[PHP-DB] Re: draw graph

[Hugh Bothwell]

"Sommai Fongnamthip" <[EMAIL PROTECTED]> wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Dear,
> How could I draw graph with gd by using PHP code with custom log scale?

How 'bout:

function drawLogGraph($arr) {
    $xoffs = 20;
    $yoffs = 180;
    $drawwidth = 160;
    $drawheight = -160;

    $logscale = -10;        // height of a 10x division
    $logscalebase = 1;        // '0' on your graph

    $numbars = count($arr);
    $perbar = $drawwidth / $numbars;

    $barwidth = 0.8;          // ... fractional draw width
    $halfsp = (1 - $barwidth) * 0.5;

    $img = ImageCreateFromPNG("graphbackground.png") or die("Could not load
background");

    for ($i = 0; $i < $numbars; $i++) {
        $barleft = $perbar * ($i + $halfsp);
        $barright = $perbar * ($i + 1 - $halfsp);
        $bartop = (log10($arr[$i]) - $logscalebase) * $logscale;

        ImageFilledRectangle($img, $xoffs + $barleft, $yoffs + $bartop,
$xoffs + $barright, $yoffs, 1);
    }

    return $img;
}



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