- // TODO: QLinearGradient is not gamma-correct; we might want to correct for that.
- QLinearGradient on(0, 0, 0, height);
- on.setColorAt(0.0f, QColor(255, 0, 0));
- on.setColorAt(0.5f, QColor(255, 255, 0));
- on.setColorAt(1.0f, QColor(0, 255, 0));
- QColor off(80, 80, 80);
-
- int min_on_y = lufs_to_pos(range_high_lu, height);
- int max_on_y = lufs_to_pos(range_low_lu, height);
-
- // Draw bars colored up until the level, then gray from there.
- for (int level = -18; level < 9; ++level) {
- int min_y = lufs_to_pos(level + 1.0f, height) + 1;
- int max_y = lufs_to_pos(level, height) - 1;
-
- painter.fillRect(margin, min_y, width - 2 * margin, max_y - min_y, off);
- int min_draw_y = std::max(min_y, min_on_y);
- int max_draw_y = std::min(max_y, max_on_y);
- if (min_draw_y < max_draw_y) {
- painter.fillRect(margin, min_draw_y, width - 2 * margin, max_draw_y - min_draw_y, on);
+ for (int y = 0; y < height; ++y) {
+ // Find coverage of “on” rectangles in this pixel row.
+ double coverage = 0.0;
+ for (int level = floor(min_level); level <= ceil(max_level); ++level) {
+ double min_y = lufs_to_pos(level + 1.0, height, min_level, max_level) + 1.0;
+ double max_y = lufs_to_pos(level, height, min_level, max_level) - 1.0;
+ min_y = std::max<double>(min_y, y);
+ min_y = std::min<double>(min_y, y + 1);
+ max_y = std::max<double>(max_y, y);
+ max_y = std::min<double>(max_y, y + 1);
+ coverage += max_y - min_y;
+ }
+
+ double on_r, on_g, on_b;
+ if (is_on) {
+ double t = double(y) / height;
+ if (t <= 0.5) {
+ on_r = 1.0;
+ on_g = 2.0 * t;
+ on_b = 0.0;
+ } else {
+ on_r = 1.0 - 2.0 * (t - 0.5);
+ on_g = 1.0;
+ on_b = 0.0;
+ }
+ } else {
+ on_r = on_g = on_b = 0.05;