[Tizen] Re-implemented render external texture gl for impeller to avoid change FlutterOpenGLTexture and use deprecated api #23

xiaowei-guan · 2026-01-12T09:36:15Z

We have supported render external texture gl for Impeller
flutter-tizen/engine#368
But this PR has two issues:

It modify FlutterOpenGLTexture, it added additional variables, not a good design.

  /// The pixel data buffer.
  const uint8_t* buffer;
  /// The size of pixel buffer.
  size_t buffer_size;
  /// Callback invoked that the gpu surface texture start binding.
  BoolCallback bind_callback;
  /// The type of the texture.
  FlutterGLImpellerTextureType impeller_texture_type;

It uses Deprecated API

  // Deprecated: use BlitPass::AddCopy instead.
  [[nodiscard]] bool SetContents(const uint8_t* contents,
                                 size_t length,
                                 size_t slice = 0,
                                 bool is_opaque = false);

So I tried to revert offical PR to render external gl for impeller
flutter/engine#56277
But this PR doesn't work on Tizen platform, I think This PR may not have been verified.
To avoid change FlutterOpenGLTexture and use deprecated api, so I re-implemented render external texture gl for impeller based on this offical PR.
Fix flutter-tizen/embedder#131

…id change FlutterOpenGLTexture and use deprecated api

JSUYA

Sorry for the late review.
I left a comment. Please check it.

JSUYA · 2026-01-23T08:25:37Z

engine/src/flutter/shell/platform/embedder/embedder_external_texture_gl.cc

+  auto it = impeller_gl_textures_.find(texture->name);
+  if (it != impeller_gl_textures_.end()) {
+    image = it->second;
+  } else {
+    impeller::TextureDescriptor desc;
+    desc.size = impeller::ISize(texture->width, texture->height);
+    desc.storage_mode = impeller::StorageMode::kDevicePrivate;
+    desc.format = impeller::PixelFormat::kR8G8B8A8UNormInt;
+    if (texture->target == GL_TEXTURE_EXTERNAL_OES) {
+      desc.type = impeller::TextureType::kTextureExternalOES;
+    } else {
+      desc.type = impeller::TextureType::kTexture2D;
    }
-    return nullptr;
-  }
-
-  if (!image) {
-    // In case Skia rejects the image, call the release proc so that
-    // embedders can perform collection of intermediates.
-    if (texture->destruction_callback) {
-      texture->destruction_callback(texture->user_data);
+    impeller::ContextGLES& context =
+        impeller::ContextGLES::Cast(*aiks_context->GetContext());
+    impeller::HandleGLES handle = context.GetReactor()->CreateHandle(
+        impeller::HandleType::kTexture, texture->name);
+
+    image =
+        impeller::TextureGLES::WrapTexture(context.GetReactor(), desc, handle);
+    if (!image) {
+      // In case Skia rejects the image, call the release proc so that
+      // embedders can perform collection of intermediates.
+      if (texture->destruction_callback) {
+        texture->destruction_callback(texture->user_data);
+      }
+      FML_LOG(ERROR) << "Could not create external texture";
+      return nullptr;
    }
-    FML_LOG(ERROR) << "Could not create external texture";
-    return nullptr;
-  }

-  if (texture->destruction_callback) {
-    texture->destruction_callback(texture->user_data);
-  }
+    image->SetCoordinateSystem(
+        impeller::TextureCoordinateSystem::kUploadFromHost);

-  return impeller::DlImageImpeller::Make(image);
-}
-
-sk_sp<DlImage> EmbedderExternalTextureGL::ResolveTextureImpellerSurface(
-    impeller::AiksContext* aiks_context,
-    std::unique_ptr<FlutterOpenGLTexture> texture) {
-  impeller::TextureDescriptor desc;
-  desc.size = impeller::ISize(texture->width, texture->height);
-  desc.storage_mode = impeller::StorageMode::kDevicePrivate;
-  desc.format = impeller::PixelFormat::kR8G8B8A8UNormInt;
-  desc.type = impeller::TextureType::kTextureExternalOES;
-  impeller::ContextGLES& context =
-      impeller::ContextGLES::Cast(*aiks_context->GetContext());
-  std::shared_ptr<impeller::TextureGLES> image =
-      std::make_shared<impeller::TextureGLES>(context.GetReactor(), desc);
-  image->MarkContentsInitialized();
-  image->SetCoordinateSystem(
-      impeller::TextureCoordinateSystem::kUploadFromHost);
-  if (!image->Bind()) {
-    if (texture->destruction_callback) {
-      texture->destruction_callback(texture->user_data);
-    }
-    FML_LOG(ERROR) << "Could not bind texture";
-    return nullptr;
-  }
-
-  if (!image) {
-    // In case Skia rejects the image, call the release proc so that
-    // embedders can perform collection of intermediates.
-    if (texture->destruction_callback) {
-      texture->destruction_callback(texture->user_data);
-    }
-    FML_LOG(ERROR) << "Could not create external texture";
-    return nullptr;
-  }
-
-  if (!texture->bind_callback(texture->user_data)) {
-    if (texture->destruction_callback) {
-      texture->destruction_callback(texture->user_data);
+    if (texture->destruction_callback &&
+        !context.GetReactor()->RegisterCleanupCallback(
+            handle,
+            [callback = texture->destruction_callback,
+             user_data = texture->user_data]() { callback(user_data); })) {
+      FML_LOG(ERROR) << "Could not register destruction callback";
+      return nullptr;
    }
-    return nullptr;
-  }
-
-  if (texture->destruction_callback) {
-    texture->destruction_callback(texture->user_data);
+    impeller_gl_textures_[texture->name] = image;


@@ -138,6 +140,11 @@ sk_sp<DlImage> EmbedderExternalTextureGL::ResolveTextureImpeller( return nullptr; } + auto it = impeller_gl_textures_.find(texture->name); + if (it != impeller_gl_textures_.end()) { + std::shared_ptr<impeller::TextureGLES> image = it->second; + return impeller::DlImageImpeller::Make(image); + } + impeller::TextureDescriptor desc; desc.size = impeller::ISize(texture->width, texture->height); @@ -166,6 +173,8 @@ sk_sp<DlImage> EmbedderExternalTextureGL::ResolveTextureImpeller( return nullptr; } + impeller_gl_textures_[texture->name] = image; + return impeller::DlImageImpeller::Make(image); }

If I understand correctly...
If you want to reuse a texture, we can minimize code diffs by immediately returning the image.
However, I have a few questions.

When will the images(textures) remaining in impeller_gl_textures_ be removed ?

Will calling impeller_gl_textures_.clear in OnTextureUnregistered() cause problems?

Will this cause problems if the texture size changes?

When will the images(textures) remaining in impeller_gl_textures_ be removed ?
==> Replace map with LRU cache, why use LRU cache

If a FlutterOpenGLTexture has the same handle, we cannot immediately destroy impeller::TextureGLES, otherwise it will cause a black screen issue.

If there are multiple different FlutterOpenGLTextures, excessive handles should be destroyed to avoid out-of-memory errors. This case does not exist on the Tizen platform.

Will calling impeller_gl_textures_.clear in OnTextureUnregistered() cause problems?
==>LRU cache will clear data when OnTextureUnregistered called.
Will this cause problems if the texture size changes?
==>LRU cache will update texture when texture size change.

JSUYA · 2026-01-29T08:44:36Z

engine/src/flutter/shell/platform/embedder/embedder_external_texture_gl.cc

+  size_t i = 1u;
+  for (; i < kTextureMaxSize; i++) {
+    if (textures_[i].key == data.key) {
+      break;
+    }
+  }
+  for (auto j = i; j > 0; j--) {
+    textures_[j] = textures_[j - 1];


If the key is not found, textures_[6] will be accessed because i becomes kTextureMaxSize(6). If there is no scenario where the key is not found, there is no problem, but I recommend adding a check code(like RemoveTexture) to prevent a crash.

Yes,you are right. add a check code.

JSUYA · 2026-01-29T08:58:56Z

engine/src/flutter/shell/platform/embedder/embedder_external_texture_gl.cc

+      auto result = textures_[i].value;
+      UpdateTexture(Data{.key = key_value,
+                         .value = result,


Do we need result? I think you can just pass textures_[i].value
.value = textures_[i].value,

JSUYA · 2026-01-29T09:05:00Z

engine/src/flutter/shell/platform/embedder/embedder_external_texture_gl.cc

+  if (!updated_image) {
+    textures_[0] = data;
+  }
+  UpdateTexture(data);


um... I may be misunderstanding, but you are looking for key and then looking for it again in UpdateTexture(). Shouldn't you just pass the idx?

This is because we need to consider another scenario: if the Texture's size changes, the corresponding width and height also need to be updated.
https://github.com/flutter-tizen/flutter/pull/23/changes#diff-c2fbc9e4861def16024ee77dc86670de2ab09742bdfd1cf83364b891df991c60R285-R289

if (texture_data.has_value() && size_change) { std::shared_ptr<impeller::TextureGLES> old_gles_texture = texture_data.value().value; old_gles_texture->Leak(); std::shared_ptr<impeller::TextureGLES> new_gles_texture = CreateTextureGLES(aiks_context, texture.get()); if (new_gles_texture) { texture_lru_.UpdateTexture(TextureLRU::Data{.key = texture->name, .value = new_gles_texture, .width = texture->width, .height = texture->height});

JSUYA · 2026-01-29T09:14:23Z

engine/src/flutter/shell/platform/embedder/embedder_external_texture_gl.h

+ public:
+  struct Data {
+    GLuint key = 0u;
+    std::shared_ptr<impeller::TextureGLES> value;


How about texture instead of value? I think it would be good more readability.

xiaowei-guan requested review from JSUYA, gin7773 and seungsoo47 January 12, 2026 09:37

xiaowei-guan mentioned this pull request Jan 12, 2026

Revert impeller render texture code for gles flutter-tizen/embedder#140

Open

[Tizen] Re-implemented render external texture gl for impeller to avo…

8f298e4

…id change FlutterOpenGLTexture and use deprecated api

JSUYA reviewed Jan 23, 2026

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Replace map with LRU cache

c596644

JSUYA reviewed Jan 29, 2026

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xiaowei-guan added 2 commits January 29, 2026 22:56

Update Add and Update method

449ff0b

Fix code review issues

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[Tizen] Re-implemented render external texture gl for impeller to avoid change FlutterOpenGLTexture and use deprecated api #23

[Tizen] Re-implemented render external texture gl for impeller to avoid change FlutterOpenGLTexture and use deprecated api #23

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[Tizen] Re-implemented render external texture gl for impeller to avoid change FlutterOpenGLTexture and use deprecated api #23

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