/// <summary>
/// 複素数がインターリーブされたデータを離散フーリエ変換します。
/// </summary>
/// <param name="invert">逆離散フーリエ変換を行うかの真偽値。</param>
/// <param name="data">複素数がインターリーブされた配列。</param>
public void TransformComplex(bool invert, double[] data)
{
if (data == null)
{
throw new ArgumentNullException("data");
}
if (data.Length != this.n)
{
throw new ArgumentOutOfRangeException("data");
}
FastFourier.cdft(this.n, invert, data, this.ip, this.w);
if (invert)
{
double f = 2.0 / this.n;
for (int j = 0; j < this.n; j++)
{
data[j] *= f;
}
}
}
public override void Draw(float[] data)
{
float dx = (float)this.size.Width / (float)(data.Length / 8);
float y_offset = +20.0f;
int fftSize = data.Length / 2;
int height = this.size.Height / 2;
if (this.buffer.Length != fftSize)
{
this.buffer = new PointF[fftSize / 4];
this.lchannel = new double[fftSize];
this.rchannel = new double[fftSize];
this.fft_buffer = new double[fftSize * 2];
this.fft = new FastFourier(fftSize);
}
this.graphics.Clear(this.backgroundColor);
for (int i = 0, j = 0, k = 1; i < fftSize; i++, j += 2, k += 2)
{
this.lchannel[i] = data[j];
this.rchannel[i] = data[k];
}
// L channel
{
Window.Hanning(lchannel);
Channel.Interleave(lchannel, this.fft_buffer, fftSize);
this.fft.TransformComplex(false, this.fft_buffer);
for (int i = 0, j = 0, k = 1; i < fftSize / 4; i++, j += 2, k += 2)
{
double d = 20.0 * Math.Log10(Math.Sqrt(this.fft_buffer[j] * this.fft_buffer[j] + this.fft_buffer[k] * this.fft_buffer[k]) / fftSize) + y_offset;
if (d <= -height)
d = -height;
else if (d > 0.0)
d = 0.0;
this.buffer[i] = new PointF(i * dx, -(float)d);
}
this.graphics.DrawLines(this.p, this.buffer);
}
// R channel
{
Window.Hanning(rchannel);
Channel.Interleave(rchannel, this.fft_buffer, fftSize);
this.fft.TransformComplex(false, this.fft_buffer);
for (int i = 0, j = 0, k = 1; i < fftSize / 4; i++, j += 2, k += 2)
{
double d = 20.0 * Math.Log10(Math.Sqrt(this.fft_buffer[j] * this.fft_buffer[j] + this.fft_buffer[k] * this.fft_buffer[k]) / fftSize) + y_offset;
if (d <= -height)
d = -height;
else if (d > 0.0)
d = 0.0;
this.buffer[i] = new PointF(i * dx, this.size.Height / 2 - (float)d);
}
this.graphics.DrawLines(this.p, this.buffer);
}
this.graphics.DrawLine(this.p, 0, height, this.size.Width, height);
this.graphics.Flush();
}
public unsafe override void Draw(float[] data)
{
float dx = (float)this.size.Width / (float)(data.Length / 4);
const float y_offset = +210.0f;
const float y_amplifier = 100.0f;
int fftSize = data.Length;
if (fftSize != this.fft_buffer.Length)
{
this.fft = new FastFourier(fftSize);
this.re = new double[fftSize];
this.fft_buffer = new double[fftSize * 2];
this.spectrum = new Bitmap(1, fftSize / 8);
}
data.CopyTo(re, 0);
Window.Hanning(this.re);
Channel.Interleave(this.re, this.fft_buffer, fftSize);
this.fft.TransformComplex(false, this.fft_buffer);
for (int i = 0, j = 0, k = 1; i < fftSize / 8; i++, j += 2, k += 2)
{
re[i] = y_amplifier * Math.Log10(Math.Sqrt(this.fft_buffer[j] * this.fft_buffer[j] + this.fft_buffer[k] * this.fft_buffer[k]) / (fftSize * 4)) + y_offset;
if (re[i] < -255.0)
re[i] = -255.0;
else if (re[i] > 0.0)
re[i] = 0.0;
}
var bdata = this.bitmap.LockBits(new Rectangle(0, 0, this.bitmap.Width, this.bitmap.Height),
ImageLockMode.ReadWrite,
PixelFormat.Format32bppArgb);
{
for (byte* i = (byte*)bdata.Scan0, j = i + 4, l = i + bdata.Width * bdata.Height * 4; j < l; i++, j++)
*i = *j;
}
this.bitmap.UnlockBits(bdata);
bdata = this.spectrum.LockBits(new Rectangle(0, 0, 1, fftSize / 8),
ImageLockMode.ReadWrite,
PixelFormat.Format32bppArgb);
{
int j = 0;
for (byte* i = (byte*)bdata.Scan0, l = i + bdata.Height * 4; i < l; j++)
{
byte b = (byte)(255.0 + re[j]);
*i++ = b;
*i++ = b;
*i++ = b;
*i++ = 255;
}
}
this.spectrum.UnlockBits(bdata);
this.graphics.DrawImage(this.spectrum, this.size.Width - 1, this.size.Height - 1, 1, -this.size.Height);
this.graphics.Flush();
}