VB.NET 2010 - WM_GETTEXT/WM_GETTEXTLENGTH on a RichTextBox, ability to get only the last line & update whenever the window updates? (SendMessage/GetWindow/etc)
I'm using something like this to get all the text in a RichTextBox of another window.. ChatWindowHandler = the hwnd of the richtextbox...
Dim length As IntPtr = SendMessage(ChatWindowHand
Dim Hndl As IntPtr = Marshal.AllocHGlobal(lengt
Dim NumText As Integer = SendMessage(ChatWindowHand
'copy the characters from the unmanaged memory to a managed string
TextBox1.Text = Marshal.PtrToStringUni(Hnd
This works well for getting text from an external richtextbox window. However, what I want to do is get the last line submitted ONLY and add it to the textbox instead of always getting ALL the information.. Is that possible?
Also, is it possible to get text only when the richtextbox update (aka when text is added to the richtextbox?)
If both are not possible... How can I get new text with a timer? Have to note that the richtextbox is sometimes cleared, so it needs to be able to detect this..
Any ideas? Thanks!
Dim length As IntPtr = SendMessage(ChatWindowHand
Dim Hndl As IntPtr = Marshal.AllocHGlobal(lengt
Dim NumText As Integer = SendMessage(ChatWindowHand
'copy the characters from the unmanaged memory to a managed string
TextBox1.Text = Marshal.PtrToStringUni(Hnd
This works well for getting text from an external richtextbox window. However, what I want to do is get the last line submitted ONLY and add it to the textbox instead of always getting ALL the information.. Is that possible?
Also, is it possible to get text only when the richtextbox update (aka when text is added to the richtextbox?)
If both are not possible... How can I get new text with a timer? Have to note that the richtextbox is sometimes cleared, so it needs to be able to detect this..
Any ideas? Thanks!
ASKER
I've been looking at EM_GETLINE,
I know
Dim lines As Integer = SendMessage(ChatWindowHand
should work,
Dim lngLength = SendMessage(ChatWindowHand
ReDim Buffer(lngLength + 1)
Buffer(0) = lngLength + 1
SendMessage(ChatWindowHand
I think its the lngLength causing the issue because it seems to be returning the same value with any line.. Could be wrong about the EM_GETLINE too but I think it should be something like that anyways.
I know
Dim lines As Integer = SendMessage(ChatWindowHand
should work,
Dim lngLength = SendMessage(ChatWindowHand
ReDim Buffer(lngLength + 1)
Buffer(0) = lngLength + 1
SendMessage(ChatWindowHand
I think its the lngLength causing the issue because it seems to be returning the same value with any line.. Could be wrong about the EM_GETLINE too but I think it should be something like that anyways.
ASKER CERTIFIED SOLUTION
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Hi,
The EM_ constants don't automatically marshal across process boundries like the WM counterparts (WM_GETTEXT). You would have to add marshal code to get it to work for control handles in another process. In order to do that you would have to also use VirtualAllocEx, WriteProcessMemory, ReadProcessMemory. You have to allocate a buffer in the address space of the other process and pass the memory address to SendMessage instead of local buffering.
The EM_ constants don't automatically marshal across process boundries like the WM counterparts (WM_GETTEXT). You would have to add marshal code to get it to work for control handles in another process. In order to do that you would have to also use VirtualAllocEx, WriteProcessMemory, ReadProcessMemory. You have to allocate a buffer in the address space of the other process and pass the memory address to SendMessage instead of local buffering.
ASKER
Actually that coding there was almost perfect, thanks!
Yeah I was wrong the EM_GETLINE is within the WM_USER range so it is marshaled correctly! I should have looked first at the value anything above WM_USER(&H400) doesn't perform default marshaling some of them include EM_STREAMOUT, EM_STREAMIN.
http://msdn.microsoft.com/en-us/library/bb761586(VS.85).aspx
http://msdn.microsoft.com/en-us/library/bb761584(VS.85).aspx
It's not possible using straight VB.Net to get notified when the text changes. To do that would require a language that supports external hooking like Delphi or C++.