MahApps.Metro - ToolTip

One style, applied implicitly, that turns WPF's tooltip into a flat bordered card in the theme colours and fades it in and out.

The default tooltip

<Button Content="Save" ToolTip="Save the current document" />

Styles/Controls.xaml applies MahApps.Styles.ToolTip to every ToolTip, so the quick start is all the setup there is. There is no second style and no variant.

What the style sets

Property	Set to
`Background`	`MahApps.Brushes.Control.Background`
`BorderBrush`	`MahApps.Brushes.Gray7`
`BorderThickness`	`1`
`Foreground`	`MahApps.Brushes.ThemeForeground`
`FontSize`	`MahApps.Font.Size.Tooltip`, which is 12
`Padding`	`6 3`
`SnapsToDevicePixels`	`True`

All seven are ordinary properties on a border the template draws, so all seven can be changed on the control:

The default tooltip, a recoloured one, and one without a border

<Button Content="Save">
    <Button.ToolTip>
        <ToolTip Content="Save the document"
                 Background="{DynamicResource MahApps.Brushes.Accent}"
                 BorderBrush="{DynamicResource MahApps.Brushes.AccentBase}"
                 Foreground="{DynamicResource MahApps.Brushes.IdealForeground}" />
    </Button.ToolTip>
</Button>

Note what is missing: the template's border has no CornerRadius binding, so a tooltip is always square-cornered — ControlsHelper.CornerRadius does nothing here, unlike on a Label or a Button. There is no drop shadow either.

Both are already fixed in develop and will arrive with the next release: the border gets CornerRadius="{TemplateBinding mah:ControlsHelper.CornerRadius}", and a HasDropShadow setter — True by default — applies a new MahApps.DropShadowEffect.ToolTip. Until then, rounding a tooltip means replacing the template, and if you do, mind the visual states below.

The fade

The template's root border is written as Opacity="0", and an OpenStates visual state group fades it to 1 over 0.3 seconds when the tooltip opens, then back to 0 over 0.4 on close.

That means a replacement template must keep those visual states. Drop them and you get a tooltip that is measured, positioned and completely invisible — with no error to tell you why. If you write your own, copy the VisualStateManager.VisualStateGroups block across with it, or start the root at Opacity="1" and give up the fade.

Content

The template's presenter is a mah:ContentControlEx, which is what makes ControlsHelper.ContentCharacterCasing work on a tooltip:

Normal, Upper and Lower casing

<ToolTip Content="Save the document" mah:ControlsHelper.ContentCharacterCasing="Upper" />

Being a ContentControl, a tooltip is not limited to a string. ContentTemplate and ContentStringFormat are template-bound, and anything you put in the content is laid out normally:

A tooltip holding a panel

<Button Content="Save">
    <Button.ToolTip>
        <ToolTip>
            <StackPanel MaxWidth="220">
                <TextBlock FontWeight="SemiBold" Text="Save" />
                <TextBlock Margin="0 2 0 0"
                           TextWrapping="Wrap"
                           Text="Writes the current document to disk. Ctrl+S does the same." />
            </StackPanel>
        </ToolTip>
    </Button.ToolTip>
</Button>

A tooltip does not size itself, so give a wrapping block a MaxWidth or a long sentence turns into one very long line.

Timing and placement

None of this is MahApps — the style changes how a tooltip looks, not when it appears. That stays with WPF's ToolTipService, and the library sets no defaults for it:

Attached property	WPF default
`InitialShowDelay`	1000 ms	how long the pointer has to rest first
`ShowDuration`	`Int32.MaxValue`	how long it stays, which is until the pointer leaves
`BetweenShowDelay`	100 ms	grace period in which the next tooltip appears at once
`ShowOnDisabled`	`False`	set it to show why a control is disabled
`Placement`, `PlacementTarget`	`Mouse`

<Button Content="Save"
        IsEnabled="False"
        ToolTip="Nothing to save yet"
        ToolTipService.ShowOnDisabled="True" />

ShowOnDisabled is the one worth remembering: a disabled control with an unexplained reason is exactly where a tooltip earns its keep, and by default it will not show one.

The five seconds quoted for ShowDuration in most places is not what WPF registers. The default is Int32.MaxValue, on .NET Framework and on modern .NET alike, so a tooltip stays for as long as the pointer rests on the control. Setting the property shortens it rather than lengthening it.

Slider and RangeSlider have their own value tooltip through AutoToolTipPlacement, which is a separate mechanism and does not use this style. Validation errors are drawn by CustomValidationPopup rather than by a tooltip — see Validation.

What the style sets

The fade

Content

Timing and placement

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