I don't understand why I can't get the png graphics to show up on my pages. I followed the instructions on the column today to get the president graph up but when I call it up it comes up blank.
This code creates the png picture and I put it in a file named chart.php
<?php
/ chart.php /
$data = array(
"Jan" => 55,
"Feb" => 54,
"Mar" => 53,
"Apr" => 33,
"May" => 13,
"Jun" => 15,
"Jul" => 23,
"Aug" => 28,
"Sep" => 32,
"Oct" => 45,
"Nov" => 73,
"Dec" => 71);
// create image
$width = 480;
$height = 250;
$image = imagecreate($width, $height);
// colors
$white = imagecolorallocate($image, 0xFF, 0xFF, 0xFF);
$navy = imagecolorallocate($image, 0x00, 0x00, 0x80);
$black = imagecolorallocate($image, 0x00, 0x00, 0x00);
$gray = imagecolorallocate($image, 0xC0, 0xC0, 0xC0);
// layout
$maxval = max($data);
$nval = sizeof($data);
$vmargin = 20; // top (bottom) vertical margin for title (x-labels)
$hmargin = 38; // left horizontal margin for y-labels
$base = floor(($width - $hmargin) / $nval); // distance between columns
$ysize = $height - 2 $vmargin; // y-size of plot
$xsize = $nval $base; // x-size of plot
// title
$titlefont = 3;
$title = "Presidential Approval Ratings 2000 (in %)";
$txtsz = imagefontwidth($titlefont) strlen($title); // pixel-width of title
$xpos = (int)($hmargin + ($xsize - $txtsz)/2); // center the title
$xpos = max(1, $xpos); // force positive coordinates
$ypos = 3; // distance from top
imagestring($image, $titlefont, $xpos, $ypos, $title , $black);
// y labels and grid lines
$labelfont = 2;
$ngrid = 4; // number of grid lines
$dydat = $maxval / $ngrid; // data units between grid lines
$dypix = $ysize / ($ngrid + 1); // pixels between grid lines
for ($i = 0; $i <= ($ngrid + 1); $i++) {
// iterate over y ticks
// height of grid line in units of data
$ydat = (int)($i $dydat);
// height of grid line in pixels
$ypos = $vmargin + $ysize - (int)($i$dypix);
$txtsz = imagefontwidth($labelfont) strlen($ydat); // pixel-width of label
$txtht = imagefontheight($labelfont); // pixel-height of label
$xpos = (int)(($hmargin - $txtsz) / 2);
$xpos = max(1, $xpos);
imagestring($image, $labelfont, $xpos,
$ypos - (int)($txtht/2), $ydat, $black);
if (!($i == 0) && !($i > $ngrid)) {
imageline($image, $hmargin - 3,
$ypos, $hmargin + $xsize, $ypos, $gray);
// don't draw at Y=0 and top
}
}
// columns and x labels
$padding = 3; // half of spacing between columns
$yscale = $ysize / (($ngrid+1) $dydat); // pixels per data unit
for ($i = 0; list($xval, $yval) = each($data); $i++) {
// vertical columns
$ymax = $vmargin + $ysize;
$ymin = $ymax - (int)($yval$yscale);
$xmax = $hmargin + ($i+1)$base - $padding;
$xmin = $hmargin + $i$base + $padding;
imagefilledrectangle($image, $xmin, $ymin, $xmax, $ymax, $navy);
// x labels
$txtsz = imagefontwidth($labelfont) * strlen($xval);
$xpos = $xmin + (int)(($base - $txtsz) / 2);
$xpos = max($xmin, $xpos);
$ypos = $ymax + 3; // distance from x axis
imagestring($image, $labelfont, $xpos, $ypos, $xval, $black);
}
// plot frame
imagerectangle($image, $hmargin, $vmargin,
$hmargin + $xsize, $vmargin + $ysize, $black);
// flush image
header("Content-type: image/png"); // or "Content-type: image/png"
imagepng($image); // or imagepng($image)
imagedestroy($image);
?>
Then you are supposed to just call it up with this HTML in some other page.
<BODY>
<H1>Everybody Loves your_country's_president</H1>
<IMG SRC="chart.php" HEIGHT="250" WIDTH="480">
</BODY>
It won't show up on my page. The picture comes up with an X meaning it's not there. This seems simple and I don't know what I am doing wrong to call up the graph. Anyone else get this to work on their pages? Here is a link for the column I read here to do this. Thanks
http://www.phpbuilder.com/columns/wiesendanger20001218.php3?page=5
