shift-shell/containments/taskpanel/package/contents/ui/TaskSwitcher.qml

/*
 *   Copyright 2015 Marco Martin <notmart@gmail.com>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library General Public License as
 *   published by the Free Software Foundation; either version 2, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Library General Public License for more details
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this program; if not, write to the
 *   Free Software Foundation, Inc.,
 *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

import QtQuick 2.12
import QtQuick.Layouts 1.1
import QtQuick.Window 2.2
import org.kde.taskmanager 0.1 as TaskManager
import org.kde.plasma.core 2.1 as PlasmaCore
import org.kde.plasma.components 3.0 as PlasmaComponents
import org.kde.plasma.private.nanoshell 2.0 as NanoShell
import org.kde.plasma.private.mobileshell 1.0 as MobileShell

NanoShell.FullScreenOverlay {
    id: window

    visible: false
    width: Screen.width
    height: Screen.height
    property int offset: 0
    property int overShoot: units.gridUnit * 2
    property int tasksCount: window.model.count
    property int currentTaskIndex: -1
    property TaskManager.TasksModel model

    Component.onCompleted: plasmoid.nativeInterface.panel = window;

    enum MovementDirection {
        None = 0,
        Up,
        Down
    }

    onTasksCountChanged: {
        if (tasksCount == 0) {
            hide();
        }
    }
    color: Qt.rgba(0, 0, 0, 0.6 * Math.min(
        (Math.min(tasksView.contentY, tasksView.height) / tasksView.height),
        ((tasksView.contentHeight - tasksView.contentY - window.height) / tasksView.height)))

    function show() {
        if (window.model.count == 0) {
            return;
        }

        visible = true;
        scrollAnim.from = tasksView.contentY;
        scrollAnim.to = window.height;
        scrollAnim.restart();
    }
    function hide() {
        if (!window.visible) {
            return;
        }
        scrollAnim.from = tasksView.contentY;
        if (tasksView.contentY + window.height < tasksView.contentHeight/2) {
            scrollAnim.to = 0;
        } else {
            scrollAnim.to = tasksView.contentHeight - window.height;
        }
        scrollAnim.restart();
    }

    function setSingleActiveWindow(id) {
        if (id < 0) {
            return;
        }
        for (var i = 0 ; i < tasksModel.count; i++) {
            var idx = window.model.index(i, 0)
            if (i == id) {
                window.model.requestActivate(idx);
            } else if (!tasksModel.data(idx, TaskManager.AbstractTasksModel.IsMinimized)) {
                tasksModel.requestToggleMinimized(idx);
            }
        }
    }

    onOffsetChanged: tasksView.contentY = offset + grid.y
    onVisibleChanged: {
        if (!visible) {
            tasksView.contentY = 0;
        }
        MobileShell.HomeScreenControls.taskSwitcherVisible = visible;
    }

    SequentialAnimation {
        id: scrollAnim
        property alias to: internalAnim.to
        property alias from: internalAnim.from
        ScriptAction {
            script: window.showFullScreen();
        }
        NumberAnimation {
            id: internalAnim
            target: tasksView
            properties: "contentY"
            duration: units.longDuration
            easing.type: Easing.InOutQuad
        }
        ScriptAction {
            script: {
                if (tasksView.contentY <= 0 || tasksView.contentY >= tasksView.contentHeight - window.height) {
                    window.visible = false;
                    setSingleActiveWindow(currentTaskIndex);
                }
            }
        }
    }

    Flickable {
        id: tasksView
        width: window.width
        height: window.height
        contentWidth: width
        contentHeight: mainArea.implicitHeight
        property int flickState: TaskSwitcher.MovementDirection.None

        readonly property int movementDirection: {
            if (flickState != TaskSwitcher.MovementDirection.None) {
                return flickState;
            } else if (verticalVelocity < 0) {
                return TaskSwitcher.MovementDirection.Up;
            } else if (verticalVelocity > 0)  {
                return TaskSwitcher.MovementDirection.Down;
            } else {
                return TaskSwitcher.MovementDirection.None;
            }
        }

        onFlickingVerticallyChanged: {
            if (flickingVertically) {
                flickState = verticalVelocity < 0 ? TaskSwitcher.MovementDirection.Up : TaskSwitcher.MovementDirection.Down;
            } else if (/*!draggingVertically &&*/ !flickingVertically) {
               draggingVerticallyChanged();
               flickState = TaskSwitcher.MovementDirection.None
            }
            
        }

        onDraggingVerticallyChanged: {
            if (draggingVertically) {
                return;
            }

            let beforeBeginning = contentY <  window.height;
            let afterEnd = contentY > contentHeight - window.height * 2;

            let topCloseCondition = contentY <  window.height / 10 * 9;
            let bottomClosecondition = contentY > contentHeight - window.height * 2 - window.height / 10;

            switch (movementDirection) {
            case TaskSwitcher.MovementDirection.Up: {
                if (topCloseCondition) {
                    hide();
                } else if (beforeBeginning) {
                    show();
                } else if (afterEnd) {
                    scrollAnim.from = tasksView.contentY;
                    scrollAnim.to = tasksView.contentHeight - window.height * 2;
                    scrollAnim.restart();
                }
                break;
            }
            case TaskSwitcher.MovementDirection.Down: {
                if (bottomClosecondition) {
                    hide();
                } else if (beforeBeginning) {
                    show();
                } else if (afterEnd) {
                    scrollAnim.from = tasksView.contentY;
                    scrollAnim.to = tasksView.contentHeight - window.height * 2;
                    scrollAnim.restart();
                }
                break;
            }
            case TaskSwitcher.MovementDirection.None:
            default:
                if (beforeBeginning) {
                    show();
                } else if (afterEnd) {
                    scrollAnim.from = tasksView.contentY;
                    scrollAnim.to = tasksView.contentHeight - window.height * 2;
                    scrollAnim.restart();
                }
                break;
            }
        }

        MouseArea {
            id: mainArea
            parent: tasksView.contentItem
            width: tasksView.width
            implicitHeight: window.height * 2 + Math.max(window.height, grid.implicitHeight)
            onClicked: window.hide()

            Grid {
                id: grid
                anchors {
                    left: parent.left
                    right: parent.right
                    bottom: parent.bottom
                    bottomMargin: window.height
                }
                columns: 2

                Repeater {
                    model: window.model
                    delegate: Task {}
                }

                move: Transition {
                    NumberAnimation {
                        properties: "x,y"
                        duration: units.longDuration
                        easing.type: Easing.InOutQuad
                    }
                }
            }
        }

    }

    PlasmaComponents.RoundButton {
        anchors {
            horizontalCenter: parent.horizontalCenter
            bottom: parent.bottom
        }
        icon.name: "start-here-kde"
        icon.width: units.iconSizes.medium
        icon.height: units.iconSizes.medium
        onClicked: {
            currentTaskIndex = -1;
            window.hide();
            //plasmoid.nativeInterface.showDesktop = true;

            root.minimizeAll();
        }
    }
}