Zoom of a form
lazarus / 31-LCL

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luca · 2020-08-24 15:07

I'd like to implement a form that can zoom its contents.
Something like the scale factor in Firemonkey app.

Do you know if it's possible in Lazarus?

Regards
Luca

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Handoko · 2020-08-24 15:12

I never try Firemonkey. But I know Lazarus can do such thing. On the
link below go to User Interface category then click the Scaling a Form
demo:

https://wiki.freepascal.org/Portal:HowTo_Demos

Unfortunately it did not work correctly on Lazarus 1.8.0, not sure if
the bug has been already fixed or not.

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luca · 2020-08-24 15:24

Hi,
Firemonkey is implemented in Delphi as an alternative to VCL
applications.

Your solution it's ok for graphical elements but is not exactly what
I'm looking for; I'd like to have something similar to CTRL + {+/-}
zooming function in a browser: controls, fonts and all graphical
elements are reduced maintaing the rigth proportions.

My idea is to have a sort of ScalingPanel to implement this feature.

Regards
Luca

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winni · 2020-08-24 15:36

Hi!

A demo with the BGRA library.
I use it because it makes good images if you zoom in.
You can download the BGRAbitmapPack from the Online Package Manager.

Take a Form, an Image and a Button.
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  uses ....,
BGRABitmap, BGRADefaultBitmap, BGRABitmapTypes;  procedure
TForm1.Button1Click(Sender: TObject);var R, small : Trect;    bmp:
TBGRABitmap;beginImage1.Canvas.brush.color :=
clWhite;Image1.Canvas.fillrect (0,0,Image1.width, Image1.Height); bmp
:= TBGRAbitmap.create;bmp.LoadFromDevice(Form1.Canvas.Handle);small :=
Rect(50,50,50+bmp.width div 2, 50+bmp.height div
2);BGRAReplace(bmp,bmp.GetPart(small));BGRAReplace
(bmp,bmp.Resample(bmp.width * 2, bmp.Height * 2) );R :=
Rect(0,0,bmp.width, bmp.height);Image1.Canvas.CopyRect
(R,bmp.canvas,R);bmp.free;end;                             We copy the
canvas of Form1 into bmp.
Then we  take a part of the image starting at 50/50.
Now we resize it to the double size.
And finally we draw it on the Image.canvas.

Winni

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jamie · 2020-08-24 16:12

That reminds me..

 The little ICON MS uses when you click your middle button over the
Web browser, it gives you a different cursor,..

If I was to use that cursor would I expect to have a failing app on
older OSes ? nothing less than W2k/Xp or course.

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Handoko · 2020-08-24 16:45

Quote from: luca on August 24, 2020, 05:24:30 pmMy idea is to have a
sort of ScalingPanel to implement this feature.

I'm not sure but maybe you can try TFrame:
https://wiki.freepascal.org/Frames

TFrame is a kind of form that can be inserted into a form, and it has
scale feature.