TCustomEdit text indentation
lazarus / 31-LCL

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scribly · 2013-10-23 18:38

Does anyone know what the best way is to make a TCustomEdit descendant
that has no indentation between the start of the control (0,0) and the
outputed text?
Or is there a way to get the amount of indentation?

I'm asking because some of my code uses canvas.textrect to output some
text, and I'd like to have an borderless editbox right after that at
the same height. (Even with borderstyle set to bsNone the text starts
after a small offset)

I know I can just adjust the top and left of the edit by a specific
amount I can gather from my system, but I'm sure that is a really bad
idea (I already tried centering the textrect output by the height of
the edit but then the height is still off by 1 pixel)

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howardpc · 2013-10-23 21:15

With edits you're constrained by the way the OS widget is implemented.
If all you want is to display text (no editing required) some
improvement on this basic skeleton component will suffice:

Code: [Select]unit borderless_text;

{$mode objfpc}{$H+}

interface

uses
  Classes, Controls, types;

type

  { TBorderlessText }

  TBorderlessText=class(TGraphicControl)
 protected
   class function GetControlClassDefaultSize: TSize; override;
   procedure Paint; override;
 public
   constructor Create(anOwner: TComponent);
 published
   property Text;
 end;

implementation

{ TBorderlessText }

class function TBorderlessText.GetControlClassDefaultSize: TSize;
begin
  Result.cy:=15;
  Result.cx:=200;
end;

constructor TBorderlessText.Create(anOwner: TComponent);
begin
  inherited Create(anOwner);
  with GetControlClassDefaultSize do
    SetInitialBounds(Left, Top, cx, cy);
end;

procedure TBorderlessText.Paint;
begin
  Canvas.Brush.Color:=Color;
  Canvas.FillRect(ClientRect);
  Canvas.TextOut(0,0,Text);
  inherited Paint;
end;
    
end.

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scribly · 2013-10-23 21:45

It's specifically for editing.
I have a custom drawn listview, and when the 3th column is clicked i
want to go into edit mode. I do that by creating an TEdit, but i was
wondering if i could make it look better by ditching that border,
giving it a correct background and make it look like it belongs in the
row

I could of course implement a full text editor that does look and
works good (copy/paste, context menu, key handling) but i was hoping a
custom edit might save a lot of time on something not very important
(the editing and other parts work fine, this is just a matter of
aesthetics)

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howardpc · 2013-10-23 22:04

Quote from: scribly on October 23, 2013, 08:38:23 pmI know I can just
adjust the top and left of the edit by a specific amount I can gather
from my system, but I'm sure that is a really bad idea
I don't think a TCustomEdit having a negative offset of a few pixels
in either direction is a bad idea unless it starts to clip other text,
which is unlikely with bsNone.
Try it and see!

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engkin · 2013-10-24 01:36

Windows has an edit message called EM_POSFROMCHAR. Use it to ask your
TCustomEdit about the first letter.

Maybe something like this

Code: [Select]var
  xyCombined: DWord;
  xOffset, yOffset:Word;
begin
  xyCombined := SendMessage(YourEdit.Handle, EM_POSFROMCHAR, 0, 0);
  xOffset := xyCombined and $FFFF;
  yOffset := xyCombined shr 16;

I believe the distance you are asking about is related to the chosen
font and its size and whether a border is included or not. If my
assumption is correct, you only need to send that message once and
every time a change related to the font occurs.

Edit:
A better way using another edit message EM_GETRECT

Code: [Select]var
  textRect: TRect;
  xOffset, yOffset: Word;
begin
  SendMessage(YourEdit.Handle, EM_GETRECT, 0, Integer(@textRect));
  xOffset := textRect.Left;
  yOffset := textRect.Top;