Question

I m using the CommunityToolkit.Maui.Views.DrawingView to capture a customer signature. Once they have finished i hide the DrawingView and display it as in image, so as to not interfere with scrolling. The code used to switch between the editor and the image is:

private async void ElEditSignatureButton_Clicked(object sender, EventArgs e)
{
    if (!EditingSignature)
    {
        ElCustomerSignatureImage.IsVisible = false;
        ElCustomerSignatureDraw.IsVisible = true;
        ElEditSignatureButton.Source = ImageSource.FromFile("tick.png");
        EditingSignature = true;
    }
    else
    {
        if (ElCustomerSignatureDraw.Lines.Count > 0)
        {
            Stream stream = await ElCustomerSignatureDraw.GetImageStream(ElCustomerSignatureImage.Width, ElCustomerSignatureImage.Height);

            byte[] bytes = new byte[stream.Length];
            stream.Write(bytes, 0, bytes.Length);
            SignatureImage = bytes;

            ElCustomerSignatureImage.Source = ImageSource.FromStream(() => new MemoryStream(bytes));

            ElCustomerSignatureDraw.IsVisible = false;
            ElCustomerSignatureImage.IsVisible = true;
            ElEditSignatureButton.Source = ImageSource.FromFile("pencil.png");
            EditingSignature = false;
        }
        else
        {
            await DisplayAlert("Customer Report", "Signature Required", "Ok");
        }
    }
}

然而,在这样做时,没有显示这种形象。

If i change it to remove the convertion to byte[] (for use later when submitting) the image works:

Stream stream = await ElCustomerSignatureDraw.GetImageStream(ElCustomerSignatureImage.Width, ElCustomerSignatureImage.Height);

ElCustomerSignatureImage.Source = ImageSource.FromStream(() => stream);

在撰写本报告时,我发现:

Stream stream = await ElCustomerSignatureDraw.GetImageStream(ElCustomerSignatureImage.Width, ElCustomerSignatureImage.Height);

ElCustomerSignatureImage.Source = ImageSource.FromStream(() => stream);

Stream stream2 = await ElCustomerSignatureDraw.GetImageStream(ElCustomerSignatureImage.Width, ElCustomerSignatureImage.Height);

byte[] bytes = new byte[stream2.Length];
stream2.Write(bytes, 0, bytes.Length);
SignatureImage = bytes;

Does anyone know why the first example doesn t work? I mean a stream of bytes should just be a stream of bytes regardless of it s method of creation.

EDIT: 矫正,即说行之有效的最后选择, by变具有正确的长度,但数据是所有0, 认为也是第一个例子的问题。

Answer 1

Ok After much trial and error i found code that poplated both the byte array and the image control correctly:

Stream stream = await ElCustomerSignatureDraw.GetImageStream(ElCustomerSignatureImage.Width, ElCustomerSignatureImage.Height);

MemoryStream temp = new MemoryStream();
stream.CopyTo(temp);
SignatureImage = temp.ToArray();

stream.Position = 0;
ElCustomerSignatureImage.Source = ImageSource.FromStream(() => stream);

因此,出于某种原因,《记忆》。 ToArray()工程,但记忆犹新。没有任何理由。

Answer 2

你们可以尝试利用这一渠道。阅读而不是流。撰写:

Stream stream = await ElCustomerSignatureDraw.GetImageStream(ElCustomerSignatureImage.Width, ElCustomerSignatureImage.Height);

ElCustomerSignatureImage.Source = ImageSource.FromStream(() => stream);

Stream stream2 = await ElCustomerSignatureDraw.GetImageStream(ElCustomerSignatureImage.Width, ElCustomerSignatureImage.Height);

byte[] bytes = new byte[stream2.Length];
stream2.Read(bytes, 0, bytes.Length);
SignatureImage = bytes;

注: Length > int.MaxValue, 这将造成错误或数据损失。

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