我有一个使用 Xamarin Forms
TabbedPage
的应用程序,它具有允许用户暂停和播放页面的功能。请看下面的代码。
共享代码
public partial class MainPage : TabbedPage
{
public MainPage()
{
InitializeComponent();
var homePage = new NavigationPage(new HomePage())
{
Title = "Home",
Icon = "ionicons_2_0_1_home_outline_25.png"
};
var phrasesPage = new NavigationPage(new PhrasesPage())
{
Title = "Play",
Icon = "ionicons_2_0_1_play_outline_25.png"
};
Children.Add(homePage);
Children.Add(phrasesPage);
}
}
在 iOS 渲染器中:
public class TabbedPageRenderer : TabbedRenderer
{
private MainPage _page;
protected override void OnElementChanged(VisualElementChangedEventArgs e)
{
base.OnElementChanged(e);
var tabbarController = (UITabBarController)this.ViewController;
if (null != tabbarController)
{
tabbarController.ViewControllerSelected += OnTabBarReselected;
}
}
void OnTabBarReselected(object sender, UITabBarSelectionEventArgs e)
{
var tabs = Element as TabbedPage;
var playTab = tabs.Children[4];
if (TabBar.SelectedItem.Title == "Play") {
if (tabs != null)
{
playTab.Title = "Pause";
playTab.Icon = "ionicons_2_0_1_pause_outline_22.png";
}
App.pauseCard = false;
}
else {
if (tabs != null) {
playTab.Title = "Play";
playTab.Icon = "ionicons_2_0_1_play_outline_25.png";
}
App.pauseCard = true;
}
}
安卓渲染器
public class MyTabbedPageRenderer: TabbedPageRenderer, TabLayout.IOnTabSelectedListener
{
if (e.PropertyName == "Renderer")
{
viewPager = (ViewPager)ViewGroup.GetChildAt(0);
tabLayout = (TabLayout)ViewGroup.GetChildAt(1);
setup = true;
ColorStateList colors = null;
if ((int)Build.VERSION.SdkInt >= 23)
{
colors = Resources.GetColorStateList(Resource.Color.icon_tab, Forms.Context.Theme);
}
else
{
colors = Resources.GetColorStateList(Resource.Color.icon_tab);
}
for (int i = 0; i < tabLayout.TabCount; i++)
{
var tab = tabLayout.GetTabAt(i);
var icon = tab.Icon;
if (icon != null)
{
icon = Android.Support.V4.Graphics.Drawable.DrawableCompat.Wrap(icon);
Android.Support.V4.Graphics.Drawable.DrawableCompat.SetTintList(icon, colors);
}
}
}
void TabLayout.IOnTabSelectedListener.OnTabReselected(TabLayout.Tab tab)
{
var tabs = Element as TabbedPage;
var playTab = tabs.Children[4];
var selectedPosition = tab.Position;
if(selectedPosition == 4)
{
if (playTab.Title == "Play")
{
if (tabs != null)
{
playTab.Title = "Pause";
playTab.Icon = "ionicons_2_0_1_pause_outline_22.png";
}
App.pauseCard = false;
}
else
{
if (tabs != null)
{
playTab.Title = "Play";
playTab.Icon = "ionicons_2_0_1_play_outline_25.png";
}
App.pauseCard = true;
}
}
}
}
这在 iOS
中完美运行。但不知何故,在 Android
中,只有 Title
会发生变化,而 Icon
不会。任何人都知道我缺少什么或应该怎么做?此外,这是否可以在共享代码中完成,而不是在每个平台的代码中重复几乎完全相同的行?
最佳答案
您可以通过使用在 TabRenderer
的 OnTabReselected
参数中传递给您的选项卡来完成此操作。
您可以使用此对象移动您的整个逻辑。
这是我的整个渲染器文件(Android):
[assembly: ExportRenderer(typeof(SWTabSelection.MainPage), typeof(SWTabSelection.Droid.MyTabbedPageRenderer))]
namespace SWTabSelection.Droid
{
public class MyTabbedPageRenderer : TabbedPageRenderer, TabLayout.IOnTabSelectedListener
{
private ViewPager viewPager;
private TabLayout tabLayout;
private bool setup;
public MyTabbedPageRenderer() { }
public MyTabbedPageRenderer(Context context) : base(context)
{
//Use this constructor for newest versions of XF saving the context parameter
// in a field so it can be used later replacing the Xamarin.Forms.Forms.Context which is deprecated.
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (e.PropertyName == "Renderer")
{
viewPager = (ViewPager)ViewGroup.GetChildAt(0);
tabLayout = (TabLayout)ViewGroup.GetChildAt(1);
setup = true;
ColorStateList colors = GetTabColor();
for (int i = 0; i < tabLayout.TabCount; i++)
{
var tab = tabLayout.GetTabAt(i);
SetTintColor(tab, colors);
}
}
}
void TabLayout.IOnTabSelectedListener.OnTabReselected(TabLayout.Tab tab)
{
// To have the logic only on he tab on position 1
if(tab == null || tab.Position != 1)
{
return;
}
if(tab.Text == "Play")
{
tab.SetText("Pause");
tab.SetIcon(Resource.Drawable.ionicons_2_0_1_pause_outline_25);
App.pauseCard = false;
}
else
{
tab.SetText("Play");
tab.SetIcon(Resource.Drawable.ionicons_2_0_1_play_outline_25);
App.pauseCard = true;
}
SetTintColor(tab, GetTabColor());
}
void SetTintColor(TabLayout.Tab tab, ColorStateList colors)
{
var icon = tab?.Icon;
if(icon != null)
{
icon = Android.Support.V4.Graphics.Drawable.DrawableCompat.Wrap(icon);
Android.Support.V4.Graphics.Drawable.DrawableCompat.SetTintList(icon, colors);
}
}
ColorStateList GetTabColor()
{
return ((int)Build.VERSION.SdkInt >= 23)
? Resources.GetColorStateList(Resource.Color.icon_tab, Forms.Context.Theme)
: Resources.GetColorStateList(Resource.Color.icon_tab);
}
}
}
我在上面的代码中遇到的唯一问题是图标没有采用 Tint 颜色,因此创建了一个函数,其逻辑与设置 Tint 的逻辑相同,我在 Tab Reselection 上使用它。如果您的应用中只有一个选项卡,您可以在 Android 主题/样式 xml 中设置全局色调。
希望这对您有所帮助。
关于c# - 在 Android 中重新选择选项卡时如何更改 TabbedPage 图标?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/49585447/