diff layer/ScrollableImageCache.h @ 1043:fccee028a522 3.0-integration

Merge from branch "spectrogram-minor-refactor"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layer/ScrollableImageCache.h	Thu Feb 04 11:18:08 2016 +0000
@@ -0,0 +1,145 @@
+/* -*- 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 SCROLLABLE_IMAGE_CACHE_H
+#define SCROLLABLE_IMAGE_CACHE_H
+
+#include "base/BaseTypes.h"
+
+#include "view/LayerGeometryProvider.h"
+
+#include <QImage>
+#include <QRect>
+#include <QPainter>
+
+/**
+ * A cached image for a view that scrolls horizontally, primarily the
+ * spectrogram. The cache object holds an image, reports the size of
+ * the image (likely the same as the underlying view, but it's the
+ * caller's responsibility to set the size appropriately), can scroll
+ * the image, and can report and update which contiguous horizontal
+ * range of the image is valid.
+ *
+ * The only way to *update* the valid area in a cache is to draw to it
+ * using the drawImage call.
+ */
+class ScrollableImageCache
+{
+public:
+    ScrollableImageCache(const LayerGeometryProvider *v = 0) :
+	m_v(v),
+	m_left(0),
+	m_width(0),
+	m_startFrame(0),
+	m_zoomLevel(0)
+    {}
+
+    void invalidate() {
+	m_width = 0;
+    }
+    
+    bool isValid() const {
+	return m_width > 0;
+    }
+
+    QSize getSize() const {
+	return m_image.size();
+    }
+    
+    void resize(QSize newSize) {
+	m_image = QImage(newSize, QImage::Format_ARGB32_Premultiplied);
+	invalidate();
+    }
+	
+    int getValidLeft() const {
+	return m_left;
+    }
+    
+    int getValidWidth() const {
+	return m_width;
+    }
+
+    int getValidRight() const {
+	return m_left + m_width;
+    }
+
+    QRect getValidArea() const {
+	return QRect(m_left, 0, m_width, m_image.height());
+    }
+    
+    int getZoomLevel() const {
+	return m_zoomLevel;
+    }
+    
+    void setZoomLevel(int zoom) {
+	m_zoomLevel = zoom;
+	invalidate();
+    }
+
+    sv_frame_t getStartFrame() const {
+	return m_startFrame;
+    }
+
+    /**
+     * Set the start frame and invalidate the cache. To scroll,
+     * i.e. to set the start frame while retaining cache validity
+     * where possible, use scrollTo() instead.
+     */
+    void setStartFrame(sv_frame_t frame) {
+	m_startFrame = frame;
+	invalidate();
+    }
+    
+    const QImage &getImage() const {
+	return m_image;
+    }
+
+    /**
+     * Set the new start frame for the cache, if possible also moving
+     * along any existing valid data within the cache so that it
+     * continues to be valid for the new start frame.
+     */
+    void scrollTo(sv_frame_t newStartFrame);
+
+    /**
+     * Take a left coordinate and width describing a region, and
+     * adjust them so that they are contiguous with the cache valid
+     * region and so that the union of the adjusted region with the
+     * cache valid region contains the supplied region.
+     */
+    void adjustToTouchValidArea(int &left, int &width,
+				bool &isLeftOfValidArea) const;
+    /**
+     * Draw from an image onto the cache. The supplied image must have
+     * the same height as the cache and the full height is always
+     * drawn. The left and width parameters determine the target
+     * region of the cache, the imageLeft and imageWidth parameters
+     * the source region of the image.
+     */
+    void drawImage(int left,
+		   int width,
+		   QImage image,
+		   int imageLeft,
+		   int imageWidth);
+    
+private:
+    const LayerGeometryProvider *m_v;
+    QImage m_image;
+    int m_left;  // of valid region
+    int m_width; // of valid region
+    sv_frame_t m_startFrame;
+    int m_zoomLevel;
+};
+
+#endif