diff base/ZoomLevel.h @ 1551:4de4284d0596

Merge from branch zoom

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/base/ZoomLevel.h	Wed Oct 10 08:44:15 2018 +0100
@@ -0,0 +1,124 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    Sonic Visualiser
+    An audio file viewer and annotation editor.
+    Centre for Digital Music, Queen Mary, University of London.
+    
+    This program is free software; you can redistribute it and/or
+    modify it under the terms of the GNU General Public License as
+    published by the Free Software Foundation; either version 2 of the
+    License, or (at your option) any later version.  See the file
+    COPYING included with this distribution for more information.
+*/
+
+#ifndef SV_ZOOM_LEVEL_H
+#define SV_ZOOM_LEVEL_H
+
+#include "BaseTypes.h"
+
+#include <ostream>
+#include <cmath>
+
+/** Display zoom level. Can be an integer number of samples per pixel,
+ *  or an integer number of pixels per sample.
+ */
+struct ZoomLevel {
+
+    enum Zone {
+        FramesPerPixel, // zoomed out (as in classic SV)
+        PixelsPerFrame  // zoomed in beyond 1-1 (interpolating the waveform)
+    };
+
+    Zone zone;
+    int level;
+
+    ZoomLevel() : zone(FramesPerPixel), level(1) { }
+    ZoomLevel(Zone z, int lev) : zone(z), level(lev) { }
+    
+    bool operator<(const ZoomLevel &other) const {
+        if (zone == FramesPerPixel) {
+            if (other.zone == zone) {
+                return level < other.level;
+            } else {
+                return false;
+            }
+        } else {
+            if (other.zone == zone) {
+                return level > other.level;
+            } else {
+                return false;
+            }
+        }
+    }
+
+    bool operator==(const ZoomLevel &other) const {
+        return (zone == other.zone && level == other.level);
+    }
+
+    ZoomLevel incremented() const {
+        if (zone == FramesPerPixel) {
+            return { zone, level + 1 };
+        } else if (level == 1) {
+            return { FramesPerPixel, 2 };
+        } else if (level == 2) {
+            return { FramesPerPixel, 1 };
+        } else {
+            return { zone, level - 1 };
+        }
+    }
+
+    ZoomLevel decremented() const {
+        if (zone == PixelsPerFrame) {
+            return { zone, level + 1 };
+        } else if (level == 1) {
+            return { PixelsPerFrame, 2 };
+        } else {
+            return { zone, level - 1 };
+        }
+    }
+
+    /** Inexact conversion. The result is a whole number if we are
+     *  zoomed in enough (in PixelsPerFrame zone), a fraction
+     *  otherwise.
+     */
+    double framesToPixels(double frames) const {
+        if (zone == PixelsPerFrame) {
+            return frames * level;
+        } else {
+            return frames / level;
+        }
+    }
+
+    /** Inexact conversion. The result is a whole number if we are
+     *  zoomed out enough (in FramesPerPixel zone), a fraction
+     *  otherwise.
+     */
+    double pixelsToFrames(double pixels) const {
+        if (zone == PixelsPerFrame) {
+            return pixels / level;
+        } else {
+            return pixels * level;
+        }
+    }
+
+    /** Return a ZoomLevel that approximates the given ratio of pixels
+     *  to frames.
+     */
+    static ZoomLevel fromRatio(int pixels, sv_frame_t frames) {
+        if (pixels < frames) {
+            return { FramesPerPixel, int(round(double(frames)/pixels)) };
+        } else {
+            int r = int(round(pixels/double(frames)));
+            if (r > 1) {
+                return { PixelsPerFrame, r };
+            } else {
+                return { FramesPerPixel, 1 };
+            }
+        }
+    }
+};
+
+std::ostream &operator<<(std::ostream &s, const ZoomLevel &z);
+
+#endif