------------------------------------------------------------------------
510 auto [new_glyphs, glyph_sizes] = CollectNewGlyphs(last_atlas, text_frames);
511 if (new_glyphs.size() == 0) {
512 return last_atlas;
513 }
514
515 // ---------------------------------------------------------------------------
516 // Step 2: Determine if the additional missing glyphs can be appended to the
517 // existing bitmap without recreating the atlas.
518 // ---------------------------------------------------------------------------
519 std::vector<Rect> glyph_positions;
520 glyph_positions.reserve(new_glyphs.size());
521 size_t first_missing_index = 0;
522
523 if (last_atlas->GetTexture()) {
524 // Append all glyphs that fit into the current atlas.
525 first_missing_index = AppendToExistingAtlas(
526 last_atlas, new_glyphs, glyph_positions, glyph_sizes,
527 atlas_context->GetAtlasSize(), atlas_context->GetHeightAdjustment(),
528 atlas_context->GetRectPacker());
529
530 // ---------------------------------------------------------------------------
531 // Step 3a: Record the positions in the glyph atlas of the newly added
532 // glyphs.
533 // ---------------------------------------------------------------------------
534 for (size_t i = 0; i < first_missing_index; i++) {
535 last_atlas->AddTypefaceGlyphPositionAndBounds(
536 new_glyphs[i], glyph_positions[i], glyph_sizes[i]);
537 }
538
539 std::shared_ptr<CommandBuffer> cmd_buffer = context.CreateCommandBuffer();
540 std::shared_ptr<BlitPass> blit_pass = cmd_buffer->CreateBlitPass();
541
542 fml::ScopedCleanupClosure closure([&]() {
543 blit_pass->EncodeCommands();
544 if (!context.EnqueueCommandBuffer(std::move(cmd_buffer))) {
545 VALIDATION_LOG << "Failed to submit glyph atlas command buffer";
546 }
547 });
548
549 // ---------------------------------------------------------------------------
550 // Step 4a: Draw new font-glyph pairs into the a host buffer and encode
551 // the uploads into the blit pass.
552 // ---------------------------------------------------------------------------
553 if (!UpdateAtlasBitmap(*last_atlas, blit_pass, host_buffer,
554 last_atlas->GetTexture(), new_glyphs, 0,
555 first_missing_index)) {
556 return nullptr;
557 }
558
559 // If all glyphs fit, just return the old atlas.
560 if (first_missing_index == new_glyphs.size()) {
561 return last_atlas;
562 }
563 }
564
565 int64_t height_adjustment = atlas_context->GetAtlasSize().height;
566 const int64_t max_texture_height =
567 context.GetResourceAllocator()->GetMaxTextureSizeSupported().height;
568
569 // IF the current atlas size is as big as it can get, then "GC" and create an
570 // atlas with only the required glyphs. OpenGLES cannot reliably perform the
571 // blit required here, as 1) it requires attaching textures as read and write
572 // framebuffers which has substantially smaller size limits that max textures
573 // and 2) is missing a GLES 2.0 implementation and cap check.
574 bool blit_old_atlas = true;
575 std::shared_ptr<GlyphAtlas> new_atlas = last_atlas;
576 if (atlas_context->GetAtlasSize().height >= max_texture_height ||
577 context.GetBackendType() == Context::BackendType::kOpenGLES) {
578 blit_old_atlas = false;
579 new_atlas = std::make_shared<GlyphAtlas>(
580 type, /*initial_generation=*/last_atlas->GetAtlasGeneration() + 1);
581
582 auto [update_glyphs, update_sizes] =
583 CollectNewGlyphs(new_atlas, text_frames);
584 new_glyphs = std::move(update_glyphs);
585 glyph_sizes = std::move(update_sizes);
586
587 glyph_positions.clear();
588 glyph_positions.reserve(new_glyphs.size());
589 first_missing_index = 0;
590
591 height_adjustment = 0;
592 atlas_context->UpdateRectPacker(nullptr);
593 atlas_context->UpdateGlyphAtlas(new_atlas, {0, 0}, 0);
594 }
595
596 // A new glyph atlas must be created.
597 ISize atlas_size = ComputeNextAtlasSize(atlas_context, //
598 new_glyphs, //
599 glyph_positions, //
600 glyph_sizes, //
601 first_missing_index, //
602 max_texture_height //
603 );
604
605 atlas_context->UpdateGlyphAtlas(new_atlas, atlas_size, height_adjustment);
606 if (atlas_size.IsEmpty()) {
607 return nullptr;
608 }
609 FML_DCHECK(new_glyphs.size() == glyph_positions.size());
610
611 TextureDescriptor descriptor;
612 switch (type) {
613 case GlyphAtlas::Type::kAlphaBitmap:
614 descriptor.format =
615 context.GetCapabilities()->GetDefaultGlyphAtlasFormat();
616 break;
617 case GlyphAtlas::Type::kColorBitmap:
618 descriptor.format = PixelFormat::kR8G8B8A8UNormInt;
619 break;
620 }
621 descriptor.size = atlas_size;
622 descriptor.storage_mode = StorageMode::kDevicePrivate;
623 descriptor.usage = TextureUsage::kShaderRead;
624 std::shared_ptr<Texture> new_texture =
625 context.GetResourceAllocator()->CreateTexture(descriptor);
626 if (!new_texture) {
627 return nullptr;
628 }
629
630 new_texture->SetLabel("GlyphAtlas");
631
632 std::shared_ptr<CommandBuffer> cmd_buffer = context.CreateCommandBuffer();
633 std::shared_ptr<BlitPass> blit_pass = cmd_buffer->CreateBlitPass();
634
635 fml::ScopedCleanupClosure closure([&]() {
636 blit_pass->EncodeCommands();
637 if (!context.EnqueueCommandBuffer(std::move(cmd_buffer))) {
638 VALIDATION_LOG << "Failed to submit glyph atlas command buffer";
639 }
640 });
641
642 // Now append all remaining glyphs. This should never have any missing data...
643 auto old_texture = new_atlas->GetTexture();
644 new_atlas->SetTexture(std::move(new_texture));
645
646 // ---------------------------------------------------------------------------
647 // Step 3a: Record the positions in the glyph atlas of the newly added
648 // glyphs.
649 // ---------------------------------------------------------------------------
650 for (size_t i = first_missing_index; i < glyph_positions.size(); i++) {
651 new_atlas->AddTypefaceGlyphPositionAndBounds(
652 new_glyphs[i], glyph_positions[i], glyph_sizes[i]);
653 }
654
655 // ---------------------------------------------------------------------------
656 // Step 4a: Draw new font-glyph pairs into the a host buffer and encode
657 // the uploads into the blit pass.
658 // ---------------------------------------------------------------------------
659 if (!BulkUpdateAtlasBitmap(*new_atlas, blit_pass, host_buffer,
660 new_atlas->GetTexture(), new_glyphs,
661 first_missing_index, new_glyphs.size())) {
662 return nullptr;
663 }
664
665 // Blit the old texture to the top left of the new atlas.
666 if (blit_old_atlas && old_texture) {
667 blit_pass->AddCopy(old_texture, new_atlas->GetTexture(),
668 IRect::MakeSize(new_atlas->GetTexture()->GetSize()),
669 {0, 0});
670 }
671
672 // ---------------------------------------------------------------------------
673 // Step 8b: Record the texture in the glyph atlas.
674 // ---------------------------------------------------------------------------
675
676 return new_atlas;
677 }
678
679 } // namespace impeller
allocator.h
type
GLenum type
Definition: blit_command_gles.cc:151
buffer_view
BufferView buffer_view
Definition: blit_command_gles.cc:152
buffer_view.h
impeller::BackendCast< TypefaceSkia, Typeface >::Cast
static TypefaceSkia & Cast(Typeface &base)
Definition: backend_cast.h:13
impeller::Context
To do anything rendering related with Impeller, you need a context.
Definition: context.h:46
impeller::Context::CreateCommandBuffer
virtual std::shared_ptr< CommandBuffer > CreateCommandBuffer() const =0
Create a new command buffer. Command buffers can be used to encode graphics, blit,...
impeller::Context::GetCapabilities
virtual const std::shared_ptr< const Capabilities > & GetCapabilities() const =0
Get the capabilities of Impeller context. All optionally supported feature of the platform,...
impeller::Context::GetBackendType
virtual BackendType GetBackendType() const =0
Get the graphics backend of an Impeller context.
impeller::Context::GetResourceAllocator
virtual std::shared_ptr< Allocator > GetResourceAllocator() const =0
Returns the allocator used to create textures and buffers on the device.
impeller::Context::BackendType::kOpenGLES
@ kOpenGLES
impeller::Context::EnqueueCommandBuffer
virtual bool EnqueueCommandBuffer(std::shared_ptr< CommandBuffer > command_buffer)
Enqueue command_buffer for submission by the end of the frame.
Definition: context.cc:19
impeller::Font::GetTypeface
const std::shared_ptr< Typeface > & GetTypeface() const
The typeface whose intrinsic properties this font modifies.
Definition: font.cc:27
impeller::Font::GetMetrics
const Metrics & GetMetrics() const
Definition: font.cc:45
impeller::GlyphAtlas
A texture containing the bitmap representation of glyphs in different fonts along with the ability to...
Definition: glyph_atlas.h:70
impeller::GlyphAtlas::FindFontGlyphBounds
std::optional< FrameBounds > FindFontGlyphBounds(const FontGlyphPair &pair) const
Find the location of a specific font-glyph pair in the atlas.
Definition: glyph_atlas.cc:87
impeller::GlyphAtlas::Type
Type
Describes how the glyphs are represented in the texture.
Definition: glyph_atlas.h:74
impeller::GlyphAtlas::Type::kAlphaBitmap
@ kAlphaBitmap
impeller::GlyphAtlas::Type::kColorBitmap
@ kColorBitmap
impeller::GlyphAtlas::GetType
Type GetType() const
Describes how the glyphs are represented in the texture.
Definition: glyph_atlas.cc:58
impeller::GlyphAtlas::GetTexture
const std::shared_ptr< Texture > & GetTexture() const
Get the texture for the glyph atlas.
Definition: glyph_atlas.cc:62
impeller::HostBuffer
Definition: host_buffer.h:28
impeller::HostBuffer::Emplace
BufferView Emplace(const BufferType &buffer, size_t alignment=0)
Emplace non-uniform data (like contiguous vertices) onto the host buffer.
Definition: host_buffer.h:93
impeller::RectanglePacker::Factory
static std::shared_ptr< RectanglePacker > Factory(int width, int height)
Return an empty packer with area specified by width and height.
Definition: rectangle_packer.cc:175
impeller::TextFrame::ComputeSubpixelPosition
static Point ComputeSubpixelPosition(const TextRun::GlyphPosition &glyph_position, AxisAlignment alignment, const Matrix &transform)
Definition: text_frame.cc:69
impeller::TextFrame::RoundScaledFontSize
static Scalar RoundScaledFontSize(Scalar scale)
Definition: text_frame.cc:41
impeller::TypefaceSkia::GetSkiaTypeface
const sk_sp< SkTypeface > & GetSkiaTypeface() const
Definition: typeface_skia.cc:31
impeller::TypographerContext::IsValid
virtual bool IsValid() const
Definition: typographer_context.cc:17
impeller::TypographerContextSkia::TypographerContextSkia
TypographerContextSkia()
impeller::TypographerContextSkia::~TypographerContextSkia
~TypographerContextSkia() override
impeller::TypographerContextSkia::CreateGlyphAtlasContext
std::shared_ptr< GlyphAtlasContext > CreateGlyphAtlasContext(GlyphAtlas::Type type) const override
Definition: typographer_context_skia.cc:86
impeller::TypographerContextSkia::Make
static std::shared_ptr< TypographerContext > Make()
Definition: typographer_context_skia.cc:77
impeller::TypographerContextSkia::CreateGlyphAtlas
std::shared_ptr< GlyphAtlas > CreateGlyphAtlas(Context &context, GlyphAtlas::Type type, HostBuffer &host_buffer, const std::shared_ptr< GlyphAtlasContext > &atlas_context, const std::vector< std::shared_ptr< TextFrame >> &text_frames) const override
Definition: typographer_context_skia.cc:488
command_buffer.h
formats.h
font_glyph_pair.h
glyph.h
glyph_atlas.h
host_buffer.h
impeller
Definition: allocation.cc:12
impeller::BytesPerPixelForPixelFormat
constexpr size_t BytesPerPixelForPixelFormat(PixelFormat format)
Definition: formats.h:466
impeller::Join
Join
Definition: path.h:25
impeller::Join::kRound
@ kRound
impeller::Join::kMiter
@ kMiter
impeller::Join::kBevel
@ kBevel
impeller::ComputeGlyphSize
static Rect ComputeGlyphSize(const SkFont &font, const SubpixelGlyph &glyph, Scalar scale)
Definition: typographer_context_skia.cc:387
impeller::Scalar
float Scalar
Definition: scalar.h:18
impeller::PairsFitInAtlasOfSize
static size_t PairsFitInAtlasOfSize(const std::vector< FontGlyphPair > &pairs, const ISize &atlas_size, std::vector< Rect > &glyph_positions, const std::vector< Rect > &glyph_sizes, int64_t height_adjustment, const std::shared_ptr< RectanglePacker > &rect_packer, size_t start_index)
Definition: typographer_context_skia.cc:137
impeller::DrawGlyph
static void DrawGlyph(SkCanvas *canvas, const SkPoint position, const ScaledFont &scaled_font, const SubpixelGlyph &glyph, const Rect &scaled_bounds, const std::optional< GlyphProperties > &prop, bool has_color)
Definition: typographer_context_skia.cc:208
impeller::GetImageInfo
static SkImageInfo GetImageInfo(const GlyphAtlas &atlas, Size size)
Definition: typographer_context_skia.cc:90
impeller::BulkUpdateAtlasBitmap
static bool BulkUpdateAtlasBitmap(const GlyphAtlas &atlas, std::shared_ptr< BlitPass > &blit_pass, HostBuffer &host_buffer, const std::shared_ptr< Texture > &texture, const std::vector< FontGlyphPair > &new_pairs, size_t start_index, size_t end_index)
Batch render to a single surface.
Definition: typographer_context_skia.cc:255
impeller::Point
TPoint< Scalar > Point
Definition: point.h:327
impeller::StorageMode::kDevicePrivate
@ kDevicePrivate
impeller::Cap
Cap
Definition: path.h:19
impeller::Cap::kRound
@ kRound
impeller::Cap::kButt
@ kButt
impeller::Cap::kSquare
@ kSquare
impeller::AppendToExistingAtlas
static size_t AppendToExistingAtlas(const std::shared_ptr< GlyphAtlas > &atlas, const std::vector< FontGlyphPair > &extra_pairs, std::vector< Rect > &glyph_positions, const std::vector< Rect > &glyph_sizes, ISize atlas_size, int64_t height_adjustment, const std::shared_ptr< RectanglePacker > &rect_packer)
Definition: typographer_context_skia.cc:103
impeller::ComputeNextAtlasSize
static ISize ComputeNextAtlasSize(const std::shared_ptr< GlyphAtlasContext > &atlas_context, const std::vector< FontGlyphPair > &extra_pairs, std::vector< Rect > &glyph_positions, const std::vector< Rect > &glyph_sizes, size_t glyph_index_start, int64_t max_texture_height)
Definition: typographer_context_skia.cc:167
impeller::PixelFormat::kR8G8B8A8UNormInt
@ kR8G8B8A8UNormInt
impeller::Size
TSize< Scalar > Size
Definition: size.h:171
impeller::ISize
ISize64 ISize
Definition: size.h:174
impeller::UpdateAtlasBitmap
static bool UpdateAtlasBitmap(const GlyphAtlas &atlas, std::shared_ptr< BlitPass > &blit_pass, HostBuffer &host_buffer, const std::shared_ptr< Texture > &texture, const std::vector< FontGlyphPair > &new_pairs, size_t start_index, size_t end_index)
Definition: typographer_context_skia.cc:314
impeller::DefaultUniformAlignment
constexpr size_t DefaultUniformAlignment()
Definition: platform.h:14
impeller::kPadding
constexpr auto kPadding
Definition: typographer_context_skia.cc:49
impeller::TextureUsage::kShaderRead
@ kShaderRead
platform.h
rect.h
rectangle_packer.h
render_pass.h
render_target.h
size.h
scale
const Scalar scale
Definition: stroke_path_geometry.cc:316
impeller::BufferView
Definition: buffer_view.h:19
impeller::FontGlyphPair
A font along with a glyph in that font rendered at a particular scale and subpixel position.
Definition: font_glyph_pair.h:110
impeller::FontGlyphPair::glyph
SubpixelGlyph glyph
Definition: font_glyph_pair.h:114
impeller::FontGlyphPair::scaled_font
ScaledFont scaled_font
Definition: font_glyph_pair.h:113
impeller::Glyph::index
uint16_t index
Definition: glyph.h:22
impeller::IPoint16
Definition: rectangle_packer.h:16
impeller::IPoint16::y
int16_t y() const
Definition: rectangle_packer.h:18
impeller::IPoint16::x
int16_t x() const
Definition: rectangle_packer.h:17
impeller::ScaledFont
A font and a scale. Used as a key that represents a typeface within a glyph atlas.
Definition: font_glyph_pair.h:40
impeller::ScaledFont::font
Font font
Definition: font_glyph_pair.h:41
impeller::ScaledFont::scale
Scalar scale
Definition: font_glyph_pair.h:42
impeller::SubpixelGlyph
A glyph and its subpixel position.
Definition: font_glyph_pair.h:60
impeller::SubpixelGlyph::properties
std::optional< GlyphProperties > properties
Definition: font_glyph_pair.h:63
impeller::SubpixelGlyph::subpixel_offset
Point subpixel_offset
Definition: font_glyph_pair.h:62
impeller::SubpixelGlyph::glyph
Glyph glyph
Definition: font_glyph_pair.h:61
impeller::TPoint< Scalar >
impeller::TPoint::y
Type y
Definition: point.h:31
impeller::TPoint::x
Type x
Definition: point.h:30
impeller::TRect< Scalar >
impeller::TRect::GetTop
constexpr auto GetTop() const
Definition: rect.h:357
impeller::TRect::GetLeft
constexpr auto GetLeft() const
Definition: rect.h:355
impeller::TRect< Scalar >::MakeXYWH
constexpr static TRect MakeXYWH(Type x, Type y, Type width, Type height)
Definition: rect.h:136
impeller::TRect::MakeSize
constexpr static TRect MakeSize(const TSize< U > &size)
Definition: rect.h:150
impeller::TRect< Scalar >::MakeLTRB
constexpr static TRect MakeLTRB(Type left, Type top, Type right, Type bottom)
Definition: rect.h:129
impeller::TSize< Scalar >
impeller::TSize::Area
constexpr Type Area() const
Definition: size.h:120
impeller::TSize::height
Type height
Definition: size.h:29
impeller::TSize::width
Type width
Definition: size.h:28
impeller::TSize::Ceil
constexpr TSize Ceil() const
Definition: size.h:114
impeller::TSize::IsEmpty
constexpr bool IsEmpty() const
Returns true if either of the width or height are 0, negative, or NaN.
Definition: size.h:123
impeller::TextureDescriptor
A lightweight object that describes the attributes of a texture that can then used an allocator to cr...
Definition: texture_descriptor.h:38
impeller::TextureDescriptor::usage
TextureUsageMask usage
Definition: texture_descriptor.h:44
impeller::TextureDescriptor::size
ISize size
Definition: texture_descriptor.h:42
impeller::TextureDescriptor::storage_mode
StorageMode storage_mode
Definition: texture_descriptor.h:39
impeller::TextureDescriptor::format
PixelFormat format
Definition: texture_descriptor.h:41
texture_descriptor.h
data
std::shared_ptr< const fml::Mapping > data
Definition: texture_gles.cc:64
typeface_skia.h
typographer_context.h
typographer_context_skia.h
validation.h