AudioThumbnail: Add new member to set an AudioBuffer as source

modules/juce_audio_basics/buffers/juce_AudioDataConverters.h

@@ -436,6 +436,9 @@ public:
         /** Adds a number of samples to the pointer's position. */
         Pointer& operator+= (int samplesToJump) noexcept        { this->advanceDataBy (data, samplesToJump); return *this; }
 
+        /** Returns a new pointer with the specified offset from this pointer's position. */
+        Pointer operator+ (int samplesToJump) const             { return Pointer { *this } += samplesToJump; }
+
         /** Writes a stream of samples into this pointer from another pointer.
             This will copy the specified number of samples, converting between formats appropriately.
         */

modules/juce_audio_utils/gui/juce_AudioThumbnail.cpp

@@ -83,6 +83,66 @@ private:
     int8 values[2];
 };
 
+
+//==============================================================================
+template <typename T>
+class AudioBufferReader  : public AudioFormatReader
+{
+public:
+    AudioBufferReader (const AudioBuffer<T>* bufferIn, double rate)
+        : AudioFormatReader (nullptr, "AudioBuffer"), buffer (bufferIn)
+    {
+        sampleRate = rate;
+        bitsPerSample = 32;
+        lengthInSamples = buffer->getNumSamples();
+        numChannels = (unsigned int) buffer->getNumChannels();
+        usesFloatingPointData = std::is_floating_point_v<T>;
+    }
+
+    bool readSamples (int* const* destChannels,
+                      int numDestChannels,
+                      int startOffsetInDestBuffer,
+                      int64 startSampleInFile,
+                      int numSamples) override
+    {
+        clearSamplesBeyondAvailableLength (destChannels, numDestChannels, startOffsetInDestBuffer,
+                                           startSampleInFile, numSamples, lengthInSamples);
+
+        const auto numAvailableSamples = (int) ((int64) buffer->getNumSamples() - startSampleInFile);
+        const auto numSamplesToCopy = std::clamp (numAvailableSamples, 0, numSamples);
+
+        if (numSamplesToCopy == 0)
+            return true;
+
+        for (int i = 0; i < numDestChannels; ++i)
+        {
+            if (void* targetChannel = destChannels[i])
+            {
+                const auto dest = DestType (targetChannel) + startOffsetInDestBuffer;
+
+                if (i < buffer->getNumChannels())
+                    dest.convertSamples (SourceType (buffer->getReadPointer (i) + startSampleInFile), numSamplesToCopy);
+                else
+                    dest.clearSamples (numSamples);
+            }
+        }
+
+        return true;
+    }
+
+private:
+    using SourceNumericalType =
+        std::conditional_t<std::is_same_v<T, int>, AudioData::Int32,
+                           std::conditional_t<std::is_same_v<T, float>, AudioData::Float32, void>>;
+
+    using DestinationNumericalType = std::conditional_t<std::is_floating_point_v<T>, AudioData::Float32, AudioData::Int32>;
+
+    using DestType   = AudioData::Pointer<DestinationNumericalType, AudioData::LittleEndian, AudioData::NonInterleaved, AudioData::NonConst>;
+    using SourceType = AudioData::Pointer<SourceNumericalType,      AudioData::LittleEndian, AudioData::NonInterleaved, AudioData::Const>;
+
+    const AudioBuffer<T>* buffer;
+};
+
 //==============================================================================
 class AudioThumbnail::LevelDataSource   : public TimeSliceClient
 {
@@ -687,6 +747,16 @@ void AudioThumbnail::setReader (AudioFormatReader* newReader, int64 hash)
         setDataSource (new LevelDataSource (*this, newReader, hash));
 }
 
+void AudioThumbnail::setSource (const AudioBuffer<float>* newSource, double rate, int64 hash)
+{
+    setReader (new AudioBufferReader<float> (newSource, rate), hash);
+}
+
+void AudioThumbnail::setSource (const AudioBuffer<int>* newSource, double rate, int64 hash)
+{
+    setReader (new AudioBufferReader<int> (newSource, rate), hash);
+}
+
 int64 AudioThumbnail::getHashCode() const
 {
     return source == nullptr ? 0 : source->hashCode;

modules/juce_audio_utils/gui/juce_AudioThumbnail.h

@@ -99,6 +99,18 @@ public:
     */
     void setReader (AudioFormatReader* newReader, int64 hashCode) override;
 
+    /** Sets an AudioBuffer as the source for the thumbnail.
+
+        The buffer contents aren't copied and you must ensure that the lifetime of the buffer is
+        valid for as long as the AudioThumbnail uses it as its source. Calling this function will
+        start reading the audio in a background thread (unless the hash code can be looked-up
+        successfully in the thumbnail cache).
+    */
+    void setSource (const AudioBuffer<float>* newSource, double sampleRate, int64 hashCode);
+
+    /** Same as the other setSource() overload except for int data. */
+    void setSource (const AudioBuffer<int>* newSource, double sampleRate, int64 hashCode);
+
     /** Resets the thumbnail, ready for adding data with the specified format.
         If you're going to generate a thumbnail yourself, call this before using addBlock()
         to add the data.