A mostly working version of the delegate which will be used for painting

the table

src/danboorupostdelegate.cpp

@@ -0,0 +1,151 @@
+/*
+ * <one line to give the library's name and an idea of what it does.>
+ * Copyright 2013  Luca Beltrame <lbeltrame@kde.org>
+ *
+ * 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) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "danboorupostdelegate.h"
+
+#include "libdanbooru/danboorupost.h"
+
+#include <QListView>
+#include <QPainter>
+#include <QDebug>
+#include <QApplication>
+
+#include <KPushButton>
+
+namespace Danbooru {
+
+    const int DanbooruPostDelegate::MARGIN = 5;
+
+    DanbooruPostDelegate::DanbooruPostDelegate(QListView* itemView):QStyledItemDelegate(itemView),
+                                                                    m_itemView(itemView)
+    {
+
+
+        //FIXME: Copied directly from Gwenview without understanding
+
+        #define pm(x) itemView->style()->pixelMetric(QStyle::x)
+        m_margin = pm(PM_ToolBarItemMargin);
+        m_spacing = pm(PM_ToolBarItemSpacing);
+        #undef pm
+
+        const int iconSize = KIconLoader::global()->currentSize(
+            KIconLoader::Toolbar
+        );
+
+        const QSize sz = itemView->style()->sizeFromContents(
+            QStyle::CT_ToolButton, 0,
+            QSize(iconSize, iconSize));
+
+        m_buttonSize = qMax(sz.width(), sz.height());
+
+        m_downloadButton =  new KPushButton(KIcon("download"),
+                                            QString(), itemView);
+        m_viewButton = new KPushButton(KIcon("view-preview"), QString(),
+                                             itemView);
+
+        m_downloadButton->hide();
+        m_viewButton->hide();
+
+        m_downloadButton->resize(m_buttonSize, m_buttonSize);
+        m_viewButton->resize(m_buttonSize, m_buttonSize);
+
+    }
+
+    void DanbooruPostDelegate::paint(QPainter* painter,
+                                     const QStyleOptionViewItem& option,
+                                     const QModelIndex& index) const
+    {
+
+        if (!index.isValid()) {
+            return;
+        }
+
+        QStyle *style = QApplication::style();
+
+        style->drawPrimitive(QStyle::PE_PanelItemViewItem, &option, painter, 0);
+        painter->setRenderHint(QPainter::Antialiasing);
+
+        QPixmap pixmap = index.data(Qt::DecorationRole).value<QPixmap>();
+
+        if (pixmap.isNull()) {
+            return;
+        }
+
+        // Scaling is unavoidable to keep things in the right dimension
+        //TODO: Replace fixed values by configurable values
+
+        QPixmap scaled = pixmap.scaled(256-MARGIN, 256-MARGIN,
+                                       Qt::KeepAspectRatio,
+                                       Qt::SmoothTransformation);
+
+
+        QRect rect = option.rect;
+
+        // Draw in the center
+
+        QPoint centerCoordinate = rect.center() - QPoint(scaled.width() / 2,
+                                                         scaled.height() / 2);
+
+        // Get the bottom coordinate for the buttons, made as center - half
+        // of the pixmap width (left) then half of the height minus the button
+        // size and margin (because the move() call later on uses the
+        // coordinates as TOP coordinates, while we want the bottom of the
+        // button to align with the bottom of the pixmap)
+
+        QPoint scaleFactor = QPoint(
+            -(scaled.width() / 2) + (MARGIN / 2),
+            (scaled.height() / 2) - m_buttonSize + (MARGIN * 1.5)
+        );
+
+        QPoint bottomCoordinate = rect.center() + scaleFactor;
+
+        painter->drawPixmap(centerCoordinate, scaled);
+
+        if (option.state & QStyle::State_MouseOver) {
+
+            m_downloadButton->move(centerCoordinate + QPoint(MARGIN / 2, 0));
+            m_viewButton->move(bottomCoordinate);
+
+            m_downloadButton->show();
+            m_viewButton->show();
+
+        } else if (!hoveredIndex().isValid()) {
+            m_downloadButton->hide();
+            m_viewButton->hide();
+        }
+
+    }
+
+    QSize DanbooruPostDelegate::sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const
+    {
+        Q_UNUSED(option)
+        Q_UNUSED(index)
+        return m_itemView->gridSize();
+    }
+
+    QModelIndex DanbooruPostDelegate::hoveredIndex() const
+    {
+        const QPoint pos = m_itemView->viewport()->mapFromGlobal(QCursor::pos());
+        return m_itemView->indexAt(pos);
+    }
+
+} // namespace Danbooru

src/danboorupostdelegate.h

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+/*
+ * This file is part of Danbooru Client.
+ * Copyright 2013  Luca Beltrame <lbeltrame@kde.org>
+ *
+ * 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) version 3 or any later version
+ * accepted by the membership of KDE e.V. (or its successor approved
+ * by the membership of KDE e.V.), which shall act as a proxy
+ * defined in Section 14 of version 3 of the license.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef DANBOORUPOSTDELEGATE_H
+#define DANBOORUPOSTDELEGATE_H
+
+#include <QStyledItemDelegate>
+
+class QListView;
+class QPainter;
+class KPushButton;
+
+namespace Danbooru {
+
+    class DanbooruPostDelegate : public QStyledItemDelegate
+    {
+
+    Q_OBJECT
+
+
+    public:
+       DanbooruPostDelegate(QListView* itemView);
+
+       void paint(QPainter* painter, const QStyleOptionViewItem& option,
+                   const QModelIndex& index) const;
+       QSize sizeHint(const QStyleOptionViewItem& option,
+                       const QModelIndex& index) const;
+
+       QModelIndex hoveredIndex() const;
+
+       QList<QWidget*> createItemWidgets() const;
+       void updateItemWidgets( const QList<QWidget*> widgets,
+                               const QStyleOptionViewItem& option,
+                               const QPersistentModelIndex & index) const;
+
+    private:
+
+        QListView* m_itemView;
+        KPushButton* m_downloadButton;
+        KPushButton* m_viewButton;
+
+        int m_buttonSize;
+        int m_margin;
+        int m_spacing;
+
+        static const int MARGIN;
+
+    };
+
+} // namespace Danbooru
+
+#endif // DANBOORUPOSTDELEGATE_H