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Maintain the current scroll position when zooming #172

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merged 1 commit into from
Oct 1, 2020
Merged

Maintain the current scroll position when zooming #172

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21 changes: 14 additions & 7 deletions plotview.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -330,7 +330,7 @@ void PlotView::exportSamples(std::shared_ptr<AbstractSampleSource> src)

if (dialog.exec()) {
QStringList fileNames = dialog.selectedFiles();

size_t start, end;
if (cursorSelection.isChecked()) {
start = selectedSamples.minimum;
Expand All @@ -350,7 +350,7 @@ void PlotView::exportSamples(std::shared_ptr<AbstractSampleSource> src)
size_t step = viewRange.length();

for (index = start; index < end; index += step) {
size_t length = std::min(step, end - index);
size_t length = std::min(step, end - index);
auto samples = sampleSrc->getSamples(index, length);
if (samples != nullptr) {
for (auto i = 0; i < length; i += decimation.value()) {
Expand Down Expand Up @@ -387,6 +387,8 @@ void PlotView::setCursorSegments(int segments)

void PlotView::setFFTAndZoom(int size, int zoom)
{
auto oldSamplesPerColumn = samplesPerColumn();

// Set new FFT size
fftSize = size;
if (spectrogramPlot != nullptr)
Expand All @@ -401,7 +403,7 @@ void PlotView::setFFTAndZoom(int size, int zoom)
horizontalScrollBar()->setSingleStep(10);
horizontalScrollBar()->setPageStep(100);

updateView(true);
updateView(true, samplesPerColumn() < oldSamplesPerColumn);
}

void PlotView::setPowerMin(int power)
Expand Down Expand Up @@ -542,15 +544,20 @@ void PlotView::updateViewRange(bool reCenter)
sampleToColumn(zoomSample) - zoomPos
);
}
// zoomSample = viewRange.minimum + viewRange.length() / 2;
// zoomPos = width() / 2;
zoomSample = viewRange.minimum + viewRange.length() / 2;
zoomPos = width() / 2;
}

void PlotView::updateView(bool reCenter)
void PlotView::updateView(bool reCenter, bool expanding)
{
if (!expanding) {
updateViewRange(reCenter);
}
horizontalScrollBar()->setMaximum(std::max(0, sampleToColumn(mainSampleSource->count()) - width()));
verticalScrollBar()->setMaximum(std::max(0, plotsHeight() - viewport()->height()));
updateViewRange(reCenter);
if (expanding) {
updateViewRange(reCenter);
}

// Update cursors
range_t<int> newSelection = {
Expand Down
4 changes: 2 additions & 2 deletions plotview.h
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Original file line number Diff line number Diff line change
Expand Up @@ -71,7 +71,7 @@ public slots:
size_t zoomSample;

int fftSize = 1024;
int zoomLevel = 0;
int zoomLevel = 1;
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I changed this to 1 because 0 is invalid and causes PlotView::samplesPerColumn() to crash due to a division by zero.

int powerMin;
int powerMax;
bool cursorsEnabled;
Expand All @@ -87,7 +87,7 @@ public slots:
int plotsHeight();
size_t samplesPerColumn();
void updateViewRange(bool reCenter);
void updateView(bool reCenter = false);
void updateView(bool reCenter = false, bool expanding = false);
void paintTimeScale(QPainter &painter, QRect &rect, range_t<size_t> sampleRange);

int sampleToColumn(size_t sample);
Expand Down