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Source/Utilities/SampleLoader.h

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+/*
+  ==============================================================================
+
+    SampleLoader.h
+    Created: 14 Jun 2024 5:37:01pm
+    Author:  binya
+
+  ==============================================================================
+*/
+
+#pragma once
+
+#include <JuceHeader.h>
+
+#include "BufferUtils.h"
+
+/** A utility thread for asynchronously loading samples */
+class LoaderThread final : public juce::Thread
+{
+public:
+    LoaderThread(std::unique_ptr<juce::AudioFormatReader> formatReader, int threadID) : Thread("Loader_Thread_" + juce::String(threadID)),
+        reader{std::move(formatReader)}
+    {
+    }
+
+    ~LoaderThread() override
+    {
+        stopThread(-1);
+    }
+
+    void cancel()
+    {
+        canceled = true;
+    }
+
+    juce::AudioBuffer<float>* releaseSample() { return newSample.release(); }
+    juce::AudioFormatReader* releaseReader() { return reader.release(); }
+    const juce::String& getLoadedSampleHash() const { return sampleHash; }
+
+private:
+    void run() override
+    {
+        newSample = std::make_unique<juce::AudioBuffer<float>>(int(reader->numChannels), int(reader->lengthInSamples));
+        reader->read(&*newSample, 0, int(reader->lengthInSamples), 0, true, true);
+        sampleHash = getSampleHash(*newSample);
+
+        if (canceled)
+            newSample = nullptr;
+
+        signalThreadShouldExit();
+    }
+
+    std::unique_ptr<juce::AudioFormatReader> reader;
+    std::unique_ptr<juce::AudioBuffer<float>> newSample;
+    juce::String sampleHash;
+    bool canceled{ false };
+};
+
+/** Asynchronously loads a sample */
+class SampleLoader final : public juce::Thread::Listener
+{
+public:
+    void loadSample(std::unique_ptr<juce::AudioFormatReader> formatReader, 
+        const std::function<void(const std::unique_ptr<juce::AudioBuffer<float>>& loadedSample, const juce::String& sampleHash, const std::unique_ptr<juce::AudioFormatReader>& reader)>& onCompletion)
+    {
+        loading = true;
+        completionCallback = onCompletion;
+        for (const auto& thread : threads)
+        {
+            thread->cancel();
+            thread->removeListener(this);
+        }
+        
+        auto newThread = std::make_unique<LoaderThread>(std::move(formatReader), ++ids);
+        newThread->addListener(this);
+        newThread->startThread();
+        threads.emplace_back(std::move(newThread));
+    }
+
+    bool isLoading() const { return loading; }
+
+private:
+    void exitSignalSent() override
+    {
+        juce::MessageManager::callAsync([this]() -> void {
+            auto& lastThread = threads[threads.size() - 1];
+            completionCallback(std::unique_ptr<juce::AudioBuffer<float>>(lastThread->releaseSample()), lastThread->getLoadedSampleHash(), std::unique_ptr<juce::AudioFormatReader>(lastThread->releaseReader()));
+            loading = false;
+        });
+    }
+
+    //==============================================================================
+    int ids{ 0 };
+    std::vector<std::unique_ptr<LoaderThread>> threads;
+
+    std::function<void(std::unique_ptr<juce::AudioBuffer<float>>, const juce::String&, std::unique_ptr<juce::AudioFormatReader>)> completionCallback;
+    bool loading{ false };
+};