Move everything into a separate futatabi/ subdir, for the upcoming merge with Futatabi.

[nageru] / nageru / vu_common.cpp

diff --git a/nageru/vu_common.cpp b/nageru/vu_common.cpp
new file mode 100644 (file)
index 0000000..171f50d
--- /dev/null
+++ b/nageru/vu_common.cpp
@@ -0,0 +1,73 @@
+#include "vu_common.h"
+
+#include <QColor>
+#include <QPainter>
+#include <algorithm>
+#include <cmath>
+
+using namespace std;
+
+double lufs_to_pos(float level_lu, int height, float min_level, float max_level)
+{
+       // Note: “max” is the loudest level, but y=0 is top of screen.
+
+       // Handle -inf.
+       if (level_lu < min_level) {
+               return height - 1;
+       }
+
+       double y = height * (level_lu - max_level) / (min_level - max_level);
+       y = max<double>(y, 0);
+       y = min<double>(y, height - 1);
+
+       // If we are big enough, snap to pixel grid instead of antialiasing
+       // the edges; the unevenness will be less noticeable than the blurriness.
+       double height_per_level = height / (max_level - min_level) - 2.0;
+       if (height_per_level >= 10.0) {
+               y = round(y);
+       }
+
+       return y;
+}
+
+void draw_vu_meter(QPainter &painter, int width, int height, int horizontal_margin, double segment_margin, bool is_on, float min_level, float max_level, bool flip, int y_offset)
+{
+       painter.fillRect(horizontal_margin, y_offset, width - 2 * horizontal_margin, height, Qt::black);
+
+       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) + segment_margin * 0.5;
+                       double max_y = lufs_to_pos(level, height, min_level, max_level) - segment_margin * 0.5;
+                       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;
+               }
+
+               // Correct for coverage and do a simple gamma correction.
+               int r = lrintf(255 * pow(on_r * coverage, 1.0 / 2.2));
+               int g = lrintf(255 * pow(on_g * coverage, 1.0 / 2.2));
+               int b = lrintf(255 * pow(on_b * coverage, 1.0 / 2.2));
+               int draw_y = flip ? (height - y - 1) : y;
+               painter.fillRect(horizontal_margin, draw_y + y_offset, width - 2 * horizontal_margin, 1, QColor(r, g, b));
+       }
+}