src/selectionmode/backgroundcolorhelper.h

   1 /*
   2     This file is part of the KDE project
   3     SPDX-FileCopyrightText: 2022 Felix Ernst <felixernst@kde.org>
   4
   5     SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
   6 */
   7
   8 #ifndef BACKGROUNDCOLORHELPER_H
   9 #define BACKGROUNDCOLORHELPER_H
  10
  11 #include <QColor>
  12 #include <QObject>
  13 #include <QPointer>
  14
  15 #include <memory>
  16
  17 class QWidget;
  18
  19 namespace SelectionMode
  20 {
  21
  22 /**
  23  * @brief A Singleton class for managing the colors of selection mode widgets.
  24  */
  25 class BackgroundColorHelper : public QObject
  26 {
  27     Q_OBJECT
  28 public:
  29     static BackgroundColorHelper *instance();
  30
  31     /**
  32      * Changes the background color of @p widget to a distinct color scheme matching color which makes it clear that the widget belongs to the selection mode.
  33      * The background color of @p widget will from now on be updated automatically when the palette of the application changes.
  34      */
  35     void controlBackgroundColor(QWidget *widget);
  36
  37 protected:
  38     bool eventFilter(QObject *obj, QEvent *event) override;
  39
  40 private:
  41     BackgroundColorHelper();
  42
  43     /**
  44      * Called when the palette of the application changes.
  45      * Triggers updateBackgroundColor() and the updates the background color of m_colorControlledWidgets.
  46      * @see updateBackgroundColor
  47      */
  48     void slotPaletteChanged();
  49
  50     /** Calculates a new m_colorControlledWidgets based on the current color scheme of the application. */
  51     void updateBackgroundColor();
  52
  53 private:
  54     /// The widgets who have given up control over the background color to BackgroundColorHelper.
  55     std::vector<QPointer<QWidget>> m_colorControlledWidgets;
  56     /// The color to be used for the widgets' backgrounds.
  57     QColor m_backgroundColor;
  58
  59     /// Singleton object
  60     static BackgroundColorHelper *s_instance;
  61 };
  62
  63 }
  64
  65 #endif // BACKGROUNDCOLORHELPER_H