While in Canvas how to read inputs from users?
lazarus / 39-Graphics

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Groeneg · 2020-07-08 09:04

I am programming a simulation using Canvas and it works fine and looks
good. Nice graphics and text outputs work fine.

However I now want to use user input to control the flow of the
simulation.
1. Wait until user presses key
2. Increase animation speed by pressing +/- (decrease and increase
delay value)
3. End generation by pressing N
3. End simulation by pressing Q
And so on.

But if I use Keypressed or Read etc. it doesn't work. I think it is
because the latter functions only work in CRT mode but I'm not sure.
So if there are any tips, pointers or examples I would much appreciate
it.

With regards Gerard

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Ñuño_Martínez · 2020-07-08 10:45

Try with TForm events related with keys, they are OnKeyDown,
OnKeyPress and OnKeyUp

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winni · 2020-07-08 10:52

Hi!

As Ñuño_Martínez said: use the keyboard events of the main form.

Set the KeyboardPreview of Form1 in the OI to true.

Connect to the keypress event of Form1:

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 procedure
TForm1.FormKeyPress(Sender: TObject; var Key: char);begincase Key
of'+' : .....'-' :  ....'N': .....'Q': self.close;end; //
caseend;  Winni

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Groeneg · 2020-07-08 12:11

Ok thanks, I will try this and keep you posted.

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Handoko · 2020-07-08 13:42

KeyPress, KeyUp and KeyDown are okay for GUI applications but for
animations or games I recommend GetKeyState, using it you can get
smooth even inertia movement. You can get the demo on recent versions
of Lazarus:

Lazarus main menu > Tools > Example Projects > provide the keyword:
sprite

For your information, don't open any demo directly from the source. It
is better to copy it to a new location (for example Desktop) to
prevent security or other issues.

If you interested to learn from the previous discussion, here:
https://forum.lazarus.freepascal.org/index.php/topic,41178.msg285678.h
tml#msg285678