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()
}
// simple demonstrates how to draw images using the Draw and DrawRect methods.
// It also gives an example of a basic event loop.
func simple() (err error) {
runtime.GOMAXPROCS(runtime.NumCPU())
defer profile.Start(profile.CPUProfile).Stop()
// Open the window.
err = win.Open(width, height, win.Resizeable)
if err != nil {
return err
}
defer win.Close()
// Load image resources.
err = loadResources()
if err != nil {
return err
}
defer freeResources()
// start and frames will be used to calculate the average FPS of the
// application.
start := time.Now()
frames := 0
// Render the images onto the window.
err = render()
if err != nil {
return err
}
// Update and event loop.
for {
// Display window updates on screen.
err = win.Update()
if err != nil {
return err
}
frames++
// Poll events until the event queue is empty.
for e := win.PollEvent(); e != nil; e = win.PollEvent() {
fmt.Printf("%T event: %v\n", e, e)
switch obj := e.(type) {
case we.KeyPress:
r := obj.Key.String()
err = zz(r)
case we.KeyRepeat:
r := obj.Key.String()
err = zz(r)
case we.KeyRune:
r := obj.String()
err = zz(r)
}
if err != nil {
return err
}
switch e.(type) {
case we.Close:
displayFPS(start, frames)
// Close the application.
return nil
case we.Resize:
// Rerender the images onto the window after resize events.
err = render()
if err != nil {
return err
}
}
}
// Cap refresh rate at 30 FPS.
time.Sleep(time.Second / 30)
}
}