ClipParameters.cpp

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/*  SPDX-License-Identifier: GPL-2.0-or-later */
/**********************************************************************
 
Audacity: A Digital Audio Editor
 
ClipParameters.cpp
 
Matthieu Hodgkinson split from class WaveChannelView.cpp
 
**********************************************************************/
#include "ClipParameters.h"
#include "ClipInterface.h"
#include "ZoomInfo.h"
 
namespace
{
// Returns an offset in seconds to be applied to the right clip
// boundary so that it does not overlap the last sample
double CalculateAdjustmentForZoomLevel(double avgPixPerSecond, bool showSamples)
{
   constexpr double pixelsOffset { 2 }; // The desired offset in pixels
   if (showSamples)
      // adjustment so that the last circular point doesn't appear
      // to be hanging off the end
      return pixelsOffset /
             avgPixPerSecond; // pixels / ( pixels / second ) = seconds
   return .0;
}
 
double GetPixelsPerSecond(const wxRect& viewRect, const ZoomInfo& zoomInfo)
{
   const auto h = zoomInfo.PositionToTime(0, 0, true);
   const auto trackRectT1 = zoomInfo.PositionToTime(viewRect.width, 0, true);
   return viewRect.width / (trackRectT1 - h);
}
 
bool ShowIndividualSamples(
   int sampleRate, double stretchRatio, double pixelsPerSecond)
{
   const auto secondsPerSample = stretchRatio / sampleRate;
   const auto pixelsPerSample = pixelsPerSecond * secondsPerSample;
   return pixelsPerSample > 0.5;
}
 
double GetBlankSpaceBeforePlayEndTime(const ClipTimes& clip)
{
   return 0.99 * clip.GetStretchRatio() / clip.GetRate();
}
} // namespace
 
ClipParameters::ClipParameters(
   const ClipTimes& clip, const wxRect& rect, const ZoomInfo& zoomInfo)
    : trackRectT0 { zoomInfo.PositionToTime(0, 0, true) }
    , averagePixelsPerSecond { GetPixelsPerSecond(rect, zoomInfo) }
    , showIndividualSamples { ShowIndividualSamples(
         clip.GetRate(), clip.GetStretchRatio(), averagePixelsPerSecond) }
{
   const auto trackRectT1 = zoomInfo.PositionToTime(rect.width, 0, true);
   const auto stretchRatio = clip.GetStretchRatio();
   const auto playStartTime = clip.GetPlayStartTime();
 
   const double clipLength = clip.GetPlayEndTime() - clip.GetPlayStartTime();
 
   // Hidden duration because too far left.
   const auto tpre = trackRectT0 - playStartTime;
   const auto tpost = trackRectT1 - playStartTime;
 
   const auto blank = GetBlankSpaceBeforePlayEndTime(clip);
 
   // Calculate actual selection bounds so that t0 > 0 and t1 < the
   // end of the track
   t0 = std::max(tpre, .0);
   t1 = std::min(tpost, clipLength - blank) +
        CalculateAdjustmentForZoomLevel(
           averagePixelsPerSecond, showIndividualSamples);
 
   // Make sure t1 (the right bound) is greater than 0
   if (t1 < 0.0)
   {
      t1 = 0.0;
   }
 
   // Make sure t1 is greater than t0
   if (t0 > t1)
   {
      t0 = t1;
   }
 
   // The variable "hiddenMid" will be the rectangle containing the
   // actual waveform, as opposed to any blank area before
   // or after the track, as it would appear without the fisheye.
   hiddenMid = rect;
 
   // If the left edge of the track is to the right of the left
   // edge of the display, then there's some unused area to the
   // left of the track.  Reduce the "hiddenMid"
   hiddenLeftOffset = 0;
   if (tpre < 0)
   {
      // Fix Bug #1296 caused by premature conversion to (int).
      wxInt64 time64 = zoomInfo.TimeToPosition(playStartTime, 0, true);
      if (time64 < 0)
         time64 = 0;
      hiddenLeftOffset = (time64 < rect.width) ? (int)time64 : rect.width;
 
      hiddenMid.x += hiddenLeftOffset;
      hiddenMid.width -= hiddenLeftOffset;
   }
 
   // If the right edge of the track is to the left of the right
   // edge of the display, then there's some unused area to the right
   // of the track.  Reduce the "hiddenMid" rect by the
   // size of the blank area.
   if (tpost > t1)
   {
      wxInt64 time64 = zoomInfo.TimeToPosition(playStartTime + t1, 0, true);
      if (time64 < 0)
         time64 = 0;
      const int hiddenRightOffset =
         (time64 < rect.width) ? (int)time64 : rect.width;
 
      hiddenMid.width = std::max(0, hiddenRightOffset - hiddenLeftOffset);
   }
   // The variable "mid" will be the rectangle containing the
   // actual waveform, as distorted by the fisheye,
   // as opposed to any blank area before or after the track.
   mid = rect;
 
   // If the left edge of the track is to the right of the left
   // edge of the display, then there's some unused area to the
   // left of the track.  Reduce the "mid"
   leftOffset = 0;
   if (tpre < 0)
   {
      wxInt64 time64 = zoomInfo.TimeToPosition(playStartTime, 0, false);
      if (time64 < 0)
         time64 = 0;
      leftOffset = (time64 < rect.width) ? (int)time64 : rect.width;
 
      mid.x += leftOffset;
      mid.width -= leftOffset;
   }
 
   // If the right edge of the track is to the left of the right
   // edge of the display, then there's some unused area to the right
   // of the track.  Reduce the "mid" rect by the
   // size of the blank area.
   if (tpost > t1)
   {
      wxInt64 time64 = zoomInfo.TimeToPosition(playStartTime + t1, 0, false);
      if (time64 < 0)
         time64 = 0;
      const int distortedRightOffset =
         (time64 < rect.width) ? (int)time64 : rect.width;
 
      mid.width = std::max(0, distortedRightOffset - leftOffset);
   }
}
 
wxRect ClipParameters::GetClipRect(
   const ClipTimes& clip, const ZoomInfo& zoomInfo, const wxRect& viewRect,
   bool* outShowSamples)
{
   const auto pixelsPerSecond = GetPixelsPerSecond(viewRect, zoomInfo);
   const auto showIndividualSamples = ShowIndividualSamples(
      clip.GetRate(), clip.GetStretchRatio(), pixelsPerSecond);
   const auto clipEndingAdjustment =
      CalculateAdjustmentForZoomLevel(pixelsPerSecond, showIndividualSamples);
   if (outShowSamples != nullptr)
      *outShowSamples = showIndividualSamples;
   constexpr auto edgeLeft =
      static_cast<ZoomInfo::int64>(std::numeric_limits<int>::min());
   constexpr auto edgeRight =
      static_cast<ZoomInfo::int64>(std::numeric_limits<int>::max());
   const auto left = std::clamp(
      zoomInfo.TimeToPosition(clip.GetPlayStartTime(), viewRect.x, true),
      edgeLeft, edgeRight);
   const auto right = std::clamp(
      zoomInfo.TimeToPosition(
         clip.GetPlayEndTime() - GetBlankSpaceBeforePlayEndTime(clip) +
            clipEndingAdjustment,
         viewRect.x, true),
      edgeLeft, edgeRight);
   if (right >= left)
   {
      // after clamping we can expect that left and right
      // are small enough to be put into int
      return wxRect(
         static_cast<int>(left), viewRect.y,
         std::max(1, static_cast<int>(right - left)), viewRect.height);
   }
   return wxRect();
}