Supported "kinetic scrolling" as an option in Kvantum Manager

Kvantum/ChangeLog

@@ -1,3 +1,7 @@
+V0.12.1
+---------
+ * Added a hacking option for kinetic scrolling to Kvantum Manager. Although Qt's kinetic scrolling has bugs, it doesn't cause crashes with Qt ≥ 5.13.1.
+
 V0.12.0
 ---------
  * Basic support for FreeBSD.

Kvantum/NEWS

@@ -1,5 +1,5 @@
 Latest version:
 
-	8 Oct 2019, V0.12.1
+	10 Oct 2019, V0.12.1
 
 See "ChangeLog" for changes.

Kvantum/kvantummanager/KvantumManager.cpp

@@ -47,6 +47,10 @@ KvantumManager::KvantumManager (const QString& lang, QWidget *parent) : QMainWin
     modifiedSuffix_ = " (" + tr ("modified") + ")";
     kvDefault_ = "Kvantum (" + tr ("default") + ")";
 
+#if (QT_VERSION < QT_VERSION_CHECK(5,13,1))
+    ui->checkBoxKineticScrolling->setEnabled (false);
+#endif
+
     ui->openTheme->setIcon(symbolicIcon::icon (":/Icons/data/document-open.svg"));
     ui->deleteTheme->setIcon(symbolicIcon::icon (":/Icons/data/edit-delete.svg"));
     ui->useTheme->setIcon(symbolicIcon::icon (":/Icons/data/dialog-ok.svg"));
@@ -881,6 +885,7 @@ void KvantumManager::defaultThemeButtons()
     ui->checkBoxDark->setChecked (defaultSettings.value ("respect_darkness").toBool());
     ui->checkBoxGrip->setChecked (defaultSettings.value ("force_size_grip").toBool());
     ui->checkBoxScrollJump->setChecked (defaultSettings.value ("middle_click_scroll").toBool());
+    ui->checkBoxKineticScrolling->setChecked (defaultSettings.value ("kinetic_scrolling").toBool());
     ui->checkBoxJumpWorkaround->setChecked (defaultSettings.value ("scroll_jump_workaround").toBool());
     ui->checkBoxNormalBtn->setChecked (defaultSettings.value ("normal_default_pushbutton").toBool());
     ui->checkBoxIconlessBtn->setChecked (defaultSettings.value ("iconless_pushbutton").toBool());
@@ -1394,6 +1399,7 @@ void KvantumManager::tabChanged (int index)
                 ui->checkBoxDark->setChecked (themeSettings.value ("respect_darkness").toBool());
                 ui->checkBoxGrip->setChecked (themeSettings.value ("force_size_grip").toBool());
                 ui->checkBoxScrollJump->setChecked (themeSettings.value ("middle_click_scroll").toBool());
+                ui->checkBoxKineticScrolling->setChecked (themeSettings.value ("kinetic_scrolling").toBool());
                 ui->checkBoxJumpWorkaround->setChecked (themeSettings.value ("scroll_jump_workaround").toBool());
                 ui->checkBoxNormalBtn->setChecked (themeSettings.value ("normal_default_pushbutton").toBool());
                 ui->checkBoxIconlessBtn->setChecked (themeSettings.value ("iconless_pushbutton").toBool());
@@ -2090,6 +2096,7 @@ void KvantumManager::writeConfig()
         hackKeys.insert("respect_darkness", boolToStr (ui->checkBoxDark->isChecked()));
         hackKeys.insert("force_size_grip", boolToStr (ui->checkBoxGrip->isChecked()));
         hackKeys.insert("middle_click_scroll", boolToStr (ui->checkBoxScrollJump->isChecked()));
+        hackKeys.insert("kinetic_scrolling", boolToStr (ui->checkBoxKineticScrolling->isChecked()));
         hackKeys.insert("scroll_jump_workaround", boolToStr (ui->checkBoxJumpWorkaround->isChecked()));
         hackKeys.insert("normal_default_pushbutton", boolToStr (ui->checkBoxNormalBtn->isChecked()));
         hackKeys.insert("iconless_pushbutton", boolToStr (ui->checkBoxIconlessBtn->isChecked()));
@@ -2164,6 +2171,7 @@ void KvantumManager::writeConfig()
         if (themeSettings.value ("normal_default_pushbutton").toBool() != ui->checkBoxNormalBtn->isChecked()
             || themeSettings.value ("iconless_pushbutton").toBool() != ui->checkBoxIconlessBtn->isChecked()
             || themeSettings.value ("middle_click_scroll").toBool() != ui->checkBoxScrollJump->isChecked()
+            || themeSettings.value ("kinetic_scrolling").toBool() != ui->checkBoxKineticScrolling->isChecked()
             || themeSettings.value ("opaque_colors").toBool() != ui->checkBoxOpaqueColors->isChecked()
             || qMin(qMax(themeSettings.value ("tint_on_mouseover").toInt(),0),100) != ui->spinTint->value()
             || qMin(qMax(themeSettings.value ("disabled_icon_opacity").toInt(),0),100) != ui->spinOpacity->value())

Kvantum/kvantummanager/kvantummanager.ui

@@ -616,7 +616,21 @@ as far as possible.</string>
                  </property>
                 </widget>
                </item>
-               <item row="7" column="3">
+               <item row="8" column="1">
+                <widget class="QCheckBox" name="checkBoxGrip">
+                 <property name="toolTip">
+                  <string>Show size grips of dialogs and statusbars
+as far as possible.</string>
+                 </property>
+                 <property name="whatsThis">
+                  <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;Show size grips of dialogs and statusbars as far as possible?&lt;/p&gt;&lt;p&gt;By default, the application decides whether they should be shown, but this hack could be useful for resizing windows easily when there is no window border.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+                 </property>
+                 <property name="text">
+                  <string>Force size grips</string>
+                 </property>
+                </widget>
+               </item>
+               <item row="8" column="3">
                 <widget class="QLabel" name="labelTint">
                  <property name="toolTip">
                   <string>The highlight color is used for tinting.
@@ -630,7 +644,7 @@ Hard-coded icons/styles may not respect this key.</string>
                  </property>
                 </widget>
                </item>
-               <item row="7" column="4">
+               <item row="8" column="4">
                 <widget class="QSpinBox" name="spinTint">
                  <property name="toolTip">
                   <string>The highlight color is used for tinting.
@@ -647,21 +661,18 @@ Hard-coded icons/styles may not respect this key.</string>
                  </property>
                 </widget>
                </item>
-               <item row="8" column="1">
-                <widget class="QCheckBox" name="checkBoxGrip">
+               <item row="9" column="1">
+                <widget class="QCheckBox" name="checkBoxScrollJump">
                  <property name="toolTip">
-                  <string>Show size grips of dialogs and statusbars
-as far as possible.</string>
-                 </property>
-                 <property name="whatsThis">
-                  <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;Show size grips of dialogs and statusbars as far as possible?&lt;/p&gt;&lt;p&gt;By default, the application decides whether they should be shown, but this hack could be useful for resizing windows easily when there is no window border.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+                  <string>By default, the scroll slider jumps to a position
+when the scrollbar is left clicked.</string>
                  </property>
                  <property name="text">
-                  <string>Force size grips</string>
+                  <string>Scroll jump with middle click</string>
                  </property>
                 </widget>
                </item>
-               <item row="8" column="3">
+               <item row="9" column="3">
                 <widget class="QLabel" name="labelOpacity">
                  <property name="toolTip">
                   <string>Useful with monochrome icon sets and
@@ -676,7 +687,7 @@ reduced by other means.</string>
                  </property>
                 </widget>
                </item>
-               <item row="8" column="4">
+               <item row="9" column="4">
                 <widget class="QSpinBox" name="spinOpacity">
                  <property name="toolTip">
                   <string>Useful with monochrome icon sets and
@@ -697,18 +708,21 @@ reduced by other means.</string>
                  </property>
                 </widget>
                </item>
-               <item row="9" column="1">
-                <widget class="QCheckBox" name="checkBoxScrollJump">
+               <item row="10" column="1">
+                <widget class="QCheckBox" name="checkBoxKineticScrolling">
                  <property name="toolTip">
-                  <string>By default, the scroll slider jumps to a position
-when the scrollbar is left clicked.</string>
+                  <string>Scroll some scrollable widgets by flicking them
+with the left mouse button.
+
+Warning: Qt's kinetic scrolling has bugs and may
+seriously interfere with other jobs.</string>
                  </property>
                  <property name="text">
-                  <string>Scroll jump with middle click</string>
+                  <string>Kinetic scrolling</string>
                  </property>
                 </widget>
                </item>
-               <item row="9" column="3">
+               <item row="10" column="3">
                 <widget class="QLabel" name="labelLxqtMenu">
                  <property name="toolTip">
                   <string>Has effect only when the main menu is NOT styled by LXQt.
@@ -723,7 +737,7 @@ or through logging out and in again.</string>
                  </property>
                 </widget>
                </item>
-               <item row="9" column="4">
+               <item row="10" column="4">
                 <widget class="QSpinBox" name="spinLxqtMenu">
                  <property name="toolTip">
                   <string>Has effect only when the main menu is NOT styled by LXQt.

Kvantum/style/polishing.cpp

@@ -41,6 +41,7 @@
 #include <QDialog>
 #include <QLayout> // only for forceSizeGrip
 #include <QCompleter> // only for combo menu change in  Kvantum Manager
+#include <QScroller>
 
 namespace Kvantum
 {
@@ -771,11 +772,26 @@ void Style::polish(QWidget *widget)
   }
   else if (QAbstractScrollArea *sa = qobject_cast<QAbstractScrollArea*>(widget))
   {
+    QWidget *vp = sa->viewport();
+#if (QT_VERSION >= QT_VERSION_CHECK(5,13,1))
+    if(hspec_.kinetic_scrolling
+       && vp && !vp->testAttribute(Qt::WA_StyleSheetTarget) && !QScroller::hasScroller(vp)
+       && !widget->autoFillBackground() && !widget->inherits("QComboBoxListView")
+       && !widget->inherits("QTextEdit") && !widget->inherits("QPlainTextEdit")
+       && !widget->inherits("KSignalPlotter"))
+    {
+      QScroller::grabGesture(vp, QScroller::LeftMouseButtonGesture);
+      auto sp = QScroller::scroller(vp)->scrollerProperties();
+      sp.setScrollMetric(QScrollerProperties::OvershootScrollTime, static_cast<qreal>(0.3));
+      sp.setScrollMetric(QScrollerProperties::OvershootScrollDistanceFactor, static_cast<qreal>(0.1));
+      sp.setScrollMetric(QScrollerProperties::OvershootDragDistanceFactor, static_cast<qreal>(0.1));
+      QScroller::scroller(vp)->setScrollerProperties(sp);
+    }
+#endif
     if (/*sa->frameShape() == QFrame::NoFrame &&*/ // Krita and digiKam aren't happy with this
         sa->backgroundRole() == QPalette::Window
         || sa->backgroundRole() == QPalette::Button) // inside toolbox
     {
-      QWidget *vp = sa->viewport();
       if (vp && (vp->backgroundRole() == QPalette::Window
                  || vp->backgroundRole() == QPalette::Button))
       { // remove ugly flat backgrounds (when the window backround is styled)
@@ -1101,6 +1117,23 @@ void Style::unpolish(QWidget *widget)
     else if (qobject_cast<QToolBox*>(widget))
       widget->setBackgroundRole(QPalette::Button);
 
+#if (QT_VERSION >= QT_VERSION_CHECK(5,13,1))
+    if (hspec_.kinetic_scrolling)
+    {
+      if (QAbstractScrollArea *sa = qobject_cast<QAbstractScrollArea*>(widget))
+      {
+        QWidget *vp = sa->viewport();
+        if (vp && !vp->testAttribute(Qt::WA_StyleSheetTarget)
+            && !widget->autoFillBackground() && !widget->inherits("QComboBoxListView")
+            && !widget->inherits("QTextEdit") && !widget->inherits("QPlainTextEdit")
+            && !widget->inherits("KSignalPlotter"))
+        {
+          QScroller::ungrabGesture(vp);
+        }
+      }
+    }
+#endif
+
     if (qobject_cast<QMenu*>(widget) || widget->inherits("QTipLabel"))
     {
       if (blurHelper_)

Kvantum/style/themeconfig/ThemeConfig.cpp

@@ -1194,6 +1194,9 @@ hacks_spec ThemeConfig::getHacksSpec() const
   v = getValue(KSL("Hacks"),KSL("middle_click_scroll"));
   r.middle_click_scroll = v.toBool();
 
+  v = getValue(KSL("Hacks"),KSL("kinetic_scrolling"));
+  r.kinetic_scrolling = v.toBool();
+
   v = getValue(KSL("Hacks"),KSL("scroll_jump_workaround"));
   r.scroll_jump_workaround = v.toBool();
 

Kvantum/style/themeconfig/specs.h

@@ -302,6 +302,8 @@ typedef struct {
   /* should the scroll jump be done by middle clicking?
      (By default, it's done by left clicking.) */
   bool middle_click_scroll;
+  /* enable kinetic scrolling? */
+  bool kinetic_scrolling;
   /* workaround for annoying Qt5 scroll jumps? */
   bool scroll_jump_workaround;
 } hacks_spec;
@@ -609,6 +611,7 @@ static inline void default_hacks_spec(hacks_spec &hspec) {
   hspec.iconless_menu = false;
   hspec.single_top_toolbar = false;
   hspec.middle_click_scroll = false;
+  hspec.kinetic_scrolling = false;
   hspec.scroll_jump_workaround = false;
 }
 }