Thumbnail Coding: Resize Images Proportionally?

Matthew_B

Hi all,
I'm trying to modify a Wordpress theme to make it resize images into proportional thumbnails, to keep the same relative height / width of the original image - ideally to be displayed inside a 190px x 190px thumbnail box with letterboxing, if that's possible.
So far as I can tell, these are the bits of code that deal with the image display process - any help on how to tweak it to implement the above function would be much appreciated!:
[code=php]	function product_listing_li_default($post,$args=array())
	{
		global $Product,$General,$thumb_url;
		$image_width = $this->get_image_width($post->image_width);
		$image_height = $this->get_image_height($post->image_height);
		$product_image_arr = $this->get_product_image($post,'large','latest',1);
		$attachment_id = $product_image_arr[0]['id'];
		$alt = get_post_meta($attachment_id, '_wp_attachment_image_alt', true);
				$attach_data = get_post($attachment_id);
				$title = $attach_data->post_title;
				if($title ==''){ $title = $post->post_title; }
				if($alt ==''){ $alt = $post->post_title; }


				if($product_image_arr[0]){
				$crop_image = $General->vt_resize($attachment_id, $product_image_arr[0]['file'], $image_width, $image_height, $crop = false );
				$post_images = $crop_image['url'];
				}
		if($product_image_arr[0][0]==''){
		$product_image= get_template_directory_uri().'/images/no-image.png';
		}else{
		$product_image = $post_images;
		}

		$is_image_border = 0;
		if(is_category())
		{
			if(get_option('ptthemes_prdlstcatimage_border')){$is_image_border = 1;}
		}elseif(is_home() && $_REQUEST['ptype']=='store')
		{
			if(get_option('ptthemes_prdlistimage_border')){$is_image_border = 1;}
		}else
		{
			if(get_option('ptthemes_prdlsthomeimage_border')){$is_image_border = 1;}
		}
		$data = get_post_meta( $post->ID, 'key', true );
                    $product_price = $Product->get_product_price($post->ID);
		/* width:<?php //echo $image_width;?>px; height:<?php// echo $image_height; */
		?>
                    <a href="<?php echo get_permalink( $post->ID) ?>" class="product_thumb" style="width:<?php echo $image_width."px"; ?>; height:<?php echo $image_height."px"; ?>; overflow:hidden; <?php if($is_image_border){?>border:1px solid;<?php }?>" *>
            <?php
		if($Product->get_product_price_sale($post->ID)>0)
		{
		?>
              <img src="<?php echo get_stylesheet_directory_uri(); ?>/images/sale.png" alt="" class="sale_img" />
              <?php
		}
		$thumb_url .= $this->get_image_cutting_edge($args);
		?> *<img src="<?php echo $product_image; ?>" *<?php if($is_image_border){?> border="1"<?php }?> width="<?php echo $image_width; ?>" height="<?php echo $image_height; ?>"/></a>

           <?php
	}
	function get_image_height($image_height='')
	{
		if($image_height=='')
		{
			$image_height = get_option('ptthemes_image_height');	
		}
		return $image_height;
	}
	function get_image_width($image_width='')
	{
		if($image_width=='')
		{
			$image_width = get_option('ptthemes_image_width');	
		}
		return $image_width;
	}
	function product_listing_li_shorted($post,$display_order,$args=array())
	{
		global $Product,$General,$thumb_url;
		$image_width = $this->get_image_width($post->image_width);
		$image_height = $this->get_image_height($post->image_height);
		$product_image_arr = $this->get_product_image($post,'large','shorted');
		$attachment_id = $product_image_arr[0]['id'];
		$alt = get_post_meta($attachment_id, '_wp_attachment_image_alt', true);
				$attach_data = get_post($attachment_id);
				$title = $attach_data->post_title;
				if($title ==''){ $title = $post->post_title; }
				if($alt ==''){ $alt = $post->post_title; }


				if($product_image_arr[0]){
				$crop_image = $General->vt_resize($attachment_id, $product_image_arr[0]['file'], $image_width,$image_height, $crop = false );
				$post_images = $crop_image['url'];
				}
		$data = get_post_meta( $post->ID, 'key', true );
                 $product_price = $Product->get_product_price($post->ID);
		$content_strt_str ='';
		$content_strt_end ='';
		foreach($display_order as $key=>$val)
		{

			if($key=='image')
			{
				$is_image_border=0;
				if(is_category())
				{
					if(get_option('ptthemes_prdlstcatimage_border')){$is_image_border = 1;}
				}elseif(is_home() && $_REQUEST['ptype']=='store')
				{
					if(get_option('ptthemes_prdlistimage_border')){$is_image_border = 1;}
				}else
				{
					if(get_option('ptthemes_prdlsthomeimage_border')){$is_image_border = 1;}
				}

			?>
                     <a href="<?php the_permalink() ?>" class="product_thumb" >
                    <?php	if($Product->get_product_price_sale($post->ID)>0){?>
			<img src="<?php echo get_stylesheet_directory_uri(); ?>/images/sale.png" alt="" class="sale_img" */>
			<?php }?>
                    <?php $thumb_url .= $this->get_image_cutting_edge($args);?>
                    <img src="<?php echo $post_images;?>" alt="<?php the_title(); ?>" *<?php if($is_image_border){?> border="1"<?php }?> width="<?php echo $image_width; ?>" height="<?php echo $image_height; ?>"/></a>


	function show_product_images($post)
	{
		global $thumb_url,$General;
		//$product_image_arr = $this->get_product_image($pid);
		$product_image_arr = $this->get_product_image($post,'large','detail');*

		$image_width = apply_filters('ec_prd_detail_bimg_resize_filter',$image_width);

		if($image_width==''){
		$image_width =300; }
		$image_height = apply_filters('ec_prd_detail_bimg_resize_hfilter',$image_height);
		if($image_height==''){
		$image_height = 300; }
		$attachment_id = $product_image_arr[0]['id'];
		$alt = get_post_meta($attachment_id, '_wp_attachment_image_alt', true);
				$attach_data = get_post($attachment_id);
				$title = $attach_data->post_title;
				if($title ==''){ $title = $post->post_title; }
				if($alt ==''){ $alt = $post->post_title; }


				if($product_image_arr[0][0]){
				$crop_image = $General->vt_resize($attachment_id, $product_image_arr[0][0], $image_width, $image_height, $crop = false );
				$post_images = $crop_image['url'];
				}
		if($product_image_arr)
		{
	 *if($product_image_arr[0][0]){ ?> * * * **
             <a class="zoom product_main_img" rel="group" title="" href="<?php echo $product_image_arr[0][0]; ?>" *>
            <img src="<?php echo bloginfo('template_directory'); ?>/images/zoom.png" alt="" class="i_zoom" />
            <img src="<?php echo $post_images;?>" alt="" />
             </a>
             <?php } ?>
            <?php*
	 *if(count($product_image_arr)>1)
	 *{*
			if(is_category())
				{
					if(get_option('ptthemes_prdlstcatimage_border')){$is_image_border = 1;}
				}elseif(is_home() && $_REQUEST['ptype']=='store')
				{
					if(get_option('ptthemes_prdlistimage_border')){$is_image_border = 1;}
				}else
				{
					if(get_option('ptthemes_prdlsthomeimage_border')){$is_image_border = 1;}
				}
			for($im=1;$im<count($product_image_arr);$im++)
			{
				$image_width1 = apply_filters('ec_prd_detail_timg_resize_filter',$image_width1);
				if(!$image_width1){
				$image_width1 = 100;
				}
				$image_height1 = apply_filters('ec_prd_detail_timg_resize_hfilter',$image_height1);
				if(!$image_height1){
				$image_height1 = 100;
				}
				$attachment_id = $product_image_arr[$im]['id'];
				$alt = get_post_meta($attachment_id, '_wp_attachment_image_alt', true);
				$attach_data = get_post($attachment_id);
				$title = $attach_data->post_title;	if($title ==''){ $title = $post->post_title; }
				$crop_image = $General->vt_resize($attachment_id, $product_image_arr[$im][0], $image_width1, $image_height1, $crop = false );
				$post_images = $crop_image['url'];
				$ext_arr = explode('.',$product_image_arr[$im][0]);

				$fileext = strtolower($ext_arr[count($ext_arr)-1]);
				if(in_array($fileext,array('jpg','jpeg','gif','png')))
				{
			?>
                      <a class="zoom smaller" rel="group" title="" href="<?php echo $product_image_arr[$im][0]; ?>"><img src="<?php echo $post_images; ?>" alt="<?php echo $alt; ?>" title="<?php echo $title; ?>" <?php if($is_image_border){?> border="1"<?php }?>/></a>
                <?php
				}
			}
	 *}
	 *return true;
		}else
		{ ?>
			 <a class="zoom product_main_img" rel="group" title="" href="<?php echo $product_image_arr[0]; ?>" *>

          <img src="<?php echo *get_template_directory_uri().'/images/no-image1.png'; ?><?php echo apply_filters('ec_prd_detail_bimg_resize_filter','&amp;w=200&amp;zc=1&amp;q=80')?><?php echo $thumb_url;?>" alt="" />
     </a>

		<?php }
           }

	function get_image_cutting_edge($args=array())
	{
		if($args['image_cut'])
		{
			$cut_post =$args['image_cut'];
		}else
		{
			$cut_post = get_option('ptthemes_image_x_cut');
		}
		if($cut_post)
		{

			if($cut_post=='top')
			{
				$thumb_url .= "&amp;a=t";	
			}elseif($cut_post=='bottom')
			{
				$thumb_url .= "&amp;a=b";	
			}elseif($cut_post=='left')
			{
				$thumb_url .= "&amp;a=l";
			}elseif($cut_post=='right')
			{
				$thumb_url .= "&amp;a=r";
			}elseif($cut_post=='top right')
			{
				$thumb_url .= "&amp;a=tr";
			}elseif($cut_post=='top left')
			{
				$thumb_url .= "&amp;a=tl";
			}elseif($cut_post=='bottom right')
			{
				$thumb_url .= "&amp;a=br";
			}elseif($cut_post=='bottom left')
			{
				$thumb_url .= "&amp;a=bl";
			}
		}
		return $thumb_url;
	}
	[/code]
Ashley_Sheridan

Rather than re-write your code for you, I'll give you pointers on how it should be done:
Calculate the ratio of width to height on the original image.
Check to see which is the longest side on the original image
Set that side to the size of your box you want it to fit in
calculate the other side of the original image now using what was the longest side (should be same as the box you're fitting it in) and the ratio from step 1