如何从 canvas Windows Phone 8.1（通用应用程序）创建 base64 字符串

Question

我有一个捕获签名的应用程序，我已经绘制了签名，现在我想捕获信息并创建一个 base64 字符串。

Answer 1

抱歉，这是对我有用的代码，并不完美。请随时查看，如果您发现任何问题，请提供反馈。谢谢

在此示例中，canvas 名称为 Display

    private async Task<string> generateBase64Bitmap()
    {
        // Initialization  

        try
        {
            // Initialization.  
            Size canvasSize = this.Display.RenderSize;
            Point defaultPoint = this.Display.RenderTransformOrigin;
            // Sezing to output image dimension.  
            this.Display.Measure(canvasSize);
            this.Display.UpdateLayout();
            this.Display.Arrange(new Rect(defaultPoint, canvasSize));
            // Convert canvas to bmp.  
            var bmp = new RenderTargetBitmap();
            await bmp.RenderAsync(this.Display, (int)(this.Display.ActualWidth / 4), (int)(this.Display.ActualHeight / 4));
            // Setting.  
            var bitmap = (RenderTargetBitmap) bmp;

            //var bytes = (await bitmap.GetPixelsAsync()).ToArray();
            return await toBase64(bitmap);

        }
        catch (Exception ex)
        {
            //this.ShowMessage(ex.ToString(), "Error");
        }
        return string.Empty;
    }


    private async Task<string> toBase64(RenderTargetBitmap bmp)
    {
        var img = (await bmp.GetPixelsAsync()).ToArray();

        var encoded = new InMemoryRandomAccessStream();
        var encoder = await BitmapEncoder.CreateAsync(
            BitmapEncoder.PngEncoderId, encoded);
        encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Straight,
            (uint)bmp.PixelWidth, (uint)bmp.PixelHeight, 96, 96, img);
        await encoder.FlushAsync();
        encoded.Seek(0);

        //read bytes
        var bytes = new byte[encoded.Size];
        await encoded.AsStream().ReadAsync(bytes, 0, bytes.Length);

        return Convert.ToBase64String(bytes);
    }

调用方法使用（将异步添加到您的方法）：

string encodedImgBase64 = await generateBase64Bitmap();

如何从 canvas Windows Phone 8.1（通用应用程序）创建 base64 字符串

How create a base64 string from a canvas Windows Phone 8.1(Universal app)

c#

xaml

windows-phone-8.1

win-universal-app