[WPSL] [C＃]如何旋转ListBox的项目 [英] [WPSL][C#]How to rotate the items of a ListBox

问题描述

您好。我将图像绑定到列表框，在OnOrientationChange事件中我想旋转图像以直立显示它。这是列表框和代码的XAML ...

Hi. I'm binding images to a listbox and in OnOrientationChange event I want to rotate the images to display it upright. Here's the XAML of the Listbox and Code...

<!--My Friends ListBox-->
                <ListBox Visibility="Collapsed" ScrollViewer.VerticalScrollBarVisibility="Disabled" ScrollViewer.HorizontalScrollBarVisibility="Auto"  x:Name="MyFriendsList" VerticalAlignment="Top" Height="120" Grid.Row="0" Grid.ColumnSpan="3" Grid.Column="0">
            
                    <ListBox.ItemsPanel>
                        <ItemsPanelTemplate>
                            <StackPanel VerticalAlignment="Center" Orientation="Horizontal" />
                        </ItemsPanelTemplate>
                    </ListBox.ItemsPanel>
                    <ListBox.ItemTemplate>
                        <DataTemplate>
                            <Image Source="{Binding}" Stretch = "Uniform" Margin="5,5,5,5"/>
                        </DataTemplate>
                    </ListBox.ItemTemplate>
                </ListBox>

protected override void OnOrientationChanged(OrientationChangedEventArgs e)
        {
            //get friends
            this.Loaded += async (s, e) =>
            {
                var images = await GetImages();
                MyFriendsList.ItemsSource = images;
            };
        }

private async System.Threading.Tasks.Task<ObservableCollection<ImageSource>> GetImages()
        {
            ObservableCollection<ImageSource> images = new ObservableCollection<ImageSource>();
            Windows.Storage.StorageFolder folder;
            IReadOnlyList<StorageFile> files = null;
            StorageFile myphoto = null;

            try
            {
                IsolatedStorageFile.GetUserStoreForApplication().CreateDirectory("myfriends");
                folder = await Windows.Storage.ApplicationData.Current.LocalFolder.GetFolderAsync("myfriends");
                files = await folder.GetFilesAsync();
            }
            catch (Exception ex)
            {
                this.Dispatcher.BeginInvoke(delegate()
                {
                    txtDebug.Text = "No friends to display.\n" + ex.Message;
                });
            }

            if (files.Count < 1 || files == null)
            {
                //go back, no friends yet
                return images;
            }
            foreach (var file in files)
            {
                if (file.Name.EndsWith(".jpg"))
                {
                    BitmapImage bimage = new BitmapImage();
                    bimage.SetSource(await file.OpenStreamForReadAsync());
                    images.Add(bimage);
                }
            }
            return images;
        }

 private Stream RotateStream(Stream stream, int angle)
        {
            stream.Position = 0;
            if (angle % 90 != 0 || angle < 0) throw new ArgumentException();
            if (angle % 360 == 0) return stream;

            BitmapImage bitmap = new BitmapImage();
            bitmap.SetSource(stream);
            WriteableBitmap wbSource = new WriteableBitmap(bitmap);

            WriteableBitmap wbTarget = null;
            if (angle % 180 == 0)
            {
                wbTarget = new WriteableBitmap(wbSource.PixelWidth, wbSource.PixelHeight);
            }
            else
            {
                wbTarget = new WriteableBitmap(wbSource.PixelHeight, wbSource.PixelWidth);
            }

            for (int x = 0; x < wbSource.PixelWidth; x++)
            {
                for (int y = 0; y < wbSource.PixelHeight; y++)
                {
                    switch (angle % 360)
                    {
                        case 90:
                            wbTarget.Pixels[(wbSource.PixelHeight - y - 1) + x * wbTarget.PixelWidth] = wbSource.Pixels[x + y * wbSource.PixelWidth];
                            break;
                        case 180:
                            wbTarget.Pixels[(wbSource.PixelWidth - x - 1) + (wbSource.PixelHeight - y - 1) * wbSource.PixelWidth] = wbSource.Pixels[x + y * wbSource.PixelWidth];
                            break;
                        case 270:
                            wbTarget.Pixels[y + (wbSource.PixelWidth - x - 1) * wbTarget.PixelWidth] = wbSource.Pixels[x + y * wbSource.PixelWidth];
                            break;
                    }
                }
            }
            MemoryStream targetStream = new MemoryStream();
            wbTarget.SaveJpeg(targetStream, wbTarget.PixelWidth, wbTarget.PixelHeight, 0, 100);
            return targetStream;
        

每次设备旋转时旋转图像的简单方法是什么？先感谢您。 ps你能否指出我能做些什么更简单。

What's a simple way to rotate the images everytime the device rotates? Thank you in advance. ps Can you also point out if there is something I can do simpler.

推荐答案

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我不清楚你到底想要实现的目标，但是你呢？应用一个可能会好得多旋转变换而不是旋转像素缓冲区。

It's not clear to me exactly what you're trying to achieve here, but you'll probably be much better off applying a rotation transform rather than rotating the pixel buffer.

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