Bài viết [VB.NET] Hàm thay đổi kích thước ảnh

Mã:

   Private Shared Function FixedSize(ByVal imgPhoto As Image, ByVal Width As Integer, ByVal Height As Integer) As Image
        Dim sourceWidth As Integer = imgPhoto.Width
        Dim sourceHeight As Integer = imgPhoto.Height
        Dim sourceX As Integer = 0
        Dim sourceY As Integer = 0
        Dim destX As Integer = 0
        Dim destY As Integer = 0
 
        Dim nPercent As Single = 0
        Dim nPercentW As Single = 0
        Dim nPercentH As Single = 0
 
        nPercentW = (CSng(Width) / CSng(sourceWidth))
        nPercentH = (CSng(Height) / CSng(sourceHeight))
 
        'if we have to pad the height pad both the top and the bottom
        'with the difference between the scaled height and the desired height
        If nPercentH < nPercentW Then
            nPercent = nPercentH
            destX = CInt(Math.Truncate((Width - (sourceWidth * nPercent)) / 2))
        Else
            nPercent = nPercentW
            destY = CInt(Math.Truncate((Height - (sourceHeight * nPercent)) / 2))
        End If
 
        Dim destWidth As Integer = CInt(Math.Truncate(sourceWidth * nPercent))
        Dim destHeight As Integer = CInt(Math.Truncate(sourceHeight * nPercent))
 
        Dim bmPhoto As New Bitmap(Width, Height, PixelFormat.Format24bppRgb)
        bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution)
 
        Dim grPhoto As Graphics = Graphics.FromImage(bmPhoto)
        grPhoto.Clear(Color.Linen)
        grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic
 
        grPhoto.DrawImage(imgPhoto, New Rectangle(destX, destY, destWidth, destHeight), New Rectangle(sourceX, sourceY, sourceWidth, sourceHeight), GraphicsUnit.Pixel)
 
        grPhoto.Dispose()
        Return bmPhoto
    End Function

Gọi hàm:

Mã:

Dim resized = FixedSize(imgPath, 200, 200)
resized.Save(NewCopy, ImageFormat.Jpeg)
resized.Dispose()