Advance text rendering on canvas
lazarus / 31-LCL

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stoffman · 2021-07-11 09:24

Hi,

I'm familiar with TextOut. But I'm looking for something along the
lines of Win32 DrawTextEx (That provides alignment, word wrapping and
some other niceties) that is also cross platform. It would be great if
it also supports different colors (TextOut/DrawTextEx uses the current
pen color)  

Any suggestions ?

https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-
drawtextexa

Thanks,

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wp · 2021-07-11 09:31

AFAIK, DrawTextEx is not available in LCLIntf, in contrast to
DrawText. The basic DrawText functionality is also available in the
TCanvas.TextRect method which respects the TextStyle record of
TCanvas.
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i type 
TTextStyle = packed record    Alignment : TAlignment;  // TextRect
Only: horizontal alignment     Layout    : TTextLayout; // TextRect
Only: vertical alignment     SingleLine: boolean;     // If WordBreak
is false then process #13, #10 as                             //
standard chars and perform no Line breaking.     Clipping  : boolean;
   // TextRect Only: Clip Text to passed Rectangle     ExpandTabs:
boolean;     // Replace #9 by apropriate amount of spaces (default is
usually 8)     ShowPrefix: boolean;     // TextRect Only: Process
first single '&' per                             //    line as an
underscore and draw '&&' as '&'     Wordbreak : boolean;     //
TextRect Only: If line of text is too long                           
 //    too fit between left and right boundaries                     
      //    try to break into multiple lines between                 
          //    words                             //    See also
EndEllipsis.     Opaque    : boolean;     // TextRect: Fills
background with current Brush                             // TextOut :
Fills background with current                             //         
 foreground color     SystemFont: Boolean;     // Use the system font
instead of Canvas Font        RightToLeft: Boolean;    //For
RightToLeft text reading (Text Direction)     EndEllipsis: Boolean;  
 // TextRect Only: If line of text is too long                       
    //    to fit between left and right boundaries                   
        //    truncates the text and adds "..."                      
     //    If Wordbreak is set as well, Workbreak will               
            //    dominate.  end;   TCanvas = class(TFPCustomCanvas) 
...    procedure TextRect(const ARect: TRect; X, Y: integer; const
Text: string);    procedure TextRect(ARect: TRect; X, Y: integer;
const Text: string;                       const Style: TTextStyle);
virtual;  end;

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jamie · 2021-07-11 12:07

it's unfortunate the canvas.TextRect(… did not define the TRECT as a
VAR because you can not use that function if all you want to do is
simply calculate the rectangle without painting.


However, all is not lost..

 the LCLINTF unit which makes cross platform calls does have the
DrawText which accepts the same parameters as the windows counter
part..

 So all one needs to do is just include the unit.