Implement unified diff editor

Change-Id: I93e0bfd71a8a650afbe2ca9e0f1f3dbfc9d57db0
Reviewed-by: Jarek Kobus <jaroslaw.kobus@digia.com>

src/plugins/diffeditor/selectabletexteditorwidget.cpp

@@ -0,0 +1,125 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+
+#include "selectabletexteditorwidget.h"
+
+#include <QPainter>
+#include <QTextBlock>
+
+namespace DiffEditor {
+
+SelectableTextEditorWidget::SelectableTextEditorWidget(QWidget *parent)
+    : BaseTextEditorWidget(parent)
+{
+    setFrameStyle(QFrame::NoFrame);
+}
+
+SelectableTextEditorWidget::~SelectableTextEditorWidget()
+{
+
+}
+
+void SelectableTextEditorWidget::paintEvent(QPaintEvent *e)
+{
+    paintSelections(e);
+    BaseTextEditorWidget::paintEvent(e);
+}
+
+void SelectableTextEditorWidget::paintSelections(QPaintEvent *e)
+{
+    QPainter painter(viewport());
+
+    QPointF offset = contentOffset();
+    QTextBlock firstBlock = firstVisibleBlock();
+    QTextBlock currentBlock = firstBlock;
+
+    while (currentBlock.isValid()) {
+        if (currentBlock.isVisible()) {
+            qreal top = blockBoundingGeometry(currentBlock).translated(offset).top();
+            qreal bottom = top + blockBoundingRect(currentBlock).height();
+
+            if (top > e->rect().bottom())
+                break;
+
+            if (bottom >= e->rect().top()) {
+                const int blockNumber = currentBlock.blockNumber();
+
+                paintSelections(painter, m_selections.value(blockNumber),
+                                currentBlock, top);
+            }
+        }
+        currentBlock = currentBlock.next();
+    }
+}
+
+void SelectableTextEditorWidget::paintSelections(QPainter &painter,
+                                           const QList<DiffSelection> &selections,
+                                           const QTextBlock &block,
+                                           int top)
+{
+    QPointF offset = contentOffset();
+    painter.save();
+
+    QTextLayout *layout = block.layout();
+    QTextLine textLine = layout->lineAt(0);
+    QRectF lineRect = textLine.naturalTextRect().translated(offset.x(), top);
+    QRect clipRect = contentsRect();
+    painter.setClipRect(clipRect);
+    for (int i = 0; i < selections.count(); i++) {
+        const DiffSelection &selection = selections.at(i);
+
+        if (!selection.format)
+            continue;
+        if (selection.start == -1 && selection.end == 0)
+            continue;
+        if (selection.start == selection.end && selection.start >= 0)
+            continue;
+
+        painter.save();
+        const QBrush &brush = selection.format->background();
+        painter.setPen(brush.color());
+        painter.setBrush(brush);
+
+        const int x1 = selection.start <= 0
+                ? -1
+                : textLine.cursorToX(selection.start) + offset.x();
+        const int x2 = selection.end < 0
+                ? clipRect.right()
+                : textLine.cursorToX(selection.end) + offset.x();
+        painter.drawRect(QRectF(QPointF(x1, lineRect.top()),
+                                QPointF(x2, lineRect.bottom())));
+
+        painter.restore();
+    }
+    painter.restore();
+}
+
+
+} // namespace DiffEditor
+