TextEditor: bound increase and decreaseFontZoom to a 10% grid

This allows to get back to a 100% font zoom with the keyboard shortcuts
by zooming to an odd zoom factor by other means.

Change-Id: Ie90853367b17c207e9c47fc108b8d6f451e0f838
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>

src/plugins/texteditor/texteditor.cpp

@@ -6891,6 +6891,18 @@ static void showZoomIndicator(QWidget *editor, const int newZoom)
                                      Utils::FadingIndicator::SmallText);
 }
 
+void TextEditorWidget::increaseFontZoom()
+{
+    d->clearVisibleFoldedBlock();
+    showZoomIndicator(this, TextEditorSettings::increaseFontZoom());
+}
+
+void TextEditorWidget::decreaseFontZoom()
+{
+    d->clearVisibleFoldedBlock();
+    showZoomIndicator(this, TextEditorSettings::decreaseFontZoom());
+}
+
 void TextEditorWidget::zoomF(float delta)
 {
     d->clearVisibleFoldedBlock();

src/plugins/texteditor/texteditor.h

@@ -349,6 +349,8 @@ public:
     void pasteWithoutFormat();
     void switchUtf8bom();
 
+    void increaseFontZoom();
+    void decreaseFontZoom();
     void zoomF(float delta);
     void zoomReset();
 

src/plugins/texteditor/texteditoractionhandler.cpp

@@ -394,11 +394,11 @@ void TextEditorActionHandlerPrivate::createActions()
             QKeySequence(),
             G_EDIT_COLLAPSING, advancedEditMenu);
     registerAction(INCREASE_FONT_SIZE,
-            [] (TextEditorWidget *w) { w->zoomF(1.f); }, false, Tr::tr("Increase Font Size"),
+            [] (TextEditorWidget *w) { w->increaseFontZoom(); }, false, Tr::tr("Increase Font Size"),
             QKeySequence(Tr::tr("Ctrl++")),
             G_EDIT_FONT, advancedEditMenu);
     registerAction(DECREASE_FONT_SIZE,
-            [] (TextEditorWidget *w) { w->zoomF(-1.f); }, false, Tr::tr("Decrease Font Size"),
+            [] (TextEditorWidget *w) { w->decreaseFontZoom(); }, false, Tr::tr("Decrease Font Size"),
             QKeySequence(Tr::tr("Ctrl+-")),
             G_EDIT_FONT, advancedEditMenu);
     registerAction(RESET_FONT_SIZE,

src/plugins/texteditor/texteditorsettings.cpp

@@ -560,20 +560,33 @@ Utils::Id TextEditorSettings::languageId(const QString &mimeType)
     return d->m_mimeTypeToLanguage.value(mimeType);
 }
 
-static void setFontZoom(int zoom)
+static int setFontZoom(int zoom)
 {
+    zoom = qMax(10, zoom);
+    if (d->m_fontSettings.fontZoom() != zoom) {
         d->m_fontSettings.setFontZoom(zoom);
         d->m_fontSettings.toSettings(Core::ICore::settings());
         emit textEditorSettings().fontSettingsChanged(d->m_fontSettings);
     }
+    return zoom;
+}
+
+int TextEditorSettings::increaseFontZoom()
+{
+    const int previousZoom = d->m_fontSettings.fontZoom();
+    return setFontZoom(previousZoom + 10 - previousZoom % 10);
+}
+
+int TextEditorSettings::decreaseFontZoom()
+{
+    const int previousZoom = d->m_fontSettings.fontZoom();
+    const int delta = previousZoom % 10;
+    return setFontZoom(previousZoom - (delta == 0 ? 10 : delta));
+}
 
 int TextEditorSettings::increaseFontZoom(int step)
 {
-    const int previousZoom = d->m_fontSettings.fontZoom();
+    return setFontZoom(d->m_fontSettings.fontZoom() + step);
-    const int newZoom = qMax(10, previousZoom + step);
-    if (newZoom != previousZoom)
-        setFontZoom(newZoom);
-    return newZoom;
 }
 
 void TextEditorSettings::resetFontZoom()

src/plugins/texteditor/texteditorsettings.h

@@ -76,6 +76,8 @@ public:
 
     static void registerMimeTypeForLanguageId(const char *mimeType, Utils::Id languageId);
     static Utils::Id languageId(const QString &mimeType);
+    static int increaseFontZoom();
+    static int decreaseFontZoom();
     static int increaseFontZoom(int step);
     static void resetFontZoom();