From 5b81ef9c12146416bf44cbf8cb18afbaaa9d9706 Mon Sep 17 00:00:00 2001
From: Dany Thinnes <dany@projekt-hirnfrei.de>
Date: Mon, 25 May 2026 02:50:52 +0200
Subject: [PATCH] =?UTF-8?q?Vertikale=20Linien=20zur=20Visualisierung=20von?=
 =?UTF-8?q?=20Einspr=C3=BCngen=20implementiert?=
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---
 src/editor/CodeEditor.cpp | 120 ++++++++++++++++++++++++++++++++++++++
 src/editor/CodeEditor.h   |   1 +
 2 files changed, 121 insertions(+)

diff --git a/src/editor/CodeEditor.cpp b/src/editor/CodeEditor.cpp
index 367d1fd..21c80ce 100644
--- a/src/editor/CodeEditor.cpp
+++ b/src/editor/CodeEditor.cpp
@@ -194,6 +194,126 @@ void CodeEditor::updateLineNumberArea(const QRect &rect, int dy)
     }
 }
 
+void CodeEditor::paintEvent(QPaintEvent *event)
+{
+    // Zuerst den normalen Editor-Inhalt zeichnen
+    QPlainTextEdit::paintEvent(event);
+
+    // Danach die Einrück-Führungslinien darüber legen
+    const int tabSize = m_settings->tabSize();
+    if (tabSize <= 0)
+    {
+        return;
+    }
+
+    QPainter painter(viewport());
+
+    // Farbe: subtil, passt zu Hell- und Dunkeltheme
+    QColor guideColor = palette().color(QPalette::Text);
+    guideColor.setAlpha(30);
+    painter.setPen(QPen(guideColor, 1, Qt::SolidLine));
+
+    const QFontMetrics fm(font());
+    const int spaceWidth = fm.horizontalAdvance(' ');
+    const int tabPixels  = tabSize * spaceWidth;
+
+    if (tabPixels <= 0)
+    {
+        return;
+    }
+
+    // X-Startposition des Textes direkt aus dem Layout des ersten Blocks holen.
+    // Das ist der einzige zuverlässige Weg — Qt berücksichtigt intern Margins,
+    // Gutter und Frame-Abstände die sich nicht sauber manuell nachrechnen lassen.
+    int textOriginX = 0;
+    {
+        QTextBlock firstBlock = firstVisibleBlock();
+        if (!firstBlock.isValid())
+        {
+            firstBlock = document()->begin();
+        }
+        if (firstBlock.isValid())
+        {
+            const QRectF blockRect = blockBoundingGeometry(firstBlock)
+                                         .translated(contentOffset());
+            // Position des ersten Zeichens im Layout
+            const QTextLayout *layout = firstBlock.layout();
+            if (layout && layout->lineCount() > 0)
+            {
+                textOriginX = static_cast<int>(blockRect.left()
+                              + layout->lineAt(0).position().x());
+            }
+            else
+            {
+                textOriginX = static_cast<int>(blockRect.left());
+            }
+        }
+    }
+
+    // Horizontalen Scroll-Offset berücksichtigen
+    const int scrollX = horizontalScrollBar()->value();
+
+    // Sichtbaren Zeilenbereich bestimmen
+    QTextBlock block  = firstVisibleBlock();
+    const int  bottom = event->rect().bottom();
+
+    while (block.isValid())
+    {
+        const QRectF blockRect = blockBoundingGeometry(block).translated(contentOffset());
+
+        if (blockRect.top() > bottom)
+        {
+            break;
+        }
+
+        if (block.isVisible())
+        {
+            const QString text = block.text();
+
+            // Einrückungstiefe der Zeile zählen (Leerzeichen / Tabs)
+            int indentSpaces = 0;
+            for (const QChar &ch : text)
+            {
+                if (ch == ' ')
+                {
+                    ++indentSpaces;
+                }
+                else if (ch == '\t')
+                {
+                    // Tab auffüllen auf nächsten Tab-Stop
+                    indentSpaces = ((indentSpaces / tabSize) + 1) * tabSize;
+                }
+                else
+                {
+                    break;
+                }
+            }
+
+            const int indentStops = indentSpaces / tabSize;
+
+            // Für jeden Einrückungslevel eine vertikale Linie zeichnen
+            for (int stop = 1; stop <= indentStops; ++stop)
+            {
+                const int xPixel = textOriginX + stop * tabPixels - scrollX;
+
+                // Nur im sichtbaren Bereich zeichnen
+                if (xPixel < lineNumberAreaWidth() || xPixel > viewport()->width())
+                {
+                    continue;
+                }
+
+                const int y1 = static_cast<int>(blockRect.top());
+                const int y2 = static_cast<int>(blockRect.bottom());
+
+                painter.drawLine(xPixel, y1, xPixel, y2);
+            }
+        }
+
+        block = block.next();
+    }
+}
+
+
 void CodeEditor::resizeEvent(QResizeEvent *event)
 {
     QPlainTextEdit::resizeEvent(event);
diff --git a/src/editor/CodeEditor.h b/src/editor/CodeEditor.h
index dd52331..603a07f 100644
--- a/src/editor/CodeEditor.h
+++ b/src/editor/CodeEditor.h
@@ -45,6 +45,7 @@ signals:
 protected:
     void resizeEvent(QResizeEvent *event) override;
     void keyPressEvent(QKeyEvent *event) override;
+    void paintEvent(QPaintEvent *event) override;
 
 private slots:
     void updateLineNumberAreaWidth(int newBlockCount);