I have tried in many places but all have gone in vain. I am hopeful of getting a solution in this forum.
I have a vb.net app in which there are many panels. I want to take a bitmap of a panel which is hidden behind the panel which is showing on the screen. Kindly let me know how to do this.
Regards
Renga
asked how to capture a bitmap of a panel that is hidden behind another panel. was correct to warn that a control that has never been rendered on-screen may not contain drawable pixels, and ’s DrawToBitmap-based idea is on the right track (note: in ’s example the Bitmap constructor uses Height then Width — that should be Width then Height).
A pragmatic, generally reliable approach for most WinForms controls is to ensure the control has an active handle/layout and then call DrawToBitmap into a correctly sized Bitmap. The following helper is a compact, safe pattern (dispose the returned Bitmap when finished):
Imports System.Drawing
Imports System.Drawing.Imaging
Public Function CaptureControlBitmap(ctrl As Control) As Bitmap
If ctrl Is Nothing Then Throw New ArgumentNullException("ctrl")
Dim w = Math.Max(1, ctrl.Width)
Dim h = Math.Max(1, ctrl.Height)
If Not ctrl.Created Then
ctrl.CreateControl()
ctrl.PerformLayout()
ctrl.Refresh()
Application.DoEvents()
End If
Dim bmp As New Bitmap(w, h, PixelFormat.Format32bppArgb)
Try
ctrl.DrawToBitmap(bmp, New Rectangle(0, 0, w, h))
Return bmp
Catch
bmp.Dispose()
Throw
End Try
End FunctionTroubleshooting and important caveats:
This provides a practical starting point while keeping in mind the limits noted by and the z-order/size detail from .
Jump to Post— rproffitt 3,266Why this may be a fools errand is because the panel may not have content as VB and many other apps don't render the view if it's not on screen.
So do try the method noted at but given it's not onscreen …
Why this may be a fools errand is because the panel may not have content as VB and many other apps don't render the view if it's not on screen.
So do try the method noted at but given it's not onscreen it may not have content.
See if this works. Panel1 that has two controls: a label and a picturebox with an image; and Panel2 is on top of Panel1 and hidding it. Besides, form "HiddenPanel" has 2 buttons to show hidden panel1 contents in panel2, and to clear panel2.
Imports System.Drawing.Imaging
Public Class HiddenPanel
Function getPanelsBitmap(pnl As Panel) As Bitmap
Dim bmp As New Bitmap(pnl.Height, pnl.Width)
Try
Dim vCtrl(-1) As Control, iv As Int32
Dim vZ(-1) As Int32
For Each ctr As Control In pnl.Controls
ReDim Preserve vCtrl(iv), vZ(iv)
vCtrl(iv) = ctr
' save the control's z-index:
vZ(iv) = ctr.Parent.Controls.GetChildIndex(ctr)
iv += 1
Next
' sort controls by it's z-index:
Array.Sort(vZ, vCtrl)
Array.Reverse(vCtrl)
Dim gr As Graphics = Graphics.FromImage(bmp)
For Each ctr In vCtrl
Dim img As New Bitmap(ctr.Width, ctr.Height)
ctr.DrawToBitmap(img, New Rectangle( _
0, 0, ctr.Width, ctr.Height))
gr.DrawImage(img, ctr.Location)
Next
gr.Dispose()
Catch ex As Exception
Throw ex
End Try
Return bmp
End Function
Private Sub btnShow_Click(sender As System.Object, e As System.EventArgs) Handles btnShow.Click
Try
' picturebox2 is contained in panel2 on top and hidding panel1:
'
PictureBox2.Image = getPanelsBitmap(Panel1)
Catch ex As Exception
End Try
End Sub
Private Sub btnClear_Click(sender As System.Object, e As System.EventArgs) Handles btnClear.Click
PictureBox2.Image = Nothing
End Sub
End ClassWe're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.