# HG changeset patch
# User Chris Cannam
# Date 1454408950 0
# Node ID a2d05eba7b0b707e79f54dd670dc7abc512bc2d7
# Parent  9fc23e778bfadabeff85c6a37a647345da8b5735
Add overlooked file!

diff -r 9fc23e778bfa -r a2d05eba7b0b layer/ScrollableImageCache.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layer/ScrollableImageCache.cpp	Tue Feb 02 10:29:10 2016 +0000
@@ -0,0 +1,194 @@
+/* -*- 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.
+*/
+
+#include "ScrollableImageCache.h"
+
+#include <iostream>
+using namespace std;
+
+#define DEBUG_SCROLLABLE_IMAGE_CACHE 1
+
+void
+ScrollableImageCache::scrollTo(sv_frame_t newStartFrame)
+{
+    if (!m_v) throw std::logic_error("ScrollableImageCache: not associated with a LayerGeometryProvider");
+	
+    int dx = (m_v->getXForFrame(m_startFrame) -
+	      m_v->getXForFrame(newStartFrame));
+
+#ifdef DEBUG_SCROLLABLE_IMAGE_CACHE
+    cerr << "ScrollableImageCache::scrollTo: start frame " << m_startFrame
+	 << " -> " << newStartFrame << ", dx = " << dx << endl;
+#endif
+    
+    m_startFrame = newStartFrame;
+	
+    if (!isValid()) {
+	return;
+    }
+
+    int w = m_image.width();
+
+    if (dx == 0) {
+	// haven't moved
+	return;
+    }
+
+    if (dx <= -w || dx >= w) {
+	// scrolled entirely off
+	invalidate();
+	return;
+    }
+	
+    // dx is in range, cache is scrollable
+
+    int dxp = dx;
+    if (dxp < 0) dxp = -dxp;
+
+    int copylen = (w - dxp) * int(sizeof(QRgb));
+    for (int y = 0; y < m_image.height(); ++y) {
+	QRgb *line = (QRgb *)m_image.scanLine(y);
+	if (dx < 0) {
+	    memmove(line, line + dxp, copylen);
+	} else {
+	    memmove(line + dxp, line, copylen);
+	}
+    }
+	
+    // update valid area
+        
+    int px = m_left;
+    int pw = m_width;
+	
+    px += dx;
+	
+    if (dx < 0) {
+	// we scrolled left
+	if (px < 0) {
+	    pw += px;
+	    px = 0;
+	    if (pw < 0) {
+		pw = 0;
+	    }
+	}
+    } else {
+	// we scrolled right
+	if (px + pw > w) {
+	    pw = w - px;
+	    if (pw < 0) {
+		pw = 0;
+	    }
+	}
+    }
+
+    m_left = px;
+    m_width = pw;
+}
+
+void
+ScrollableImageCache::adjustToTouchValidArea(int &left, int &width,
+					     bool &isLeftOfValidArea) const
+{
+    if (left < m_left) {
+	isLeftOfValidArea = true;
+	if (left + width < m_left + m_width) {
+	    width = m_left - left;
+	}
+    } else {
+	isLeftOfValidArea = false;
+	width = left + width - (m_left + m_width);
+	left = m_left + m_width;
+	if (width < 0) width = 0;
+    }
+}
+    
+void
+ScrollableImageCache::drawImage(int left,
+				int width,
+				QImage image,
+				int imageLeft,
+				int imageWidth)
+{
+    if (image.height() != m_image.height()) {
+	cerr << "ScrollableImageCache::drawImage: ERROR: Supplied image height "
+	     << image.height() << " does not match cache height "
+	     << m_image.height() << endl;
+	throw std::logic_error("Image height must match cache height in ScrollableImageCache::drawImage");
+    }
+    if (left < 0 || width < 0 || left + width > m_image.width()) {
+	cerr << "ScrollableImageCache::drawImage: ERROR: Target area (left = "
+	     << left << ", width = " << width << ") out of bounds for cache of "
+	     << "width " << m_image.width() << endl;
+	throw std::logic_error("Target area out of bounds in ScrollableImageCache::drawImage");
+    }
+    if (imageLeft < 0 || imageWidth < 0 ||
+	imageLeft + imageWidth > image.width()) {
+	cerr << "ScrollableImageCache::drawImage: ERROR: Source area (left = "
+	     << imageLeft << ", width = " << imageWidth
+	     << ") out of bounds for image of "
+	     << "width " << image.width() << endl;
+	throw std::logic_error("Source area out of bounds in ScrollableImageCache::drawImage");
+    }
+	
+    QPainter painter(&m_image);
+    painter.drawImage(QRect(left, 0, width, m_image.height()),
+		      image,
+		      QRect(imageLeft, 0, imageWidth, image.height()));
+    painter.end();
+
+    if (!isValid()) {
+	m_left = left;
+	m_width = width;
+	return;
+    }
+	
+    if (left < m_left) {
+	if (left + width > m_left + m_width) {
+	    // new image completely contains the old valid area --
+	    // use the new area as is
+	    m_left = left;
+	    m_width = width;
+	} else if (left + width < m_left) {
+	    // new image completely off left of old valid area --
+	    // we can't extend the valid area because the bit in
+	    // between is not valid, so must use the new area only
+	    m_left = left;
+	    m_width = width;
+	} else {
+	    // new image overlaps old valid area on left side --
+	    // use new left edge, and extend width to existing
+	    // right edge
+	    m_width = (m_left + m_width) - left;
+	    m_left = left;
+	}
+    } else {
+	if (left > m_left + m_width) {
+	    // new image completely off right of old valid area --
+	    // we can't extend the valid area because the bit in
+	    // between is not valid, so must use the new area only
+	    m_left = left;
+	    m_width = width;
+	} else if (left + width > m_left + m_width) {
+	    // new image overlaps old valid area on right side --
+	    // use existing left edge, and extend width to new
+	    // right edge
+	    m_width = (left + width) - m_left;
+	    // (m_left unchanged)
+	} else {
+	    // new image completely contained within old valid
+	    // area -- leave the old area unchanged
+	}
+    }
+}
+