Backport 5.9/Master's GroupDialog code to 5.8.

Summary:
This brings us to a common baseline on the three active branches
and addresses regressions on the 5.8 branch.

5.9's code added a scrollbar and improved keyboard nav.

BUG:378042

Reviewers: #plasma, mart

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D5287

4 files changed, 139 insertions, 28 deletions

diff --git a/applets/taskmanager/package/contents/ui/GroupDialog.qml b/applets/taskmanager/package/contents/ui/GroupDialog.qml
index c87852b..4b1fee5 100644
--- a/applets/taskmanager/package/contents/ui/GroupDialog.qml
+++ b/applets/taskmanager/package/contents/ui/GroupDialog.qml
@@ -17,10 +17,11 @@
  *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA .        *
  ***************************************************************************/
 
-import QtQuick 2.0
+import QtQuick 2.4
 import QtQuick.Window 2.2
 
 import org.kde.plasma.core 2.0 as PlasmaCore
+import org.kde.plasma.extras 2.0 as PlasmaExtras
 import org.kde.draganddrop 2.0
 
 import "../code/layout.js" as LayoutManager
@@ -36,43 +37,121 @@ PlasmaCore.Dialog {
 
     property int preferredWidth: Screen.width / (3 * Screen.devicePixelRatio)
     property int preferredHeight: Screen.height / (2 * Screen.devicePixelRatio)
+    property int contentWidth: scrollArea.overflowing ? mainItem.width - (units.smallSpacing * 3) : mainItem.width
+    property TextMetrics textMetrics: TextMetrics {}
+    property alias overflowing: scrollArea.overflowing
+    property alias activeTask: focusActiveTaskTimer.targetIndex
+
+    function selectTask(task) {
+        if (!task) {
+            return;
+        }
+
+        task.forceActiveFocus();
+        scrollArea.ensureItemVisible(task);
+    }
+
+    mainItem: PlasmaExtras.ScrollArea {
+        id: scrollArea
+
+        property bool overflowing: (viewport.height < contentItem.height)
+
+        horizontalScrollBarPolicy: Qt.ScrollBarAlwaysOff
+
+        function ensureItemVisible(item) {
+            var itemTop = item.y;
+            var itemBottom = (item.y + item.height);
+
+            if (itemTop < flickableItem.contentY) {
+                flickableItem.contentY = itemTop;
+            }
+
+            if ((itemBottom - flickableItem.contentY) > viewport.height) {
+                flickableItem.contentY = Math.abs(viewport.height - itemBottom);
+            }
+        }
 
-    mainItem: Item {
         MouseHandler {
             id: mouseHandler
 
-            anchors.fill: parent
+            width: parent.width
+            height: (groupRepeater.count * (LayoutManager.verticalMargins()
+                + Math.max(theme.mSize(theme.defaultFont).height, units.iconSizes.medium)))
 
             target: taskList
-        }
+            handleWheelEvents: !scrollArea.overflowing
+
+            Timer {
+                id: focusActiveTaskTimer
+
+                property var targetIndex: null
 
-        TaskList {
-            id: taskList
+                interval: 0
+                repeat: false
 
-            anchors.fill: parent
+                onTriggered: {
+                    // Now we can home in on the previously active task
+                    // collected in groupDialog.onVisibleChanged.
 
-            Repeater {
-                id: groupRepeater
+                    if (targetIndex != null) {
+                        for (var i = 0; i < groupRepeater.count; ++i) {
+                            var task = groupRepeater.itemAt(i);
 
-                function currentIndex() {
-                    for (var i = 0; i < count; ++i) {
-                        if (itemAt(i).activeFocus) {
-                            return i;
+                            if (task.modelIndex() == targetIndex) {
+                                selectTask(task);
+                                return;
+                            }
                         }
                     }
+                }
+            }
+
+            TaskList {
+                id: taskList
+
+                anchors.fill: parent
 
-                    return -1;
+                add: Transition {
+                    // We trigger a null-interval timer in the first add
+                    // transition after setting the model so onTriggered
+                    // will run after the Flow has positioned items.
+
+                    ScriptAction {
+                        script: {
+                            if (groupRepeater.aboutToPopulate) {
+                                focusActiveTaskTimer.restart();
+                                groupRepeater.aboutToPopulate = false;
+                            }
+                        }
+                    }
                 }
 
-                onCountChanged: updateSize()
+                Repeater {
+                    id: groupRepeater
+
+                    property bool aboutToPopulate: false
+
+                    function currentIndex() {
+                        for (var i = 0; i < count; ++i) {
+                            if (itemAt(i).activeFocus) {
+                                return i;
+                            }
+                        }
+
+                        return -1;
+                    }
+
+                    onCountChanged: updateSize();
+                }
             }
         }
 
         Keys.onUpPressed: {
             var currentIndex = groupRepeater.currentIndex();
-            // In doubt focus the first item
+            // In doubt focus the last item, so we start at the bottom when user
+            // initially presses up.
             if (currentIndex === -1) {
-                groupRepeater.itemAt(0).forceActiveFocus();
+                selectTask(groupRepeater.itemAt(groupRepeater.count - 1));
                 return;
             }
 
@@ -81,18 +160,18 @@ PlasmaCore.Dialog {
                 previousIndex = groupRepeater.count - 1;
             }
 
-            groupRepeater.itemAt(previousIndex).forceActiveFocus()
+            selectTask(groupRepeater.itemAt(previousIndex));
         }
 
         Keys.onDownPressed: {
             var currentIndex = groupRepeater.currentIndex();
             // In doubt focus the first item, also wrap around.
             if (currentIndex === -1 || currentIndex + 1 >= groupRepeater.count) {
-                groupRepeater.itemAt(0).forceActiveFocus();
+                selectTask(groupRepeater.itemAt(0));
                 return;
             }
 
-            groupRepeater.itemAt(currentIndex + 1).forceActiveFocus();
+            selectTask(groupRepeater.itemAt(currentIndex + 1));
         }
 
         Keys.onEscapePressed: groupDialog.visible = false;
@@ -119,6 +198,8 @@ PlasmaCore.Dialog {
         if (visible && visualParent) {
             groupFilter.model = tasksModel;
             groupFilter.rootIndex = groupFilter.modelIndex(visualParent.itemIndex);
+
+            groupRepeater.aboutToPopulate = true;
             groupRepeater.model = groupFilter;
 
             mainItem.forceActiveFocus();
@@ -147,11 +228,14 @@ PlasmaCore.Dialog {
             for (var i = 0; i < taskList.children.length - 1; ++i) {
                 task = taskList.children[i];
 
-                if (task.textWidth > maxWidth) {
-                    maxWidth = task.textWidth;
+                textMetrics.text = task.labelText;
+                var textWidth = textMetrics.boundingRect.width;
+
+                if (textWidth > maxWidth) {
+                    maxWidth = textWidth;
                 }
 
-                task.textWidthChanged.connect(updateSize);
+                task.labelTextChanged.connect(updateSize);
             }
 
             maxWidth += LayoutManager.horizontalMargins() + units.iconSizes.medium + 2 * units.smallSpacing;
diff --git a/applets/taskmanager/package/contents/ui/MouseHandler.qml b/applets/taskmanager/package/contents/ui/MouseHandler.qml
index 94fa8b0..b5d0ea0 100644
--- a/applets/taskmanager/package/contents/ui/MouseHandler.qml
+++ b/applets/taskmanager/package/contents/ui/MouseHandler.qml
@@ -34,6 +34,7 @@ Item {
     property bool moved: false
 
     property alias hoveredItem: dropHandler.hoveredItem
+    property alias handleWheelEvents: wheelHandler.active
 
     Timer {
         id: ignoreItemTimer
@@ -145,9 +146,19 @@ Item {
         id: wheelHandler
 
         anchors.fill: parent
+
+        enabled: active && plasmoid.configuration.wheelEnabled
+
+        property bool active: true
         property int wheelDelta: 0;
-        enabled: plasmoid.configuration.wheelEnabled
 
-        onWheel: wheelDelta = TaskTools.wheelActivateNextPrevTask(null, wheelDelta, wheel.angleDelta.y);
+        onWheel: {
+            if (!active) {
+                wheel.accepted = false;
+                return;
+            }
+
+            wheelDelta = TaskTools.wheelActivateNextPrevTask(null, wheelDelta, wheel.angleDelta.y);
+        }
     }
 }
diff --git a/applets/taskmanager/package/contents/ui/Task.qml b/applets/taskmanager/package/contents/ui/Task.qml
index e17319d..41fa91c 100644
--- a/applets/taskmanager/package/contents/ui/Task.qml
+++ b/applets/taskmanager/package/contents/ui/Task.qml
@@ -31,7 +31,7 @@ import "../code/tools.js" as TaskTools
 MouseArea {
     id: task
 
-    width: groupDialog.mainItem.width
+    width: groupDialog.contentWidth
     height: Math.max(theme.mSize(theme.defaultFont).height, units.iconSizes.medium) + LayoutManager.verticalMargins()
 
     visible: false
@@ -46,7 +46,7 @@ MouseArea {
     property bool isWindow: model.IsWindow === true
     property int childCount: model.ChildCount != undefined ? model.ChildCount : 0
     property int previousChildCount: 0
-    property alias textWidth: label.implicitWidth
+    property alias labelText: label.text
     property bool pressed: false
     property int pressX: -1
     property int pressY: -1
@@ -68,6 +68,10 @@ MouseArea {
     }
 
     onChildCountChanged: {
+        if (containsMouse) {
+            groupDialog.activeTask = null;
+        }
+
         if (childCount > previousChildCount) {
             tasksModel.requestPublishDelegateGeometry(modelIndex(), backend.globalRect(task), task);
         }
@@ -147,7 +151,7 @@ MouseArea {
     }
 
     onWheel: {
-        if (plasmoid.configuration.wheelEnabled) {
+        if (plasmoid.configuration.wheelEnabled && (!inPopup || !groupDialog.overflowing)) {
             wheelDelta = TaskTools.wheelActivateNextPrevTask(task, wheelDelta, wheel.angleDelta.y);
         } else {
             wheel.accepted = false;
diff --git a/applets/taskmanager/package/contents/ui/main.qml b/applets/taskmanager/package/contents/ui/main.qml
index 74dca9e..03e712d 100644
--- a/applets/taskmanager/package/contents/ui/main.qml
+++ b/applets/taskmanager/package/contents/ui/main.qml
@@ -164,6 +164,18 @@ Item {
         }
     }
 
+    Connections {
+        enabled: plasmoid.configuration.groupPopups
+
+        target: tasksModel
+
+        onActiveTaskChanged: {
+            if (tasksModel.activeTask.parent.valid) {
+                groupDialog.activeTask = tasksModel.activeTask;
+            }
+        }
+    }
+
     TaskManager.VirtualDesktopInfo {
         id: virtualDesktopInfo
     }