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>

4 files changed, 15 insertions, 8 deletions

diff --git a/src/plugins/texteditor/generichighlighter/highlighter.cpp b/src/plugins/texteditor/generichighlighter/highlighter.cpp
index e7e5e713ab..8ece3f462e 100644
--- a/src/plugins/texteditor/generichighlighter/highlighter.cpp
+++ b/src/plugins/texteditor/generichighlighter/highlighter.cpp
@@ -23,17 +23,19 @@
 **
 ****************************************************************************/
 
-#include "highlighter.h"
-#include "highlightdefinition.h"
 #include "context.h"
-#include "rule.h"
-#include "itemdata.h"
+#include "highlightdefinition.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())
diff --git a/src/plugins/texteditor/syntaxhighlighter.cpp b/src/plugins/texteditor/syntaxhighlighter.cpp
index f72b563ca5..621df4f236 100644
--- a/src/plugins/texteditor/syntaxhighlighter.cpp
+++ b/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))
-        formats[pair.first] = fontSettings.toTextCharFormat(pair.second);
+    // C_TEXT is handled by text editor's foreground and background color,
+    // 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);
 }
 
diff --git a/tests/auto/generichighlighter/highlighterengine/highlighterengine.pro b/tests/auto/generichighlighter/highlighterengine/highlighterengine.pro
index 3270181891..d78de7871e 100644
--- a/tests/auto/generichighlighter/highlighterengine/highlighterengine.pro
+++ b/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
diff --git a/tests/auto/generichighlighter/highlighterengine/highlighterengine.qbs b/tests/auto/generichighlighter/highlighterengine/highlighterengine.qbs
index 3ea2c0da68..b0abba7776 100644
--- a/tests/auto/generichighlighter/highlighterengine/highlighterengine.qbs
+++ b/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"