Use a host interface for CustomLayer instead of function pointers (#1…

…1553)

Use a host interface for CustomLayer instead of function pointers

Co-authored-by: Julian Rex <julian.rex@mapbox.com>

include/mbgl/renderer/renderer_backend.hpp

@@ -47,10 +47,10 @@ class RendererBackend {
     // as a matched pair, exclusively through BackendScope, in two situations:
     //
     //   1. When releasing GL resources during Renderer destruction
-    //      (Including calling CustomLayerDeinitializeFunction during RenderCustomLayer destruction)
+    //      (Including calling CustomLayerHost::deinitialize during RenderCustomLayer destruction)
     //   2. When renderering through Renderer::render()
-    //      (Including calling CustomLayerDeinitializeFunction for newly added custom layers and
-    //       CustomLayerDeinitializeFunction on layer removal)
+    //      (Including calling CustomLayerHost::initialize for newly added custom layers and
+    //       CustomLayerHost::deinitialize on layer removal)
     virtual void activate() = 0;
     virtual void deactivate() = 0;
 

include/mbgl/style/layers/custom_layer.hpp

@@ -6,16 +6,7 @@ namespace mbgl {
 namespace style {
 
 /**
- * Initialize any GL state needed by the custom layer. This method is called once, from the
- * main thread, at a point when the GL context is active but before rendering for the first
- * time.
- *
- * Resources that are acquired in this method must be released in the UninitializeFunction.
- */
-using CustomLayerInitializeFunction = void (*)(void* context);
-
-/**
- * Parameters that define the current camera position for a CustomLayerRenderFunction.
+ * Parameters that define the current camera position for a `CustomLayerHost::render()` function.
  */
 struct CustomLayerRenderParameters {
     double width;
@@ -28,46 +19,49 @@ struct CustomLayerRenderParameters {
     double fieldOfView;
 };
 
-/**
- * Render the layer. This method is called once per frame. The implementation should not make
- * any assumptions about the GL state (other than that the correct context is active). It may
- * make changes to the state, and is not required to reset values such as the depth mask, stencil
- * mask, and corresponding test flags to their original values.
- * Make sure that you are drawing your fragments with a z value of 1 to take advantage of the
- * opaque fragment culling in case there are opaque layers above your custom layer.
- */
-using CustomLayerRenderFunction = void (*)(void* context, const CustomLayerRenderParameters&);
-
-/**
- * Called when the system has destroyed the underlying GL context. The
- * `CustomLayerDeinitializeFunction` will not be called in this case, however
- * `CustomLayerInitializeFunction` will be called instead to prepare for a new render.
- *
- */
-using CustomLayerContextLostFunction = void (*)(void* context);
-
-/**
- * Destroy any GL state needed by the custom layer, and deallocate context, if necessary. This
- * method is called once, from the main thread, at a point when the GL context is active.
- *
- * Note that it may be called even when the InitializeFunction has not been called.
- */
-using CustomLayerDeinitializeFunction = void (*)(void* context);
+class CustomLayerHost {
+public:
+    virtual ~CustomLayerHost() = default;
+    /**
+     * Initialize any GL state needed by the custom layer. This method is called once, from the
+     * main thread, at a point when the GL context is active but before rendering for the first
+     * time.
+     *
+     * Resources that are acquired in this method must be released in the `deinitialize` function.
+     */
+    virtual void initialize() = 0;
+
+    /**
+     * Render the layer. This method is called once per frame. The implementation should not make
+     * any assumptions about the GL state (other than that the correct context is active). It may
+     * make changes to the state, and is not required to reset values such as the depth mask, stencil
+     * mask, and corresponding test flags to their original values.
+     * Make sure that you are drawing your fragments with a z value of 1 to take advantage of the
+     * opaque fragment culling in case there are opaque layers above your custom layer.
+     */
+    virtual void render(const CustomLayerRenderParameters&) = 0;
+
+    /**
+     * Called when the system has destroyed the underlying GL context. The
+     * `deinitialize` function will not be called in this case, however
+     * `initialize` will be called instead to prepare for a new render.
+     *
+     */
+    virtual void contextLost() = 0;
+
+    /**
+     * Destroy any GL state needed by the custom layer, and deallocate context, if necessary. This
+     * method is called once, from the main thread, at a point when the GL context is active.
+     *
+     * Note that it may be called even when the `initialize` function has not been called.
+     */
+    virtual void deinitialize() = 0;
+};
 
 class CustomLayer : public Layer {
 public:
     CustomLayer(const std::string& id,
-                CustomLayerInitializeFunction,
-                CustomLayerRenderFunction,
-                CustomLayerContextLostFunction,
-                CustomLayerDeinitializeFunction,
-                void* context);
-
-    CustomLayer(const std::string& id,
-                CustomLayerInitializeFunction,
-                CustomLayerRenderFunction,
-                CustomLayerDeinitializeFunction,
-                void* context);
+                std::unique_ptr<CustomLayerHost> host);
 
     ~CustomLayer() final;
 

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/CustomLayer.java

@@ -9,20 +9,8 @@
 public class CustomLayer extends Layer {
 
   public CustomLayer(String id,
-                     long context,
-                     long initializeFunction,
-                     long renderFunction,
-                     long deinitializeFunction) {
-    this(id, context, initializeFunction, renderFunction, 0L, deinitializeFunction);
-  }
-
-  public CustomLayer(String id,
-                     long context,
-                     long initializeFunction,
-                     long renderFunction,
-                     long contextLostFunction,
-                     long deinitializeFunction) {
-    initialize(id, initializeFunction, renderFunction, contextLostFunction, deinitializeFunction, context);
+                     long host) {
+    initialize(id, host);
   }
 
   public CustomLayer(long nativePtr) {
@@ -33,9 +21,7 @@ public void update() {
     nativeUpdate();
   }
 
-  protected native void initialize(String id, long initializeFunction, long renderFunction,
-                                   long contextLostFunction, long deinitializeFunction,
-                                   long context);
+  protected native void initialize(String id, long host);
 
   protected native void nativeUpdate();
 

platform/android/MapboxGLAndroidSDKTestApp/src/main/java/com/mapbox/mapboxsdk/testapp/activity/customlayer/CustomLayerActivity.java

@@ -58,11 +58,7 @@ private void swapCustomLayer() {
       fab.setImageResource(R.drawable.ic_layers);
     } else {
       customLayer = new CustomLayer("custom",
-        ExampleCustomLayer.createContext(),
-        ExampleCustomLayer.InitializeFunction,
-        ExampleCustomLayer.RenderFunction,
-        ExampleCustomLayer.ContextLostFunction, // Optional
-        ExampleCustomLayer.DeinitializeFunction);
+        ExampleCustomLayer.createContext());
       mapboxMap.addLayerBelow(customLayer, "building");
       fab.setImageResource(R.drawable.ic_layers_clear);
     }

platform/android/src/example_custom_layer.cpp

@@ -112,18 +112,9 @@ void checkCompileStatus(GLuint shader) {
 static const GLchar * vertexShaderSource = "attribute vec2 a_pos; void main() { gl_Position = vec4(a_pos, 0, 1); }";
 static const GLchar * fragmentShaderSource = "uniform highp vec4 fill_color; void main() { gl_FragColor = fill_color; }";
 
-class ExampleCustomLayer {
+class ExampleCustomLayer: mbgl::style::CustomLayerHost {
 public:
     ~ExampleCustomLayer() {
-        __android_log_write(ANDROID_LOG_INFO, LOG_TAG, "~ExampleCustomLayer");
-        if (program) {
-            glDeleteBuffers(1, &buffer);
-            glDetachShader(program, vertexShader);
-            glDetachShader(program, fragmentShader);
-            glDeleteShader(vertexShader);
-            glDeleteShader(fragmentShader);
-            glDeleteProgram(program);
-        }
     }
 
     void initialize() {
@@ -158,8 +149,15 @@ class ExampleCustomLayer {
         GL_CHECK_ERROR(glBufferData(GL_ARRAY_BUFFER, 8 * sizeof(GLfloat), background, GL_STATIC_DRAW));
     }
 
-    void render() {
+    void render(const mbgl::style::CustomLayerRenderParameters&) {
         __android_log_write(ANDROID_LOG_INFO, LOG_TAG, "Render");
+        glUseProgram(program);
+        glBindBuffer(GL_ARRAY_BUFFER, buffer);
+        glEnableVertexAttribArray(a_pos);
+        glVertexAttribPointer(a_pos, 2, GL_FLOAT, GL_FALSE, 0, NULL);
+        glDisable(GL_STENCIL_TEST);
+        glDisable(GL_DEPTH_TEST);
+        glUniform4fv(fill_color, 1, color);
 
         GL_CHECK_ERROR(glUseProgram(program));
         GL_CHECK_ERROR(glBindBuffer(GL_ARRAY_BUFFER, buffer));
@@ -172,6 +170,23 @@ class ExampleCustomLayer {
 
     }
 
+    void contextLost() {
+        __android_log_write(ANDROID_LOG_INFO, LOG_TAG, "ContextLost");
+        program = 0;
+    }
+
+    void deinitialize() {
+        __android_log_write(ANDROID_LOG_INFO, LOG_TAG, "DeInitialize");
+        if (program) {
+            glDeleteBuffers(1, &buffer);
+            glDetachShader(program, vertexShader);
+            glDetachShader(program, fragmentShader);
+            glDeleteShader(vertexShader);
+            glDeleteShader(fragmentShader);
+            glDeleteProgram(program);
+        }
+    }
+
     GLuint program = 0;
     GLuint vertexShader = 0;
     GLuint fragmentShader = 0;
@@ -186,7 +201,8 @@ GLfloat ExampleCustomLayer::color[] = { 0.0f, 1.0f, 0.0f, 1.0f };
 
 jlong JNICALL nativeCreateContext(JNIEnv*, jobject) {
     __android_log_write(ANDROID_LOG_INFO, LOG_TAG, "nativeCreateContext");
-     return reinterpret_cast<jlong>(new ExampleCustomLayer());
+    auto exampleCustomLayer = std::make_unique<ExampleCustomLayer>();
+    return reinterpret_cast<jlong>(exampleCustomLayer.release());
 }
 
 void JNICALL nativeSetColor(JNIEnv*, jobject, jfloat red, jfloat green, jfloat blue, jfloat alpha) {
@@ -197,25 +213,6 @@ void JNICALL nativeSetColor(JNIEnv*, jobject, jfloat red, jfloat green, jfloat b
     ExampleCustomLayer::color[3] = alpha;
 }
 
-void nativeInitialize(void *context) {
-    __android_log_write(ANDROID_LOG_INFO, LOG_TAG, "nativeInitialize");
-    reinterpret_cast<ExampleCustomLayer*>(context)->initialize();
-}
-
-void nativeRender(void *context, const mbgl::style::CustomLayerRenderParameters& /*parameters*/) {
-    __android_log_write(ANDROID_LOG_INFO, LOG_TAG, "nativeRender");
-    reinterpret_cast<ExampleCustomLayer*>(context)->render();
-}
-
-void nativeContextLost(void */*context*/) {
-    __android_log_write(ANDROID_LOG_INFO, LOG_TAG, "nativeContextLost");
-}
-
-void nativeDeinitialize(void *context) {
-    __android_log_write(ANDROID_LOG_INFO, LOG_TAG, "nativeDeinitialize");
-    delete reinterpret_cast<ExampleCustomLayer*>(context);
-}
-
 extern "C" JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *) {
     __android_log_write(ANDROID_LOG_INFO, LOG_TAG, "OnLoad");
 
@@ -234,22 +231,6 @@ extern "C" JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *) {
         return JNI_ERR;
     }
 
-    env->SetStaticLongField(customLayerClass,
-        env->GetStaticFieldID(customLayerClass, "InitializeFunction", "J"),
-        reinterpret_cast<jlong>(nativeInitialize));
-
-    env->SetStaticLongField(customLayerClass,
-        env->GetStaticFieldID(customLayerClass, "RenderFunction", "J"),
-        reinterpret_cast<jlong>(nativeRender));
-
-    env->SetStaticLongField(customLayerClass,
-        env->GetStaticFieldID(customLayerClass, "ContextLostFunction", "J"),
-        reinterpret_cast<jlong>(nativeContextLost));
-
-    env->SetStaticLongField(customLayerClass,
-        env->GetStaticFieldID(customLayerClass, "DeinitializeFunction", "J"),
-        reinterpret_cast<jlong>(nativeDeinitialize));
-
     return JNI_VERSION_1_6;
 }
 

platform/android/src/style/layers/custom_layer.cpp

@@ -7,14 +7,10 @@
 namespace mbgl {
 namespace android {
 
-    CustomLayer::CustomLayer(jni::JNIEnv& env, jni::String layerId, jni::jlong initializeFunction, jni::jlong renderFunction, jni::jlong contextLostFunction, jni::jlong deinitializeFunction, jni::jlong context)
+    CustomLayer::CustomLayer(jni::JNIEnv& env, jni::String layerId, jni::jlong host)
         : Layer(env, std::make_unique<mbgl::style::CustomLayer>(
                 jni::Make<std::string>(env, layerId),
-                reinterpret_cast<mbgl::style::CustomLayerInitializeFunction>(initializeFunction),
-                reinterpret_cast<mbgl::style::CustomLayerRenderFunction>(renderFunction),
-                reinterpret_cast<mbgl::style::CustomLayerContextLostFunction>(contextLostFunction),
-                reinterpret_cast<mbgl::style::CustomLayerDeinitializeFunction>(deinitializeFunction),
-                reinterpret_cast<void*>(context))
+                std::unique_ptr<mbgl::style::CustomLayerHost>(reinterpret_cast<mbgl::style::CustomLayerHost*>(host)))
                 ) {
     }
 
@@ -53,7 +49,7 @@ namespace android {
         // Register the peer
         jni::RegisterNativePeer<CustomLayer>(
             env, CustomLayer::javaClass, "nativePtr",
-            std::make_unique<CustomLayer, JNIEnv&, jni::String, jni::jlong, jni::jlong, jni::jlong, jni::jlong, jni::jlong>,
+            std::make_unique<CustomLayer, JNIEnv&, jni::String, jni::jlong>,
             "initialize",
             "finalize",
             METHOD(&CustomLayer::update, "nativeUpdate"));

platform/android/src/style/layers/custom_layer.hpp

@@ -16,7 +16,7 @@ class CustomLayer : public Layer {
 
     static void registerNative(jni::JNIEnv&);
 
-    CustomLayer(jni::JNIEnv&, jni::String, jni::jlong, jni::jlong, jni::jlong, jni::jlong, jni::jlong);
+    CustomLayer(jni::JNIEnv&, jni::String, jni::jlong);
 
     CustomLayer(mbgl::Map&, mbgl::style::CustomLayer&);