A todo-app

This example shows how one can make a simple todo-app with plenty of animations.

The model

We make a JavaScript class to work as a model for each element and an Observable to contain them. Each Task has a title and a checked field. They also have a derived field, hidden, which observes checked. Hidden is used in markup to show and hide Tasks based on which tab is chosen.

function Task(title){
    var self = this;
    this.title = title;
    this.checked = Observable(false);
    this.hidden = Observable(function(){
        if (currentTab.value == "all"){
            return false;
        }
        else if (currentTab.value == "active"){
            return self.checked.value ? true : false;
        }
        else {
            return self.checked.value ? false : true;
        }
    });
}

An Observable is used to contain all our Tasks.

var todoList = Observable();

Our add-button looks like a cross, and is made up of two thin panels layered on top of each other. The buttons Clicked property is databound to the addItem function in JavaScript.

<BlankButton Clicked="{addItem}" Width="60" Height="60" HitTestMode="LocalBoundsAndChildren">
    <Panel Layer="Background">
        <Panel Height="1" Width="30" Background="#ddd"/>
        <Panel Width="1" Height="30" Background="#ddd"/>
    </Panel>
</BlankButton>
function addItem(arg) {
    todoList.add(new Task(titleInput.value));
}

Each item has a button which toggles whether the item is checked or not, and a button to delete it. * Note: The following UX-snippet has been stripped to show the basic structure.

<Each Items="{todoList}">
    <Grid ux:Name="itemPanel" Columns="auto,1*,auto" Alignment="Top" Height="60" Opacity="1" BoxSizing="Limit" LimitHeight="100%">


        <BlankButton Clicked="{toggleItem}" Alignment="CenterLeft" Width="60" Height="60">
            ... this button toggles an items checked state ...
        </BlankButton>

        <Panel>
            <Panel Alignment="Left">
                <Rectangle ux:Name="textLine" Height="1" Opacity="0" Margin="30,0,0,0" Color="#bbb"/>
                <Text ux:Name="itemText" Value="{title}" Alignment="CenterLeft" TextAlignment="Left" Margin="30,0,0,0" FontSize="20" Color="#999" TextWrapping="Wrap" />
            </Panel>
        </Panel>


        <WhileTrue Value="{checked}">
            <Change checkedCircleColor.Color="#50ac9a" Duration="0.3"/>
            <Change checkedIcon.Opacity="1" Duration="0.3"/>
            <Change textLine.Opacity="1" Duration="0.3"/>
            <Change itemText.Color="#ddd" Duration="0.3"/>
        </WhileTrue>

        <BlankButton Alignment="CenterRight" Clicked="{deleteItem}" Width="60" Height="60"
                HitTestMode="LocalBoundsAndChildren">
            ... the delete button ...
        </BlankButton>

        <LayoutAnimation>
            <Move RelativeTo="LayoutChange" Y="1" Duration="0.6" Easing="BounceIn"/>
        </LayoutAnimation>
        <AddingAnimation>
            <Move RelativeTo="Size" X="1" Duration="0.3" Easing="CircularInOut" />
        </AddingAnimation>
        <RemovingAnimation>
            <Move RelativeTo="Size" X="1" Duration="0.3" Easing="CircularInOut" />
        </RemovingAnimation>

        <Rectangle Height="1" ColumnSpan="3" Row="0" Alignment="Bottom" Color="#ddd"/>
    </Grid>
</Each>

Every Task-element has a delete button which is bound to the deleteItem function in javascript.

function deleteItem(arg){
    todoList.tryRemove(arg.data);
}

The tabs

The tabs in the bottom lets us toggle between vieweing "all", "completed" or "active" Tasks. They have a Rectangle whith a red border which jumps between the tabs, indicating which one is active. Such an animation is done easily with a MultiLayoutPanel.

MultiLayoutPanel lets us define several layouts which we can switch and animate between using the Placeholder class. A Placeholder lets us reference the same element in the different layouts we put inside our MultiLayoutPanel. In our case we use Placeholders to reference the red indicator-rectangle to make it move between the tabs.

<MultiLayoutPanel ux:Name="multiLayout">
    <GridLayout Columns="1*,1*,1.5*"/>
    <BlankButton ux:Name="allButton" Clicked="{showAll}">
        <Panel Alignment="Center">
            <SmallText Value="All" TextAlignment="Center"/>
            <Placeholder>
                <Rectangle ux:Name="indicator" Column="0" Row="0" CornerRadius="3" Margin="-10,-5,-10,-5">
                    <LayoutAnimation>
                        <Move RelativeTo="LayoutChange" X="1" Duration="0.5" Easing="BackIn"/>
                        <Resize RelativeTo="LayoutChange" Duration="0.5" Easing="BackIn"/>
                    </LayoutAnimation>
                    <Stroke Width="1" Brush="#E7D9DE"/>
                </Rectangle>
            </Placeholder>
        </Panel>

        <Clicked>
            <Set multiLayout.LayoutElement="allButton" />
        </Clicked>
    </BlankButton>
    <BlankButton ux:Name="activeButton" Clicked="{showActive}">
        <Panel Alignment="Center">
            <SmallText TextAlignment="Center" Value="Active" />
            <Placeholder Target="indicator"/>
        </Panel>
        <Clicked>
            <Set multiLayout.LayoutElement="activeButton"/>
        </Clicked>
    </BlankButton>
    <BlankButton ux:Name="completedButton" Clicked="{showCompleted}">
        <Panel Alignment="Center">
            <SmallText TextAlignment="Center" Value="Completed"/>
            <Placeholder Target="indicator"/>
        </Panel>
        <Clicked>
            <Set multiLayout.LayoutElement="completedButton"/>
        </Clicked>
    </BlankButton>
</MultiLayoutPanel>

Each tab-button changes the currentTab variable in JavaScript by calling the following functions.

function showAll() {
    currentTab.value = "all";
}
function showActive() {
    currentTab.value = "active";
}
function showCompleted() {
    currentTab.value = "completed";
}

Remaining indicator and clear all button

The text indicating unfinished Tasks is made using a derived Observable.

First we use observable.count(func) to calculate the number of unchecked Tasks.

var remainingCount = todoList.count(function(x){
    return x.checked.not();
});

Then we use observable.map(func) on remainingCount to create an observable string.

var remainingText = remainingCount.map(function(x){
    return x + " " + ((x == 1) ? "task" : "tasks") + " remaining";
});

We can then just databind to remainingText from UX and it will be updated whenever the number of checked Task changes. Note that Task.checked is itself observable, which is necessary for this to work.

<SmallText Value="{remainingText}" Margin="10" Alignment="Left"/>

The Clear completed button should only be visible when one or more Tasks are checked. We hide the button with a WhileDisabled trigger and databinding the buttons IsEnabled property to the canClearCompleted variable in JavaScript.

<Panel ux:Name="clearCompletedButton" Alignment="TopRight" Clicked="{clearCompleted}"  Margin="10" IsEnabled="{canClearCompleted}">
    <Text Value="Clear completed" FontSize="14" Color="#999" Margin="10,0,10,0" />
    <WhileDisabled>
        <Change clearCompletedButton.Opacity="0" Duration="0.3"/>
    </WhileDisabled>
</Panel>
var canClearCompleted = todoList.count(function(x){
    return x.checked;
}).map(function(x){
    return x > 0;
});
function clearCompleted() {
    todoList.removeWhere(function(x) { return x.checked.value; });
}