Add custom image functionality for inline mod buttons. (#5369)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/widgets/helper/IconDelegate.cpp

@@ -0,0 +1,29 @@
+#include "widgets/helper/IconDelegate.hpp"
+
+#include <QPainter>
+#include <QVariant>
+
+namespace chatterino {
+
+IconDelegate::IconDelegate(QObject *parent)
+    : QStyledItemDelegate(parent)
+{
+}
+
+void IconDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option,
+                         const QModelIndex &index) const
+{
+    auto data = index.data(Qt::DecorationRole);
+
+    if (data.type() != QVariant::Pixmap)
+    {
+        return QStyledItemDelegate::paint(painter, option, index);
+    }
+
+    auto scaledRect = option.rect;
+    scaledRect.setWidth(scaledRect.height());
+
+    painter->drawPixmap(scaledRect, data.value<QPixmap>());
+}
+
+}  // namespace chatterino

src/widgets/helper/IconDelegate.hpp

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <QStyledItemDelegate>
+
+namespace chatterino {
+
+/**
+ * IconDelegate draws the decoration role pixmap scaled down to a square icon
+ */
+class IconDelegate : public QStyledItemDelegate
+{
+public:
+    explicit IconDelegate(QObject *parent = nullptr);
+
+    void paint(QPainter *painter, const QStyleOptionViewItem &option,
+               const QModelIndex &index) const override;
+};
+
+}  // namespace chatterino