Memo Clicks

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Problem Description

Here's a simple little program which illustrates the Delphi techniques for recognizing user clicks on a TMemo and determining the line number and the  position within the line where the click occurred.

Background & Techniques

I have used the techniques previously but always had difficulty finding exactly where and how to do it. The solution is two functions added to our DFFUtils unit.  Both depend on the TMemo OnClick event exit to respond to a click with the text based location in terms of the Lines property.  

Function LineNumberClicked(Memo:TMemo):integer; returns the line number clicked relative to 0 (the first line has line number 0). For the forgetful (me), alternative names defined for this function are: ClickedMemoLine, MemoLineClicked, and MemoClickedLine.  A standard Windows message, EM_LineFromChar, is sent to retrieve the line number clicked.

Function LinePositionClicked(Memo:TMemo):integer; returns the clicked position within the line relative to 1 (the first character in the line is position number 1); Again, for the forgetful,  alternative names defined for this function are: ClickedMemoPosition and MemoPositionClicked.  Position within the line is calculated by subtractg the character index of the start of the line (from posting an EM_LineIndex message) from the TMemo SelStart property value.

 To test the routines, click anywhere on the description memo text and the program will report the line and position clicked.

Running/Exploring the Program 

bulletDownload  executable
bulletDownload source 

Suggestions for Further Explorations

 ???
   

 

Original:  August 18, 2012

Modified:  February 18, 2016

 
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