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Re^2: wxPerl image handling (short & sweet). (iewxPerl Tutorial 2)

by Steve_BZ (Hermit)
on Sep 10, 2009 at 01:06 UTC ( #794478=note: print w/ replies, xml ) Need Help??


in reply to Re: wxPerl image handling (short & sweet).
in thread wxPerl image handling (short & sweet).

As of today the following works. I made three changes:

  • Removed use Wx::Image;
  • Replaced the image file name with one on my system (ie Create "c:\\halo2.jpg" or change the file name and/or path.)
  • Replaced $bmp = $image->ConvertToBitmap();
    with $bmp=Wx::Bitmap->new( $image );
Here is the full code (don't forget to change the image path and name):

#!/usr/bin/perl use Wx; package MyApp; #As always, we need to subclass Wx::App and populate it with a frame. use strict; use vars qw(@ISA); @ISA=qw(Wx::App); sub OnInit { my $this = @_; my $frame = MyFrame->new( "Mini-image demo", [-1,-1], [-1,-1]); # if the frame didn't get created, exit early. don't use die here, as +it seems to be a little unstable... # if OnInit returns false,though, wx will clean up after itself nicely +. unless ($frame) {print "unable to create frame -- exiting."; return +undef} $frame->Show( 1 ); 1; #everything's ok, on with the show. } package MyFrame; # subclass wx::Frame to insert the image control. use vars qw(@ISA); use strict; # # All we load here are 2 constants used # to keep the image stretched to the dimensions of the window. # use Wx qw( wxWidth wxHeight); # # Wx::Image loads the Image control and all of the Image handlers. # use IO::File; @ISA=qw(Wx::Frame); sub new { my $class = shift; my $this = $class->SUPER::new( undef, -1, $_[0], $_[1], $_[2] ); # # replace the filename with something appropriate. # my $file = IO::File->new( "c:\\halo2.jpg", "r" ) or return undef; binmode $file; # # define a handler for jpeg images. # handlers are half of what translates file formats (.jpg in thi +s case) # into streams readable by wxBitmap objects for diplay. # yes, this means you typically can't cram a file's contents int +o # a wxBitmap control -- the exception being windows bitmaps. # # There is a method called 'Wx::Image::FindHandlerType', but I c +ouldn't # get the thing to work in any way, shape or form. # my $handler = Wx::JPEGHandler->new(); # # wxImages are the other half of getting images displayed -- # they hold the data stream created by a handler. # Although there's many functions that can be performed with an +wxImage, # all we're interested is turning the stream into a bitmap. # my $image = Wx::Image->new(); my $bmp; # used to hold the bitmap. # # here we load the file into $image. simple enough. # $handler->LoadFile( $image, $file ); # # and here, we turn the data in $image into a bitmap, and store +in $bmp. # if the data in $bmp is bad for some reason, $bmp->Ok() will fa +il. #$bmp = $image->ConvertToBitmap(); $bmp=Wx::Bitmap->new( $image ); if( $bmp->Ok() ) { # create a static bitmap called ImageViewer that displays the # selected image. $this->{ImageViewer}= Wx::StaticBitmap->new($this, -1, $bmp); } # At this point, we could just return the frame, and be ok. # unfortunately, the static bitmap could be *really* static and +not # resize itself when the window's resized, which'd look pretty u +gly. # # To make sure everything looks ok, we'll assign constraints to # Imageviewer. # Layout constraints determine how controls will appear within t +he # window. They consist of 4 members : left, top, width and heigh +t. # constraints are objects by themselves, and need to be assigned + to # objects in order to have any use. We'll be using this contstra +int # in order to stretch the picture out to the full size of the wi +ndow. # my $b1 = Wx::LayoutConstraints->new(); # set the upper left corner to absolute [0,0]. # if there were other controls using constraints, we could change +these to # something like $b1->left->RightOf ($widget, 5) to make this cont +rol appear # 5 pixels to the right of $widget's constraints. $b1->left->Absolute(0); $b1->top->Absolute(0); # now set the width and height to 100% each way. $b1->width->PercentOf( $this, wxWidth,100); $b1->height->PercentOf( $this, wxHeight, 100); # # Now that all the dimensions of the constraint are complete, # assign it to ImageViewer. # $this->{ImageViewer}->SetConstraints( $b1 ); $this; # return the frame object to the calling application. } package main; my $app = MyApp->new();# create an instance of the Wx::App-derived cla +ss $app->MainLoop(); # run


Comment on Re^2: wxPerl image handling (short & sweet). (iewxPerl Tutorial 2)
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Re^3: wxPerl image handling (short & sweet).
by Anonymous Monk on Dec 27, 2009 at 06:04 UTC
    Big thank you for this tutorial. It has been a massive help. ^_^
Re^3: wxPerl image handling (short & sweet).
by rp{erl}D (Initiate) on Jan 09, 2010 at 19:26 UTC
    This script didn't run for me. The error message is: OnInit must return a true return value at C:\RPD Programming\RPD wxPerl\Perlmonk s wxPerl tutorial\image.pl line 119 unable to create frame -- exiting. C:\RPD Programming\RPD wxPerl\Perlmonks wxPerl tutorial> What happened here?
      Create "c:\\halo2.jpg" or change the file name and/or path.
      Well, I just checked it again and it's fine on my system. Are you sure your wx install was OK?

      Did you create the image or change the image line?

      Steve

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