[android] SurfaceView compatible snapshot api

[android] #5587 - snapshot API on surface view, create Bitmap with a ByteBuffer

[android] #5587 - write bitmap to external storage

PreMultipliedImage approach

callback implemented

clean up code

introduce bitmap reuse

cleanup

renaming surfaceContent to bitmap

4 files changed, 48 insertions, 1 deletions

diff --git a/platform/android/src/jni.cpp b/platform/android/src/jni.cpp
index 5fc29f4c29..5907a0ff9d 100755
--- a/platform/android/src/jni.cpp
+++ b/platform/android/src/jni.cpp
@@ -45,6 +45,7 @@ std::string androidRelease;
 jni::jmethodID* onInvalidateId = nullptr;
 jni::jmethodID* onMapChangedId = nullptr;
 jni::jmethodID* onFpsChangedId = nullptr;
+jni::jmethodID* onSnapshotReadyId = nullptr;
 
 jni::jclass* latLngClass = nullptr;
 jni::jmethodID* latLngConstructorId = nullptr;
@@ -1172,6 +1173,13 @@ void nativeRemoveSource(JNIEnv *env, jni::jobject* obj, jlong nativeMapViewPtr,
     }
 }
 
+void nativeScheduleTakeSnapshot(JNIEnv *env, jni::jobject* obj, jlong nativeMapViewPtr) {
+    mbgl::Log::Error(mbgl::Event::JNI, "nativeRenderToOffscreen");
+    assert(nativeMapViewPtr != 0);
+    NativeMapView *nativeMapView = reinterpret_cast<NativeMapView *>(nativeMapViewPtr);
+    nativeMapView->scheduleTakeSnapshot();
+}
+
 // Offline calls begin
 
 jlong createDefaultFileSource(JNIEnv *env, jni::jobject* obj, jni::jstring* cachePath_, jni::jstring* assetRoot_, jlong maximumCacheSize) {
@@ -1706,6 +1714,7 @@ extern "C" JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved) {
     onInvalidateId = &jni::GetMethodID(env, nativeMapViewClass, "onInvalidate", "()V");
     onMapChangedId = &jni::GetMethodID(env, nativeMapViewClass, "onMapChanged", "(I)V");
     onFpsChangedId = &jni::GetMethodID(env, nativeMapViewClass, "onFpsChanged", "(D)V");
+    onSnapshotReadyId = &jni::GetMethodID(env, nativeMapViewClass, "onSnapshotReady","([B)V");
 
     #define MAKE_NATIVE_METHOD(name, sig) jni::MakeNativeMethod<decltype(name), name>( #name, sig )
 
@@ -1786,7 +1795,8 @@ extern "C" JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved) {
         MAKE_NATIVE_METHOD(nativeRemoveLayer, "(JLjava/lang/String;)V"),
         MAKE_NATIVE_METHOD(nativeAddSource, "(JLjava/lang/String;Lcom/mapbox/mapboxsdk/style/sources/Source;)V"),
         MAKE_NATIVE_METHOD(nativeRemoveSource, "(JLjava/lang/String;)V"),
-        MAKE_NATIVE_METHOD(nativeSetContentPadding, "(JDDDD)V")
+        MAKE_NATIVE_METHOD(nativeSetContentPadding, "(JDDDD)V"),
+        MAKE_NATIVE_METHOD(nativeScheduleTakeSnapshot, "(J)V")
     );
 
     // Offline begin
diff --git a/platform/android/src/jni.hpp b/platform/android/src/jni.hpp
index 57f84f0ccc..0810ee656d 100644
--- a/platform/android/src/jni.hpp
+++ b/platform/android/src/jni.hpp
@@ -19,6 +19,7 @@ extern std::string androidRelease;
 extern jmethodID onInvalidateId;
 extern jmethodID onMapChangedId;
 extern jmethodID onFpsChangedId;
+extern jmethodID onSnapshotReadyId;
 
 extern bool attach_jni_thread(JavaVM* vm, JNIEnv** env, std::string threadName);
 extern void detach_jni_thread(JavaVM* vm, JNIEnv** env, bool detach);
diff --git a/platform/android/src/native_map_view.cpp b/platform/android/src/native_map_view.cpp
index 0b849976eb..578e5d0033 100755
--- a/platform/android/src/native_map_view.cpp
+++ b/platform/android/src/native_map_view.cpp
@@ -194,6 +194,35 @@ void NativeMapView::render() {
 
     map->render();
 
+    if(snapshot){
+         snapshot = false;
+
+         // take snapshot
+         const unsigned int w = fbWidth;
+         const unsigned int h = fbHeight;
+         mbgl::PremultipliedImage image { w, h };
+         MBGL_CHECK_ERROR(glReadPixels(0, 0, w, h, GL_RGBA, GL_UNSIGNED_BYTE, image.data.get()));
+         const size_t stride = image.stride();
+         auto tmp = std::make_unique<uint8_t[]>(stride);
+         uint8_t *rgba = image.data.get();
+         for (int i = 0, j = h - 1; i < j; i++, j--) {
+            std::memcpy(tmp.get(), rgba + i * stride, stride);
+            std::memcpy(rgba + i * stride, rgba + j * stride, stride);
+            std::memcpy(rgba + j * stride, tmp.get(), stride);
+         }
+
+         // encode and convert to jbytes
+         std::string string = encodePNG(image);
+         jbyteArray arr = env->NewByteArray(string.length());
+         env->SetByteArrayRegion(arr,0,string.length(),(jbyte*)string.c_str());
+
+         // invoke Mapview#OnSnapshotReady
+         env->CallVoidMethod(obj, onSnapshotReadyId, arr);
+         if (env->ExceptionCheck()) {
+             env->ExceptionDescribe();
+         }
+    }
+
     if ((display != EGL_NO_DISPLAY) && (surface != EGL_NO_SURFACE)) {
         if (!eglSwapBuffers(display, surface)) {
             mbgl::Log::Error(mbgl::Event::OpenGL, "eglSwapBuffers() returned error %d",
@@ -436,6 +465,10 @@ void NativeMapView::destroySurface() {
     }
 }
 
+void NativeMapView::scheduleTakeSnapshot() {
+    snapshot = true;
+}
+
 // Speed
 /*
 typedef enum {
diff --git a/platform/android/src/native_map_view.hpp b/platform/android/src/native_map_view.hpp
index 40cb012b0b..9b5af76dfe 100755
--- a/platform/android/src/native_map_view.hpp
+++ b/platform/android/src/native_map_view.hpp
@@ -49,6 +49,8 @@ public:
     mbgl::EdgeInsets getInsets() { return insets;}
     void setInsets(mbgl::EdgeInsets insets_);
 
+    void scheduleTakeSnapshot();
+
 private:
     EGLConfig chooseConfig(const EGLConfig configs[], EGLint numConfigs);
 
@@ -79,6 +81,7 @@ private:
     bool firstTime = false;
     bool fpsEnabled = false;
     bool sizeChanged = false;
+    bool snapshot = false;
     double fps = 0.0;
 
     int width = 0;