Diff: Allow folding hunks

apps/lib/diff/diffeditor.cpp

@@ -240,7 +240,7 @@ void DiffEditor::paintEvent(QPaintEvent *e)
         auto layout = block.layout();
 
         auto hl = highlightingForLine(block.blockNumber());
-        if (hl && layout) {
+        if (block.isVisible() && hl && layout) {
             const auto changes = hl->changes;
             for (auto c : changes) {
                 // full line background is colored
@@ -282,7 +282,7 @@ void DiffEditor::paintEvent(QPaintEvent *e)
             }
         }
 
-        if (m_diffWidget->isHunk(block.blockNumber())) {
+        if (isHunkLine(block.blockNumber())) {
             p.save();
             QPen pen;
             pen.setColor(hunkSeparatorColor);
@@ -349,3 +349,42 @@ void DiffEditor::restoreState(State s)
     cursor.setPosition(qMin(cursor.document()->characterCount(), s.cursorPosition));
     setTextCursor(cursor);
 }
+
+bool DiffEditor::isHunkLine(int line) const
+{
+    return m_diffWidget->isHunk(line);
+}
+
+bool DiffEditor::isHunkFolded(int blockNumber)
+{
+    Q_ASSERT(isHunkLine(blockNumber));
+    const auto block = document()->findBlockByNumber(blockNumber).next();
+    return block.isValid() && !block.isVisible();
+}
+
+void DiffEditor::toggleFoldHunk(int blockNumber)
+{
+    Q_ASSERT(isHunkLine(blockNumber));
+    int count = m_diffWidget->hunkLineCount(blockNumber);
+    if (count == 0) {
+        return;
+    }
+    if (count == -1) {
+        count = blockCount() - blockNumber;
+    }
+
+    auto block = document()->findBlockByNumber(blockNumber).next();
+    int i = 0;
+    bool visible = !block.isVisible();
+    while (true) {
+        i++;
+        if (i == count || !block.isValid()) {
+            break;
+        }
+        block.setVisible(visible);
+        block = block.next();
+    }
+
+    viewport()->update();
+    m_lineNumArea->update();
+}

apps/lib/diff/diffeditor.h

@@ -75,6 +75,10 @@ public:
 
     KTextEditor::Range selectionRange() const;
 
+    bool isHunkLine(int line) const;
+    void toggleFoldHunk(int block);
+    bool isHunkFolded(int blockNumber);
+
 protected:
     void resizeEvent(QResizeEvent *event) override;
     void paintEvent(QPaintEvent *e) override;

apps/lib/diff/difflinenumarea.cpp

@@ -9,6 +9,7 @@
 #include <QTextBlock>
 
 #include <KTextEditor/Editor>
+// #include <KColorUtils>
 
 static constexpr int Margin = 4;
 
@@ -51,7 +52,38 @@ void LineNumArea::setLineNumData(QVector<int> data)
 
 QSize LineNumArea::sizeHint() const
 {
-    return {lineNumAreaWidth(), 0};
+    return {lineNumAreaWidth() + textEdit->fontMetrics().height(), 0};
+}
+
+static void paintTriangle(QPainter &painter, QColor c, int xOffset, int yOffset, int width, int height, bool open)
+{
+    painter.setRenderHint(QPainter::Antialiasing);
+
+    qreal size = qMin(width, height);
+
+    QPen pen;
+    pen.setJoinStyle(Qt::RoundJoin);
+    pen.setColor(c);
+    pen.setWidthF(1.5);
+    painter.setPen(pen);
+    painter.setBrush(c);
+
+    // let some border, if possible
+    size *= 0.6;
+
+    qreal halfSize = size / 2;
+    qreal halfSizeP = halfSize * 0.6;
+    QPointF middle(xOffset + (qreal)width / 2, yOffset + (qreal)height / 2);
+
+    if (open) {
+        QPointF points[3] = {middle + QPointF(-halfSize, -halfSizeP), middle + QPointF(halfSize, -halfSizeP), middle + QPointF(0, halfSizeP)};
+        painter.drawConvexPolygon(points, 3);
+    } else {
+        QPointF points[3] = {middle + QPointF(-halfSizeP, -halfSize), middle + QPointF(-halfSizeP, halfSize), middle + QPointF(halfSizeP, 0)};
+        painter.drawConvexPolygon(points, 3);
+    }
+
+    painter.setRenderHint(QPainter::Antialiasing, false);
 }
 
 void LineNumArea::paintEvent(QPaintEvent *event)
@@ -74,6 +106,8 @@ void LineNumArea::paintEvent(QPaintEvent *event)
     const QPen otherLines = m_otherLinesColor;
     painter.setFont(font());
 
+    const int w = lineNumAreaWidth();
+
     while (block.isValid() && top <= event->rect().bottom()) {
         top = bottom;
         bottom = top + textEdit->blockBoundingRect(block).height();
@@ -83,9 +117,15 @@ void LineNumArea::paintEvent(QPaintEvent *event)
                 const QString number = QString::number(n);
                 auto isCurrentLine = textEdit->textCursor().blockNumber() == blockNumber;
                 painter.setPen(isCurrentLine ? currentLine : otherLines);
-                QRect numRect(0, top, sizeHint().width(), textEdit->fontMetrics().height());
+                QRect numRect(0, top, w, textEdit->fontMetrics().height());
                 numRect.adjust(0, 0, -(Margin * 2), 0);
                 painter.drawText(numRect, Qt::AlignRight | Qt::AlignVCenter | Qt::TextDontClip, number);
+            } else if (textEdit->isHunkLine(blockNumber)) {
+                const int x = rect().width() - (textEdit->fontMetrics().height() + Margin);
+                const int y = top;
+                const int width = textEdit->fontMetrics().height();
+                const int height = width;
+                paintTriangle(painter, m_otherLinesColor, x, y, width, height, !textEdit->isHunkFolded(blockNumber));
             }
         }
 
@@ -96,3 +136,19 @@ void LineNumArea::paintEvent(QPaintEvent *event)
     painter.setPen(m_borderColor);
     painter.drawLine(rect().topRight() - QPoint(1, 0), rect().bottomRight() - QPoint(1, 0));
 }
+
+void LineNumArea::mousePressEvent(QMouseEvent *e)
+{
+    auto pos = e->pos();
+    auto r = rect();
+    r.setLeft(lineNumAreaWidth());
+    if (!r.contains(pos)) {
+        QWidget::mousePressEvent(e);
+        return;
+    }
+
+    int block = textEdit->cursorForPosition(pos).block().blockNumber();
+    if (textEdit->isHunkLine(block)) {
+        textEdit->toggleFoldHunk(block);
+    }
+}

apps/lib/diff/difflinenumarea.h

@@ -24,6 +24,7 @@ public:
 
 protected:
     void paintEvent(QPaintEvent *event) override;
+    void mousePressEvent(QMouseEvent *e) override;
 
 private:
     class DiffEditor *const textEdit;

apps/lib/diff/diffwidget.cpp

@@ -794,3 +794,22 @@ bool DiffWidget::isHunk(const int line) const
         return l.line == line;
     });
 }
+
+int DiffWidget::hunkLineCount(int hunkLine)
+{
+    for (int i = 0; i < m_lineToDiffHunkLine.size(); ++i) {
+        const auto h = m_lineToDiffHunkLine.at(i);
+        if (h.line == hunkLine) {
+            // last hunk?
+            if (i + 1 >= m_lineToDiffHunkLine.size()) {
+                return -1;
+            }
+            auto nextHunk = m_lineToDiffHunkLine.at(i + 1);
+            auto count = nextHunk.line - h.line;
+            count -= 1; // one separator line is ignored
+            return count;
+        }
+    }
+
+    return 0;
+}

apps/lib/diff/diffwidget.h

@@ -34,6 +34,7 @@ public:
     {
         return m_linesWithFileName.contains(line);
     }
+    int hunkLineCount(int hunkLine);
 
 private:
     void clearData();