Mike McIntyre's recent blog item about breaking large images into chunks in order to print them prompts me to post up an approach to the (kind of) opposite scenario which by coincidence I was working on yesterday. I had two images on a Windows Form, each in its own PictureBox control and I wanted to merge the two images, placing them side by side and printing them out on the printer.
It turned out to be pretty easy.
This function takes the two images as parameters, merges them and returns the merged image:
Public Function MergeImages(ByVal Pic1 As Image, ByVal pic2 As Image) As Image
Dim MergedImage As Image ‘ This will be the finished merged image
Dim Wide, High As Integer ' Size of merged image
' Calculate Width and Height needed for composite image
' First, the Width:
Wide = Pic1.Width + pic2.Width
' Height: Ensure that the new image is high enough for both images
' that we plan to place inside it.
If Pic1.Height >= pic2.Height Then
High = Pic1.Height
Else
High = pic2.Height
End If
' Create an empty Bitmap the correct size to hold both images side by side
Dim bm As New Bitmap(Wide, High)
' Get the Graphics object for this bitmap
Dim gr As Graphics = Graphics.FromImage(bm)
' Draw a black line round the outside (optional, but sometimes looks better when printed)
gr.DrawRectangle(Pens.Black, 0, 0, Wide - 1, High - 1)
' Draw the first source image at left side of new image
gr.DrawImage(Pic1, 0, 0)
' Draw second source image, offset to the right edge of first source image
gr.DrawImage(pic2, Pic1.Width, 0)
' Assign the merged bitmap you have just created as the image
' you are going to return for printing
MergedImage = bm
' Finished with the Graphics object – dispose of it
gr.Dispose()
' You now have an Image named MergedImage which you can print.
Return MergedImage
End Function
The next code block is the PrintPage event of a PrintDocument component that I dragged on to the form (in this example named "PrintImageDocument"). It uses the function above to create the image. It then sets the start position and size of the image for the printing before finally drawing the image on the Graphics object.
Private Sub PrintImageDocument_PrintPage(ByVal sender As Object, ByVal e As System.Drawing.Printing.PrintPageEventArgs) Handles PrintImageDocument.PrintPage
' First create the image using the function prepared above:
Dim ImageToPrint As Image = MergeImages(picValues.Image, picGraph.Image)
' Now Print it - change "20, 20" to whatever X and Y position values
' you want as your start point for printing on the page
Dim R As New Rectangle(20, 20, ImageToPrint.Width, ImageToPrint.Height)
e.Graphics.DrawImage(ImageToPrint, R)
End Sub
And finally, in this example I used a button to fire the Print event of the PrintDocument component, which (of course) causes the image to be sent to the printer for hard copy printing.
Private Sub ButtonPrint_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButtonPrint.Click
Me.PrintImageDocument.Print()
End Sub