1 files changed, 90 insertions, 0 deletions
diff --git a/src/animatedheightwidget.cpp b/src/animatedheightwidget.cpp
new file mode 100644
index 000000000..cee1a4922
--- /dev/null
+++ b/src/animatedheightwidget.cpp
@@ -0,0 +1,90 @@
+/*
+    This file is part of the KDE project
+    SPDX-FileCopyrightText: 2024 Felix Ernst <[email protected]>
+
+    SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
+*/
+
+#include "animatedheightwidget.h"
+
+#include <QGridLayout>
+#include <QPropertyAnimation>
+#include <QScrollArea>
+#include <QStyle>
+
+AnimatedHeightWidget::AnimatedHeightWidget(QWidget *parent)
+    : QWidget{parent}
+{
+    // Showing of this widget is normally animated. We hide it for now and make it small.
+    hide();
+    setMaximumHeight(0);
+
+    auto fillParentLayout = new QGridLayout(this);
+    fillParentLayout->setContentsMargins(0, 0, 0, 0);
+
+    // Put the contents into a QScrollArea. This prevents increasing the view width
+    // in case there is not enough available width for the contents.
+    m_contentsContainerParent = new QScrollArea(this);
+    fillParentLayout->addWidget(m_contentsContainerParent);
+    m_contentsContainerParent->setFrameShape(QFrame::NoFrame);
+    m_contentsContainerParent->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+    m_contentsContainerParent->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
+    m_contentsContainerParent->setWidgetResizable(true);
+
+    setMinimumWidth(0);
+}
+
+QSize AnimatedHeightWidget::sizeHint() const
+{
+    return QSize{1, preferredHeight()};
+    // 1 as width because this widget should never be the reason the DolphinViewContainer is made wider.
+}
+
+void AnimatedHeightWidget::setVisible(bool visible, Animated animated)
+{
+    setEnabled(visible);
+    if (m_heightAnimation) {
+        m_heightAnimation->stop(); // deletes because of QAbstractAnimation::DeleteWhenStopped.
+    }
+
+    if (animated == WithAnimation
+        && (style()->styleHint(QStyle::SH_Widget_Animation_Duration, nullptr, this) < 1 || GlobalConfig::animationDurationFactor() <= 0.0)) {
+        animated = WithoutAnimation;
+    }
+
+    if (animated == WithoutAnimation) {
+        setMaximumHeight(visible ? preferredHeight() : 0);
+        setVisible(visible);
+        return;
+    }
+
+    m_heightAnimation = new QPropertyAnimation(this, "maximumHeight");
+    m_heightAnimation->setDuration(2 * style()->styleHint(QStyle::SH_Widget_Animation_Duration, nullptr, this) * GlobalConfig::animationDurationFactor());
+
+    m_heightAnimation->setStartValue(height());
+    m_heightAnimation->setEasingCurve(QEasingCurve::OutCubic);
+    if (visible) {
+        show();
+        m_heightAnimation->setEndValue(preferredHeight());
+    } else {
+        m_heightAnimation->setEndValue(0);
+        connect(m_heightAnimation, &QAbstractAnimation::finished, this, &QWidget::hide);
+    }
+
+    m_heightAnimation->start(QAbstractAnimation::DeleteWhenStopped);
+}
+
+QWidget *AnimatedHeightWidget::prepareContentsContainer(QWidget *contentsContainer)
+{
+    Q_ASSERT_X(!m_contentsContainerParent->widget(),
+               "AnimatedHeightWidget::prepareContentsContainer",
+               "Another contentsContainer has already been prepared. There can only be one.");
+    contentsContainer->setParent(m_contentsContainerParent);
+    m_contentsContainerParent->setWidget(contentsContainer);
+    return contentsContainer;
+}
+
+bool AnimatedHeightWidget::isAnimationRunning() const
+{
+    return m_heightAnimation && m_heightAnimation->state() == QAbstractAnimation::Running;
+}