We have to create a php page and call it graph.php or anything else you want. In this page we have to first create a blank image with some height and width of deault values.
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What is 0,220,10,40 ? This is basically x1,y1,x2,y2 coordinate points on the blank image to create the line. Now lets take a look at the function : function imagelinethick($image, $x1, $y1, $x2, $y2, $color, $thick = 1) { /* this way it works well only for orthogonal lines imagesetthickness($image, $thick); return imageline($image, $x1, $y1, $x2, $y2, $color); */ if ($thick == 1) { return imageline($image, $x1, $y1, $x2, $y2, $color); } $t = $thick / 2 – 0.5; if ($x1 == $x2 || $y1 == $y2) { return imagefilledrectangle($image, round(min($x1, $x2) – $t), round(min($y1, $y2) – $t), round(max($x1, $x2) + $t), round(max($y1, $y2) + $t), $color); } $k = ($y2 – $y1) / ($x2 – $x1); //y = kx + q $a = $t / sqrt(1 + pow($k, 2)); $points = array( round($x1 – (1+$k)*$a), round($y1 + (1-$k)*$a), round($x1 – (1-$k)*$a), round($y1 – (1+$k)*$a), round($x2 + (1+$k)*$a), round($y2 – (1-$k)*$a), round($x2 + (1-$k)*$a), round($y2 + (1+$k)*$a), ); imagefilledpolygon($image, $points, 4, $color); return imagepolygon($image, $points, 4, $color); } This function takes all the parameters and draws a line on the blank image. This page is graph.php right ? now create a page and put this page in src like and save it as showgraph.php and access showgraph.php you can see the image |
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Do you find it interesting and want to try it out ? Copy the following code and save it on a php page and see the graph . |
graph.php ============================================ showgraph.php ===============================
showgraph.php
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when you access you can see three lines on the image… the corresponding lines of codee are
imagelinethick($img,0,220,60,40,$color1, $thick); imagelinethick($img,60,40,160,140,$color1, $thick);
imagelinethick($img,160,140,210,70,$color1, $thick);
0,220,60,40 …… four integer parameter in first line let it be x1,y1,x2,y2
in image x – axis calculated on the image from left to right ————> way
so direction is
x1——————————————————>x2
while y axis is top top bottom not like general graph from bottom to top
y1
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y2
in main image the axis will be like
y1——————————————————————-
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| x1————>x2 |
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y2
It is slightly different from general axis rules in mathematics
you have taken
$height = 220;
$width = 500;
so in the image left-bottom corner be (x1-y1) —- (0-220) not (0,0) so in the first line we have taken 0,220,60,40 as x1,y1,x2,y2 it will start from left-bottom and x2-y2, which means till 60-40
If you are creating the graph the second line should start from x2-y2 means 60-40 so second line co-ordinates are 60,40,160,140 — similarly creating the third line
We can modify this code and can make it Db data dependent too —- Now your time to implement it different ways.