Add folding to Unified diff editor

Add folding for files and chunks.

Change-Id: I0dd278d0bc69208a0c9c116b94e4ead7aec5fede
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/diffeditor/unifieddiffeditorwidget.cpp

@@ -29,6 +29,7 @@
 #include "diffeditordocument.h"
 #include "diffutils.h"
 
+#include <QHash>
 #include <QMenu>
 #include <QPainter>
 #include <QScrollBar>
@@ -58,7 +59,6 @@ UnifiedDiffEditorWidget::UnifiedDiffEditorWidget(QWidget *parent)
     settings.m_textWrapping = false;
     settings.m_displayLineNumbers = true;
     settings.m_highlightCurrentLine = false;
-    settings.m_displayFoldingMarkers = true;
     settings.m_markTextChanges = false;
     settings.m_highlightBlocks = false;
     SelectableTextEditorWidget::setDisplaySettings(settings);
@@ -82,6 +82,7 @@ UnifiedDiffEditorWidget::UnifiedDiffEditorWidget(QWidget *parent)
     m_context->setWidget(this);
     m_context->setContext(Core::Context(Constants::UNIFIED_VIEW_ID));
     Core::ICore::addContextObject(m_context);
+    setCodeFoldingSupported(true);
 }
 
 UnifiedDiffEditorWidget::~UnifiedDiffEditorWidget()
@@ -131,6 +132,7 @@ void UnifiedDiffEditorWidget::setDisplaySettings(const DisplaySettings &ds)
 {
     DisplaySettings settings = displaySettings();
     settings.m_visualizeWhitespace = ds.m_visualizeWhitespace;
+    settings.m_displayFoldingMarkers = ds.m_displayFoldingMarkers;
     SelectableTextEditorWidget::setDisplaySettings(settings);
 }
 
@@ -449,6 +451,13 @@ QString UnifiedDiffEditorWidget::showChunk(const ChunkData &chunkData,
     return diffText;
 }
 
+
+static void setFoldingIndent(const QTextBlock &block, int indent)
+{
+    if (TextEditor::TextBlockUserData *userData = TextEditor::TextDocumentLayout::userData(block))
+         userData->setFoldingIndent(indent);
+}
+
 void UnifiedDiffEditorWidget::showDiff()
 {
     QString diffText;
@@ -456,6 +465,11 @@ void UnifiedDiffEditorWidget::showDiff()
     int blockNumber = 0;
     int charNumber = 0;
 
+    // 'foldingIndent' is populated with <block number> and folding indentation
+    // value where 1 indicates start of new file and 2 indicates a diff chunk.
+    // Remaining lines (diff contents) are assigned 3.
+    QHash<int, int> foldingIndent;
+
     QMap<int, QList<DiffSelection> > selections;
 
     for (const FileData &fileData : m_controller.m_contextFileData) {
@@ -465,7 +479,9 @@ void UnifiedDiffEditorWidget::showDiff()
                 + fileData.rightFileInfo.fileName + QLatin1Char('\n');
         setFileInfo(blockNumber, fileData.leftFileInfo, fileData.rightFileInfo);
         selections[blockNumber].append(DiffSelection(&m_controller.m_fileLineFormat));
+        foldingIndent.insert(blockNumber, 1);
         blockNumber++;
+        foldingIndent.insert(blockNumber, 1);
         selections[blockNumber].append(DiffSelection(&m_controller.m_fileLineFormat));
         blockNumber++;
 
@@ -474,6 +490,7 @@ void UnifiedDiffEditorWidget::showDiff()
         charNumber += leftFileInfo.count() + rightFileInfo.count();
 
         if (fileData.binaryFiles) {
+            foldingIndent.insert(blockNumber, 2);
             selections[blockNumber].append(DiffSelection(&m_controller.m_chunkLineFormat));
             blockNumber++;
             const QString binaryLine = QLatin1String("Binary files ")
@@ -486,6 +503,7 @@ void UnifiedDiffEditorWidget::showDiff()
         } else {
             for (int j = 0; j < fileData.chunks.count(); j++) {
                 const int oldBlockNumber = blockNumber;
+                foldingIndent.insert(blockNumber, 2);
                 diffText += showChunk(fileData.chunks.at(j),
                                       (j == fileData.chunks.count() - 1)
                                       && fileData.lastChunkAtTheEndOfFile,
@@ -508,6 +526,11 @@ void UnifiedDiffEditorWidget::showDiff()
     const bool oldIgnore = m_controller.m_ignoreCurrentIndexChange;
     m_controller.m_ignoreCurrentIndexChange = true;
     setPlainText(diffText);
+
+    QTextBlock block = document()->firstBlock();
+    for (int b = 0; block.isValid(); block = block.next(), ++b)
+        setFoldingIndent(block, foldingIndent.value(b, 3));
+
     m_controller.m_ignoreCurrentIndexChange = oldIgnore;
 
     setSelections(selections);