CodeEditor Widget Styling (#1874)

* CodeEditor Widget Styling

With profileration of Qt5 styling methods, problems with presentation
can occur when using cppcheck-gui and user choosen themes. With a dark
theme, a highlighted line in the CodeEditor appears with white text on
a light background or dark colors on a dark background.

Commit makes changes to enforce a default style on the Code Editor widget.
Mechanism is provided, if desired, where a user defined styling can
be provided to CodeEditor widget.

* CodeEditor Widget Styling

With profileration of Qt5 styling methods, problems with presentation
can occur when using cppcheck-gui and user choosen themes. With a dark
theme, a highlighted line in the CodeEditor appears with white text on
a light background or dark colors on a dark background.

Commit makes changes to enforce a default style on the Code Editor widget.
Mechanism is provided, if desired, where a user defined styling can
be provided to CodeEditor widget.

2nd commit - remove declarations in gui/codeeditorstyle.h to possibly
resolve appveyor window builds.

gui/codeeditor.cpp

@@ -3,13 +3,15 @@
 #include "codeeditor.h"
 
 
-Highlighter::Highlighter(QTextDocument *parent)
+Highlighter::Highlighter( QTextDocument *parent,
-    : QSyntaxHighlighter(parent)
+                          CodeEditorStyle *widgetStyle ) :
+    QSyntaxHighlighter( parent ),
+    mWidgetStyle( widgetStyle )
 {
     HighlightingRule rule;
 
-    mKeywordFormat.setForeground(Qt::darkBlue);
+    mKeywordFormat.setForeground( mWidgetStyle->keywordColor );
-    mKeywordFormat.setFontWeight(QFont::Bold);
+    mKeywordFormat.setFontWeight( mWidgetStyle->keywordWeight );
     QStringList keywordPatterns;
     keywordPatterns << "bool"
                     << "break"
@@ -57,28 +59,32 @@ Highlighter::Highlighter(QTextDocument *parent)
         mHighlightingRules.append(rule);
     }
 
-    mClassFormat.setFontWeight(QFont::Bold);
+    mClassFormat.setForeground( mWidgetStyle->classColor );
-    mClassFormat.setForeground(Qt::darkMagenta);
+    mClassFormat.setFontWeight( mWidgetStyle->classWeight );
     rule.pattern = QRegularExpression("\\bQ[A-Za-z]+\\b");
     rule.format = mClassFormat;
     mHighlightingRules.append(rule);
 
-    mQuotationFormat.setForeground(Qt::darkGreen);
+    mQuotationFormat.setForeground( mWidgetStyle->quoteColor );
+    mQuotationFormat.setFontWeight( mWidgetStyle->quoteWeight );
     rule.pattern = QRegularExpression("\".*\"");
     rule.format = mQuotationFormat;
     mHighlightingRules.append(rule);
 
-    mSingleLineCommentFormat.setForeground(Qt::gray);
+    mSingleLineCommentFormat.setForeground( mWidgetStyle->commentColor );
+    mSingleLineCommentFormat.setFontWeight( mWidgetStyle->commentWeight );
     rule.pattern = QRegularExpression("//[^\n]*");
     rule.format = mSingleLineCommentFormat;
     mHighlightingRules.append(rule);
 
     mHighlightingRulesWithSymbols = mHighlightingRules;
 
-    mMultiLineCommentFormat.setForeground(Qt::gray);
+    mMultiLineCommentFormat.setForeground( mWidgetStyle->commentColor );
+    mMultiLineCommentFormat.setFontWeight( mWidgetStyle->commentWeight );
 
-    mSymbolFormat.setForeground(Qt::red);
+    mSymbolFormat.setForeground( mWidgetStyle->symbolFGColor );
-    mSymbolFormat.setBackground(QColor(220,220,255));
+    mSymbolFormat.setBackground( mWidgetStyle->symbolBGColor );
+    mSymbolFormat.setFontWeight( mWidgetStyle->symbolWeight );
 
     mCommentStartExpression = QRegularExpression("/\\*");
     mCommentEndExpression = QRegularExpression("\\*/");
@@ -128,12 +134,32 @@ void Highlighter::highlightBlock(const QString &text)
 }
 
 
-CodeEditor::CodeEditor(QWidget *parent) : QPlainTextEdit(parent)
+CodeEditor::CodeEditor( QWidget *parent,
+                        CodeEditorStyle *widgetStyle /*= nullptr*/ ) :
+    QPlainTextEdit(parent)
 {
+    if( widgetStyle ) mWidgetStyle = widgetStyle;
+    else mWidgetStyle = new CodeEditorStyle( defaultStyle );
+
     mLineNumberArea = new LineNumberArea(this);
-    mHighlighter = new Highlighter(this->document());
+    mHighlighter = new Highlighter(this->document(), mWidgetStyle);
     mErrorPosition = -1;
 
+    // set widget coloring by overriding widget style sheet
+    QString bgcolor = QString("background:rgb(%1,%2,%3);")
+            .arg(mWidgetStyle->widgetBGColor.red())
+            .arg(mWidgetStyle->widgetBGColor.green())
+            .arg(mWidgetStyle->widgetBGColor.blue());
+    QString fgcolor = QString("color:rgb(%1,%2,%3);")
+            .arg(mWidgetStyle->widgetFGColor.red())
+            .arg(mWidgetStyle->widgetFGColor.green())
+            .arg(mWidgetStyle->widgetFGColor.blue());
+    QString style = QString("%1 %2")
+            .arg(bgcolor)
+            .arg(fgcolor);
+    setObjectName("CodeEditor");
+    setStyleSheet(style);
+
     setFont(QFontDatabase::systemFont(QFontDatabase::FixedFont));
 
     connect(this, SIGNAL(blockCountChanged(int)), this, SLOT(updateLineNumberAreaWidth(int)));
@@ -213,9 +239,7 @@ void CodeEditor::highlightErrorLine()
 
     QTextEdit::ExtraSelection selection;
 
-    QColor lineColor = QColor(255,220,220);
+    selection.format.setBackground( mWidgetStyle->highlightBGColor );
-
-    selection.format.setBackground(lineColor);
     selection.format.setProperty(QTextFormat::FullWidthSelection, true);
     selection.cursor = QTextCursor(document());
     selection.cursor.setPosition(mErrorPosition);
@@ -228,7 +252,7 @@ void CodeEditor::highlightErrorLine()
 void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
 {
     QPainter painter(mLineNumberArea);
-    painter.fillRect(event->rect(), QColor(240,240,240));
+    painter.fillRect(event->rect(), mWidgetStyle->lineNumBGColor );
 
     QTextBlock block = firstVisibleBlock();
     int blockNumber = block.blockNumber();
@@ -238,7 +262,7 @@ void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
     while (block.isValid() && top <= event->rect().bottom()) {
         if (block.isVisible() && bottom >= event->rect().top()) {
             QString number = QString::number(blockNumber + 1);
-            painter.setPen(Qt::black);
+            painter.setPen( mWidgetStyle->lineNumFGColor );
             painter.drawText(0, top, mLineNumberArea->width(), fontMetrics().height(),
                              Qt::AlignRight, number);
         }

gui/codeeditor.h

@@ -5,6 +5,7 @@
 #include <QPlainTextEdit>
 #include <QObject>
 #include <QRegularExpression>
+#include "codeeditorstyle.h"
 
 class QPaintEvent;
 class QResizeEvent;
@@ -18,7 +19,8 @@ class Highlighter : public QSyntaxHighlighter {
     Q_OBJECT
 
 public:
-    explicit Highlighter(QTextDocument *parent);
+    explicit Highlighter( QTextDocument *parent,
+                          CodeEditorStyle *widgetStyle );
 
     void setSymbols(const QStringList &symbols);
 
@@ -42,13 +44,16 @@ private:
     QTextCharFormat mMultiLineCommentFormat;
     QTextCharFormat mQuotationFormat;
     QTextCharFormat mSymbolFormat;
+
+    CodeEditorStyle *mWidgetStyle;
 };
 
 class CodeEditor : public QPlainTextEdit {
     Q_OBJECT
 
 public:
-    explicit CodeEditor(QWidget *parent);
+    explicit CodeEditor( QWidget *parent,
+                         CodeEditorStyle *widgetStyle = nullptr );
     CodeEditor(const CodeEditor &) = delete;
     CodeEditor &operator=(const CodeEditor &) = delete;
 
@@ -74,6 +79,7 @@ private slots:
 private:
     QWidget *mLineNumberArea;
     Highlighter *mHighlighter;
+    CodeEditorStyle *mWidgetStyle;
     int mErrorPosition;
 };
 

gui/codeeditorstyle.h

@@ -0,0 +1,69 @@
+#ifndef CODEEDITORSTYLE_H
+#define CODEEDITORSTYLE_H
+
+#include <QString>
+#include <QColor>
+#include <QFont>
+
+class CodeEditorStyle {
+private:
+    CodeEditorStyle(){};
+public:
+    CodeEditorStyle(
+        const QColor& CtrlFGColor, const QColor& CtrlBGColor,
+        const QColor& HiLiBGColor,
+        const QColor& LnNumFGColor, const QColor& LnNumBGColor,
+        const QColor& KeyWdFGColor, const QFont::Weight& KeyWdWeight,
+        const QColor& ClsFGColor, const QFont::Weight& ClsWeight,
+        const QColor& QteFGColor, const QFont::Weight& QteWeight,
+        const QColor& CmtFGColor, const QFont::Weight& CmtWeight,
+        const QColor& SymbFGColor, const QColor& SymbBGColor,
+        const QFont::Weight& SymbWeight ) :
+    widgetFGColor( CtrlFGColor ),
+    widgetBGColor( CtrlBGColor ),
+    highlightBGColor( HiLiBGColor ),
+    lineNumFGColor( LnNumFGColor ),
+    lineNumBGColor( LnNumBGColor ),
+    keywordColor( KeyWdFGColor ),
+    keywordWeight( KeyWdWeight ),
+    classColor( ClsFGColor ),
+    classWeight( ClsWeight ),
+    quoteColor( QteFGColor ),
+    quoteWeight( QteWeight ),
+    commentColor( CmtFGColor ),
+    commentWeight( CmtWeight ),
+    symbolFGColor( SymbFGColor ),
+    symbolBGColor( SymbBGColor ),
+    symbolWeight( SymbWeight )
+    {}
+
+public:
+    QColor          widgetFGColor;
+    QColor          widgetBGColor;
+    QColor          highlightBGColor;
+    QColor          lineNumFGColor;
+    QColor          lineNumBGColor;
+    QColor          keywordColor;
+    QFont::Weight   keywordWeight;
+    QColor          classColor;
+    QFont::Weight   classWeight;
+    QColor          quoteColor;
+    QFont::Weight   quoteWeight;
+    QColor          commentColor;
+    QFont::Weight   commentWeight;
+    QColor          symbolFGColor;
+    QColor          symbolBGColor;
+    QFont::Weight   symbolWeight;
+};
+
+static const CodeEditorStyle defaultStyle({
+/* editor FG/BG */          Qt::black, QColor( 240, 240, 240 ),
+/* highlight BG */          QColor( 255, 220, 220 ),
+/* line number FG/BG */     Qt::black, QColor( 240, 240, 240 ),
+/* keyword FG/Weight */     Qt::darkBlue, QFont::Bold,
+/* class FG/Weight */       Qt::darkMagenta, QFont::Bold,
+/* quote FG/Weight */       Qt::darkGreen, QFont::Normal,
+/* comment FG/Weight */     Qt::gray, QFont::Normal,
+/* Symbol FG/BG/Weight */   Qt::red, QColor( 220, 220, 255 ), QFont::Normal });
+
+#endif /* CODEEDITORSTYLE_H */

gui/gui.pro

@@ -90,6 +90,7 @@ HEADERS += aboutdialog.h \
            applicationlist.h \
            checkstatistics.h \
            checkthread.h \
+           codeeditorstyle.h \
            codeeditor.h \
            common.h \
            csvreport.h \