try to narrow down #6478

[ardour.git] / libs / canvas / wave_view.cc

diff --git a/libs/canvas/wave_view.cc b/libs/canvas/wave_view.cc
index bf99748c2c5daaf3a721c77431203000d01465b6..ca026e978803427106e7df05115ddcbe9137344d 100644 (file)
--- a/libs/canvas/wave_view.cc
+++ b/libs/canvas/wave_view.cc
@@ -987,6 +987,8 @@ WaveView::generate_image (boost::shared_ptr<WaveViewThreadRequest> req, bool in_
                framepos_t sample_end = min (center + image_samples, region_end());
                const int n_peaks = llrintf ((sample_end - sample_start)/ (req->samples_per_pixel));
 
+               assert (n_peaks > 0 && n_peaks < 32767);
+
                boost::scoped_array<ARDOUR::PeakData> peaks (new PeakData[n_peaks]);
 
                /* Note that Region::read_peaks() takes a start position based on an
@@ -1000,6 +1002,13 @@ WaveView::generate_image (boost::shared_ptr<WaveViewThreadRequest> req, bool in_
                                                             req->samples_per_pixel);
 
                req->image = Cairo::ImageSurface::create (Cairo::FORMAT_ARGB32, n_peaks, req->height);
+
+               // http://cairographics.org/manual/cairo-Image-Surfaces.html#cairo-image-surface-create
+               // This function always returns a valid pointer, but it will return a pointer to a "nil" surface..
+               // but there's some evidence that req->image can be NULL.
+               // http://tracker.ardour.org/view.php?id=6478
+               assert (req->image);
+
                /* make sure we record the sample positions that were actually used */
                req->start = sample_start;
                req->end = sample_end;