Hallo.

I suggest to add function function GetTextMetrics(var TM: TTextMetric): boolean; into TCanvas class.

If user wants to work with text on Canvas and mix different fonts on one line, he needs minimally to know Ascent and Descent metrics of the font. But TCanvas has only TextExtent function. If user renders text on the screen (or printer in Win), then uses lclintf.GetTextMetrics. But if renders on TPoscriptCanvas or upcoming TCairoCanvas he must use some TCairoCanvas.GetTextMetrics or still non existing TPoscriptCanvas.GetTextMetrics.

It cause ugly non oop construction like:

{$IFDEF USE_CAIRO}
if Canvas is TCairoCanvas then
  (Canvas as TCairoCanvas).GetTextMetrics(tm)
else
  GetTextMetrics(tm);
{$ELSE}
  GetTextMetrics(tm);
{$ENDIF}

For that reason I propose to add virtual function GetTextMetrics into TCanvas.

Is this proposal acceptable?

If it is, how to move ahead to reach this goal.

Petr

Thanks all for their reactions :(

Is another place where I can discuss? Is another place where LCL core developers response my few questions?

I have done my work on cairo canvas. It can be used as separate package. Where should I put it? Certainly if comunity have an interest.

Petr

Thanks all for their reactions :(

Developers sometimes are busy with their projects :(

Is another place where I can discuss? Is another place where LCL core developers response my few questions?

In the irc channel #lazarus-ide

I have done my work on cairo canvas. It can be used as separate package. Where should I put it? Certainly if comunity have an interest.

You idea is not bad to add GetTextMetrics. Create a patch and a test. Then add them to the bug tracker.

Best regards,
Paul Ishenin.

Paul Ishenin wrote

26.03.2010 16:20, wrote: > Thanks all for their reactions :( Developers sometimes are busy with their projects :(

I suppose it :)

I'l try it.

And what to do with finished cairo canvas package? Send tarball to the list?

Petr

The only thing we need to ask ourselves is, do we need the "inner" TTextMetric or can we use some more userfriendly version ?

Marc

How to imagine myself "userfriendly"?

Petr

--- El vie 26-mar-10, escribi?:

In r24429, I added a initial version of the function GetTextMetrics to canvas, it works like standard winpi GetTextMetrics but it takes a TLCLTextMetrics record where we can add fields that can be implemented in all targets, currently only Ascender, Descender and Height are implemented in PostscriptCanvas which allows to fix a bug in TurboPower IPro print preview. Still waiting for you Cairo canvas stuff.

Jesus Reyes A.

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http://mx.mujer.yahoo.com/cocina/

I merge GetTextMetrics and Cairo will be ready.

Where I should send it? Mantis has 2kB limit.

Petr