将图像从流/流阅读器加载到图像或RawImage组件

Question

我使用AWS (v3.3.50.0)：S3 SDK (AWSSDK-S3.3.3.5.4.unitypackage)从https://aws.amazon.com/mobile/sdk/下载。我的统一版本是5.5.1。

我想下载一个放在S3桶上的映像，存储桶是配置好的，可以下载。我将字符串视为响应的数据。

但我无法将返回的StreamReader转换为S3示例GetObject()函数中的UnityEngine.UI.Image.sprite或UnityEngine.UI.RawImage.texture。

private void GetObject()
{
    ResultText.text = string.Format("fetching {0} from bucket {1}", SampleFileName, S3BucketName);
    Client.GetObjectAsync(S3BucketName, SampleFileName, (responseObj) =>
        {
            string data = null;
            var response = responseObj.Response;
            if (response.ResponseStream != null)
            {
                using (StreamReader reader = new StreamReader(response.ResponseStream))
                {
                    data = reader.ReadToEnd();
                }

                ResultText.text += "\n";
                ResultText.text += data;
            }
            Debug.Log("GetObject: " + data);
        });
}

在这方面需要帮助:)

S3桶上的图像采用PNG格式。但是在未来的JPG中，JPEG格式支持必须启用。

Answer 1

StreamReader用于文本，而不是像要下载的图像那样的二进制数据。我可以告诉您为什么要使用它，也不能告诉您为什么要在图像上执行Debug.Log("GetObject: " + data);。

下载图像，然后使用Texture2D.LoadImage将其转换为Texture2D，然后将其加载到RawImage中以显示。

public RawImage displayTexture;

private void GetObject()
{
    ResultText.text = string.Format("fetching {0} from bucket {1}", SampleFileName, S3BucketName);
    Client.GetObjectAsync(S3BucketName, SampleFileName, (responseObj) =>
    {
        byte[] data = null;
        var response = responseObj.Response;
        if (response.ResponseStream != null)
        {
            using (StreamReader reader = new StreamReader(response.ResponseStream))
            {
                using (var memstream = new MemoryStream())
                {
                    var buffer = new byte[512];
                    var bytesRead = default(int);
                    while ((bytesRead = reader.BaseStream.Read(buffer, 0, buffer.Length)) > 0)
                        memstream.Write(buffer, 0, bytesRead);
                    data = memstream.ToArray();
                }
            }

            //Display Image
            displayTexture.texture = bytesToTexture2D(data);
        }
    });
}

public Texture2D bytesToTexture2D(byte[] imageBytes)
{
    Texture2D tex = new Texture2D(2, 2);
    tex.LoadImage(imageBytes);
    return tex;
}

正如我前面提到的，使用StreamReader并不适合二进制数据。您只需使用MemoryStream就可以做到这一点。在这种情况下，新的GetObject函数应该如下所示：

private void GetObject()
{
    ResultText.text = string.Format("fetching {0} from bucket {1}", SampleFileName, S3BucketName);
    Client.GetObjectAsync(S3BucketName, SampleFileName, (responseObj) =>
    {
        byte[] data = null;
        var response = responseObj.Response;
        Stream input = response.ResponseStream;

        if (response.ResponseStream != null)
        {
            byte[] buffer = new byte[16 * 1024];
            using (MemoryStream ms = new MemoryStream())
            {
                int read;
                while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
                {
                    ms.Write(buffer, 0, read);
                }
                data = ms.ToArray();
            }

            //Display Image
            displayTexture.texture = bytesToTexture2D(data);
        }
    });
}