_current_image.reset ();
}
-Coord
-WaveView::y_extent (double s, bool /*round_to_lower_edge*/) const
+void
+WaveView::compute_tips (PeakData const & peak, WaveView::LineTips& tips) const
{
- /* it is important that this returns an integral value, so that we
- * can ensure correct single pixel behaviour.
- *
- * we need (_height - max(wave_line_width))
- * wave_line_width == 1 IFF top==bottom (1 sample per pixel or flat line)
- * wave_line_width == 2 otherwise
- * then round away from the zero line, towards peak
- */
- if (_shape == Rectified) {
- // we only ever have 1 point and align to the bottom (not center)
- return floor ((1.0 - s) * (_height - 2.0));
- } else {
- /* currently canvas rectangle is off-by-one and we
- * cannot draw a pixel at 0 (-.5 .. +.5) without it being
- * clipped. A value 1.0 (ideally one point at y=0) ends
- * up a pixel down. and a value of -1.0 (ideally y = _height-1)
- * currently is on the bottom separator line :(
- * So to make the complete waveform appear centered in
- * a region, we translate by +.5 (instead of -.5)
- * and waste two pixel of height: -4 (instad of -2)
- *
- * This needs fixing in canvas/rectangle the intersect
- * functions and probably a couple of other places as well...
+ const double effective_height = _height;
+
+ /* remember: canvas (and cairo) coordinate space puts the origin at the upper left.
+
+ So, a sample value of 1.0 (0dbFS) will be computed as:
+
+ (1.0 - 1.0) * 0.5 * effective_height
+
+ which evaluates to 0, or the top of the image.
+
+ A sample value of -1.0 will be computed as
+
+ (1.0 + 1.0) * 0.5 * effective height
+
+ which evaluates to effective height, or the bottom of the image.
+ */
+
+ const double pmax = (1.0 - peak.max) * 0.5 * effective_height;
+ const double pmin = (1.0 - peak.min) * 0.5 * effective_height;
+
+ /* remember that the bottom of the image (pmin) has larger y-coordinates
+ than the top (pmax).
+ */
+
+ double spread = (pmin - pmax) * 0.5;
+
+ /* find the nearest pixel to the nominal center. */
+ const double center = round (pmin - spread);
+
+ if (spread < 1.0) {
+ /* minimum distance between line ends is 1 pixel, and we want it "centered" on a pixel,
+ as per cairo single-pixel line issues.
+
+ NOTE: the caller will not draw a line between these two points if the spread is
+ less than 2 pixels. So only the tips.top value matters, which is where we will
+ draw a single pixel as part of the outline.
*/
- Coord pos;
- if (s < 0) {
- pos = ceil ((1.0 - s) * .5 * (_height - 4.0));
- } else {
- pos = floor ((1.0 - s) * .5 * (_height - 4.0));
- }
- return min (_height - 4.0, (max (0.0, pos)));
+ tips.top = center;
+ tips.bot = center + 1.0;
+ } else {
+ /* round spread above and below center to an integer number of pixels */
+ spread = round (spread);
+ /* top and bottom are located equally either side of the center */
+ tips.top = center - spread;
+ tips.bot = center + spread;
}
+
+ tips.top = min (effective_height, max (0.0, tips.top));
+ tips.bot = min (effective_height, max (0.0, tips.bot));
+}
+
+
+Coord
+WaveView::y_extent (double s) const
+{
+ assert (_shape == Rectified);
+ return floor ((1.0 - s) * _height);
}
void
context->fill ();
}
-struct LineTips {
- double top;
- double bot;
- double spread;
- bool clip_max;
- bool clip_min;
-
- LineTips() : top (0.0), bot (0.0), clip_max (false), clip_min (false) {}
-};
-
struct ImageSet {
Cairo::RefPtr<Cairo::ImageSurface> wave;
Cairo::RefPtr<Cairo::ImageSurface> outline;
tips[i].bot = height() - 1.0;
const double p = alt_log_meter (fast_coefficient_to_dB (max (fabs (_peaks[i].max), fabs (_peaks[i].min))));
- tips[i].top = y_extent (p, false);
- tips[i].spread = p * (_height - 1.0);
+ tips[i].top = y_extent (p);
+ tips[i].spread = p * _height;
if (_peaks[i].max >= clip_level) {
tips[i].clip_max = true;
tips[i].bot = height() - 1.0;
const double p = max(fabs (_peaks[i].max), fabs (_peaks[i].min));
- tips[i].top = y_extent (p, false);
- tips[i].spread = p * (_height - 2.0);
+ tips[i].top = y_extent (p);
+ tips[i].spread = p * _height;
if (p >= clip_level) {
tips[i].clip_max = true;
}
if (_logscaled) {
for (int i = 0; i < n_peaks; ++i) {
- double top = _peaks[i].max;
- double bot = _peaks[i].min;
+ PeakData p;
+ p.max = _peaks[i].max;
+ p.min = _peaks[i].min;
if (_peaks[i].max >= clip_level) {
- tips[i].clip_max = true;
+ tips[i].clip_max = true;
}
if (-(_peaks[i].min) >= clip_level) {
tips[i].clip_min = true;
}
- if (top > 0.0) {
- top = alt_log_meter (fast_coefficient_to_dB (top));
- } else if (top < 0.0) {
- top =-alt_log_meter (fast_coefficient_to_dB (-top));
+ if (p.max > 0.0) {
+ p.max = alt_log_meter (fast_coefficient_to_dB (p.max));
+ } else if (p.max < 0.0) {
+ p.max =-alt_log_meter (fast_coefficient_to_dB (-p.max));
} else {
- top = 0.0;
+ p.max = 0.0;
}
- if (bot > 0.0) {
- bot = alt_log_meter (fast_coefficient_to_dB (bot));
- } else if (bot < 0.0) {
- bot = -alt_log_meter (fast_coefficient_to_dB (-bot));
+ if (p.min > 0.0) {
+ p.min = alt_log_meter (fast_coefficient_to_dB (p.min));
+ } else if (p.min < 0.0) {
+ p.min = -alt_log_meter (fast_coefficient_to_dB (-p.min));
} else {
- bot = 0.0;
+ p.min = 0.0;
}
-
- tips[i].top = y_extent (top, false);
- tips[i].bot = y_extent (bot, true);
+
+ compute_tips (p, tips[i]);
tips[i].spread = tips[i].bot - tips[i].top;
}
tips[i].clip_min = true;
}
- tips[i].top = y_extent (_peaks[i].max, false);
- tips[i].bot = y_extent (_peaks[i].min, true);
+ compute_tips (_peaks[i], tips[i]);
tips[i].spread = tips[i].bot - tips[i].top;
}
/* ensure single-pixel lines */
wave_context->set_line_width (1.0);
- wave_context->translate (0.5, +1.5);
+ wave_context->translate (0.5, 0.5);
outline_context->set_line_width (1.0);
- outline_context->translate (0.5, +1.5);
+ outline_context->translate (0.5, 0.5);
clip_context->set_line_width (1.0);
- clip_context->translate (0.5, +1.5);
+ clip_context->translate (0.5, 0.5);
zero_context->set_line_width (1.0);
- zero_context->translate (0.5, +1.5);
+ zero_context->translate (0.5, 0.5);
/* the height of the clip-indicator should be at most 7 pixels,
* or 5% of the height of the waveview item.
outline_context->stroke ();
} else {
- const double height_2 = (_height - 2.5) * .5;
+ const double height_2 = _height * .5;
for (int i = 0; i < n_peaks; ++i) {
wave_context->move_to (i, tips[i].top);
wave_context->line_to (i, tips[i].bot);
}
+
/* draw square waves and other discontiguous points clearly */
if (i > 0) {
if (tips[i-1].top + 2 < tips[i].top) {
}
}
- /* zero line */
+ /* zero line, show only if there is enough spread */
if (tips[i].spread >= 5.0 && show_zero_line()) {
zero_context->move_to (i, floor(height_2));
}
if (!clipped) {
- outline_context->move_to (i, tips[i].bot + 1.0);
- /* normal lower terminal dot */
+ outline_context->move_to (i, tips[i].bot);
+ /* normal lower terminal dot; line moves up */
outline_context->rel_line_to (0, -1.0);
- outline_context->move_to (i, tips[i].top - 1.0);
- /* normal upper terminal dot */
+ outline_context->move_to (i, tips[i].top);
+ /* normal upper terminal dot, line moves down */
outline_context->rel_line_to (0, 1.0);
}
} else {
projects / ardour.git / commitdiff