diff base/ZoomLevel.h @ 1532:5360f7aba189 zoom

Pull out ZoomLevel, add inexact frame/pixel conversion functions and streaming

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/base/ZoomLevel.h	Wed Sep 19 15:41:44 2018 +0100
@@ -0,0 +1,98 @@
+/* -*- 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 <ostream>
+
+/** 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
+    double framesToPixels(double frames) const {
+        if (zone == PixelsPerFrame) {
+            return frames * level;
+        } else {
+            return frames / level;
+        }
+    }
+
+    /// Inexact
+    double pixelsToFrames(double pixels) const {
+        if (zone == PixelsPerFrame) {
+            return pixels / level;
+        } else {
+            return pixels * level;
+        }
+    }
+};
+
+std::ostream &operator<<(std::ostream &s, const ZoomLevel &z);
+
+#endif