Is it possible to resize images and asynchronously load them in pictureboxes without saving?(Visual Basic)(Solved)

Question

The pictures i need to load are pretty big in mb size. I am trying to resize their dimensions in order to reduce the ram usage when they are loaded in pictureboxes(they dont need to be perfect in quality as its something like a preview. But the command PictureBox1.LoadAsync() needs an image location path. I want to resize the images and instatly load them to pictureboxes without saving them in a hard drive. Is that possible?

Any suggestions about it or any further questions\ways to reduce ram usage are appriciated..

(I solved the issue (from 5-6 ram usage to <2) by loading the thumbnails of the images)

Answer 1

Hi @Theodosis ,
The following example is to load pictures from a URL, then reset the resolution, and finally display one of them in picture box.
Here's the code you can refer to.

    Private newBitmap As Bitmap  
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load  
        PictureBox1.SizeMode = PictureBoxSizeMode.StretchImage  
    End Sub  
    Private Async Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click  
        Dim imgLst As List(Of Bitmap) = Await GetImagesFromURL("image url")  
        newBitmap = New Bitmap(imgLst(0))  
        ' Set bitmap resolution  
        newBitmap.SetResolution(50, 50)  
        PictureBox1.Image = newBitmap  
    End Sub  
  
    Private Sub Form1_FormClosing(sender As Object, e As FormClosingEventArgs) Handles MyBase.FormClosing  
        PictureBox1.Image = Nothing  
        newBitmap.Dispose()  
    End Sub  
    Private Async Function GetImagesFromURL(url As String) As Task(Of List(Of Bitmap))  
        Dim images = New List(Of Bitmap)()  
  
        Using client = New HttpClient()  
            Dim response = Await client.GetAsync(url)  
  
            If response IsNot Nothing AndAlso response.StatusCode = HttpStatusCode.OK Then  
  
                Using stream = Await response.Content.ReadAsStreamAsync()  
                    Dim memStream = New MemoryStream()  
                    Await stream.CopyToAsync(memStream)  
                    memStream.Position = 0  
                    images.Add(New Bitmap(memStream))  
                End Using  
            End If  
        End Using  
  
        Return images  
    End Function  

Hope it could be helpful.

Best Regards,
Xingyu Zhao
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Answer 2

In case of WPF and UWP applications, see the usage of DecodePixelWidth property: https://learn.microsoft.com/en-us/dotnet/desktop/wpf/graphics-multimedia/how-to-load-an-image-as-a-thumbnail.