I am plotting a graph, using GD::Graph and I would like to put labels inside the graph at key locations along my lines.

I am able to get_hotspots() only after I plot. Then I need to create and draw the new text. If I display the data at this time my labels will not appear. I need to plot again, then my labels will appear. However, when I plot twice like this I get a ghosted image of of the entire graph with the second image being stretched so it is noticeable.

In the examples, sample71.pl does plot, get_hotspots(), draw and then save_chart through save.pl and it has no problem. I am writing CGI so I just print an img tag with src="data:.." to display the image.

Here is a code snippet 

# need this plot in order for hotspots to have data
my $plotdata = $graph->plot($rows)->gif;

my $gd = $graph->gd;
my $red = $gd->colorResolve(255,0,0);
my @l = $graph->get_hotspot(1, 3);
my ($x, $y) = ( ($l[1] + $l[3])/2, ($l[2] + $l[4])/2 );
my $gdta;

$gdta = GD::Text::Align->new($gd,
     text => 'maximum',
     font => ['../Dustismo_Sans.ttf', GD::Font->Small],
     ptsize => 12,
     colour => $red,
     valign => 'bottom',
     halign => 'center',
 ) or warn $gdta->error;

$gdta->draw($x, $y + 2);

# must re-plot to get hotspots visible
# without this call to plot, the graph is fine (sans labels)
# but with it I get labels and a ghosting problem
$plotdata = $graph->plot($rows)->png;

my $uri = URI->new("data:");
$uri->media_type("image/png");
$uri->data($plotdata);
print qq(<img src="$uri" alt="Didn't work."></html>\n);

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I tried throwing away the plotdata from either plot call but could not get what I wanted. Thanks in advance Mark

In reply to gd::graph hotspots by elmoz

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