Develop Reference

how to convert mat to imageSource on UWP

I'm trying to convert mat image to something that I could set as ImageSource on UWP but I could not find any solution.
The only solution I found show me very bad image:
https://i.stack.imgur.com/uB8oT.png
Here's my code:
VideoCapture _capture = new VideoCapture(0);
while (true)
{
using (Mat mat = new Mat())
{
bool ok = _capture.Read(mat);
if (ok)
{
await Dispatcher.RunAsync(CoreDispatcherPriority.High,
async () =>
{
byte[] imageArray = mat.GetRawData();
WriteableBitmap writableBitmap = new WriteableBitmap(mat.Width, mat.Height);
using (MemoryStream memoryStream = new MemoryStream(imageArray))
{
using (Stream stream = writableBitmap.PixelBuffer.AsStream())
{
await memoryStream.CopyToAsync(stream);
}
}
imageCamera.Source = writableBitmap;
});
}
}

how to convert mat to imageSource on UWP
Currently, the Image control only supports images that use BGRA8 encoding and pre-multiplied or no alpha channel. Before attempting to display an image, test to make sure it has the correct format, and if not, use the SoftwareBitmap static Convert method to convert the image to the supported format.
SoftwareBitmap outputBitmap = SoftwareBitmap.CreateCopyFromBuffer(
writeableBitmap.PixelBuffer,
BitmapPixelFormat.Bgra8,
writeableBitmap.PixelWidth,
writeableBitmap.PixelHeight
);
var source = new SoftwareBitmapSource();
await source.SetBitmapAsync(outputBitmap);

How to create Image from string in Base64 (UWP)

I am making a Note application where I can draw with Windows ink and also paste images. I want to save the images and ink in a single file. Therefore I am converting the image to a string in base64 format so that I can easily serialize it. My problem is when I try to recreate the image from the string.
My code to decode the image data into a base64 string:
var decoder = await BitmapDecoder.CreateAsync(imageStream);
var pixels = await decoder.GetPixelDataAsync();
var bytes = pixels.DetachPixelData();
base64String = Convert.ToBase64String(bytes);
My code to encode the base64 string into an image again (This code does NOT work! The image is not added to the redCanvas):
var bytes = Convert.FromBase64String(base64String);
BitmapImage bitmapImage = new BitmapImage();
using (InMemoryRandomAccessStream stream = new InMemoryRandomAccessStream())
{
await stream.WriteAsync(bytes.AsBuffer());
stream.Seek(0);
bitmapImage.SetSource(stream);
}
Image image = new Image();
image.Source = bitmapImage;
// Add the image to a second canvas
redCanvas.Children.Add(image);
Full code for pasting the image and creating the base64 string:
private async Task myButton_ClickAsync(object sender, RoutedEventArgs e)
{
var dataPackageView = Windows.ApplicationModel.DataTransfer.Clipboard.GetContent();
if (dataPackageView.Contains(StandardDataFormats.Bitmap))
{
IRandomAccessStreamReference imageReceived = null;
imageReceived = await dataPackageView.GetBitmapAsync();
if (imageReceived != null)
{
using (var imageStream = await imageReceived.OpenReadAsync())
{
var bitmapImage = new BitmapImage();
bitmapImage.SetSource(imageStream);
var decoder = await BitmapDecoder.CreateAsync(imageStream);
var pixels = await decoder.GetPixelDataAsync();
var bytes = pixels.DetachPixelData();
base64String = Convert.ToBase64String(bytes);
TextBox_Image_Base64.Text = base64;
Image image = new Image();
// Add the image to a list of Images
ListImages.Add(image);
blueCanvas.Children.Add(image);
image.Source = bitmapImage;
TextBlock_Status.Text = "Status : Image is retrieved from the
clipboard and pasted successfully.";
}
}
}
else
{
TextBlock_Status.Text = "Status : Bitmap format is not available in clipboard";
}
}
Anyone have any suggestions as to how I can recreate the image from the string?
Screenshot from my app showing that I am able to paste an image and decode it into a string

How to create Image from string in Base64 (UWP)
We suggest you convet stream buffer to Base64 from imageStream diteactly, but not from PixelData. you could use CryptographicBuffer class to approach.
using (var imageStream = await imageReceived.OpenReadAsync())
{
var buffer = new Windows.Storage.Streams.Buffer((uint)imageStream.Size);
await imageStream.ReadAsync(buffer, (uint)imageStream.Size, InputStreamOptions.None);
String strBase64New = CryptographicBuffer.EncodeToBase64String(buffer);
}
Retrive from base64 string
public static async Task<BitmapImage> LoadBase64(string base64)
{
byte[] bytes = Convert.FromBase64String(base64);
var bitmap = new BitmapImage();
using (MemoryStream ms = new MemoryStream(bytes))
{
await bitmap.SetSourceAsync(ms.AsRandomAccessStream());
}
return bitmap;
}

Setting System.Uri from android uri string xamarin

I have a camerapage which takes a picture, resizes it to a thumbnail and saves this resized image to a file locally on the android phone. I then try to send this uri-string to a viewmodel which is supposed to set its ImageSource property from this uri. I am currently unable to load the image from the url.
Here is my code:
In CameraPage(inside Take photo method)
var documentsPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
using (var imageStream = new MemoryStream())
{
await image.CompressAsync(Bitmap.CompressFormat.Jpeg, 40, imageStream);
image.Recycle();
imageBytes = imageStream.ToArray();
var thumbnail =await DependencyService.Get<IPicResizer>().GetResizedImage(imageBytes);
// Temporary file to store the downloaded image
Java.IO.File tmpFile = new Java.IO.File(documentsPath + "/"+fileName + ".jpg");
tmpFile.ParentFile.Mkdirs();
// String path = MediaStore.Images.Media.InsertImage(this.Context.ContentResolver, documentsPath, fileName, ""); //(this.Context.ContentResolver, image, imgName.ToString(), null);
uri = Android.Net.Uri.Parse(tmpFile.Path);
// The FileOutputStream to the temporary file
var fOutStream = new FileOutputStream(tmpFile);
try
{
fOutStream.Write(thumbnail, 0, thumbnail.Length);
fOutStream.Flush();
fOutStream.Close();
DialogService.HideLoading();
DialogService.ShowSuccess("Saved picture at: " + uri.ToString());
}
catch (Java.IO.FileNotFoundException ex)
{
DialogService.ShowError(ex.InnerException.Message);
}
catch (Java.IO.IOException ex)
{
DialogService.ShowError(ex.InnerException.Message);
}
camera.StartPreview();
await App.Current.MainPage.Navigation.PushModalAsync(new InfoPage(imageBytes, tmpFile.AbsolutePath), false);
}
InfoPages view model:
ImageSource Source {get;set;}
public InfoViewModel(byte[] image, string imageUri)
{
if (image != null)
{
_image = image;
imageurl = new Uri("file:///" + imageUri, UriKind.Absolute);
Source = ImageSource.FromUri(imageurl);
}
}
All help is appreciated :)

Image source to writeablebitmap in windows phone 8.1

I'm working on windows phone 8.1 application. I have different pictures locally in app and displaying those pictures in list view. Now select one picture id and pass it to detail screen, where I have to save that file .
My detail.Xaml screen contain image control named as Imaged.
I got image on detail page and press image save button. I'm using this Sample app https://code.msdn.microsoft.com/windowsapps/Save-Edited-Picture-16d910c4/sourcecode?fileId=119937&pathId=946309183 "Sample"
My detail page Code is here.
string tempimg;
protected override void OnNavigatedTo(NavigationEventArgs e)
{
var imagePath = e.Parameter as string;
imaged.Source = new BitmapImage(new Uri(imagePath, UriKind.RelativeOrAbsolute));
tempimg = imagePath;
}
My SaveImage button code is here.
if (tempimg == null)
return;
// WriteableBitmap abc = new WriteableBitmap(400, 400);
string filename = "Image-" + DateTime.Now.ToFileTime() + ".jpeg";
// await SaveWriteableBitmapAsJpeg(img, filename);
Blockquote
await SaveWriteableBitmapAsJpeg(tempimg, filename);
private static async Task SaveWriteableBitmapAsJpeg(WriteableBitmap bmp, string fileName)
{
// Create file in Pictures library and write jpeg to it
var outputFile = await KnownFolders.CameraRoll.CreateFileAsync(fileName, CreationCollisionOption.ReplaceExisting);
using (var writeStream = await outputFile.OpenAsync(FileAccessMode.ReadWrite))
{
await EncodeWriteableBitmap(bmp, writeStream, BitmapEncoder.JpegEncoderId);
}
}
private static async Task EncodeWriteableBitmap(WriteableBitmap bmp, IRandomAccessStream writeStream, Guid encoderId)
{
// Copy buffer to pixels
byte[] pixels;
using (var stream = bmp.PixelBuffer.AsStream())
{
pixels = new byte[(uint)stream.Length];
await stream.ReadAsync(pixels, 0, pixels.Length);
}
// Encode pixels into stream
var encoder = await BitmapEncoder.CreateAsync(encoderId, writeStream);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Premultiplied,
(uint)bmp.PixelWidth, (uint)bmp.PixelHeight,
96, 96, pixels);
await encoder.FlushAsync();
}
My this function "await SaveWriteableBitmapAsJpeg(tempimg, filename);" creates a problem. I just have the image source while that require the writeablebitmap. I just want to save image and not able to proceed from here. let me know the exact solution or problem.

Windows 8 - Save Image in XAML as local file ( inside Application folder )

In my Windows store application, i am displaying a picture using Image control in XAML. Source of the Image control is set, code wise using WriteableBitmap. I am trying to send this image as attachment in email. Is there any easy way for that? I am trying to save that image locally( within application ) and attach that saved image to email. But not able to save locally. Any help is appreciated.
Here is the code.
bitmap = await WriteableBitmapRenderExtensions.Render(dataCanvas);
image.Source = bitmap;
dataCanvas is a Canvas control consists of two images, one place above another. Actually i have to place a sunglass top of users face and display it as another image in xaml. Also email that image.

Check out the WriteableBitmapSaveExtensions class in WinRT XAML Toolkit for all the SaveToFile() extension methods you can use to save your WriteableBitmap.
The core one is this:
public static async Task SaveToFile(
this WriteableBitmap writeableBitmap,
StorageFile outputFile,
Guid encoderId)
{
Stream stream = writeableBitmap.PixelBuffer.AsStream();
byte[] pixels = new byte[(uint)stream.Length];
await stream.ReadAsync(pixels, 0, pixels.Length);
using (var writeStream = await outputFile.OpenAsync(FileAccessMode.ReadWrite))
{
var encoder = await BitmapEncoder.CreateAsync(encoderId, writeStream);
encoder.SetPixelData(
BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Premultiplied,
(uint)writeableBitmap.PixelWidth,
(uint)writeableBitmap.PixelHeight,
96,
96,
pixels);
await encoder.FlushAsync();
using (var outputStream = writeStream.GetOutputStreamAt(0))
{
await outputStream.FlushAsync();
}
}
}
You can get the encoder ID using an overload of the method:
public static async Task<StorageFile> SaveToFile(
this WriteableBitmap writeableBitmap,
StorageFolder storageFolder,
string fileName,
CreationCollisionOption options = CreationCollisionOption.ReplaceExisting)
{
StorageFile outputFile =
await storageFolder.CreateFileAsync(
fileName,
options);
Guid encoderId;
var ext = Path.GetExtension(fileName);
if (new[] { ".bmp", ".dib" }.Contains(ext))
{
encoderId = BitmapEncoder.BmpEncoderId;
}
else if (new[] { ".tiff", ".tif" }.Contains(ext))
{
encoderId = BitmapEncoder.TiffEncoderId;
}
else if (new[] { ".gif" }.Contains(ext))
{
encoderId = BitmapEncoder.GifEncoderId;
}
else if (new[] { ".jpg", ".jpeg", ".jpe", ".jfif", ".jif" }.Contains(ext))
{
encoderId = BitmapEncoder.JpegEncoderId;
}
else if (new[] { ".hdp", ".jxr", ".wdp" }.Contains(ext))
{
encoderId = BitmapEncoder.JpegXREncoderId;
}
else //if (new [] {".png"}.Contains(ext))
{
encoderId = BitmapEncoder.PngEncoderId;
}
await writeableBitmap.SaveToFile(outputFile, encoderId);
return outputFile;
}

Any subclass of BitmapSource (including WritableBitmap) can be passed to a BitmapEncoder. A BitmapEncoder takes a Stream to which the encoded JPEG, PNG or other image is written.
You can then use a mailer library to reference the stream used by the encoder, or use the Share contract, and pass the stream directly.
Example:
var bitmap = new WritableBitmap();
// ... draw your bitmap
var tempPath = // path to where you want to save (probably in your appx temp);
var encoder = new PngBitmapEncoder();
encoder.Frames.Add(bitmap);
using (var fs = new FileStream(tempPath))
{
encoder.Save(fs);
}
// use the image saved to tempPath
// http://msdn.microsoft.com/en-us/library/windows/apps/xaml/hh871370.aspx