Mercurial > hg > svgui
view layer/ScrollableImageCache.h @ 1306:5db672d6de4f
Better rendering for widget cells
author | Chris Cannam |
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date | Mon, 25 Jun 2018 15:29:47 +0100 |
parents | a34a2a25907c |
children | bc2cb82050a0 |
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/* -*- 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 "LayerGeometryProvider.h" #include <QImage> #include <QRect> #include <QPainter> /** * A cached image for a view that scrolls horizontally, such as a * 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() : m_validLeft(0), m_validWidth(0), m_startFrame(0), m_zoomLevel(0) {} void invalidate() { m_validWidth = 0; } bool isValid() const { return m_validWidth > 0; } QSize getSize() const { return m_image.size(); } /** * Set the size of the cache. If the new size differs from the * current size, the cache is invalidated. */ void resize(QSize newSize) { if (getSize() != newSize) { m_image = QImage(newSize, QImage::Format_ARGB32_Premultiplied); invalidate(); } } int getValidLeft() const { return m_validLeft; } int getValidWidth() const { return m_validWidth; } int getValidRight() const { return m_validLeft + m_validWidth; } QRect getValidArea() const { return QRect(m_validLeft, 0, m_validWidth, m_image.height()); } int getZoomLevel() const { return m_zoomLevel; } /** * Set the zoom level. If the new zoom level differs from the * current one, the cache is invalidated. (Determining whether to * invalidate the cache here is the only thing the zoom level is * used for.) */ void setZoomLevel(int zoom) { if (m_zoomLevel != zoom) { m_zoomLevel = zoom; invalidate(); } } sv_frame_t getStartFrame() const { return m_startFrame; } /** * Set the start frame. If the new start frame differs from the * current one, the cache is invalidated. To scroll, i.e. to set * the start frame while retaining cache validity where possible, * use scrollTo() instead. */ void setStartFrame(sv_frame_t frame) { if (m_startFrame != frame) { m_startFrame = frame; invalidate(); } } const QImage &getImage() const { return m_image; } /** * Set the new start frame for the cache, according to the * geometry of the supplied LayerGeometryProvider, 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(const LayerGeometryProvider *v, 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. Does not * modify anything about the cache, only about the arguments. */ 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: QImage m_image; int m_validLeft; int m_validWidth; sv_frame_t m_startFrame; int m_zoomLevel; }; #endif