Question

有没有办法更改Xamarin.Forms Xaml文件中添加的ContextAction菜单的颜色。 IsDestructive="True"将菜单颜色设置为红色。但我需要另一个菜单看起来像绿色或其他颜色。

这是我的Forms Xaml代码..

<ListView x:Name="planList" ItemsSource="{x:Static local:SampleData.PLAN_DATA}" RowHeight="150" HorizontalOptions="FillAndExpand">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <ViewCell.ContextActions>
                    <MenuItem Clicked="OnEditClick" Text="Edit" CommandParameter="{Binding .}"/> <!-- THIS HAS TO BE GREEN COLOR -->
                    <MenuItem Clicked="OnDeleteClick" Text="Delete" IsDestructive="True" />
                </ViewCell.ContextActions>
                <ViewCell.View>
                    <StackLayout Orientation="Vertical"  HorizontalOptions="Start" VerticalOptions="FillAndExpand">
                        <!--Non Editable State-->
                        <StackLayout Orientation="Horizontal" Spacing="28" IsVisible="{Binding isNotSaveState}">
                            <Frame  WidthRequest="130" HeightRequest="50" BackgroundColor="#151617" HorizontalOptions="Start">
                                <Label Text="{Binding from}" TextColor="#ff9600" FontSize="Medium" FontFamily="Helvetica"/>
                            </Frame>
                        </StackLayout>
                        <!--Editable State-->
                        <StackLayout Orientation="Horizontal" Spacing="0"  IsVisible="{Binding isSaveState}">
                            <StackLayout Orientation="Horizontal" Spacing="5">
                                <Label Text="From" TextColor="#838288"  FontSize="Medium" FontFamily="Helvetica"/>
                                <Entry Text="" BackgroundColor="Red"/>
                            </StackLayout>
                            <Button Text="Save" BackgroundColor="Green" CommandParameter="{Binding .}" Clicked="onSaveClick" />
                        </StackLayout>
                    </StackLayout>
                </ViewCell.View>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

这是我的渲染器..

[assembly: ExportRenderer(typeof(MyApp.Views.Cells.CustomViewCell), typeof(MyApp.iOS.Views.Cells.CustomViewCellRenderer))]
namespace MyApp.iOS.Views.Cells
{

    public class CustomViewCellRenderer : ViewCellRenderer
    {
        public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv)
        {
            UITableViewCell cell = base.GetCell(item, reusableCell, tv);

            // I have no Idea how to access the Swipe Menus from Renderer

            //cell.EditingAccessory
            //cell.EditingAccessoryView

            return cell;
        }        
    }
}

Answer 1

Xamarin通过子类化ContextActionsCell的本机单元UITableViewCell实现上下文菜单。

但是，截至今天 Xamarin.Forms.Platform.iOS （1.4.0.6340-pre2）程序集，设置手势和按钮的ContextActionsCell仍然是{{1} } class，对于改变任何东西都是不可访问或可继承的。

但等等！

不过，您可以使用反思来更改上述{{1}}内容。

示例：

internal

注意1：这将改变所有上下文菜单的破坏性背景颜色。

注意2：如果您还想更改正常颜色，则字段名称为internal。

注3：Xamarin可能会创建这些类// Get UIImage with a green color fill CGRect rect = new CGRect (0, 0, 1, 1); CGSize size = rect.Size; UIGraphics.BeginImageContext (size); CGContext currentContext = UIGraphics.GetCurrentContext (); currentContext.SetFillColor (0, 1, 0, 1); currentContext.FillRect (rect); var backgroundImage = UIGraphics.GetImageFromCurrentImageContext (); currentContext.Dispose (); // This is the assembly full name which may vary by the Xamarin.Forms version installed. // NullReferenceException is raised if the full name is not correct. var t = Type.GetType("Xamarin.Forms.Platform.iOS.ContextActionsCell, Xamarin.Forms.Platform.iOS, Version=1.3.1.0, Culture=neutral, PublicKeyToken=null"); // Now change the static field value! var field = t.GetField ("destructiveBackground", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static); field.SetValue (null, backgroundImage);，目的是API和行为将来可能会发生变化。以上示例可能会在即将发布的版本中中断。

Answer 2

Xamarin.Forms.2.3.3.193＆amp; Xamarin.Forms.Platform.iOS（2.x）版本号版本= 2.0.0.0 和字段名称案例已更改为 NormalBackground ＆amp;的 DestructiveBackground

using System; using CoreGraphics; using Foundation; using UIKit; using Xamarin.Forms.Platform.iOS; using Xamarin.Forms; using System.Reflection; [assembly: ExportRenderer(typeof(ViewCell), typeof(App.Renderers.CustomViewCellRenderer))] namespace App.Renderers { public class CustomViewCellRenderer : ViewCellRenderer { public override UITableViewCell GetCell(Cell item, UITableViewCell reusableCell, UITableView tv) { UITableViewCell cell = base.GetCell(item, reusableCell, tv); try { // This is the assembly full name which may vary by the Xamarin.Forms version installed. // NullReferenceException is raised if the full name is not correct. var globalContextViewCell = Type.GetType("Xamarin.Forms.Platform.iOS.ContextActionsCell, Xamarin.Forms.Platform.iOS, Version=2.0.0.0, Culture=neutral, PublicKeyToken=null"); // Now change the static field value! "NormalBackground" OR "DestructiveBackground" if(globalContextViewCell != null) { var normalButton = globalContextViewCell.GetField("NormalBackground", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static); if (normalButton != null) { normalButton.SetValue(null, getImageBasedOnColor("ff9500")); } var destructiveButton = globalContextViewCell.GetField("DestructiveBackground", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static); if (destructiveButton != null) { destructiveButton.SetValue(null, getImageBasedOnColor("B3B3B3")); } } } catch (Exception e) { Console.WriteLine("Error in setting background color of Menu Item : " + e.ToString()); } return cell; } private UIImage getImageBasedOnColor(string colorCode) { // Get UIImage with a green color fill CGRect rect = new CGRect(0, 0, 1, 1); CGSize size = rect.Size; UIGraphics.BeginImageContext(size); CGContext currentContext = UIGraphics.GetCurrentContext(); currentContext.SetFillColor(Color.FromHex(colorCode).ToCGColor()); currentContext.FillRect(rect); var backgroundImage = UIGraphics.GetImageFromCurrentImageContext(); currentContext.Dispose(); return backgroundImage; } } }

如何在iOS ViewCellRenderer中更改窗体ViewList的MenuItem颜色？

2 个答案: