comparison base/ZoomConstraint.h @ 0:da6937383da8

initial import

+/* -*- c-basic-offset: 4 -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    A waveform viewer and audio annotation editor.
+    Chris Cannam, Queen Mary University of London, 2005
+    
+    This is experimental software.  Not for distribution.
+*/
+
+#ifndef _ZOOM_CONSTRAINT_H_
+#define _ZOOM_CONSTRAINT_H_
+
+#include <stdlib.h>
+
+/**
+ * ZoomConstraint is a simple interface that describes a limitation on
+ * the available zoom sizes for a view, for example based on cache
+ * strategy or a (processing) window-size limitation.
+ *
+ * The default ZoomConstraint imposes no actual constraint.
+ */
+
+class ZoomConstraint
+{
+public:
+    enum RoundingDirection {
+	RoundDown,
+	RoundUp,
+	RoundNearest
+    };
+
+    /**
+     * Given the "ideal" block size (frames per pixel) for a given
+     * zoom level, return the nearest viable block size for this
+     * constraint.
+     *
+     * For example, if a block size of 1523 frames per pixel is
+     * requested but the underlying model only supports value
+     * summaries at powers-of-two block sizes, return 1024 or 2048
+     * depending on the rounding direction supplied.
+     */
+    virtual size_t getNearestBlockSize(size_t requestedBlockSize,
+				       RoundingDirection = RoundNearest)
+	const
+    {
+	return requestedBlockSize;
+    }
+};
+
+#endif
+