Now we can use drawer to view the state information of the native app, and set its state using the spinner.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2004633002

Committed: https://skia.googlesource.com/skia/+/4e4e30823fba0047b93a56bfcf05c04ca57e82ec

Review-Url: https://codereview.chromium.org/2004633002
diff --git a/tools/viewer/sk_app/Window.cpp b/tools/viewer/sk_app/Window.cpp
index ba905e0..1c798df 100644
--- a/tools/viewer/sk_app/Window.cpp
+++ b/tools/viewer/sk_app/Window.cpp
@@ -32,12 +32,16 @@
     return false;
 }
 
+static void default_ui_state_changed_func(
+        const SkString& stateName, const SkString& stateValue, void* userData) {}
+
 static void default_paint_func(SkCanvas*, void* userData) {}
 
 Window::Window() : fCharFunc(default_char_func)
                  , fKeyFunc(default_key_func)
                  , fMouseFunc(default_mouse_func)
                  , fTouchFunc(default_touch_func)
+                 , fUIStateChangedFunc(default_ui_state_changed_func)
                  , fPaintFunc(default_paint_func) {
 }
 
@@ -62,6 +66,10 @@
     return fTouchFunc(owner, state, x, y, fTouchUserData);
 }
 
+void Window::onUIStateChanged(const SkString& stateName, const SkString& stateValue) {
+    return fUIStateChangedFunc(stateName, stateValue, fUIStateChangedUserData);
+}
+
 void Window::onPaint() {
     markInvalProcessed();
     sk_sp<SkSurface> backbuffer = fWindowContext->getBackbufferSurface();
diff --git a/tools/viewer/sk_app/Window.h b/tools/viewer/sk_app/Window.h
index 65e1542..9ca4231 100644
--- a/tools/viewer/sk_app/Window.h
+++ b/tools/viewer/sk_app/Window.h
@@ -12,6 +12,7 @@
 #include "SkRect.h"
 #include "SkTouchGesture.h"
 #include "SkTypes.h"
+#include "SkJSONCPP.h"
 
 class SkCanvas;
 
@@ -27,6 +28,7 @@
 
     virtual void setTitle(const char*) = 0;
     virtual void show() = 0;
+    virtual void setUIState(const Json::Value& state) {}  // do nothing in default
 
     // Shedules an invalidation event for window if one is not currently pending.
     // Make sure that either onPaint or markInvalReceived is called when the client window consumes
@@ -110,6 +112,8 @@
     typedef bool(*OnKeyFunc)(Key key, InputState state, uint32_t modifiers, void* userData);
     typedef bool(*OnMouseFunc)(int x, int y, InputState state, uint32_t modifiers, void* userData);
     typedef bool(*OnTouchFunc)(int owner, InputState state, float x, float y, void* userData);
+    typedef void(*OnUIStateChangedFunc)(
+            const SkString& stateName, const SkString& stateValue, void* userData);
     typedef void(*OnPaintFunc)(SkCanvas*, void* userData);
 
     void registerCharFunc(OnCharFunc func, void* userData) {
@@ -137,10 +141,16 @@
         fTouchUserData = userData;
     }
 
+    void registerUIStateChangedFunc(OnUIStateChangedFunc func, void* userData) {
+        fUIStateChangedFunc = func;
+        fUIStateChangedUserData = userData;
+    }
+
     bool onChar(SkUnichar c, uint32_t modifiers);
     bool onKey(Key key, InputState state, uint32_t modifiers);
     bool onMouse(int x, int y, InputState state, uint32_t modifiers);
     bool onTouch(int owner, InputState state, float x, float y);  // multi-owner = multi-touch
+    void onUIStateChanged(const SkString& stateName, const SkString& stateValue);
     void onPaint();
     void onResize(uint32_t width, uint32_t height);
 
@@ -164,6 +174,9 @@
     void*        fMouseUserData;
     OnTouchFunc  fTouchFunc;
     void*        fTouchUserData;
+    OnUIStateChangedFunc
+                 fUIStateChangedFunc;
+    void*        fUIStateChangedUserData;
     OnPaintFunc  fPaintFunc;
     void*        fPaintUserData;
 
diff --git a/tools/viewer/sk_app/android/Window_android.cpp b/tools/viewer/sk_app/android/Window_android.cpp
index ed03c81..4f33870 100644
--- a/tools/viewer/sk_app/android/Window_android.cpp
+++ b/tools/viewer/sk_app/android/Window_android.cpp
@@ -41,6 +41,10 @@
     fSkiaAndroidApp->setTitle(title);
 }
 
+void Window_android::setUIState(const Json::Value& state) {
+    fSkiaAndroidApp->setUIState(state);
+}
+
 bool Window_android::attach(BackendType attachType, const DisplayParams& params) {
     if (kVulkan_BackendType != attachType) {
         return false;
diff --git a/tools/viewer/sk_app/android/Window_android.h b/tools/viewer/sk_app/android/Window_android.h
index f7d348b..f1c0798 100644
--- a/tools/viewer/sk_app/android/Window_android.h
+++ b/tools/viewer/sk_app/android/Window_android.h
@@ -28,6 +28,7 @@
 
     bool attach(BackendType attachType, const DisplayParams& params) override;
     void onInval() override;
+    void setUIState(const Json::Value& state) override;
 
     void paintIfNeeded();
 
diff --git a/tools/viewer/sk_app/android/surface_glue_android.cpp b/tools/viewer/sk_app/android/surface_glue_android.cpp
index 958b787..daf26a3 100644
--- a/tools/viewer/sk_app/android/surface_glue_android.cpp
+++ b/tools/viewer/sk_app/android/surface_glue_android.cpp
@@ -46,6 +46,7 @@
     fAndroidApp = env->NewGlobalRef(androidApp);
     jclass cls = env->GetObjectClass(fAndroidApp);
     fSetTitleMethodID = env->GetMethodID(cls, "setTitle", "(Ljava/lang/String;)V");
+    fSetStateMethodID = env->GetMethodID(cls, "setState", "(Ljava/lang/String;)V");
     fNativeWindow = nullptr;
     pthread_create(&fThread, nullptr, pthread_main, this);
 }
@@ -70,6 +71,12 @@
     fPThreadEnv->DeleteLocalRef(titleString);
 }
 
+void SkiaAndroidApp::setUIState(const Json::Value& state) const {
+    jstring jstr = fPThreadEnv->NewStringUTF(state.toStyledString().c_str());
+    fPThreadEnv->CallVoidMethod(fAndroidApp, fSetStateMethodID, jstr);
+    fPThreadEnv->DeleteLocalRef(jstr);
+}
+
 void SkiaAndroidApp::postMessage(const Message& message) const {
     SkDEBUGCODE(auto writeSize =) write(fPipes[1], &message, sizeof(message));
     SkASSERT(writeSize == sizeof(message));
@@ -139,6 +146,12 @@
                                              message.fTouchY);
             break;
         }
+        case kUIStateChanged: {
+            skiaAndroidApp->fWindow->onUIStateChanged(*message.stateName, *message.stateValue);
+            delete message.stateName;
+            delete message.stateValue;
+            break;
+        }
         default: {
             // do nothing
         }
@@ -229,4 +242,17 @@
     skiaAndroidApp->postMessage(message);
 }
 
+extern "C" JNIEXPORT void JNICALL Java_org_skia_viewer_ViewerActivity_onUIStateChanged(
+    JNIEnv* env, jobject activity, jlong handle, jstring stateName, jstring stateValue) {
+    auto skiaAndroidApp = (SkiaAndroidApp*)handle;
+    Message message(kUIStateChanged);
+    const char* nameChars = env->GetStringUTFChars(stateName, nullptr);
+    const char* valueChars = env->GetStringUTFChars(stateValue, nullptr);
+    message.stateName = new SkString(nameChars);
+    message.stateValue = new SkString(valueChars);
+    skiaAndroidApp->postMessage(message);
+    env->ReleaseStringUTFChars(stateName, nameChars);
+    env->ReleaseStringUTFChars(stateValue, valueChars);
+}
+
 }  // namespace sk_app
diff --git a/tools/viewer/sk_app/android/surface_glue_android.h b/tools/viewer/sk_app/android/surface_glue_android.h
index a469833..3bbf3af 100644
--- a/tools/viewer/sk_app/android/surface_glue_android.h
+++ b/tools/viewer/sk_app/android/surface_glue_android.h
@@ -12,6 +12,8 @@
 
 #include <android/native_window_jni.h>
 
+#include "SkString.h"
+
 #include "../Application.h"
 #include "../Window.h"
 
@@ -25,7 +27,8 @@
     kDestroyApp,
     kContentInvalidated,
     kKeyPressed,
-    kTouched
+    kTouched,
+    kUIStateChanged,
 };
 
 struct Message {
@@ -35,6 +38,9 @@
     int fTouchOwner, fTouchState;
     float fTouchX, fTouchY;
 
+    SkString* stateName;
+    SkString* stateValue;
+
     Message() {}
     Message(MessageType t) : fType(t) {}
 };
@@ -49,8 +55,9 @@
     void postMessage(const Message& message) const;
     void readMessage(Message* message) const;
 
-    // This must be called in SkiaAndroidApp's own pthread because the JNIEnv is thread sensitive
+    // These must be called in SkiaAndroidApp's own pthread because the JNIEnv is thread sensitive
     void setTitle(const char* title) const;
+    void setUIState(const Json::Value& state) const;
 
 private:
     pthread_t fThread;
@@ -58,7 +65,7 @@
     int fPipes[2];  // 0 is the read message pipe, 1 is the write message pipe
     JavaVM* fJavaVM;
     JNIEnv* fPThreadEnv;
-    jmethodID fSetTitleMethodID;
+    jmethodID fSetTitleMethodID, fSetStateMethodID;
 
     // This must be called in SkiaAndroidApp's own pthread because the JNIEnv is thread sensitive
     ~SkiaAndroidApp();