编辑：这可以很容易地通过CSS实现，在撰写本文时我不太了解CSS
我使用PHP创建了一个缩略图生成器。生成的缩略图应该是相同大小的。但问题是上传的图片具有不同的宽高比，如横向或纵向，则缩略图会变得丑陋。因此，我创建了上面的图片以进行澄清。无论上传什么样的图片，它都将放入矩形图片中。所以长宽比不会改变，缩略图将是相同的大小。请问有人能帮助我或提供一些想法吗？
PHP-创建缩略图并保持宽高比
5
- Gijo Varghese
6
我认为这些资源会有所帮助：
https://dev59.com/ImQn5IYBdhLWcg3wg3aR
http://math.stackexchange.com/questions/180804/how-to-get-the-aspect-ratio-of-an-image - LeaveAirykson
@LeaveAirykson 好的，让我试一下... - Gijo Varghese
@LeaveAirykson 谢谢。有用了一点点。完成了一半。现在我需要的是将得到的图像放入一个白色矩形中。你能帮我吗？ - Gijo Varghese
看看这个答案，它可能会有所帮助 为图像添加空格并将文件保存到服务器。 - LeaveAirykson
看一下这篇帖子http://stackoverflow.com/questions/6384722/how-to-resize-a-image-in-php-to-fit-it-into-a-box-of-custom-size-preserving-its 这可能会对你有所帮助。 - Subedi Kishor
虽然CSS是一个很酷的工具，但我不会在缩略图创建方面使用它，除非它是可以调整大小的动态图像。原因是“缩略图”应该是文件大小较小的小图像。CSS只会告诉浏览器缩小大版本，这意味着大文件大小可能会破坏页面加载的连续性。 - WASasquatch
4个回答
15
define('THUMBNAIL_IMAGE_MAX_WIDTH', 150);
define('THUMBNAIL_IMAGE_MAX_HEIGHT', 150);
function generate_image_thumbnail($source_image_path, $thumbnail_image_path)
{
list($source_image_width, $source_image_height, $source_image_type) = getimagesize($source_image_path);
switch ($source_image_type) {
case IMAGETYPE_GIF:
$source_gd_image = imagecreatefromgif($source_image_path);
break;
case IMAGETYPE_JPEG:
$source_gd_image = imagecreatefromjpeg($source_image_path);
break;
case IMAGETYPE_PNG:
$source_gd_image = imagecreatefrompng($source_image_path);
break;
}
if ($source_gd_image === false) {
return false;
}
$source_aspect_ratio = $source_image_width / $source_image_height;
$thumbnail_aspect_ratio = THUMBNAIL_IMAGE_MAX_WIDTH / THUMBNAIL_IMAGE_MAX_HEIGHT;
if ($source_image_width <= THUMBNAIL_IMAGE_MAX_WIDTH && $source_image_height <= THUMBNAIL_IMAGE_MAX_HEIGHT) {
$thumbnail_image_width = $source_image_width;
$thumbnail_image_height = $source_image_height;
} elseif ($thumbnail_aspect_ratio > $source_aspect_ratio) {
$thumbnail_image_width = (int) (THUMBNAIL_IMAGE_MAX_HEIGHT * $source_aspect_ratio);
$thumbnail_image_height = THUMBNAIL_IMAGE_MAX_HEIGHT;
} else {
$thumbnail_image_width = THUMBNAIL_IMAGE_MAX_WIDTH;
$thumbnail_image_height = (int) (THUMBNAIL_IMAGE_MAX_WIDTH / $source_aspect_ratio);
}
$thumbnail_gd_image = imagecreatetruecolor($thumbnail_image_width, $thumbnail_image_height);
imagecopyresampled($thumbnail_gd_image, $source_gd_image, 0, 0, 0, 0, $thumbnail_image_width, $thumbnail_image_height, $source_image_width, $source_image_height);
$img_disp = imagecreatetruecolor(THUMBNAIL_IMAGE_MAX_WIDTH,THUMBNAIL_IMAGE_MAX_WIDTH);
$backcolor = imagecolorallocate($img_disp,0,0,0);
imagefill($img_disp,0,0,$backcolor);
imagecopy($img_disp, $thumbnail_gd_image, (imagesx($img_disp)/2)-(imagesx($thumbnail_gd_image)/2), (imagesy($img_disp)/2)-(imagesy($thumbnail_gd_image)/2), 0, 0, imagesx($thumbnail_gd_image), imagesy($thumbnail_gd_image));
imagejpeg($img_disp, $thumbnail_image_path, 90);
imagedestroy($source_gd_image);
imagedestroy($thumbnail_gd_image);
imagedestroy($img_disp);
return true;
}
generate_image_thumbnail('original_image.jpg', 'thumb_image.jpg'); //call the function
使用该代码，您将获得类似于以下内容的东西：
- kraysak
2
1在第37行，需要这样写：$img_disp = imagecreatetruecolor（THUMBNAIL_IMAGE_MAX_WIDTH，THUMBNAIL_IMAGE_MAX_HEIGHT）;（将第二个参数替换为THUMBNAIL_IMAGE_MAX_HEIGHT）。 - Olaf
2这不适用于带有黑色文本的PNG透明图像，将创建一个黑色图像缩略图。 - Muhammad Omer Aslam
1
看一下我Mr Thumb Image Resizing的源代码。 :)
public function proportion($max_width, $max_height) {
if (!( $this->halt )) {
if ($this->image['extension'] == 'gif') {
$this->image['ratio'] = ( $this->image['width'] > $this->image['height'] ) ? $max_width / $this->image['width'] : $max_height / $this->image['height'];
if ($this->image['width'] > $max_width || $this->image['height'] > $max_height) {
$new_width = $this->image['width'] * $this->image['ratio'];
$new_height = $this->image['height'] * $this->image['ratio'];
} else {
$new_width = $this->image['width'];
$new_height = $this->image['height'];
}
$this->image['composite'] = imagecreatetruecolor($new_width, $new_height);
imagecopyresampled($this->image['composite'], $this->image['render'], 0, 0, 0, 0, $new_width, $new_height, $this->image['width'], $this->image['height']);
$this->image['colorcount'] = imagecolorstotal($this->image['render']);
imagetruecolortopalette($this->image['composite'], true, $this->image['colorcount']);
imagepalettecopy($this->image['composite'], $this->image['render']);
$this->image['transparentcolor'] = imagecolortransparent($this->image['render']);
imagefill($this->image['composite'], 0, 0, $this->image['transparentcolor']);
imagecolortransparent($this->image['composite'], $this->image['transparentcolor']);
} else {
$this->image['ratio'] = ( $this->image['width'] > $this->image['height'] ) ? $max_width / $this->image['width'] : $max_height / $this->image['height'];
if ($this->image['width'] > $max_width || $this->image['height'] > $max_height) {
$new_width = $this->image['width'] * $this->image['ratio'];
$new_height = $this->image['height'] * $this->image['ratio'];
} else {
$new_width = $this->image['width'];
$new_height = $this->image['height'];
}
$this->image['composite'] = imagecreatetruecolor($new_width, $new_height);
imagecopyresampled($this->image['composite'], $this->image['render'], 0, 0, 0, 0, $new_width, $new_height, $this->image['width'], $this->image['height']);
}
} else {
echo 'Execution halted!';
}
}
- WASasquatch
2
我对PHP不熟悉。您能告诉我如何调用此函数，将文件名和目标放在哪里之类的吗？ - Gijo Varghese
@user3392772 点击链接。在
example.php 下查看其使用示例 http://www.phpclasses.org/browse/file/28565.html 将 $image 变量更改为 $image = $_GET['i']，将允许您在基本的 HTML 标签中链接图像，例如 <img src="example.php?i=images/myimage.jpg" alt="My Image" /> 您还可以将最大宽度和高度变量更改为查询，以便在运行时定义宽度/高度 <img src="example.php?i=images/myimage.jpg&w=200&h=300" alt="My Image" /> - WASasquatch0
这里有一个可能会帮到你的函数。你告诉它你想要保持的宽度，它将在保持长宽比的同时生成缩略图。
public static function makeThumb($src, $dest, $desired_width, $format = 'image/jpeg')
{
/* read the source image */
$source_image = null;
if($format == 'image/jpeg')
{
$source_image = imagecreatefromjpeg($src);
}
else if($format == 'image/png')
{
$source_image = imagecreatefrompng($src);
}
$width = imagesx($source_image);
$height = imagesy($source_image);
/* find the "desired height" of this thumbnail, relative to the desired width */
$desired_height = floor($height * ($desired_width / $width));
/* create a new, "virtual" image */
$virtual_image = imagecreatetruecolor($desired_width, $desired_height);
imageAlphaBlending($virtual_image, false);
imageSaveAlpha($virtual_image, true);
/* copy source image at a resized size */
imagecopyresampled($virtual_image, $source_image, 0, 0, 0, 0, $desired_width, $desired_height, $width, $height);
/* create the physical thumbnail image to its destination */
if($format == 'image/jpeg')
{
imagejpeg($virtual_image, $dest);
}
else if($format == 'image/png')
{
imagepng($virtual_image, $dest);
}
}
- lewsid
1
@lewisd 我试过这个了。它只调整图像的大小，而不是根据我在图片中展示的那样。 - Gijo Varghese
0
使用ImageMagick API。请查看此链接。
define('THUMB_WIDTH', 60);
define('THUMB_HEIGHT', 80);
define('MAGICK_PATH','/usr/local/bin/');
function makeThumbnail($in, $out) {
$width = THUMB_WIDTH;
$height = THUMB_HEIGHT;
list($w,$h) = getimagesize($in);
$thumbRatio = $width/$height;
$inRatio = $w/$h;
$isLandscape = $inRatio > $thumbRatio;
$size = ($isLandscape ? '1000x'.$height : $width.'x1000');
$xoff = ($isLandscape ? floor((($inRatio*$height)-$width)/2) : 0);
$command = MAGICK_PATH."convert $in -resize $size -crop {$width}x{$height}+{$xoff}+0 ".
"-colorspace RGB -strip -quality 90 $out";
exec($command);
}
请参考以下链接 - http://coffeeshopped.com/2009/01/creating-image-thumbnails-using-php-and-imagemagick 或者 http://in1.php.net/manual/en/class.imagick.php
- Chetan Gawai
4
我使用函数makeThumbnail('test.jpg','new.jpg')进行调用，但是没有任何反应。 - Gijo Varghese
你需要安装ImageMagick。请查看此链接 - http://www.php.net/manual/en/imagick.setup.php - Chetan Gawai
安装在服务器上怎么样？这可行吗？ - Gijo Varghese
是的，这绝对是可能的。 - Chetan Gawai
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