Add skipFrame method to Engine

Author: adazem009

include/scratchcpp/iengine.h

@@ -90,6 +90,13 @@ class LIBSCRATCHCPP_EXPORT IEngine
         /*! Returns true if breakFrame() was called. */
         virtual bool breakingCurrentFrame() = 0;
 
+        /*!
+         * Call this from a block implementation to skip a frame and run the next frame immediately.\n
+         * The screen will be refreshed according to the frame rate.
+         * \note This also works in "run without screen refresh" custom blocks.
+         */
+        virtual void skipFrame() = 0;
+
         /*!
          * Registers the given block section.
          * \see <a href="blockSections.html">Block sections</a>

src/engine/engine.cpp

@@ -227,6 +227,8 @@ void Engine::run()
 
     while (true) {
         auto lastFrameTime = std::chrono::steady_clock::now();
+        m_skipFrame = false;
+
         // Execute the frame
         frame();
         if (m_runningScripts.size() <= 0)
@@ -236,10 +238,15 @@ void Engine::run()
         auto currentTime = std::chrono::steady_clock::now();
         auto elapsedTime = std::chrono::duration_cast<std::chrono::milliseconds>(currentTime - lastFrameTime);
         auto sleepTime = frameDuration - elapsedTime;
+        bool timeOut = sleepTime <= std::chrono::milliseconds::zero();
 
-        if (sleepTime > std::chrono::milliseconds::zero())
+        if (!timeOut && !m_skipFrame)
             std::this_thread::sleep_for(sleepTime);
 
+        if ((m_skipFrame && timeOut) || !m_skipFrame) {
+            // TODO: Repaint here
+        }
+
         lastFrameTime = currentTime;
     }
 }
@@ -259,6 +266,12 @@ bool libscratchcpp::Engine::breakingCurrentFrame()
     return m_breakFrame;
 }
 
+void Engine::skipFrame()
+{
+    breakFrame();
+    m_skipFrame = true;
+}
+
 void Engine::registerSection(std::shared_ptr<IBlockSection> section)
 {
     if (section) {

src/engine/engine.h

@@ -40,6 +40,8 @@ class Engine : public IEngine
         void breakFrame() override;
         bool breakingCurrentFrame() override;
 
+        void skipFrame() override;
+
         void registerSection(std::shared_ptr<IBlockSection> section) override;
         unsigned int functionIndex(BlockFunc f) override;
 
@@ -88,6 +90,7 @@ class Engine : public IEngine
         std::vector<BlockFunc> m_functions;
 
         bool m_breakFrame = false;
+        bool m_skipFrame = false;
 };
 
 } // namespace libscratchcpp

test/mocks/enginemock.h

@@ -28,6 +28,8 @@ class EngineMock : public IEngine
         MOCK_METHOD(void, breakFrame, (), (override));
         MOCK_METHOD(bool, breakingCurrentFrame, (), (override));
 
+        MOCK_METHOD(void, skipFrame, (), (override));
+
         MOCK_METHOD(void, registerSection, (std::shared_ptr<IBlockSection>), (override));
         MOCK_METHOD(unsigned int, functionIndex, (BlockFunc), (override));