I'm too bad in math! can't figure the correct function to resize images

Question

This is driving me crazy, just becasue I don't have the
logical brains it takes:
I want to dynamically (PHP) resize images, according to a max
width and max height parameters.
What's giving me a problem is that max width and max height
are not equal, AND the images should be
resized only if their original size is too big:
$max_width = 650;
$max_height = 500;
$size = getimagesize($image);
$img_width = $size[0];
$img_height = $size[1];
Now how do I write a function that will resize images of any
possible size, *only if they need to*,
to fit in the maximum size *rectangle*?...
I have tried for hours to get it right, and I am ending up
with a function so full of conditionals
and sub-sub-conditionals that I'm getting completely lost.
I hope you can help, I'm sure it should be very simple...
seb ( [email protected])
http://webtrans1.com | high-end web
design
Downloads: Slide Show, Directory Browser, Mailing List

Answer 1

here's the solution. This will correctly and proportionally
reduce image size according to ANY max
width and max height, no matter what the difference between
max width and max height:
if(($width <= $max_width) && ($height <=
$max_height)){
// The image is the right size already
$targetwidth = $width;
$targetheight = $height;
}else{
// if width > height
if($width >= $height){ // if height > width
$targetwidth = $max_width;
$targetheight = $targetwidth * ($height / $width);
// here we must check again if reduced height is not still
greater than max_height
if($targetheight > $max_height){
$targetheight = $max_height;
$targetwidth = $targetheight * ($width / $height);
}elseif($height > $width){ // if height > width
$targetheight = $max_height;
$targetwidth = $targetheight * ($width / $height);
// here we must check again if reduced width is not still
greater than max_width
if($targetwidth > $max_width){
$targetwidth = $max_width;
$targetheight = $targetwidth * ($height / $width);
(_seb_) wrote:
> Actually I did some tests, and it does not work!
>
> Here's the problem:
>
> $maxwidth = 600;
> $maxheight = 400; // max height is smaller than max
width!
>
> Then the method tests whether the image is taller or
wider, and resizes
> it to maxwidth or maxheight accordingly.
> So, if an image is 700px wide and 699px high, it will be
reduced
> according to $max_width, because the image is wider than
tall.
>
> *The resulting resized image will be taller than
$max_height*.
>
> That's the problem I have been running into.
>
> I cannot find a simple mathematic solution, without
getting lost in
> endless conditionals. I have found many examples of
resizing according
> to max width and max height parameters, but not one that
addresses this
> issue.
>
> (_seb_) wrote:
>> thanks Sonjey - that worked
>>
>> Sonjay wrote:
>>> This is the basic code that I've used on several
sites. It checks to
>>> see if
>>> the image needs to be resized, and if so, it
does the math to figure
>>> out the
>>> new proportional dimensions, whether you need to
resize to a
>>> specified width
>>> or to a specified height.
>>> $size = getimagesize($file);
>>> // Specify desired maximum dimensions
>>> $maxwidth = 650;
>>> $maxheight = 500;
>>> if ( ($size[0] <= $maxwidth) &&
($size[1] <= $maxheight) ) {
>>> // The image is the right size already
>>> $targetwidth = $size[0];
>>> $targetheight = $size[1];
>>> } else {
>>> // if width > height
>>> if ( $size[0] >= $size[1] ) { // if height
> width
>>> $targetwidth = $maxwidth;
>>> $targetheight = $targetwidth * ($size[1] /
$size[0]);
>>> } elseif ($size[1] > $size[0]) { // if height
> width
>>> $targetheight = $maxheight;
>>> $targetwidth = $targetheight * ($size[0] /
$size[1]);
>>> }
>>> } // END ELSE
>>>
>>> Now you have your target width and target height
set proportionally,
>>> and you
>>> can proceed with your resizing operation, using
$targetwidth and
>>> $targetheight.
>>>
>>
>>
>
>
seb ( [email protected])
http://webtrans1.com | high-end web
design
Downloads: Slide Show, Directory Browser, Mailing List