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revert drawing of rectified waves back to previous approach since it (might be) slightly more efficient and is simpler to understand; add comments

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This commit is contained in:
Paul Davis 2014-06-23 15:12:30 -04:00
parent 437099fff9
commit a743e68a0c
1 changed files with 55 additions and 12 deletions
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67
libs/canvas/wave_view.cc
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@ -512,52 +512,90 @@ WaveView::draw_image (Cairo::RefPtr<Cairo::ImageSurface>& image, PeakData* _peak
context->set_line_width (0.5);
context->translate (0.5, 0.0);
/* draw the lines */
/* the height of the clip-indicator should be at most 7 pixels,
* or 5% of the height of the waveview item.
*/
const double clip_height = min (7.0, ceil (_height * 0.05));
/* There are 3 possible components to draw at each x-axis position: the
waveform "line", the zero line and an outline/clip indicator. We
have to decide which of the 3 to draw at each position, pixel by
pixel. This makes the rendering less efficient but it is the only
way I can see to do this correctly.
With only 1 pixel of spread between the top and bottom of the line,
we just draw the upper outline/clip indicator.
With 2 pixels of spread, we draw the upper and lower outline clip
indicators.
With 3 pixels of spread we draw the upper and lower outline/clip
indicators and at least 1 pixel of the waveform line.
With 5 pixels of spread, we draw all components.
We can do rectified as two separate passes because we have a much
easier decision regarding whether to draw the waveform line. We
always draw the clip/outline indicators.
*/
if (_shape == WaveView::Rectified) {
for (int i = 0; i < n_peaks; ++i) {
/* waveform line */
if (tips[i].spread >= 2.0) {
context->move_to (i, tips[i].top);
context->line_to (i, tips[i].bot);
context->stroke ();
}
context->save ();
}
context->stroke ();
/* outline/clip indicators */
set_source_rgba (context, _outline_color);
for (int i = 0; i < n_peaks; ++i) {
context->move_to (i, tips[i].top);
if (_global_show_waveform_clipping && (tips[i].clip_max || tips[i].clip_min)) {
/* clip-indicating upper terminal line */
set_source_rgba (context, _clip_color);
context->rel_line_to (0, clip_height);
context->rel_line_to (0, min (clip_height, floor (tips[i].spread)));
context->stroke ();
set_source_rgba (context, _outline_color);
} else {
/* normal upper terminal dot */
set_source_rgba (context, _outline_color);
context->rel_line_to (0, 1.0);
context->stroke ();
}
context->restore ();
}
} else {
/* Note the use of cairo save/restore pairs to retain the drawing
context for the waveform lines, which is already set
correctly when we reach here.
*/
for (int i = 0; i < n_peaks; ++i) {
/* waveform line */
if (tips[i].spread >= 3.0) {
context->move_to (i, tips[i].top);
context->line_to (i, tips[i].bot);
context->stroke ();
}
if (tips[i].spread >= 3.0 && show_zero_line()) {
/* zero line */
if (tips[i].spread >= 5.0 && show_zero_line()) {
context->save ();
set_source_rgba (context, _zero_color);
context->move_to (0, _height/2.0);
@ -568,11 +606,13 @@ WaveView::draw_image (Cairo::RefPtr<Cairo::ImageSurface>& image, PeakData* _peak
context->save ();
/* upper outline/clip indicator */
context->move_to (i, tips[i].top);
if (_global_show_waveform_clipping && ((_shape == WaveView::Rectified && (tips[i].clip_max || tips[i].clip_min)) || tips[i].clip_max)) {
/* clip-indicating upper terminal line */
set_source_rgba (context, _clip_color);
context->rel_line_to (0, clip_height);
context->rel_line_to (0, min (clip_height, floor (tips[i].spread)));
context->stroke ();
} else {
/* normal upper terminal dot */
@ -584,12 +624,15 @@ WaveView::draw_image (Cairo::RefPtr<Cairo::ImageSurface>& image, PeakData* _peak
context->restore ();
if (tips[i].spread >= 2.0) {
/* lower outline/clip indicator */
context->save ();
context->move_to (i, tips[i].bot);
if (_global_show_waveform_clipping && _shape != WaveView::Rectified && tips[i].clip_min) {
/* clip-indicating lower terminal line */
set_source_rgba (context, _clip_color);
context->rel_line_to (0, -clip_height);
context->rel_line_to (0, -(min (clip_height, floor (tips[i].spread))));
context->stroke ();
} else {
/* normal lower terminal dot */