func update(buf audio.PCM32Samples, dec audio.Decoder) error {
n, err := dec.Read(buf)
if err != nil {
return err
}
fmt.Println(len(buf), n)
if n == 0 {
return errutil.NewNoPos("EOF")
}
// The x scale is relative to the number of frames.
xscale := len(buf) / width
// The y scale is relative to the range of values from the frames.
yscale := Range(buf) / height
i := image.NewRGBA(image.Rect(0, 0, width, height))
draw.Draw(i, i.Bounds(), &image.Uniform{black}, image.ZP, draw.Src)
oldx, oldy := 0, height/2
for x := 0; x < width; x += 2 {
// loudness from the frame scaled down to the image.
loudness := int(buf[x*xscale]) / (yscale + 1)
// To center the oscilloscope on the y axis we add height/2.
y := loudness + height/2
// draw a line between (x, y) and (oldx, oldy)
line(i, x, y, oldx, oldy)
// Update old x/y.
oldx, oldy = x, y
}
// Change image.Image type to win.Image.
img, err := win.ReadImage(i)
if err != nil {
return errutil.Err(err)
}
// Draw image to window.
err = win.Draw(image.ZP, img)
if err != nil {
return errutil.Err(err)
}
// Display window updates on screen.
return win.Update()
}
// loadResources loads the background and foreground images.
func loadResources() (err error) {
c := canvas.NewCanvas(width, height)
for x := 0; x < c.Bounds().Size().X; x++ {
for y := 0; y < c.Bounds().Size().Y; y++ {
c.Set(x, y, color.RGBA{0, 0, 0, 255})
}
}
f := fractal.Fractal{
Src: c.RGBA,
Iter: iterations,
Center: complex(centerReal, centerImag),
Zoom: zoom,
}
mandel.Smooth(&f)
// Load background image.
fractalImg, err = win.ReadImage(f.Src)
if err != nil {
return err
}
return nil
}
