The RichTextBox control does not have built-in functionality for resizing images. You have 2 options available, resize the image before loading it to the control or use a workaround by extracting the image from the RichTextBox, resizing it, and then replacing the original image with the resized one. If you know the resize height and width, I will suggest to use the first option -
Private Sub btnImage_Click(sender As Object, e As EventArgs) Handles btnImage.Click
OpenFileDialog1.Title = "RTE - Insert Image File"
OpenFileDialog1.DefaultExt = "TextBox1"
OpenFileDialog1.Filter = "Bitmap Files|*.bmp|JPEG Files|*.jpg|GIF Files|*.gif|PNG Files|*.png"
OpenFileDialog1.FilterIndex = 1
OpenFileDialog1.ShowDialog()
If OpenFileDialog1.FileName = "" Then Exit Sub
Try
Dim strImagePath As String = OpenFileDialog1.FileName
Dim img As Image = Image.FromFile(strImagePath)
' Resize your image
Dim newWidth As Integer = 200 ' Set your width
Dim newHeight As Integer = CInt(img.Height * (newWidth / img.Width)) ' Calculate the proportional height
Dim resizedImage As New Bitmap(img, newWidth, newHeight)
' Copy the resized image to clipboard
Clipboard.SetImage(resizedImage)
' Check if the RichTextBox can accept images
If Me.TextBox1.CanPaste(DataFormats.GetFormat(DataFormats.Bitmap)) Then
Me.TextBox1.Paste()
End If
Catch ex As Exception
MessageBox.Show("Unable to insert image format selected.", "RTE - Paste", MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
End Sub
The workaround -
Private Sub ResizeImageInRichTextBox()
' Get the currently loaded image in the RichTextBox
Dim selectedImage As Image = GetSelectedImageFromRichTextBox()
If selectedImage Is Nothing Then
MessageBox.Show("No image is currently selected.", "Resize Image", MessageBoxButtons.OK, MessageBoxIcon.Warning)
Return
End If
' Resize the image
Dim newWidth As Integer = 200 ' Set your width
Dim newHeight As Integer = CInt(selectedImage.Height * (newWidth / selectedImage.Width)) ' Calculate the height in relation to the width
Dim resizedImage As New Bitmap(selectedImage, newWidth, newHeight)
' Replace the image in the RichTextBox with your resized image
ReplaceSelectedImageInRichTextBox(resizedImage)
End Sub
Private Function GetSelectedImageFromRichTextBox() As Image
' Get the text range in your RichTextBox
Dim selectedRange As TextRange = New TextRange(RichTextBox1.Selection.Start, RichTextBox1.Selection.End)
' Check if the range contains an image
If selectedRange.GetPropertyValue(TextElement.FontFamilyProperty).ToString() = "EmbeddedImage" Then
' Get the image object from your range
Dim imageObject As InlineUIContainer = TryCast(selectedRange.GetPropertyValue(TextElement.InlineUIContainerProperty), InlineUIContainer)
If imageObject IsNot Nothing AndAlso imageObject.Child.GetType() = GetType(Image) Then
Return DirectCast(imageObject.Child, Image)
End If
End If
Return Nothing
End Function
Private Sub ReplaceSelectedImageInRichTextBox(newImage As Image)
' Remove the selected image
RichTextBox1.Selection.Start.DeleteVisual()
RichTextBox1.Selection.End.DeleteVisual()
' Create a new container with your resized image
Dim newImageContainer As New InlineUIContainer(newImage)
' Insert the new container
RichTextBox1.Selection.Insert(newImageContainer)
' Reset the selection to the newly inserted image
RichTextBox1.Selection.Select(newImageContainer.ElementStart, newImageContainer.ElementEnd)
End Sub