Show FPS in UI state

tools/viewer/Viewer.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include "Viewer.h"
 
 #include "GMSlide.h"
@@ skipping 49 matching lines @@
     " [Vulkan]"
 };
 
 const char* kName = "name";
 const char* kValue = "value";
 const char* kOptions = "options";
 const char* kSlideStateName = "Slide";
 const char* kBackendStateName = "Backend";
 const char* kSoftkeyStateName = "Softkey";
 const char* kSoftkeyHint = "Please select a softkey";
-
+const char* kFpsStateName = "FPS";
 
 Viewer::Viewer(int argc, char** argv, void* platformData)
     : fCurrentMeasurement(0)
     , fDisplayStats(false)
     , fBackendType(sk_app::Window::kVulkan_BackendType)
     , fZoomCenterX(0.0f)
     , fZoomCenterY(0.0f)
     , fZoomLevel(0.0f)
     , fZoomScale(SK_Scalar1)
 {
@@ skipping 82 matching lines @@
     fAnimTimer.run();
 
     // set up first frame
     fCurrentSlide = 0;
     setupCurrentSlide(-1);
 
     fWindow->show();
 }
 
 void Viewer::initSlides() {
+    fAllSlideNames = Json::Value(Json::arrayValue);
+
     const skiagm::GMRegistry* gms(skiagm::GMRegistry::Head());
     while (gms) {
         SkAutoTDelete<skiagm::GM> gm(gms->factory()(nullptr));
 
         if (!SkCommandLineFlags::ShouldSkip(FLAGS_match, gm->getName())) {
             sk_sp<Slide> slide(new GMSlide(gm.release()));
             fSlides.push_back(slide);
         }
 
         gms = gms->next();
@@ skipping 220 matching lines @@
 
 void Viewer::onIdle(double ms) {
     // Record measurements
     fMeasurements[fCurrentMeasurement++] = ms;
     fCurrentMeasurement &= (kMeasurementCount - 1);  // fast mod
     SkASSERT(fCurrentMeasurement < kMeasurementCount);
 
     fAnimTimer.updateTime();
     if (fSlides[fCurrentSlide]->animate(fAnimTimer) || fDisplayStats) {
         fWindow->inval();
+        updateUIState(); // Update the FPS
     }
 }
 
 void Viewer::updateUIState() {
     // Slide state
     Json::Value slideState(Json::objectValue);
     slideState[kName] = kSlideStateName;
     slideState[kValue] = fSlides[fCurrentSlide]->getName().c_str();
-    Json::Value allSlideNames(Json::arrayValue);
-    for(auto slide : fSlides) {
-        allSlideNames.append(Json::Value(slide->getName().c_str()));
+    if (fAllSlideNames.size() == 0) {
+        for(auto slide : fSlides) {
+            fAllSlideNames.append(Json::Value(slide->getName().c_str()));
+        }
     }
-    slideState[kOptions] = allSlideNames;
+    slideState[kOptions] = fAllSlideNames;
 
     // Backend state
     Json::Value backendState(Json::objectValue);
     backendState[kName] = kBackendStateName;
     backendState[kValue] = kBackendTypeStrings[fBackendType];
     backendState[kOptions] = Json::Value(Json::arrayValue);
     for (auto str : kBackendTypeStrings) {
         backendState[kOptions].append(Json::Value(str));
     }
 
     // Softkey state
     Json::Value softkeyState(Json::objectValue);
     softkeyState[kName] = kSoftkeyStateName;
     softkeyState[kValue] = kSoftkeyHint;
     softkeyState[kOptions] = Json::Value(Json::arrayValue);
     softkeyState[kOptions].append(kSoftkeyHint);
     for (const auto& softkey : fCommands.getCommandsAsSoftkeys()) {
         softkeyState[kOptions].append(Json::Value(softkey.c_str()));
     }
 
+    // FPS state
+    Json::Value fpsState(Json::objectValue);
+    fpsState[kName] = kFpsStateName;
+    double measurement = fMeasurements[
+            (fCurrentMeasurement + (kMeasurementCount-1)) % kMeasurementCount
+    ];
+    fpsState[kValue] = SkStringPrintf("%8.3lf ms", measurement).c_str();
+    fpsState[kOptions] = Json::Value(Json::arrayValue);
+
     Json::Value state(Json::arrayValue);
     state.append(slideState);
     state.append(backendState);
     state.append(softkeyState);
+    state.append(fpsState);
 
     fWindow->setUIState(state);
 }
 
 void Viewer::onUIStateChanged(const SkString& stateName, const SkString& stateValue) {
     // For those who will add more features to handle the state change in this function:
     // After the change, please call updateUIState no notify the frontend (e.g., Android app).
     // For example, after slide change, updateUIState is called inside setupCurrentSlide;
     // after backend change, updateUIState is called in this function.
     if (stateName.equals(kSlideStateName)) {
@@ skipping 26 matching lines @@
         }
     } else if (stateName.equals(kSoftkeyStateName)) {
         if (!stateValue.equals(kSoftkeyHint)) {
             fCommands.onSoftkey(stateValue);
             updateUIState(); // This is still needed to reset the value to kSoftkeyHint
         }
     } else {
         SkDebugf("Unknown stateName: %s", stateName.c_str());
     }
 }