Fix painting of current line in generic and python editors

The generic highlighter and the python editor explicitly map some tokens
to the format C_TEXT. Unfortunately this format is special, because it's
foreground and background colors are handled by setting the editor's
palette, and should not be used for setting the format on characters.

If the format is explicitly set on characters, their background will be
oblique and overpaint e.g. the highlight for the current line, which
looks pretty ugly.

Handle this directly in SyntaxHighlighter::formatForCategory for all
syntax highlighters, by returning an empty QTextCharFormat for C_TEXT.

Change-Id: Ifaeb556754ca8106ad6e55d7062b13b45457a809
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/texteditor/generichighlighter/highlighter.cpp

@@ -23,17 +23,19 @@
 **
 ****************************************************************************/
 
-#include "highlighter.h"
-#include "highlightdefinition.h"
 #include "context.h"
-#include "rule.h"
+#include "highlightdefinition.h"
-#include "itemdata.h"
+#include "highlighter.h"
 #include "highlighterexception.h"
+#include "itemdata.h"
 #include "progressdata.h"
 #include "reuse.h"
+#include "rule.h"
 #include "tabsettings.h"
 
 #include <coreplugin/messagemanager.h>
+#include <texteditor/fontsettings.h>
+#include <texteditor/texteditorsettings.h>
 #include <utils/qtcassert.h>
 
 #include <QCoreApplication>
@@ -567,7 +569,7 @@ void Highlighter::applyFormat(int offset,
             // think this approach would fit better. If there are other ideas...
             QBrush bg = format.background();
             if (bg.style() == Qt::NoBrush)
-                bg = formatForCategory(C_TEXT).background();
+                bg = TextEditorSettings::fontSettings().toTextCharFormat(C_TEXT).background();
             if (itemData->color().isValid() && isReadableOn(bg.color(), itemData->color()))
                 format.setForeground(itemData->color());
             if (itemData->isItalicSpecified())

src/plugins/texteditor/syntaxhighlighter.cpp

@@ -836,8 +836,12 @@ void SyntaxHighlighter::highlightBlock(const QString &text)
 
 void SyntaxHighlighterPrivate::updateFormats(const FontSettings &fontSettings)
 {
-    for (const auto &pair : qAsConst(formatCategories))
+    // C_TEXT is handled by text editor's foreground and background color,
-        formats[pair.first] = fontSettings.toTextCharFormat(pair.second);
+    // so use empty format for that
+    for (const auto &pair : qAsConst(formatCategories)) {
+        formats[pair.first] = pair.second == C_TEXT ? QTextCharFormat()
+                                                    : fontSettings.toTextCharFormat(pair.second);
+    }
     whitespaceFormat = fontSettings.toTextCharFormat(C_VISUAL_WHITESPACE);
 }
 

tests/auto/generichighlighter/highlighterengine/highlighterengine.pro

@@ -1,4 +1,4 @@
-QTC_PLUGIN_DEPENDS += coreplugin
+QTC_PLUGIN_DEPENDS += coreplugin texteditor
 include(../../qttest.pri)
 QT += gui
 PLUGINSDIR = $$IDE_SOURCE_TREE/src/plugins

tests/auto/generichighlighter/highlighterengine/highlighterengine.qbs

@@ -4,6 +4,7 @@ QtcAutotest {
     name: "Highlighter engine autotest"
     Depends { name: "Core" }
     Depends { name: "Utils" }
+    Depends { name: "TextEditor" }
     Depends { name: "Qt.widgets" }
     Group {
         name: "Sources from TextEditor plugin"