如何在 GridView 中旋转图像

Question

使用带有 Mvvm Cross 的 Xamarin Android 在 GridView 中显示了一组图像，但问题是有两个按钮可旋转时钟和反时钟方向，每次单击时所有单元格（或图像）都应旋转 90 度网格视图。 我怎样才能实现它？ 这是我的 viewModel 集合，它将绑定到 GridView，

private ObservableCollection<Snapshot> _snapshotsItemSource;
    public ObservableCollection<Snapshot> SnapshotsItemSource
    {
        get { return _snapshotsItemSource; }
        set
        {
            _snapshotsItemSource = value;
            RaisePropertyChanged(() => SnapshotsItemSource);
        }

    }

我的模型对象是，

public class Snapshot : MvxViewModel
{
    string _ID;
    public string ID
    {
        get
        {
            return _ID;
        }
        set
        {
            _ID = value;
            ImageUrl = string.Format("http://{0}:{1}/GetSnapshot?ID={2}", TIConstants.Device.IpAdd, TIConstants.PortNo, value);
        }
    }

    string _ImageUrl;
    public string ImageUrl
    {
        get
        {
            return _ImageUrl;
        }
        set
        {
            _ImageUrl = value;
            RaisePropertyChanged("ImageUrl");
        }
    }
}

我的观点是，

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:mvvm="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<MvvmCross.Binding.Droid.Views.MvxGridView
    android:id="@+id/gvSnapshots"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:numColumns="3"
    android:layout_alignParentTop="true"
    mvvm:MvxItemTemplate="@layout/snapshotcellview"
    mvvm:MvxBind="ItemsSource SnapshotsItemSource" />
<RelativeLayout
    android:background="@color/white"
    android:layout_width="match_parent"
    android:layout_height="@dimen/section_height"
    android:orientation="horizontal"
    android:layout_alignParentBottom="true">
    <ImageButton
        android:id="@+id/btnRotateLeft"
        android:layout_alignParentLeft="true"
        android:src="@drawable/abc_text_select_handle_left_mtrl_dark"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
    <ImageButton
        android:id="@+id/btnRotateRight"
        android:layout_alignParentRight="true"
        android:src="@drawable/abc_text_select_handle_left_mtrl_dark"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</RelativeLayout>

Answer 1

试试 Glide，对你有帮助吗

Glide
    .with( context )
    .load( "image Url" )
    .transform( new RotateTransformation( context, 90f ))
    .into( imageView );

Answer 2

public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        // Use this to return your custom view for this Fragment
        // return inflater.Inflate(Resource.Layout.YourFragment, container, false);

        base.OnCreateView(inflater, container, savedInstanceState);
        var view = this.BindingInflate(Resource.Layout.SnapshotsView, null);

        var toolbar = ((MainActivity)this.Activity).FindViewById(Resource.Id.toolbar);
        var txtTitle = ((MainActivity)this.Activity).FindViewById<TextView>(Resource.Id.TitleText);
        txtTitle.Text = ViewModel.ViewTitle;
        RegisterEvents();
        ViewModel.SetItemSource();

        var btnLeft = view.FindViewById<ImageButton>(Resource.Id.btnRotateLeft);
        btnLeft.Click += BtnLeft_Click;

        var btnRight = view.FindViewById<ImageButton>(Resource.Id.btnRotateRight);
        btnRight.Click += BtnRight_Click;

        grid = view.FindViewById<MvxGridView>(Resource.Id.gvSnapshots);
        mAdapter = new SnapshotsDataViewAdapter(this.Activity, (IMvxAndroidBindingContext)BindingContext);
        grid.Adapter = mAdapter;
        grid.OnItemClickListener = this;
        return view;
    }

    void BtnLeft_Click(object sender, EventArgs e)
    {
        currentRotation = currentRotation + 1;
        mAdapter.NotifyDataSetChanged();
    }

    void BtnRight_Click(object sender, EventArgs e)
    {
        currentRotation = currentRotation - 1;
        mAdapter.NotifyDataSetChanged();
    }

static int currentRotation = 0;
    static float RotationTranslation = 0;
    private class SnapshotsDataViewAdapter : MvxAdapter
    {
        SnapshotsViewModel mViewModel;
        public SnapshotsDataViewAdapter(FragmentActivity context, IMvxAndroidBindingContext bindingContext) : base(context, bindingContext)
        {
            mViewModel = bindingContext.DataContext as SnapshotsViewModel;
        }

        protected override View GetBindableView(View convertView, object dataContext, ViewGroup parent, int templateId)
        {
            View row = convertView;  

            try 
            {  
                var item = (BSSnapshot)dataContext;
                if (row == null) 
                {  
                   row = BindingContext.BindingInflate(templateId, parent, false);  
                }  


                var imgView = row.FindViewById<ImageView>(Resource.Id.imgRotate1);  
                Picasso.With(Android.App.Application.Context).Load(item.ImageUrl).Into(imgView);

                imgView.Rotation = currentRotation*90;

            }
            catch (Exception ex) 
            {  
                System.Diagnostics.Debug.WriteLine(ex.Message);  
            } 
            finally 
            {}  
            return row; 
        }

    }

在这里我使用了 Picasso，因为 Glide 无法添加到项目中并且它工作正常。