JUCE/modules/juce_dsp/frequency/juce_Windowing.h

/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{
namespace dsp
{

/**
    A class which provides multiple windowing functions useful for filter design
    and spectrum analyzers.

    The different functions provided here can be used by creating either a
    WindowingFunction object, or a static function to fill an array with the
    windowing method samples.

    @tags{DSP}
*/
template <typename FloatType>
class JUCE_API  WindowingFunction
{
public:
    //==============================================================================
    /** The windowing methods available. */
    enum WindowingMethod
    {
        rectangular = 0,
        triangular,
        hann,
        hamming,
        blackman,
        blackmanHarris,
        flatTop,
        kaiser,
        numWindowingMethods
    };

    //==============================================================================
    /** This constructor automatically fills a buffer of the specified size using
        the fillWindowingTables function and the specified arguments.

        @see fillWindowingTables
    */
    WindowingFunction (size_t size, WindowingMethod,
                       bool normalise = true, FloatType beta = 0);

    //==============================================================================
    /** Fills the content of the object array with a given windowing method table.

        @param size         the size of the destination buffer allocated in the object
        @param type         the type of windowing method being used
        @param normalise    if the result must be normalised, creating a DC amplitude
                            response of one
        @param beta         an optional argument useful only for Kaiser's method
                            which must be positive and sets the properties of the
                            method (bandwidth and attenuation increases with beta)
    */
    void fillWindowingTables (size_t size, WindowingMethod type,
                              bool normalise = true, FloatType beta = 0) noexcept;

    /** Fills the content of an array with a given windowing method table.

        @param samples      the destination buffer pointer
        @param size         the size of the destination buffer allocated in the object
        @param normalise    if the result must be normalised, creating a DC amplitude
                            response of one
        @param beta         an optional argument useful only for Kaiser's method,
                            which must be positive and sets the properties of the
                            method (bandwidth and attenuation increases with beta)
    */
    static void fillWindowingTables (FloatType* samples, size_t size, WindowingMethod,
                                     bool normalise = true, FloatType beta = 0) noexcept;

    /** Multiplies the content of a buffer with the given window. */
    void multiplyWithWindowingTable (FloatType* samples, size_t size) noexcept;

    /** Returns the name of a given windowing method. */
    static const char* getWindowingMethodName (WindowingMethod) noexcept;


private:
    //==============================================================================
    Array<FloatType> windowTable;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (WindowingFunction)
};

} // namespace dsp
} // namespace juce