After using the ImagesService to transform an uploaded image, I would like to store it back into a new Blob file and make it available through getServingUrl() as provided by the ImagesService.
Storing the image in a new AppEngineFile as described here works fine and I am able to open and view it locally using the dev server.
However when passing the blobKey for the new AppEngineFile to ImagesService.getServingUrl() a
java.lang.IllegalArgumentException: Could not read blob.
exception is thrown. Any ideas what the problem could be? This is the code I use to transform and store an uploaded image (blobKey and blobInfo correspond to the uploaded file, not the newly created one).
/* Transform image in existing Blob file */
Image originalImage = ImagesServiceFactory.makeImageFromBlob(blobKey);
Transform verticalFlip = ImagesServiceFactory.makeVerticalFlip();
ImagesService imagesService = ImagesServiceFactory.getImagesService();
Image newImage = imagesService.applyTransform(verticalFlip, originalImage);
/* Store newImage in an AppEngineFile */
FileService fileService = FileServiceFactory.getFileService();
AppEngineFile file = fileService.createNewBlobFile(blobInfo.getContentType());
FileWriteChannel writeChannel = fileService.openWriteChannel(file, true);
ByteBuffer buffer = ByteBuffer.wrap(newImage.getImageData());
writeChannel.write(buffer);
/* closeFinally assigns BlobKey to new file object */
writeChannel.closeFinally();
BlobKey newBlobKey = fileService.getBlobKey(file);
Edit:
The above code is correct, the problem was storing a String representation of the new blob key using newBlobKey.toString() instead of newBlobKey.getKeyString().
Why would you want to do that? Once you transform an image it is cached and anyway it is always fast. If you really feel you want to save it just use urlfetch to read the data and store them in the BlobStore ;-)
The following works fine when executed at the end of the code posted in the question:
String url = imagesService.getServingUrl(newBlobKey)
The URL can then be used to scale and crop the new image as described in the docs
http://code.google.com/appengine/docs/java/images/overview.html#Transforming_Images_from_the_Blobstore
Related
i want to display an image stored in mysql database
the problem is that i can't convert the blob format into a Uint8list ; i searched and found soulitions but none of them works
Grab the blob from JSON:
var blob = yourJSONMapHere['yourJSONKeyHere'];
var image = BASE64.decode(blob); // image is a Uint8List
Now, use image in a Image.memory
new Container( child: new Image.memory(image));
this soulition didn't work because base64.decode need a string source not a blob file to convert
Don't know if it is relatable to this particular case but had similar issue with Cloud Firestore.
Created blob for storing in this way:
Blob myBlob = Blob(await audioFile.readAsBytes());
saved to Firestore in one field as usual
Then tried to read it back and couldn't figure it out how to get Uint8List from blob I get back from Firestore.
my solution:
//extract blob from field of Firestore document
Blob audioBlob = audioDocFromDb.get("fieldName");
//use .bytes on blob from this source
//package:cloud_firestore_platform_interface/src/blob.dart
Uint8List audioBytes = audioBlob.bytes;
this worked for me.
In my case I was packing up recorded audio and trying to play it back.
I had this problem too, i know the solution now, after many attempts:
Dont forget to upvote!
Uint8List image = Uint8List.fromList(blob.toBytes());
Image.memory(image);
This function has always saved me for getting bytes from a file that is uploaded to a URL.
import 'package:http/http.dart' as http;
// urlImageBlob is the URL where our file is hosted.
Uint8List fileBytes = await http.readBytes(Uri.parse(urlImageBlob));
// Display if are image.
Image.memory(fileBytes);
I'm trying to update a placeholder image with a new image that has an updated URL. The URL in fact is a valid Google Static Map URL that I'm using in other contexts successfully. I'm using the Google Document API to manipulate the document. Following the code I've been using:
var element = body.findElement(DocumentApp.ElementType.INLINE_IMAGE).getElement();
var imageMap = element.asInlineImage();
// if there was an image found in document
if (imageMap != null) {
// get current parent and index inside parent
var parent = imageMap.getParent();
var childIndex = parent.getChildIndex(imageMap);
// remove image from paragraph
imageMap = imageMap.removeFromParent();
// get static image url for territory
var url = getStaticMapURLForTerritory(id);
Logger.log(url);
imageMap.setLinkUrl(url);
// create a new image
parent.insertInlineImage(childIndex, imageMap)
}
This seems to work fine in that it does update the image url correctly. However, the image itself (the result of the url) is not updated. When I click on the link URL it does return the correct image.
Is there a way to force a refetch of the image blob associated with the URL? I've also attempted to use UrlFetchApp but that complains about a missing size parameter (google static api) which is certainly included in the url string and within the max 640x640 bounds.
I've exhausted all my options unless....
TIA, --Paul
setLinkUrl only does that: sets the link. To actually add a new image you'll have to get its blob:
function replaceImage() {
// [...]
// get static image url for territory
const url = getStaticMapURLForTerritory(id)
const response = UrlFetchApp.fetch(url)
// create a new image
parent.insertInlineImage(childIndex, response.getBlob())
.setAltDescription(img.getAltDescription())
.setAltTitle(img.getAltTitle())
.setWidth(img.getWidth())
.setHeight(img.getHeight())
.setLinkUrl(url)
}
References
Class InlineImage (Google Apps Script reference)
In the end, my goal is to send a raw image data from the front-end, then split that image into however many pages, and lastly send that pdf back to the front-end for download.
But every time I use the theDoc.addImageFile(), it tells me that the "Image is not in a suitable format". I'm using this as reference: https://www.websupergoo.com/helppdfnet/source/5-abcpdf/doc/1-methods/addimagefile.htm
To troubleshoot, I thought that the image might not be rendering correctly, so I added a File.WriteAllBytes to view the rendered image and it was exactly what I wanted, but still not adding to the PDF. I also tried sending the actual path of a previously rendered image thinking that the new image might not have been fully created yet, but it also gave me the same error. Lastly, I thought PNGs might be problematic and changed to JPG but it did not work.
Here is the code:
[HttpPost]
public IActionResult PrintToPDF(string imageString)
{
// Converts dataUri to bytes
var base64Data = Regex.Match(imageString, #"data:image/(?<type>.+?),(?<data>.+)").Groups["data"].Value;
var binData = Convert.FromBase64String(base64Data);
/* Ultimately will be removed, but used for debugging image */
string path = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
string imgName= "Test.jpg";
string filename = Path.Combine(path, imgName);
System.IO.File.WriteAllBytes(filename, binData);
/***********************************************************/
using (Doc theDoc = new Doc())
{
// Using explicit path
theDoc.AddImageFile(#"C:\Users\User\Documents\Test.jpg", 1);
// Using variable
//theDoc.AddImageFile(filename, 1);
// What I really want
//theDoc.AddImageFile(binData , 1);
theDoc.Page = theDoc.AddPage();
theDoc.AddText("Thanks");
Response.Headers.Clear();
Response.Headers.Add("content-disposition", "attachment; filename=test.pdf");
return new FileStreamResult(theDoc.GetStream(), "application/pdf");
}
}
Try something like this (not tested, but cleaned up from my own code):
public int AddImageFile(Doc doc, byte[] data, int insertBeforePageID)
{
int pageid;
using (var img = new XImage())
{
img.SetData(data);
doc.Page = doc.AddPage(insertBeforePageID);
pageid = doc.Page;
doc.AddImage(img);
img.Clear();
}
return pageid;
}
To add a JPEG from a byte array you need Doc.AddImageData instead of Doc.AddImageFile. Note that AddImageFile / AddImageData do not support PNG - for that you would definitely need to use an XImage. The XImage.SetData documentation has the currently supported image formats.
I'm using the Microsoft Bot Framework with Cognitive Services to generate images from a source image that the user uploads via the bot. I'm using C#.
The Cognitive Services API returns a byte[] or a Stream representing the treated image.
How can I send that image directly to my user? All the docs and samples seem to point to me having to host the image as a publically addressable URL and send a link. I can do this but I'd rather not.
Does anyone know how to simple return the image, kind of like the Caption Bot does?
You should be able to use something like this:
var message = activity.CreateReply("");
message.Type = "message";
message.Attachments = new List<Attachment>();
var webClient = new WebClient();
byte[] imageBytes = webClient.DownloadData("https://placeholdit.imgix.net/~text?txtsize=35&txt=image-data&w=120&h=120");
string url = "data:image/png;base64," + Convert.ToBase64String(imageBytes)
message.Attachments.Add(new Attachment { ContentUrl = url, ContentType = "image/png" });
await _client.Conversations.ReplyToActivityAsync(message);
The image source of HTML image elements can be a data URI that contains the image directly rather than a URL for downloading the image. The following overloaded functions will take any valid image and encode it as a JPEG data URI string that may be provided directly to the src property of HTML elements to display the image. If you know ahead of time the format of the image returned, then you might be able to save some processing by not re-encoding the image as JPEG by just returning the image encoded as base 64 with the appropriate image data URI prefix.
public string ImageToBase64(System.IO.Stream stream)
{
// Create bitmap from stream
using (System.Drawing.Bitmap bitmap = System.Drawing.Bitmap.FromStream(stream) as System.Drawing.Bitmap)
{
// Save to memory stream as jpeg to set known format. Could also use PNG with changes to bitmap save
// and returned data prefix below
byte[] outputBytes = null;
using (System.IO.MemoryStream outputStream = new System.IO.MemoryStream())
{
bitmap.Save(outputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
outputBytes = outputStream.ToArray();
}
// Encoded image byte array and prepend proper prefix for image data. Result can be used as HTML image source directly
string output = string.Format("data:image/jpeg;base64,{0}", Convert.ToBase64String(outputBytes));
return output;
}
}
public string ImageToBase64(byte[] bytes)
{
using (System.IO.MemoryStream inputStream = new System.IO.MemoryStream())
{
inputStream.Write(bytes, 0, bytes.Length);
return ImageToBase64(inputStream);
}
}
I am using the following piece of code from blob tutorial at https://www.windowsazure.com/en-us/develop/net/how-to-guides/blob-storage/#configure-access
I was successfully able to upload the image into the blob storage.
CloudStorageAccount storageAccount = CloudStorageAccount.Parse(
RoleEnvironment.GetConfigurationSettingValue("BlobConnectionString"));
// Create the blob client
CloudBlobClient blobClient = storageAccount.CreateCloudBlobClient();
// Retrieve reference to a previously created container
CloudBlobContainer container = blobClient.GetContainerReference("mycontainer");
// Retrieve reference to a blob named "myblob"
CloudBlob blob = container.GetBlobReference("myblob");
BlobStream blobstream = blob.OpenRead();
objimg = System.Drawing.Image.FromStream(blobstream, true);
I am trying to retrieve the image from blob and store it in objimg, which will be at a later point be used in the UI.
Howeverwhen the execution comes to 'System.Drawing.Image.FromStream' the page is getting stuck showing Waiting status.
Why is this happening? In the view 'window.setInterval' should call a controller function to return the obtained image. How should i send it to the view and set it in the View?
Thanks,
Anil