Get Row and Column positions Fast in a Textbox or Rich Textbox (clean-up)
This short article will show you how you can EASILY obtain an accurate logical text row count, plus the logical row and column number the cursor is located at in a Textbox or Rich Textbox. Line wraps that will force several additional displayed lines are no problem at all, and the returned indexes will account for them. Plus, afterward, I will show you how you can quickly dress up a selection in a textbox so that it is not always at the bottom of the textbox. Because these textbox controls have to manage these row and column counts and indexes anyway, why not let THEM do ALL the work for you.
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<b><font SIZE="5" face="Arial"><p><br> Get Row and Column Positions Fast in a Textbox or Rich Textbox<br> </font></b><font face="Arial"> <span style="font-family: Arial">By David Ross Goben<br> <br></span> <i>You are free to use this information, plus the included snippets in your own code without even acknowledging my work or me.</i><br> <br>A number of people have asked me over the years how to grab the line count, line number, and column position the cursor is located at in a Textbox or Rich Textbox. Other queries regarded positioning the cursor for display.<br> <br> I have seen a number of samples published here, but they involved VB-only solutions, usually using the <i>Split()</i> function. This is fine for short lines, but if you are writing a text editor (every programmer should write at least one text editor during their career - I have written 8 descent ones, 2 multi-document editors, and VERY profitable professional word-processing and spell-checker packages that used to sell for the Tandy Model I/III/4 TRS-80s).<br> <br> Most examples for obtaining the row count, row number, and column usually employ a lot of math, because it is a rather complex thing to do. This is due to the reason that multi-line text boxes more often than not have lots of line wraps and such, which forces most VB-only methods to fail miserably.<br> <br> However, by utilizing just a single API function and 4 constants, we can obtain everything we need in just a very few lines of code by letting the Textbox or Rich Textbox do all the work for us.<br> <br> We will require the <b>SendMessage()</b> API, but we want to use it without the <b><i>As Any</i></b> frivolity that the VB6 API Viewer provides (the API Viewer is activated under the <b><i>Add-Ins</i></b> menu via the <b><i>Add-In Manager</i></b>; select the <b><i>VB 6 API Viewer</i></b> and ensure that the <b><i>Loaded/Unloaded</i></b> and <b><i>Load on Startup</i></b> options are checked). As such, we will rename it <b>SendMessageByNum()</b>, and change its <i>lParam</i> from <b><i>As Any</i></b> to <b><i>As Long</i></b>. We will also grab 4 constants from the API Viewer: <i>EM_LINEFROMCHAR, EM_LINEINDEX, EM_GETLINECOUNT, </i>and<i> EM_LINESCROLL</i>.<br> <br> So far, we have the following code in our module or form or class (or wherever you need to use these things in):<br> <br> </font><font SIZE="4" face="Arial"> <b><font FACE="Courier New" SIZE="2" COLOR="#000080"> Private Declare Function </font><font FACE="Courier New" SIZE="2">SendMessageByNum</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> Lib "</font><font FACE="Courier New" SIZE="2">user32</font><font FACE="Courier New" SIZE="2" COLOR="#000080">" Alias "</font><font FACE="Courier New" SIZE="2">SendMessageA</font><font FACE="Courier New" SIZE="2" COLOR="#000080">" _<br> (ByVal </font> <font FACE="Courier New" SIZE="2">hwnd</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> As </font><font FACE="Courier New" SIZE="2">Long</font><font FACE="Courier New" SIZE="2" COLOR="#000080">, _<br> ByVal </font> <font FACE="Courier New" SIZE="2">wMsg</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> As </font><font FACE="Courier New" SIZE="2">Long</font><font FACE="Courier New" SIZE="2" COLOR="#000080">, _<br> ByVal </font> <font FACE="Courier New" SIZE="2">wParam</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> As </font><font FACE="Courier New" SIZE="2">Long</font><font FACE="Courier New" SIZE="2" COLOR="#000080">, _<br> ByVal </font> <font FACE="Courier New" SIZE="2">lParam</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> As </font><font FACE="Courier New" SIZE="2">Long</font><font FACE="Courier New" SIZE="2" COLOR="#000080">) As </font><font FACE="Courier New" SIZE="2">Long<br> <br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080">Private Const EM_LINEFROMCHAR As </font><font FACE="Courier New" SIZE="2">Long</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> = &</font><font FACE="Courier New" SIZE="2">HC9<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080">Private Const EM_LINEINDEX As </font><font FACE="Courier New" SIZE="2">Long</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> = &</font><font FACE="Courier New" SIZE="2">HBB<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080">Private Const EM_GETLINECOUNT As </font><font FACE="Courier New" SIZE="2">Long</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> = &</font><font FACE="Courier New" SIZE="2">HBA<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080">Private Const EM_LINESCROLL As </font><font FACE="Courier New" SIZE="2">Long</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> = &</font><font FACE="Courier New" SIZE="2">HB6<br> </font></b></font><font face="Arial"><br> We have just set up for using the API. The actual Code is little longer than this, though we will make it a bit longer for reasons of clarity.<br> <br> Note that I declared the API and all the constants Private. Some people prefer to declare them as Public and use them willy-nilly throughout their application, but this is messy. Keep them local and private to one file, and simply write public server subroutines and functions to be invoked from the outside. By wrapping these system services inside controllable environments (wrapping is just a fancy way of saying we are placing a stronger layer of control between the user and the system services), we are less likely to make a goof, and hence our code is more <i>robust</i> (a fancy term we developers like to use to say something is <i>bullet-proof</i> or <i>goof-proof</i>), and it is also easier to debug if we do discover an error.<br> <br> The following code is designed to work with either a standard Textbox or Rich Textbox (the RTB is enabled via the <i>Project/Components</i> menu and checking the <b><i>Microsoft Rich Textbox Control 6.0</i></b> item).<br> <br> All you need to do is add the following 3 functions:<br> <br> </font><font SIZE="4" face="Arial"> <b><font FACE="Courier New" SIZE="2" COLOR="#008000"> '*******************<br> ' GetLineCount<br> ' Get the line count<br> '*******************<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080">Public Function </font> <font FACE="Courier New" SIZE="2">GetLineCount</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> (</font><font FACE="Courier New" SIZE="2">tBox</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> As </font><font FACE="Courier New" SIZE="2">Object</font><font FACE="Courier New" SIZE="2" COLOR="#000080">) As </font><font FACE="Courier New" SIZE="2">Long<br> GetLineCount</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> = </font><font FACE="Courier New" SIZE="2">SendMessageByNum</font><font FACE="Courier New" SIZE="2" COLOR="#000080">( </font><font FACE="Courier New" SIZE="2">tBox</font><font FACE="Courier New" SIZE="2" COLOR="#000080">.hwnd, </font><font FACE="Courier New" SIZE="2">EM_GETLINECOUNT, 0&, 0&)<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080">End Function<br> <br> </font><font FACE="Courier New" SIZE="2" COLOR="#008000"> '*******************<br> ' GetLineNum<br> ' Get current line number<br> '*******************<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080">Public Function </font> <font FACE="Courier New" SIZE="2">GetLineNum</font><font FACE="Courier New" SIZE="2" COLOR="#000080">( </font><font FACE="Courier New" SIZE="2">tBox</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> As </font> <font FACE="Courier New" SIZE="2">Object</font><font FACE="Courier New" SIZE="2" COLOR="#000080">) As </font><font FACE="Courier New" SIZE="2">Long<br> GetLineNum</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> = </font><font FACE="Courier New" SIZE="2">SendMessageByNum</font><font FACE="Courier New" SIZE="2" COLOR="#000080">( </font><font FACE="Courier New" SIZE="2">tBox</font><font FACE="Courier New" SIZE="2" COLOR="#000080">.hwnd, EM_LINEFROMCHAR</font> <font FACE="Courier New" SIZE="2" COLOR="#000080">, </font><font FACE="Courier New" SIZE="2">tBox</font><font FACE="Courier New" SIZE="2" COLOR="#000080">.SelStart, </font><font FACE="Courier New" SIZE="2">0</font><font FACE="Courier New" SIZE="2" COLOR="#000080">&)<br> End Function<br> <br> </font><font FACE="Courier New" SIZE="2" COLOR="#008000"> '*******************<br> ' GetColPos<br> ' Get current Column<br> '*******************<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080">Public Function </font> <font FACE="Courier New" SIZE="2">GetColPos</font><font FACE="Courier New" SIZE="2" COLOR="#000080">( </font><font FACE="Courier New" SIZE="2">tBox</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> As </font><font FACE="Courier New" SIZE="2">Object</font><font FACE="Courier New" SIZE="2" COLOR="#000080">) As </font><font FACE="Courier New" SIZE="2">Long<br> GetColPos</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> = </font><font FACE="Courier New" SIZE="2">tBox</font><font FACE="Courier New" SIZE="2" COLOR="#000080">.SelStart - </font><font FACE="Courier New" SIZE="2">SendMessageByNum</font><font FACE="Courier New" SIZE="2" COLOR="#000080">( </font><font FACE="Courier New" SIZE="2">tBox</font><font FACE="Courier New" SIZE="2" COLOR="#000080">.hwnd, EM_LINEINDEX</font> <font FACE="Courier New" SIZE="2" COLOR="#000080">, </font> <font FACE="Courier New" SIZE="2">-1</font><font FACE="Courier New" SIZE="2" COLOR="#000080">&, </font><font FACE="Courier New" SIZE="2">0</font><font FACE="Courier New" SIZE="2" COLOR="#000080">&)<br> End Function<br> </font></b></font><font face="Arial" COLOR="#000080"> <br> </font><font face="Arial">By declaring <i>tBox</i> as <i>Object</i> instead of a specific <i>TextBox</i> or <i>RichTextbox</i>, we can now use these functions for either, though you can surely define them specifically for your object, which will result in slightly faster-running code.<br> <br> Some people prefer line numbers and column positions to start with 1, not 0. In this case, all you need to do is add 1 to the results of GetLineNum() and GetColPos().<br> <br> How easy are they to invoke? Almost too easy. Suppose we have 3 labels on a form named <b>lblLines</b>, which will report the line count in the textbox, a label named <b>lblRow</b> to report the current row, and a label named <b>lblCol</b> to report the column position in the row. These are in place to service a Rich Textbox control named <b>rtbText</b> (although I am using labels in this example, you can just as easily designate panels in a Statusbar control as the targets). Suppose further that we want to report line and column numbers from 1, not zero. We could write a subroutine to gather all three pieces of information, or just the items we require. Suppose we wanted all three. We would need only the following 3 lines of code:<br> <br> </font><b><font size="2" face="Courier New" color="#000080">Me.lblLines.Caption = "Lines: " & CStr(GetLineCount(Me.rtbText))<br> Me.lblRow.Caption = "Row: " & CStr(GetLineNum(Me.rtbText) + 1)<br> Me.lblCol.Caption = "Col: " & CStr(GetColPos(Me.rtbText) + 1)<br> <br> </font></b><font face="Arial">The final thing we may want to do is <b><i>pretty up</i></b> the display. Suppose you have written a routine that searches through the text for a character sequence, and then you want to display it on the screen. Normally when you use the <b>SelStart</b> properties of the textbox, it tends to display at the bottom of the textbox and looks kind of goofy. It looks a whole lot better if it is displayed near the top of the Textbox, except when the selection is forced down due to being near the bottom of the text anyway.<br> <br> The fast trick around this is so simple that a lot of people never think of it. Simply first set the <b>SelStart</b> property of the text box to the very bottom of the text (</font><font face="Courier New"><b>tBox.SelStart = Len(tBox.Text)</b></font><font face="Arial">) and then point <b>SelStart</b> to the text you actually want pointed to. But it would be even nicer if it were possible to display the target text a couple of line down from the top, so the user could see what preceded it. All this can be accomplished with the following subroutine:<br> <br> </font><font SIZE="4" face="Arial"> <b><font FACE="Courier New" SIZE="2" COLOR="#008000"> '*******************<br> ' AdjustTextDisplay<br> ' place current position<br> ' at top of display, and<br> ' scroll display up 2 lines<br> '*******************<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080">Public Sub </font> <font FACE="Courier New" SIZE="2">AdjustTextDisplay</font><font FACE="Courier New" SIZE="2" COLOR="#000080">( </font><font FACE="Courier New" SIZE="2">tBox</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> As </font><font FACE="Courier New" SIZE="2">Object</font><font FACE="Courier New" SIZE="2" COLOR="#000080">)<br> Dim </font><font FACE="Courier New" SIZE="2">cPos</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> As </font><font FACE="Courier New" SIZE="2">Long<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080"> Dim </font> <font FACE="Courier New" SIZE="2">cLen</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> As </font><font FACE="Courier New" SIZE="2">Long<br> <br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080"> With </font> <font FACE="Courier New" SIZE="2">tBox<br> cPos</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> = .SelStart </font><font FACE="Courier New" SIZE="2" COLOR="#008000"> 'Save selection<br> </font><font FACE="Courier New" SIZE="2">cLen</font><font FACE="Courier New" SIZE="2" COLOR="#000080"> = .SelLength </font> <font FACE="Courier New" SIZE="2" COLOR="#008000"> 'Save anything highlighted</font><font FACE="Courier New" SIZE="2" COLOR="#000080"><br> .SelStart = Len(.Text) </font> <font FACE="Courier New" SIZE="2" COLOR="#008000">'bottom of text<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080"> .SelStart = </font><font FACE="Courier New" SIZE="2">cPos </font> <font FACE="Courier New" SIZE="2" COLOR="#008000"> 'force top of display<br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080"> .SelLength = </font><font FACE="Courier New" SIZE="2">cLen <font color="#008000">'reselecting any selection</font><br> </font><font FACE="Courier New" SIZE="2" COLOR="#000080"> Call </font><font FACE="Courier New" SIZE="2">SendMessageByNum</font><font FACE="Courier New" SIZE="2" COLOR="#000080">( </font><font FACE="Courier New" SIZE="2">tBox</font><font FACE="Courier New" SIZE="2" COLOR="#000080">.hwnd, EM_LINESCROLL</font><font FACE="Courier New" SIZE="2" COLOR="#000080">, </font><font FACE="Courier New" SIZE="2">0</font><font FACE="Courier New" SIZE="2" COLOR="#000080">&, </font><font FACE="Courier New" SIZE="2">-2</font><font FACE="Courier New" SIZE="2" COLOR="#000080">&)<br> End With<br> End Sub<br> </font></b></font><font FACE="Arial" COLOR="#000080"> <br> </font><font face="Arial"> This subroutine will even work if the text box contains only one line of text, because if the API sub-system finds that the text box cannot actually scroll, it will not try to force it.<br> <br> If you know how many lines will typically be displayed in the text box, you could actually display the selected text in the middle of the text box by replacing the <b>-2&</b> parameter in the <b>SendMessageByNum()</b> invocation, which tells the control to scroll up 2 lines without changing the selection point, to the number of lines displayable in the textbox divided by two.<br> <br> And that is all there is to it. It is very simple, very fast, and very efficient.<br> <br> - David<br> </p>
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