fix(🤖): fix minor threading issue on Android (#2725)

The main goal of this PR is to refactor the platforms-specific Skia code in a way that will make the Graphite migration smoother.
It also fixes a minor issue on Android where one onscreen contextes could created in many threads instead of only once. This issue is most likely not affecting any users.

apps/paper/src/Examples/WebGPU/utils.ts

@@ -7,26 +7,26 @@ import {
   Skia,
 } from "@shopify/react-native-skia";
 import { Dimensions, PixelRatio } from "react-native";
-import { useSharedValue } from "react-native-reanimated";
+import { runOnUI, useSharedValue } from "react-native-reanimated";
 import { useCanvasEffect } from "react-native-wgpu";
 
+const pd = PixelRatio.get();
+
 export const useSkiaContext = () => {
   const context = useSharedValue<SkiaContext | null>(null);
   const ref = useCanvasEffect(() => {
     const nativeSurface = ref.current!.getNativeSurface();
-    context.value = Skia.Context(
-      nativeSurface.surface,
-      nativeSurface.width * pd,
-      nativeSurface.height * pd
-    );
+    const { surface, width, height } = nativeSurface;
+    runOnUI(() => {
+      context.value = Skia.Context(surface, width * pd, height * pd);
+    })();
   });
   return {
     context,
     ref,
   };
 };
 
-const pd = PixelRatio.get();
 const { width, height } = Dimensions.get("window");
 const center = { x: width / 2, y: height / 2 };
 const R = width / 4;
@@ -44,6 +44,9 @@ p2.setColor(Skia.Color(c2));
 export const drawBreatheDemo = (ctx: SkiaContext, progress: number) => {
   "worklet";
   const surface = ctx.getSurface();
+  if (surface === null) {
+    throw new Error("No surface available");
+  }
   const canvas = surface.getCanvas();
   canvas.clear(Skia.Color("rgb(36, 43, 56)"));
   canvas.save();

packages/skia/android/cpp/rnskia-android/OpenGLContext.h

@@ -0,0 +1,40 @@
+#pragma once
+
+#include "SkiaOpenGLSurfaceFactory.h"
+#include "WindowContext.h"
+
+#include "include/core/SkSurface.h"
+
+class OpenGLContext {
+public:
+  OpenGLContext(const OpenGLContext &) = delete;
+  OpenGLContext &operator=(const OpenGLContext &) = delete;
+
+  static OpenGLContext &getInstance() {
+    static thread_local OpenGLContext instance;
+    return instance;
+  }
+
+  sk_sp<SkSurface> MakeOffscreen(int width, int height) {
+    return RNSkia::SkiaOpenGLSurfaceFactory::makeOffscreenSurface(
+        &_context, width, height);
+  }
+
+  sk_sp<SkImage> MakeImageFromBuffer(void *buffer) {
+    return RNSkia::SkiaOpenGLSurfaceFactory::makeImageFromHardwareBuffer(
+        &_context, buffer);
+  }
+
+  std::unique_ptr<RNSkia::WindowContext> MakeWindow(ANativeWindow *window,
+                                                    int width, int height) {
+    return RNSkia::SkiaOpenGLSurfaceFactory::makeContext(&_context, window,
+                                                         width, height);
+  }
+
+private:
+  RNSkia::SkiaOpenGLContext _context;
+
+  OpenGLContext() {
+    RNSkia::SkiaOpenGLHelper::createSkiaDirectContextIfNecessary(&_context);
+  }
+};

packages/skia/android/cpp/rnskia-android/RNSkAndroidPlatformContext.h

@@ -11,9 +11,9 @@
 
 #include "AHardwareBufferUtils.h"
 #include "JniPlatformContext.h"
+#include "OpenGLContext.h"
 #include "RNSkAndroidVideo.h"
 #include "RNSkPlatformContext.h"
-#include "SkiaOpenGLSurfaceFactory.h"
 
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdocumentation"
@@ -51,17 +51,17 @@ class RNSkAndroidPlatformContext : public RNSkPlatformContext {
   }
 
   sk_sp<SkSurface> makeOffscreenSurface(int width, int height) override {
-    return SkiaOpenGLSurfaceFactory::makeOffscreenSurface(width, height);
+    return OpenGLContext::getInstance().MakeOffscreen(width, height);
   }
 
-  std::shared_ptr<SkiaContext>
+  std::shared_ptr<WindowContext>
   makeContextFromNativeSurface(void *surface, int width, int height) override {
-    return SkiaOpenGLSurfaceFactory::makeContext(
+    return OpenGLContext::getInstance().MakeWindow(
         reinterpret_cast<ANativeWindow *>(surface), width, height);
   }
 
   sk_sp<SkImage> makeImageFromNativeBuffer(void *buffer) override {
-    return SkiaOpenGLSurfaceFactory::makeImageFromHardwareBuffer(buffer);
+    return OpenGLContext::getInstance().MakeImageFromBuffer(buffer);
   }
 
   std::shared_ptr<RNSkVideo> createVideo(const std::string &url) override {

packages/skia/android/cpp/rnskia-android/RNSkAndroidVideo.cpp

@@ -13,8 +13,8 @@
 
 #pragma clang diagnostic pop
 
+#include "OpenGLContext.h"
 #include "RNSkAndroidVideo.h"
-#include "SkiaOpenGLSurfaceFactory.h"
 
 namespace RNSkia {
 
@@ -52,7 +52,7 @@ sk_sp<SkImage> RNSkAndroidVideo::nextImage(double *timeStamp) {
   // Convert jobject to AHardwareBuffer
   AHardwareBuffer *buffer =
       AHardwareBuffer_fromHardwareBuffer(env, jHardwareBuffer);
-  return SkiaOpenGLSurfaceFactory::makeImageFromHardwareBuffer(buffer);
+  return OpenGLContext::getInstance().MakeImageFromBuffer(buffer);
 #else
   return nullptr;
 #endif

packages/skia/android/cpp/rnskia-android/RNSkOpenGLCanvasProvider.cpp

@@ -2,6 +2,8 @@
 
 #include <memory>
 
+#include "OpenGLContext.h"
+
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdocumentation"
 
@@ -20,33 +22,41 @@ RNSkOpenGLCanvasProvider::RNSkOpenGLCanvasProvider(
 RNSkOpenGLCanvasProvider::~RNSkOpenGLCanvasProvider() {}
 
 float RNSkOpenGLCanvasProvider::getScaledWidth() {
-  return _surfaceHolder ? _surfaceHolder->getWidth() : 0;
+  if (_surfaceHolder) {
+    return static_cast<float>(_surfaceHolder->getWidth());
+  }
+  return 0;
 }
 
 float RNSkOpenGLCanvasProvider::getScaledHeight() {
-  return _surfaceHolder ? _surfaceHolder->getHeight() : 0;
+  if (_surfaceHolder) {
+    return static_cast<float>(_surfaceHolder->getHeight());
+  }
+  return 0;
 }
 
 bool RNSkOpenGLCanvasProvider::renderToCanvas(
     const std::function<void(SkCanvas *)> &cb) {
-
+  JNIEnv *env = facebook::jni::Environment::current();
   if (_surfaceHolder != nullptr && cb != nullptr) {
     // Get the surface
     auto surface = _surfaceHolder->getSurface();
-    if (surface) {
-
-      // Ensure we are ready to render
-      if (!_surfaceHolder->makeCurrent()) {
-        return false;
-      }
-      _surfaceHolder->updateTexImage();
+    env->CallVoidMethod(_jSurfaceTexture, _updateTexImageMethod);
 
+    // Check for exceptions
+    if (env->ExceptionCheck()) {
+      RNSkLogger::logToConsole("updateAndRelease() failed. The exception above "
+                               "can safely be ignored");
+      env->ExceptionClear();
+    }
+    if (surface) {
       // Draw into canvas using callback
       cb(surface->getCanvas());
 
       // Swap buffers and show on screen
-      return _surfaceHolder->present();
+      _surfaceHolder->present();
 
+      return true;
     } else {
       // the render context did not provide a surface
       return false;
@@ -56,11 +66,31 @@ bool RNSkOpenGLCanvasProvider::renderToCanvas(
   return false;
 }
 
-void RNSkOpenGLCanvasProvider::surfaceAvailable(jobject surface, int width,
-                                                int height) {
+void RNSkOpenGLCanvasProvider::surfaceAvailable(jobject jSurfaceTexture,
+                                                int width, int height) {
   // Create renderer!
+  JNIEnv *env = facebook::jni::Environment::current();
+
+  _jSurfaceTexture = env->NewGlobalRef(jSurfaceTexture);
+  jclass surfaceClass = env->FindClass("android/view/Surface");
+  jmethodID surfaceConstructor = env->GetMethodID(
+      surfaceClass, "<init>", "(Landroid/graphics/SurfaceTexture;)V");
+  // Create a new Surface instance
+  jobject jSurface =
+      env->NewObject(surfaceClass, surfaceConstructor, jSurfaceTexture);
+
+  jclass surfaceTextureClass = env->GetObjectClass(_jSurfaceTexture);
+  _updateTexImageMethod =
+      env->GetMethodID(surfaceTextureClass, "updateTexImage", "()V");
+
+  // Acquire the native window from the Surface
+  auto window = ANativeWindow_fromSurface(env, jSurface);
+  // Clean up local references
+  env->DeleteLocalRef(jSurface);
+  env->DeleteLocalRef(surfaceClass);
+  env->DeleteLocalRef(surfaceTextureClass);
   _surfaceHolder =
-      SkiaOpenGLSurfaceFactory::makeWindowedSurface(surface, width, height);
+      OpenGLContext::getInstance().MakeWindow(window, width, height);
 
   // Post redraw request to ensure we paint in the next draw cycle.
   _requestRedraw();
@@ -69,6 +99,11 @@ void RNSkOpenGLCanvasProvider::surfaceDestroyed() {
   // destroy the renderer (a unique pointer so the dtor will be called
   // immediately.)
   _surfaceHolder = nullptr;
+  if (_jSurfaceTexture) {
+    JNIEnv *env = facebook::jni::Environment::current();
+    env->DeleteGlobalRef(_jSurfaceTexture);
+    _jSurfaceTexture = nullptr;
+  }
 }
 
 void RNSkOpenGLCanvasProvider::surfaceSizeChanged(int width, int height) {

packages/skia/android/cpp/rnskia-android/RNSkOpenGLCanvasProvider.h

@@ -5,7 +5,8 @@
 #include <memory>
 
 #include "RNSkView.h"
-#include "SkiaOpenGLSurfaceFactory.h"
+#include "WindowContext.h"
+
 #include <android/native_window.h>
 
 namespace RNSkia {
@@ -33,7 +34,9 @@ class RNSkOpenGLCanvasProvider
   void surfaceSizeChanged(int width, int height);
 
 private:
-  std::unique_ptr<WindowSurfaceHolder> _surfaceHolder = nullptr;
+  std::unique_ptr<WindowContext> _surfaceHolder = nullptr;
   std::shared_ptr<RNSkPlatformContext> _platformContext;
+  jobject _jSurfaceTexture = nullptr;
+  jmethodID _updateTexImageMethod = nullptr;
 };
 } // namespace RNSkia