c# - 通过 visualState 触发器更改 WrapGrid 的 maximumRowsOrColums 值不起作用

Question

我正在为我的 win 10 通用应用程序制作自适应布局。出于某种原因，当我尝试在 visualState 触发器中更改 wrapGrid 的 maximumRowsOrColumns 值时，它无法正常工作。

好吧，如果用户更改窗口大小，它实际上会起作用，但是在启动程序时，adaptiveTrigger 似乎对该值没有影响。

这是一些代码:

<Hub>
    <VisualStateManager.VisualStateGroups>
        <VisualStateGroup>
            <VisualState x:Name="wideView">
                <VisualState.StateTriggers>
                    <AdaptiveTrigger MinWindowWidth="720" />
                </VisualState.StateTriggers>
                <VisualState.Setters>
                    <Setter Target="WrapPanel.MaximumRowsOrColumns" Value="3" />
                </VisualState.Setters>
            </VisualState>
            <VisualState x:Name="narrowView">
                <VisualState.Setters>
                    <Setter Target="WrapPanel.MaximumRowsOrColumns" Value="2" />
                </VisualState.Setters>
                <VisualState.StateTriggers>
                    <AdaptiveTrigger MinWindowWidth="0" />
                </VisualState.StateTriggers>
            </VisualState>
        </VisualStateGroup>
    </VisualStateManager.VisualStateGroups>

    <HubSection>
        <DataTemplate>
            <GridView>
                <GridView.ItemsPanel>
                    <ItemsPanelTemplate>
                        <WrapGrid Orientation="Horizontal"
                                  x:Name="WrapPanel"/>
                    </ItemsPanelTemplate>
                </GridView.ItemsPanel>
                <GridViewItem>
                    <Rectangle Width="250" Height="100" Fill="Red" Margin="6" />
                </GridViewItem>
                <GridViewItem>
                    <Rectangle Width="250" Height="100" Fill="Yellow" Margin="6" />
                </GridViewItem>
                <GridViewItem>
                    <Rectangle Width="250" Height="100" Fill="Green" Margin="6" />
                </GridViewItem>
                <GridViewItem>
                    <Rectangle Width="250" Height="100" Fill="Blue" Margin="6" />
                </GridViewItem>
            </GridView>
        </DataTemplate>
    </HubSection>
</Hub>

Answer 1

如果您希望触发器在启动时起作用，您可以尝试强制应用程序以特定的宽度和高度启动。这样你的视觉状态就可以被触发。下面是您需要放入 yourfile.xaml.cs 中的片段:

ApplicationView.PreferredLaunchWindowingMode != ApplicationViewWindowingMode.Auto;
ApplicationView.PreferredLaunchViewSize = new Size { Width = 600, Height = 500 };
ApplicationView.PreferredLaunchWindowingMode = ApplicationViewWindowingMode.PreferredLaunchViewSize;

另外一个好的编码实践是从 > 标签中取出 Visual State Manager XAML，并将它们放在代码的末尾(但在 标签内)

    <Hub>
        <HubSection x:Name="HubSection" Header="Test">
            <DataTemplate>
                <GridView>
                    <GridView.ItemsPanel>
                        <ItemsPanelTemplate>
                            <WrapGrid Orientation="Horizontal"
                              x:Name="WrapPanel1" MaximumRowsOrColumns="3"/>
                        </ItemsPanelTemplate>
                    </GridView.ItemsPanel>
                    <GridViewItem >
                        <Rectangle Width="250" Height="100" Fill="Red" Margin="6" />
                    </GridViewItem>
                    <GridViewItem>
                        <Rectangle Width="250" Height="100" Fill="Yellow" Margin="6" />
                    </GridViewItem>
                    <GridViewItem>
                        <Rectangle Width="250" Height="100" Fill="Green" Margin="6" />
                    </GridViewItem>
                    <GridViewItem>
                        <Rectangle Width="250" Height="100" Fill="Blue" Margin="6" />
                    </GridViewItem>
                    <GridViewItem>
                        <Rectangle Width="250" Height="100" Fill="Orange" Margin="6" />
                    </GridViewItem>
                </GridView>
            </DataTemplate>
        </HubSection>
    </Hub>
    <VisualStateManager.VisualStateGroups>
        <VisualStateGroup>
            <VisualState x:Name="wideView">
                <VisualState.StateTriggers>
                    <AdaptiveTrigger MinWindowWidth="700" />
                </VisualState.StateTriggers>
                <VisualState.Setters>
                    <Setter Target="WrapPanel1.MaximumRowsOrColumns" Value="3"/>
                    <Setter Target="HubSection.Header" Value="WideView" />
                </VisualState.Setters>
            </VisualState>
            <VisualState x:Name="narrowView">
                <VisualState.StateTriggers>
                    <AdaptiveTrigger MinWindowWidth="0" />
                </VisualState.StateTriggers>
                <VisualState.Setters>
                    <Setter Target="WrapPanel1.MaximumRowsOrColumns" Value="2" />
                    <Setter Target="HubSection.Header" Value="Vertical" />
                </VisualState.Setters>
            </VisualState>
        </VisualStateGroup>
    </VisualStateManager.VisualStateGroups>
</Grid>