在ListView上添加"加载"-image

Question

我想添加一个"正在加载" - Image在我的ListView所有项目加载的同时,如果有很多项目被加载,我仍然需要一个很好的用户体验.

所以我想在我的上面浮动Image(动画GIF？)ListView.

如何解决这个问题,一旦你有浮动图像或控制,你如何使GIF动画？

Answer 1

这是我用来为WPF创建类似AJAX的等待微调器的一些XAML.我使用几何和动画而不是动画GIF,你可以通过调整XAML来控制大小和速率:

<!-- Style for AJAX-like wait spinners -->
<Style x:Key="WaitSpinnerStyle" TargetType="Control">
    <Setter Property="Foreground" Value="#888" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Control">
                <Viewbox Visibility="{TemplateBinding Visibility}">
                    <Canvas RenderTransformOrigin="0.5,0.5" Width="120" Height="120" >
                        <Ellipse Width="21.835" Height="21.862" Canvas.Left="20.1696" Canvas.Top="9.76358" Stretch="Fill" Fill="{TemplateBinding Foreground}" Opacity="1.0"/>
                        <Ellipse Width="20.835" Height="20.862" Canvas.Left="2.86816" Canvas.Top="29.9581" Stretch="Fill" Fill="{TemplateBinding Foreground}" Opacity="0.9"/>
                        <Ellipse Width="19.835" Height="19.862" Canvas.Left="0.00001" Canvas.Top="57.9341" Stretch="Fill" Fill="{TemplateBinding Foreground}" Opacity="0.8"/>
                        <Ellipse Width="17.835" Height="17.862" Canvas.Left="12.1203" Canvas.Top="83.3163" Stretch="Fill" Fill="{TemplateBinding Foreground}" Opacity="0.7"/>
                        <Ellipse Width="16.835" Height="16.862" Canvas.Left="36.5459" Canvas.Top="98.1380" Stretch="Fill" Fill="{TemplateBinding Foreground}" Opacity="0.6"/>
                        <Ellipse Width="14.835" Height="14.862" Canvas.Left="64.6723" Canvas.Top="96.8411" Stretch="Fill" Fill="{TemplateBinding Foreground}" Opacity="0.5"/>
                        <Ellipse Width="13.835" Height="13.862" Canvas.Left="87.6176" Canvas.Top="81.2783" Stretch="Fill" Fill="{TemplateBinding Foreground}" Opacity="0.4"/>
                        <Ellipse Width="12.835" Height="12.862" Canvas.Left="98.165"  Canvas.Top="54.4140" Stretch="Fill" Fill="{TemplateBinding Foreground}" Opacity="0.3"/>
                        <Ellipse Width="11.835" Height="11.862" Canvas.Left="92.9838" Canvas.Top="26.9938" Stretch="Fill" Fill="{TemplateBinding Foreground}" Opacity="0.2"/>
                        <Canvas.RenderTransform>
                            <RotateTransform x:Name="SpinnerRotate" Angle="0" />
                        </Canvas.RenderTransform>
                        <Canvas.Triggers>
                            <EventTrigger RoutedEvent="ContentControl.Loaded">
                                <BeginStoryboard>
                                    <Storyboard>
                                        <DoubleAnimation
                                            Storyboard.TargetName="SpinnerRotate"
                                            Storyboard.TargetProperty="Angle"
                                            From="0" To="360" Duration="0:0:01.3"
                                            RepeatBehavior="Forever" />
                                    </Storyboard>
                                </BeginStoryboard>
                            </EventTrigger>
                        </Canvas.Triggers>
                    </Canvas>
                </Viewbox>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

你这样使用它(如果你想改变颜色,请指定颜色):

<Control Style="{StaticResource WaitSpinnerStyle}" Width="35" />
<Control Style="{StaticResource WaitSpinnerStyle}" Width="35" Foreground="Green" />

上面的XAML看起来像这样(你必须想象它们在旋转!):

http://img23.imageshack.us/img23/1691/wpfwaitspinner.png

要在ListBox上方显示一个图层,请将其包装在Grid中,如下所示:

<Grid>
    <!-- LOADING overlay (for async-load) -->
    <Border HorizontalAlignment="Stretch" VerticalAlignment="Stretch" IsHitTestVisible="True" 
            Background="#40000000" CornerRadius="4"
            Visibility="{Binding Path=IsLoading, Converter={StaticResource BooleanToVisibilityConverter}}">
        <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center">
            <Control Style="{StaticResource WaitSpinnerStyle}" Width="35" Foreground="White" />
            <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Text="LOADING..." FontWeight="Bold" Margin="0,5" Foreground="White" FontSize="12" />
        </StackPanel>
    </Border>
    <ListBox />
</Grid>

使用网格意味着边框将出现在ListBox的顶部.在这种情况下,图层将显示为灰色,并将窃取任何鼠标操作,从而有效地禁用基础ListBox.

请注意,此处的绑定将IsLoaded连接到我的视图模型.我将其设置为false开始加载时,然后再次true加载到加载完成时.请注意,我从调度程序线程(在工作线程上)加载我的项目,以便在我执行此工作时更新UI.