Add some const qualifiers to BlockFile methods

src/blockfile/ODDecodeBlockFile.h

@@ -51,21 +51,21 @@ class ODDecodeBlockFile final : public SimpleBlockFile
 
    virtual ~ODDecodeBlockFile();
    //checks to see if summary data has been computed and written to disk yet.  Thread safe.  Blocks if we are writing summary data.
-   bool IsSummaryAvailable() override;
+   bool IsSummaryAvailable() const override;
 
    /// Returns TRUE if this block's complete data is ready to be accessed by Read()
-   bool IsDataAvailable() override;
+   bool IsDataAvailable() const override;
 
    /// Returns TRUE if the summary has not yet been written, but is actively being computed and written to disk
    bool IsSummaryBeingComputed() override { return false; }
 
    //Calls that rely on summary files need to be overidden
-   wxLongLong GetSpaceUsage() override;
+   wxLongLong GetSpaceUsage() const override;
    /// Gets extreme values for the specified region
    void GetMinMax(sampleCount start, sampleCount len,
-                          float *outMin, float *outMax, float *outRMS) override;
+                          float *outMin, float *outMax, float *outRMS) const override;
    /// Gets extreme values for the entire block
-   void GetMinMax(float *outMin, float *outMax, float *outRMS) override;
+   void GetMinMax(float *outMin, float *outMax, float *outRMS) const override;
    /// Returns the 256 byte summary data block
    bool Read256(float *buffer, sampleCount start, sampleCount len) override;
    /// Returns the 64K summary data block
@@ -97,32 +97,32 @@ class ODDecodeBlockFile final : public SimpleBlockFile
    void SetStart(sampleCount startSample){mStart = startSample;}
 
    ///Gets the value that indicates where the first sample in this block corresponds to the global sequence/clip.  Only for display use.
-   sampleCount GetStart(){return mStart;}
+   sampleCount GetStart() const {return mStart;}
 
    //returns the number of samples from the beginning of the track that this blockfile starts at
-   sampleCount GetGlobalStart(){return mClipOffset+mStart;}
+   sampleCount GetGlobalStart() const {return mClipOffset+mStart;}
 
    //returns the number of samples from the beginning of the track that this blockfile ends at
-   sampleCount GetGlobalEnd(){return mClipOffset+mStart+GetLength();}
+   sampleCount GetGlobalEnd() const {return mClipOffset+mStart+GetLength();}
 
    //Below calls are overrided just so we can take wxlog calls out, which are not threadsafe.
 
    /// Reads the specified data from the aliased file using libsndfile
    int ReadData(samplePtr data, sampleFormat format,
-                        sampleCount start, sampleCount len) override;
+                        sampleCount start, sampleCount len) const override;
 
    /// Read the summary into a buffer
    bool ReadSummary(void *data) override;
 
    ///Returns the type of audiofile this blockfile is loaded from.
-   unsigned int GetDecodeType() /* not override */ { return mType; }
+   unsigned int GetDecodeType() /* not override */ const { return mType; }
    // void SetDecodeType(unsigned int type) /* not override */ { mType = type; }
 
    ///sets the amount of samples the clip associated with this blockfile is offset in the wavetrack (non effecting)
    void SetClipOffset(sampleCount numSamples){mClipOffset= numSamples;}
 
    ///Gets the number of samples the clip associated with this blockfile is offset by.
-   sampleCount GetClipOffset(){return mClipOffset;}
+   sampleCount GetClipOffset() const {return mClipOffset;}
 
    //OD TODO:set ISAlias to true while we have no data?
 
@@ -133,12 +133,12 @@ class ODDecodeBlockFile final : public SimpleBlockFile
 
    ///sets the file name the summary info will be saved in.  threadsafe.
    void SetFileName(wxFileName &name) override;
-   wxFileName GetFileName() override;
+   wxFileName GetFileName() const override;
 
    /// Prevents a read on other threads of the encoded audio file.
-   void LockRead() override;
+   void LockRead() const override;
    /// Allows reading of encoded file on other threads.
-   void UnlockRead() override;
+   void UnlockRead() const override;
 
    ///// Get the name of the file where the audio data for this block is
    /// stored.
@@ -162,12 +162,12 @@ class ODDecodeBlockFile final : public SimpleBlockFile
 
    ///This lock is for the filename (string) of the blockfile that contains summary/audio data
    ///after decoding
-   ODLock mFileNameMutex;
+   mutable ODLock mFileNameMutex;
 
    ///The original file the audio came from.
    wxFileName mAudioFileName;
 
-   ODLock    mDataAvailableMutex;
+   mutable ODLock    mDataAvailableMutex;
    bool mDataAvailable;
    bool mDataBeingComputed;
 
@@ -175,7 +175,7 @@ class ODDecodeBlockFile final : public SimpleBlockFile
    ODLock mDecoderMutex;
 
    ///For accessing the audio file that will be decoded.  Used by dir manager;
-   ODLock mReadDataMutex;
+   mutable ODLock mReadDataMutex;
 
    ///for reporting after task is complete.  Only for display use.
    sampleCount mStart;