// render renders the background and foreground images onto the window.
func render() (err error) {
// Draw the entire background image onto the screen starting at the top left
// point (0, 0).
dp := image.ZP
err = win.Draw(dp, fractalImg)
if err != nil {
return err
}
return nil
}
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()
}