rendering the entire waveform data is not necissary and it becomes very slow when your waveform data is long

[ty1135]

rerendering only the visible is enough

[ujas-m-simformsolutions]

@ty1135 That is what I have done for duration labels but how do suggest to approach this for waveform data?

[ty1135]

void paintWave(Canvas canvas, Size size) {
// barWidth * (1 + spacingRatio) * pixelsPerSecond * visibleDuration.inSeconds = size.width
final visiblePixels = pixelsPerSecond! * visibleDuration.inSeconds;
final barWidth = size.width / ((1 + spacingRatio) * visiblePixels);
final spacing = barWidth * spacingRatio;
//
final secondsPerPixel = 1 / pixelsPerSecond!;
final microSecondsPerPixel = secondsPerPixel * 1000 * 1000;
final index = visibleStart ~/ microSecondsPerPixel;

final remainder = visibleStart % microSecondsPerPixel;
final offset = remainder / microSecondsPerPixel * (barWidth + spacing);

defaultPaint.strokeWidth = barWidth;

if (waveFormData != null) {
  for (int i = index;
      i <= index + visiblePixels && i < waveFormData!.length;
      i++) {
    double x = (spacing + barWidth) * (i - index) - offset + spacing;
    Offset bottom = Offset(x, scaleY(waveFormData![2 * i], size.height));
    Offset top = Offset(x, scaleY(waveFormData![2 * i + 1], size.height));
    canvas.drawLine(bottom, top, defaultPaint);
  }
}

}