从url创建imagebrush，bitmap和writeablebitmap

Question

嘿，我有一个使用silverlight API的Windows Phone 8.1应用程序。 我从blob存储中下载此图像。

图像来自以下链接： https：// [service] .blob.core.windows.net / [imagename] .png ，只需使用URI即可在多个浏览器中显示和下载图像。

我现在想将它用作基于blobstorage的imageuri的图像画笔：

// If we have a returned SAS.
                BitmapImage myOnlineImage = new BitmapImage();
                myOnlineImage.UriSource = new Uri(uploadImage.ImageUri, UriKind.RelativeOrAbsolute);
                //ImageOnlineTest.Source = myOnlineImage;
                var imageBrush = new ImageBrush
                {
                    ImageSource = myOnlineImage,
                    Stretch = Stretch.None
                };
                var source = FindChildShieldCanvas(CanvasImage, imageBrush);

                WriteableBitmap wbm = new WriteableBitmap((BitmapImage)myOnlineImage);
                ImageOnlineTest.Source = wbm;

myOnlineImage未正确创建，至少我无法将图像转换为writeablebitmapimage（从转换中获取null异常），此外，图像刷是空的，即null。 但据我所知，这是方法吗？

所以基本上

如何基于https站点的URL创建imagebrush ？

Answer 1

我自己最终解决了这个问题：

记得using System.Runtime.InteropServices.WindowsRuntime;添加using System.Runtime.InteropServices.WindowsRuntime;

// If we have a returned SAS.
                BitmapImage myOnlineImage = new BitmapImage();

                //myOnlineImage.UriSource = new Uri(uploadImage.ImageUri, UriKind.RelativeOrAbsolute);
                using (var webCLient = new Windows.Web.Http.HttpClient())
                {
                    webCLient.DefaultRequestHeaders.Add("User-Agent", "bot");
                    var responseStream = await webCLient.GetBufferAsync(new Uri(uploadImage.ImageUri, UriKind.RelativeOrAbsolute));
                    var memoryStream = new MemoryStream();//responseStream.ToArrayAsStream().ReadAsync());

                    memoryStream.Write(responseStream.ToArray(), 0, responseStream.ToArray().Length);
                    memoryStream.Position = 0;
                    myOnlineImage.SetSource(memoryStream);

                }
                //ImageOnlineTest.Source = myOnlineImage;
                var imageBrush = new ImageBrush
                {
                    ImageSource = myOnlineImage,
                    Stretch = Stretch.None
                };
                var source = FindChildShieldCanvas(CanvasImage, imageBrush);

                WriteableBitmap wbm = new WriteableBitmap((BitmapImage)myOnlineImage);

此代码适用于imagebrush和writeablebitmap

Answer 2

要从图像创建位图，您必须在设置URL之前开始初始化位图对象。

    BitmapImage myOnlineImage = new BitmapImage();
    myOnlineImage.BeginInit();
    myOnlineImage.UriSource = new Uri(uploadImage.ImageUri, UriKind.RelativeOrAbsolute);
    myOnlineImage.EndInit();

    var imageBrush = new ImageBrush
    {
        ImageSource = myOnlineImage,
        Stretch = Stretch.None
    };
    var source = FindChildShieldCanvas(CanvasImage, imageBrush);

    WriteableBitmap wbm = new WriteableBitmap((BitmapImage)myOnlineImage);
    ImageOnlineTest.Source = wbm;

Answer 3

您可以通过以下方式使用C＃执行此操作，将适当的代码替换为您的字段。

Rectangle rectangle = new Rectangle();
rectangle.StrokeThickness = 10;
rectangle.Height = 200;
rectangle.Width = 100;
rectangle.SetValue(Canvas.LeftProperty, 100d);
rectangle.SetValue(Canvas.TopProperty, 100d);
rectangle.Fill = new ImageBrush(new BitmapImage(new Uri(@"C:\User\xiaorui.dong\Pictures\profile.jpeg")));