[iOS] The size measured by the Measure method is wrong

Daoting commented 4 years ago

Current behavior

All custom controls have this error on iOS with Uno V3.0. For example:

    <Style TargetType="a:Menu">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="a:Menu">
                    <menu:MenuPanel x:Name="Panel" Background="Transparent" />
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

MenuPanel inherited from Panel. Used to place all MenuItem.

    <Style TargetType="a:MenuItem">
        <Setter Property="Background" Value="Transparent" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="a:MenuItem">
                    <Grid x:Name="RootElement" Background="{TemplateBinding Background}">
                        <Rectangle x:Name="Rect" IsHitTestVisible="False"/>
                        <Grid x:Name="ContentGrid" Margin="10">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="Auto" />
                                <ColumnDefinition Width="*" />
                                <ColumnDefinition Width="Auto" />
                            </Grid.ColumnDefinitions>
                            <TextBlock x:Name="ElementIcon"
                                       Text="{Binding Icon, Converter={StaticResource CvIconToChar}, RelativeSource={RelativeSource TemplatedParent}}"
                                       FontFamily="{StaticResource IconFont}"
                                       FontSize="20"
                                       Margin="0,0,4,0"
                                       VerticalAlignment="Center" />
                            <TextBlock x:Name="ElementText"
                                       Text="{TemplateBinding ID}"
                                       VerticalAlignment="Center"
                                       Grid.Column="1" />
                            <TextBlock x:Name="ElementSub"
                                       Text="&#xE086;"
                                       FontFamily="{StaticResource IconFont}"
                                       Visibility="Collapsed"
                                       VerticalAlignment="Center"
                                       Grid.Column="2" />
                        </Grid>

                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

MenuPanel measure items.

        Size MeasureMenu()
        {
            double width = 0;
            double height = 0;
            foreach (var mi in Children.OfType<MenuItem>())
            {
                mi.Measure(_availableSize);
                if (mi.Visibility == Visibility.Visible)
                {
                    width += mi.DesiredSize.Width;
                    if (mi.DesiredSize.Height > height)
                        height = mi.DesiredSize.Height;
                }
            }
            return new Size(width, height);
        }

mi.DesiredSize is always same as _availableSize . Other custom controls also have this error. I can't figure out the reason, the impact is relatively large. Thanks.

Expected behavior

How to reproduce it (as minimally and precisely as possible)

Environment

Nuget Package:

Package Version(s):

Affected platform(s):

[x] iOS
[ ] Android
[ ] WebAssembly
[ ] WebAssembly renderers for Xamarin.Forms
[ ] macOS
[ ] Windows
[ ] Build tasks
[ ] Solution Templates

Visual Studio:

[ ] 2017 (version: )
[x] 2019 (version: )
[ ] for Mac (version: )

Relevant plugins:

[ ] Resharper (version: )

Anything else we need to know?

jeromelaban commented 4 years ago

Thanks for the report. What's the effect of this behavior ? Can you provide a screenshot of the error ?

Daoting commented 4 years ago

These custom controls have a common feature, that is, the parent control creates child controls and then adds them to the internal Panel. No error message, just the measurement result is wrong. Take the menu as an example. Menu MenuPanel load items MenuPanel MeasureOverride

Debug