From 225e8dafd985ff1a0387731cac47f331d137f0bb Mon Sep 17 00:00:00 2001
From: hogliux <fabian.renn@gmail.com>
Date: Sat, 1 Oct 2016 10:39:22 +0100
Subject: [PATCH] Added waitForNextAudioBlockReady method to
 BufferingAudioSource

---
 .../sources/juce_BufferingAudioSource.cpp     | 37 +++++++++++++++++++
 .../sources/juce_BufferingAudioSource.h       |  7 ++++
 2 files changed, 44 insertions(+)

diff --git a/modules/juce_audio_basics/sources/juce_BufferingAudioSource.cpp b/modules/juce_audio_basics/sources/juce_BufferingAudioSource.cpp
index 7da13ab520..2898aed856 100644
--- a/modules/juce_audio_basics/sources/juce_BufferingAudioSource.cpp
+++ b/modules/juce_audio_basics/sources/juce_BufferingAudioSource.cpp
@@ -151,6 +151,41 @@ void BufferingAudioSource::getNextAudioBlock (const AudioSourceChannelInfo& info
     }
 }
 
+bool BufferingAudioSource::waitForNextAudioBlockReady (const AudioSourceChannelInfo& info, const uint32 timeout)
+{
+    if (!source || source->getTotalLength() <= 0)
+        return false;
+
+    if (nextPlayPos + info.numSamples < 0)
+        return true;
+
+    if (! isLooping() && nextPlayPos > getTotalLength())
+        return true;
+
+    const uint32 endTime = Time::getMillisecondCounter () + timeout;
+    uint32 now = Time::getMillisecondCounter();
+
+    while (now < endTime)
+    {
+        {
+            const ScopedLock sl (bufferStartPosLock);
+
+            const int validStart = static_cast<int> (jlimit (bufferValidStart, bufferValidEnd, nextPlayPos) - nextPlayPos);
+            const int validEnd   = static_cast<int> (jlimit (bufferValidStart, bufferValidEnd, nextPlayPos + info.numSamples) - nextPlayPos);
+
+            if (validStart <= 0 && validStart < validEnd && validEnd >= info.numSamples)
+                return true;
+        }
+
+        if (! bufferReadyEvent.wait (endTime - now))
+            return false;
+
+        now = Time::getMillisecondCounter();
+    }
+
+    return false;
+}
+
 int64 BufferingAudioSource::getNextReadPosition() const
 {
     jassert (source->getTotalLength() > 0);
@@ -244,6 +279,8 @@ bool BufferingAudioSource::readNextBufferChunk()
         bufferValidEnd = newBVE;
     }
 
+    bufferReadyEvent.signal();
+
     return true;
 }
 
diff --git a/modules/juce_audio_basics/sources/juce_BufferingAudioSource.h b/modules/juce_audio_basics/sources/juce_BufferingAudioSource.h
index f725d6f441..717e35d5db 100644
--- a/modules/juce_audio_basics/sources/juce_BufferingAudioSource.h
+++ b/modules/juce_audio_basics/sources/juce_BufferingAudioSource.h
@@ -92,6 +92,12 @@ public:
     /** Implements the PositionableAudioSource method. */
     bool isLooping() const override             { return source->isLooping(); }
 
+    /** A useful function to block until the next the buffer info can be filled.
+
+        This is useful for offline rendering.
+    */
+    bool waitForNextAudioBlockReady (const AudioSourceChannelInfo& info, const uint32 timeout);
+
 private:
     //==============================================================================
     OptionalScopedPointer<PositionableAudioSource> source;
@@ -99,6 +105,7 @@ private:
     int numberOfSamplesToBuffer, numberOfChannels;
     AudioSampleBuffer buffer;
     CriticalSection bufferStartPosLock;
+    WaitableEvent bufferReadyEvent;
     int64 volatile bufferValidStart, bufferValidEnd, nextPlayPos;
     double volatile sampleRate;
     bool wasSourceLooping, isPrepared, prefillBuffer;