Re: [wxperl-users] How to draw on the screen?

[Mattia B. <mb...@ds...>]

On Wed, 10 Oct 2001, Jouke Visser wrote:

>Hi,
>
>I can't find a successful way to draw on the screen using some kind of
>DC other than in an OnPaint or OnDraw method. I want to draw to a piece
>of the screen from outside of those methods. The following examplecode
>executes without errors or warnings, but shows an empty window:
>
>Any ideas why?

I don't have a wxPerl at hand here, but if you draw from 'new'
then the first paint event you get will destroy everything you painted.
If this is just a test case, and you do the drawing from an
event handler ( say in response to a menu/toolbar event ) then
I need to check at home.

Regards
Mattia

>#!/usr/bin/perl 
>use strict;
>use Wx;
>
>package MyApp;
>use base qw(Wx::App);
>
>sub OnInit {
>  my $this  = shift;
>  my $frame = MyFrame->new( undef, 'Blah', [50,50], [420, 300] );
>
>  $frame->Show(1);
>  $this->SetTopWindow( $frame );
>  $frame->Maximize(1);
>
>  return 1;
>}
>
>package MyFrame;
>use base qw(Wx::Frame);
>
>use Wx qw(wxWHITE wxBITMAP_TYPE_GIF wxDEFAULT wxNORMAL
>wxFONTENCODING_ISO8859_1);
>
>sub new {
>  my  $class = shift;
>  my  $this  = $class->SUPER::new( $_[0], -1, @_[1,2,3] );
>
>  Wx::InitAllImageHandlers();
>  
>  # create a scrolledwindow (canvas)
>  $this->{PANEL} = Wx::ScrolledWindow->new($this, -1);
>  $this->{PANEL}->SetBackgroundColour( wxWHITE );
>  $this->{PANEL}->Show(1);
>
>  # Initialize the DC
>  my $dc = Wx::ClientDC->new($this->{PANEL});
>  $this->{PANEL}->PrepareDC($dc);
>
>  # create bitmap
>  my $bmp =
>Wx::Bitmap->new("h:/pABC/SOURCES/Plaatjes-syntheseprogr/SOK.gif",
>wxBITMAP_TYPE_GIF);
>  my $image = Wx::Image->new($bmp);
>  $image->Rescale(200, 200);
>  $bmp = $image->ConvertToBitmap();
>  $dc->DrawBitmap($bmp, 250, 0, 0);
>
>  # draw some text
>  my $font = Wx::Font->new(100, wxDEFAULT, wxNORMAL, wxNORMAL, 0, "",
>wxFONTENCODING_ISO8859_1);
>  $dc->SetFont($font);
>  $dc->DrawText("S O _", 250,225);
>
>  return $this;
>}
>
>package main;
>
>my $app = MyApp->new();
>$app->MainLoop();
>
>
>