fix various AudioFileProcessor bugs (#7533)

* fix out-of-bounds crash in AudioFileProcessor

by correctly setting m_from and m_to without them interfering with each other

* fixed flattened wave caused by inaccurate math

see PR for before/after

* simply stop drawing AFP waveform when there's no more data

this fixes the single point at the end of waveforms that sometimes shows up

* fixed seemingly insignificant type confusion (?)

execution seemed fine but my debugger started freaking out,
and if gdb is telling me I got a negative-sized vector,
I'd rather fix this issue than speculate "it's probably fine"

* fixed data offset for AFP waveform vis

the data itself isn't reversed, so we have to account for that

plugins/AudioFileProcessor/AudioFileProcessorWaveView.cpp

@@ -338,10 +338,12 @@ void AudioFileProcessorWaveView::updateGraph()
 	m_graph.fill(Qt::transparent);
 	QPainter p(&m_graph);
 	p.setPen(QColor(255, 255, 255));
+
+	const auto dataOffset = m_reversed ? m_sample->sampleSize() - m_to : m_from;
 
 	const auto rect = QRect{0, 0, m_graph.width(), m_graph.height()};
 	const auto waveform = SampleWaveform::Parameters{
-		m_sample->data() + m_from, static_cast<size_t>(range()), m_sample->amplification(), m_sample->reversed()};
+		m_sample->data() + dataOffset, static_cast<size_t>(range()), m_sample->amplification(), m_sample->reversed()};
 	SampleWaveform::visualize(waveform, p, rect);
 }
 
@@ -467,9 +469,11 @@ void AudioFileProcessorWaveView::reverse()
 			- m_sample->endFrame()
 			- m_sample->startFrame()
 	);
+
+	const int fromTmp = m_from;
 
 	setFrom(m_sample->sampleSize() - m_to);
-	setTo(m_sample->sampleSize() - m_from);
+	setTo(m_sample->sampleSize() - fromTmp);
 	m_reversed = ! m_reversed;
 }
 

src/gui/SampleWaveform.cpp

@@ -44,12 +44,12 @@ void SampleWaveform::visualize(Parameters parameters, QPainter& painter, const Q
 	const float resolution = std::max(1.0f, framesPerPixel / maxFramesPerPixel);
 	const float framesPerResolution = framesPerPixel / resolution;
 
-	const size_t numPixels = std::min<size_t>(parameters.size, width);
+	size_t numPixels = std::min(parameters.size, static_cast<size_t>(width));
 	auto min = std::vector<float>(numPixels, 1);
 	auto max = std::vector<float>(numPixels, -1);
 	auto squared = std::vector<float>(numPixels, 0);
 
-	const size_t maxFrames = numPixels * static_cast<size_t>(framesPerPixel);
+	const size_t maxFrames = static_cast<size_t>(numPixels * framesPerPixel);
 
 	auto pixelIndex = std::size_t{0};
 
@@ -67,12 +67,9 @@ void SampleWaveform::visualize(Parameters parameters, QPainter& painter, const Q
 		squared[pixelIndex] += value * value;
 	}
 
-	while (pixelIndex < numPixels)
+	if (pixelIndex < numPixels)
 	{
-		max[pixelIndex] = 0.0;
-		min[pixelIndex] = 0.0;
-
-		pixelIndex++;
+		numPixels = pixelIndex;
 	}
 
 	for (auto i = std::size_t{0}; i < numPixels; i++)