help: i want to draw polygon in pascal
lazarus / 39-Graphics

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zanghaohieu · 2014-08-16 15:08

I want to draw polygons with coordinates had been entered from the
keyboard into one-dimensional array. Now that the coordinates used to
draw polygons.
Should I use google translate expressions incoherent

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typo · 2014-08-16 15:14

Use Canvas.Polygon(ArrayOfTPoint). Only be sure that the user enters
valid points (by asking him/her to pick the point with the mouse, for
instance).

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zanghaohieu · 2014-08-17 06:29

retrieve data from array coordinates to draw

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zanghaohieu · 2014-08-17 06:36

for example
type coordinates=record
  x,y:integer ;
  end;
 mang=array[0..30] of coordinates;
{Added polygon vertices}
 procedure nhapdinh(var n:byte;var p:mang);
 var i:byte;
 begin
      write('verticles :n= ');readln(n);
      for i:=1 to n do
      begin
           write('p[',i,'].x=  ');readln(p.x);
           write('p[',i,'].y=  ');readln(p.y);
      end;
 end;
typed arrays used to draw polygons

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User137 · 2014-08-17 08:52

Just change this line to:
Code: [Select]mang=array[0..30] of TPoint;You can then use
......Canvas.Polygon(mang);  where Canvas can be from any graphical
component like TForm, TImage, TImage.Picture.Bitmap, TPaintBox etc.

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howardpc · 2014-08-17 12:40

From his code snippet it seems zanghaohieu wants to draw polygons in
console window, not in a GUI environment.

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zanghaohieu · 2014-08-17 14:06

I want to enter data in console windowns, and then draw in the
graphical environment

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taazz · 2014-08-17 14:19

Quote from: zanghaohieu on August 17, 2014, 04:06:05 pmI want to enter
data in console windowns, and then draw in the graphical environment

Go all graphical and forget about the console window.

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zanghaohieu · 2014-08-17 14:31

so as not to draw polygons by taking the data from the array to draw?

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taazz · 2014-08-17 14:38

As to get the input from a graphical interface too instead of a
console window.

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zanghaohieu · 2014-08-17 15:02

please give me examples

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Bart · 2014-08-17 15:22

You coud use a TStringGrid with ColCount = 2, FixedRows = 1, RowCount
= Nr of points you want + 1 and set the text of the top cells to 'x'
and 'y'.
You will have to validate the input (but you would also need to do
that when using readln() on the console (your current code (in the
example) will crash the program if someone enters a non-valid value).

[edit]Attached demo, which lets you input coordinates in a
stringgrid[/edit]

Bart

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typo · 2014-08-17 16:03

Here a simple example (attached). Click on the form to set points.

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howardpc · 2014-08-17 16:27

And another example to show how to use a different mouse event. This
example draws just the polygon perimeter.

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zanghaohieu · 2014-08-18 13:13

thanks typo
but i have problem, you can see in this picture

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zanghaohieu · 2014-08-18 13:21

thanks howardpc
i have a same problem as

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taazz · 2014-08-18 13:24

you need lazarus to compile the samples. They will not work on the fpc
IDE.

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zanghaohieu · 2014-08-18 13:28

so i must install lazarus

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zanghaohieu · 2014-08-18 13:45

i installed lazarus
how to use this unit ?

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typo · 2014-08-18 13:54

Probably you will not have any error message.

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taazz · 2014-08-18 13:56

use the menu "project\open project" select the lpi file from the
folder you have uncompressed the sample then go to menu "run\Compile"
and the select "run\run" to see the application working.

Depending on what operating system you are on you might have to change
some project options too.