UWP - 如何平铺背景图像？

Question

在通用 Windows 应用程序中，我尝试使用背景图像（来自 ImageSource）并将其平铺到控件上。

XAML

<Grid x:Name="gridBackground">
  <ContentPresenter />
</Grid>

C#

void UpdateBackground(ImageSource source)
{
// ...
  gridBackground.Background = new ImageBrush {
    ImageSource = source,
    Stretch = Stretch.None
  };
}

根据MSDN，ImageBrush继承自TileBrush。它甚至说：

用于 ImageBrush，包括文本或平铺的装饰效果 控件或布局容器的背景。

我认为如果禁用拉伸，这应该平铺图像，但可惜，它只是在控件的中间绘制图像。我没有看到任何实际属性可以使其平铺。

在 WPF 中，有一个 TileMode 属性，可以设置 ViewPort 来指定图块的尺寸。但这在通用平台下似乎不存在。

上一个问题指的是WinRT（Windows 8），但我希望有一个基于画笔的解决方案，而不是用图像填充画布。

如何使用 UWP 平铺背景图像？

Answer 1

之前的问题涉及 WinRT (Windows 8)，但我希望有一个基于画笔的解决方案，而不是用图像填充画布。

目前，在 UWP 应用中以平铺模式显示背景图像只有两种解决方案，您知道的第一个解决方案是填充画布。

我使用的第二个是创建一个Panel并在上面绘制图像，这个想法源自

这篇文章

这种方法的作用是滥用我们在矩形中绘制重复的线条组这一事实。首先，它尝试在顶部绘制一个与我们的图块高度相同的块。然后它向下复制该块，直到到达底部。

我修改了一些代码并修复了一些问题：

public class TiledBackground : Panel
{
        public ImageSource BackgroundImage
        {
            get { return (ImageSource)GetValue(BackgroundImageProperty); }
            set { SetValue(BackgroundImageProperty, value); }
        }

        // Using a DependencyProperty as the backing store for BackgroundImage.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty BackgroundImageProperty =
            DependencyProperty.Register("BackgroundImage", typeof(ImageSource), typeof(TiledBackground), new PropertyMetadata(null, BackgroundImageChanged));


        private static void BackgroundImageChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            ((TiledBackground)d).OnBackgroundImageChanged();
        }
        private static void DesignDataChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            ((TiledBackground)d).OnDesignDataChanged();
        }

        private ImageBrush backgroundImageBrush = null;

        private bool tileImageDataRebuildNeeded = true;
        private byte[] tileImagePixels = null;
        private int tileImageWidth = 0;
        private int tileImageHeight = 0;

        private readonly BitmapPixelFormat bitmapPixelFormat = BitmapPixelFormat.Bgra8;
        private readonly BitmapTransform bitmapTransform = new BitmapTransform();
        private readonly BitmapAlphaMode bitmapAlphaMode = BitmapAlphaMode.Straight;
        private readonly ExifOrientationMode exifOrientationMode = ExifOrientationMode.IgnoreExifOrientation;
        private readonly ColorManagementMode coloManagementMode = ColorManagementMode.ColorManageToSRgb;

        public TiledBackground()
        {
            this.backgroundImageBrush = new ImageBrush();
            this.Background = backgroundImageBrush;

            this.SizeChanged += TiledBackground_SizeChanged;
        }

        private async void TiledBackground_SizeChanged(object sender, SizeChangedEventArgs e)
        {
            await this.Render((int)e.NewSize.Width, (int)e.NewSize.Height);
        }

        private async void OnBackgroundImageChanged()
        {
            tileImageDataRebuildNeeded = true;
            await Render((int)this.ActualWidth, (int)this.ActualHeight);
        }

        private async void OnDesignDataChanged()
        {
            tileImageDataRebuildNeeded = true;
            await Render((int)this.ActualWidth, (int)this.ActualHeight);
        }

        private async Task RebuildTileImageData()
        {
            BitmapImage image = BackgroundImage as BitmapImage;
            if ((image != null) && (!DesignMode.DesignModeEnabled))
            {
                string imgUri = image.UriSource.OriginalString;
                if (!imgUri.Contains("ms-appx:///"))
                {
                    imgUri += "ms-appx:///";
                }
                var imageSource = new Uri(imgUri);
                StorageFile storageFile = await StorageFile.GetFileFromApplicationUriAsync(imageSource);
                using (var imageStream = await storageFile.OpenAsync(FileAccessMode.Read))
                {
                    BitmapDecoder decoder = await BitmapDecoder.CreateAsync(imageStream);

                    var pixelDataProvider = await decoder.GetPixelDataAsync(this.bitmapPixelFormat, this.bitmapAlphaMode,
                        this.bitmapTransform, this.exifOrientationMode, this.coloManagementMode
                        );

                    this.tileImagePixels = pixelDataProvider.DetachPixelData();
                    this.tileImageHeight = (int)decoder.PixelHeight;
                    this.tileImageWidth = (int)decoder.PixelWidth;
                }
            }
        }

        private byte[] CreateBackgroud(int width, int height)
        {
            int bytesPerPixel = this.tileImagePixels.Length / (this.tileImageWidth * this.tileImageHeight);
            byte[] data = new byte[width * height * bytesPerPixel];

            int y = 0;
            int fullTileInRowCount = width / tileImageWidth;
            int tileRowLength = tileImageWidth * bytesPerPixel;

            //Stage 1: Go line by line and create a block of our pattern
            //Stop when tile image height or required height is reached
            while ((y < height) && (y < tileImageHeight))
            {
                int tileIndex = y * tileImageWidth * bytesPerPixel;
                int dataIndex = y * width * bytesPerPixel;

                //Copy the whole line from tile at once
                for (int i = 0; i < fullTileInRowCount; i++)
                {
                    Array.Copy(tileImagePixels, tileIndex, data, dataIndex, tileRowLength);
                    dataIndex += tileRowLength;
                }

                //Copy the rest - if there is any
                //Length will evaluate to 0 if all lines were copied without remainder
                Array.Copy(tileImagePixels, tileIndex, data, dataIndex,
                           (width - fullTileInRowCount * tileImageWidth) * bytesPerPixel);
                y++; //Next line
            }

            //Stage 2: Now let's copy those whole blocks from top to bottom
            //If there is not enough space to copy the whole block, skip to stage 3
            int rowLength = width * bytesPerPixel;
            int blockLength = this.tileImageHeight * rowLength;

            while (y <= (height - tileImageHeight))
            {
                int dataBaseIndex = y * width * bytesPerPixel;
                Array.Copy(data, 0, data, dataBaseIndex, blockLength);
                y += tileImageHeight;
            }

            //Copy the rest line by line
            //Use previous lines as source
            for (int row = y; row < height; row++)
                Array.Copy(data, (row - tileImageHeight) * rowLength, data, row * rowLength, rowLength);

            return data;
        }

        private async Task Render(int width, int height)
        {
            Stopwatch fullsw = Stopwatch.StartNew();

            if (tileImageDataRebuildNeeded)
                await RebuildTileImageData();

            if ((height > 0) && (width > 0))
            {
                using (var randomAccessStream = new InMemoryRandomAccessStream())
                {
                    Stopwatch sw = Stopwatch.StartNew();
                    var backgroundPixels = CreateBackgroud(width, height);
                    sw.Stop();
                    Debug.WriteLine("Background generation finished: {0} ticks - {1} ms", sw.ElapsedTicks, sw.ElapsedMilliseconds);

                    BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, randomAccessStream);
                    encoder.SetPixelData(this.bitmapPixelFormat, this.bitmapAlphaMode, (uint)width, (uint)height, 96, 96, backgroundPixels);
                    await encoder.FlushAsync();

                    if (this.backgroundImageBrush.ImageSource == null)
                    {
                        BitmapImage bitmapImage = new BitmapImage();
                        randomAccessStream.Seek(0);
                        bitmapImage.SetSource(randomAccessStream);
                        this.backgroundImageBrush.ImageSource = bitmapImage;
                    }
                    else ((BitmapImage)this.backgroundImageBrush.ImageSource).SetSource(randomAccessStream);
                }
            }
            else this.backgroundImageBrush.ImageSource = null;

            fullsw.Stop();
            Debug.WriteLine("Background rendering finished: {0} ticks - {1} ms", fullsw.ElapsedTicks, fullsw.ElapsedMilliseconds);
        }
}

用途：

<Grid x:Name="rootGrid" Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
        <tileCtrl:TiledBackground
                               BackgroundImage="Assets/avatar1.png"
                               Width="{Binding ActualWidth, ElementName=rootGrid}" Height="{Binding ActualHeight, ElementName=rootGrid}"/>
    </Grid>

查看解决方案 Github

Answer 2

所有这些变体对于 GPU 来说都很沉重。您应该使用

BorderEffect 通过 Composition API 来实现。

        var compositor = ElementCompositionPreview.GetElementVisual(this).Compositor;
        var canvasDevice = CanvasDevice.GetSharedDevice();
        var graphicsDevice = CanvasComposition.CreateCompositionGraphicsDevice(compositor, canvasDevice);

        var bitmap = await CanvasBitmap.LoadAsync(canvasDevice, new Uri("ms-appx:///YourProject/Assets/texture.jpg"));

        var drawingSurface = graphicsDevice.CreateDrawingSurface(bitmap.Size,
            DirectXPixelFormat.B8G8R8A8UIntNormalized, DirectXAlphaMode.Premultiplied);
        using (var ds = CanvasComposition.CreateDrawingSession(drawingSurface))
        {
            ds.Clear(Colors.Transparent);
            ds.DrawImage(bitmap);
        }

        var surfaceBrush = compositor.CreateSurfaceBrush(drawingSurface);
        surfaceBrush.Stretch = CompositionStretch.None;

        var border = new BorderEffect
        {
            ExtendX = CanvasEdgeBehavior.Wrap,
            ExtendY = CanvasEdgeBehavior.Wrap,
            Source = new CompositionEffectSourceParameter("source")
        };

        var fxFactory = compositor.CreateEffectFactory(border);
        var fxBrush = fxFactory.CreateBrush();
        fxBrush.SetSourceParameter("source", surfaceBrush);

        var sprite = compositor.CreateSpriteVisual();
        sprite.Size = new Vector2(1000000);
        sprite.Brush = fxBrush;

        ElementCompositionPreview.SetElementChildVisual(YourCanvas, sprite);

我尝试了 1000000x1000000 大小的精灵，并且毫不费力地工作了。

如果您的尺寸大于 16386px，

Win2d 会抛出异常。

Answer 3

实际上，现在可以创建自定义画笔（借助 Composition API 和 Win2D）来实现平铺效果。代码示例在这里：

UWP TiledBrush

简而言之，您只需子类化

XamlCompositionBrushBase

 并重写它的 

OnConnected

 方法：

public class TiledBrush : XamlCompositionBrushBase
{
  protected override void OnConnected()
  {
    var surface = LoadedImageSurface.StartLoadFromUri(ImageSourceUri);

    var surfaceBrush = Compositor.CreateSurfaceBrush(surface);

    surfaceBrush.Stretch = CompositionStretch.None;

    var borderEffect = new BorderEffect()
    {
        Source = new CompositionEffectSourceParameter("source"),
        ExtendX = Microsoft.Graphics.Canvas.CanvasEdgeBehavior.Wrap,
        ExtendY = Microsoft.Graphics.Canvas.CanvasEdgeBehavior.Wrap
    };

    var borderEffectFactory = Compositor.CreateEffectFactory(borderEffect);

    var borderEffectBrush = borderEffectFactory.CreateBrush();

    borderEffectBrush.SetSourceParameter("source", surfaceBrush);
  }
}

然后按预期使用它：

<Grid>
    <Grid.Background>
        <local:TiledBrush ImageSourceUri="Assets/Texture.jpg" />
    </Grid.Background>
</Grid>

Answer 4

查看我对

这个问题的回答：

您可以使用

Win2D 库进行平铺。他们也有示例代码； “效果”下有一个平铺示例（EffectsSample.xaml.cs

）。

Answer 5

我们在 Windows 社区工具包中有

TilesBrush

：

<Border BorderBrush="Black" BorderThickness="1" VerticalAlignment="Center" HorizontalAlignment="Center" Width="400" Height="400">
  <Border.Background>
    <brushes:TilesBrush TextureUri="ms-appx:///Assets/BrushAssets/TileTexture.png"/>
  </Border.Background>
</Border>

我们还有

TileControl

允许动画。

Answer 6

评论从C#使用Win2d时必须注意内存泄漏。如果您想动态更改位图资源，还有一些微妙之处。

请参阅此问题的答案，了解这些问题的一种解决方案：

在 WinUI 3 中重复画笔或图像平铺

Answer 7

WindowsCompositorSamples 中的“边框”示例也展示了如何执行此操作，以及旋转和缩放。

链接：

https://github.com/microsoft/WindowsCompositionSamples/tree/master/SampleGallery/Samples/SDK%2015063/BorderPlayground

Answer 8

TilesBrush 是更简单的选择。 需要 10 秒和一行代码。