Perl:Flags with Lines Tutorial

Flags Tutorials

Rectangles

Lines

Polygons

Stars

Repeats

Methods

Hard Problems

Interactive Programming Tutorials - Drawing flags using lines.

You may want to look at: [../ht50Graphics/200Lines.xml How to draw thick lines.]

Scotland

The cross of St. Andrew shows diagonal lines on a blue background.

• Complete the flag by drawing the other diagonal line.
• The white lines should be slightly thicker - try 18.

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sub drawFlag{ my ($g) = @_; my $blue = $g->colorAllocate(0,0,255); my $white= $g->colorAllocate(255,255,255); $g->filledRectangle(0,0,500,300,$blue); $g->setThickness(9); $g->line(0,0,500,300,$white); }

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England

The English flag is the cross of St. George. This is a red cross on a white background.

• The line thickness should be ¹/₅ of the height of the flag.

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sub drawFlag{ my ($g) = @_; my $red = $g->colorAllocate(255,0,0); my $white= $g->colorAllocate(255,255,255); $g->filledRectangle(0,0,500,300,$white); $g->setThickness(30); $g->line(0,0,500,300,$red); }

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test text

 

 

 

 

Botswana

The flag of Botswana has a black stripe on a white stripe on a blue background.

• The flag is 150 by 100
• The white stripe behind the black one has width 30
• The black stripe has width 20
• The pale blue has rgb: 110,184,237

.

sub drawFlag{ my ($g) = @_; my $blue = $g->colorAllocate(110,184,237); my $white= $g->colorAllocate(255,255,255); my $black= $g->colorAllocate(0,0,0); $g->filledRectangle(0,0,150,100,$blue); $g->setThickness(9); $g->line(0,0,150,100,$white); }

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Trinidad and Tobago

There is a problem with this example

Seemingly the GD library being used here does not support drawing thick lines outside the drawing area as expected. If anyone can suggest how I might fix this problem (without resorting to polygons) I would appreciate it. ajcumming@gmail.com

We can start and end lines outside the confines of the surface.

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sub drawFlag{ my ($g) = @_; my $blue = $g->colorAllocate(0,0,255); my $white= $g->colorAllocate(255,255,255); $g->filledRectangle(0,0,600,360,$white); $g->setThickness(40); $g->line(0,20+0*80,600,20+0*80,$blue); $g->line(0,20+1*80,600,20+1*80,$blue); $g->line(0,20+2*80,600,20+2*80,$blue); #Two more stripes required $g->filledRectangle(0,0,199,199,$blue); $g->line(0,100,199,100,$white); $g->line(100,0,100,199,$white); }

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test text