comparison widgets/IconLoader.cpp @ 289:4ca7562dd246

* Add icon loader that automatically inverts icons where appropriate for
  (slightly) better display on a dark background

+/* -*- 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 file copyright 2007 QMUL.
+    
+    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 "IconLoader.h"
+
+#include <QPixmap>
+#include <QApplication>
+#include <QPainter>
+#include <QPalette>
+
+static const char *autoInvertExceptions[] = {
+    // These are the icons that look OK in their default colours, even
+    // in a colour scheme with a black background.  (They may also be
+    // icons that would look worse if we tried to auto-invert them.)
+    // If we have icons that look bad when auto-inverted but that are
+    // not suitable for use without being inverted, we'll need to
+    // supply inverted versions -- the loader will load xx_inverse.png
+    // in preference to xx.png if a dark background is found.)
+    "fileclose",
+    "filenew-22",
+    "filenew",
+    "fileopen-22",
+    "fileopen",
+    "fileopenaudio",
+    "fileopensession",
+    "filesave-22",
+    "filesave",
+    "filesaveas-22",
+    "filesaveas",
+    "help",
+    "editcut",
+    "editcopy",
+    "editpaste",
+    "editdelete",
+    "exit",
+    "zoom-fit",
+    "zoom-in",
+    "zoom-out",
+    "zoom"
+};
+
+QIcon
+IconLoader::load(QString name)
+{
+    QPixmap pmap(loadPixmap(name));
+    if (pmap.isNull()) return QIcon();
+    else return QIcon(pmap);
+}
+
+QPixmap
+IconLoader::loadPixmap(QString name)
+{
+    QColor bg = QApplication::palette().window().color();
+    if (bg.red() + bg.green() + bg.blue() > 384) { // light background
+        QPixmap pmap(QString(":icons/%1").arg(name));
+        if (pmap.isNull()) {
+            pmap = QPixmap(QString(":icons/%1.png").arg(name));
+        }
+        return pmap;
+    }
+
+    QPixmap pmap(QString(":icons/%1").arg(name));
+    if (pmap.isNull()) {
+        pmap = QPixmap(QString(":icons/%1_inverse.png").arg(name));
+        if (pmap.isNull()) {
+            pmap = QPixmap(QString(":icons/%1.png").arg(name));
+        }
+    }
+    if (pmap.isNull()) return pmap;
+
+    for (int i = 0; i < sizeof(autoInvertExceptions)/
+                        sizeof(autoInvertExceptions[0]); ++i) {
+        if (autoInvertExceptions[i] == name) {
+            return pmap;
+        }
+    }
+
+    // No suitable inverted icon found for black background; try to
+    // auto-invert the default one
+
+    QImage img = pmap.toImage().convertToFormat(QImage::Format_ARGB32);
+
+    for (int y = 0; y < img.height(); ++y) {
+        for (int x = 0; x < img.width(); ++x) {
+
+            QRgb rgba = img.pixel(x, y);
+            QColor colour = QColor
+                (qRed(rgba), qGreen(rgba), qBlue(rgba), qAlpha(rgba));
+
+            int alpha = colour.alpha();
+            if (colour.saturation() < 5 && colour.alpha() > 10) {
+                colour.setHsv(colour.hue(),
+                              colour.saturation(),
+                              255 - colour.value());
+                colour.setAlpha(alpha);
+                img.setPixel(x, y, colour.rgba());
+            }
+        }
+    }
+
+    pmap = QPixmap::fromImage(img);
+    return pmap;
+}
+