PHP图片等比缩放类SimpleImage使用方法和使用实例分

SimpleImage：PHP图片等比缩放的魔法棒

你是否曾遇到过需要等比缩放图片的情况？使用PHP的SimpleImage类，这一切都变得轻而易举。让我们深入了解这个强大的工具的使用方法，并分享一些实用的例子。

设定宽度，等比例缩放

```php

引入SimpleImage魔法棒

$image = new SimpleImage();

$image->load('原始图片.jpg');

$image->resizeToWidth(250);

$image->saveAs('缩放后的图片.jpg');

```

只需要简单的几行代码，你就可以将图片等比缩放到指定的宽度。

设定高度，等比例缩放

```php

引入SimpleImage魔法棒

$image = new SimpleImage();

$image->load('原始图片.jpg');

$image->resizeToHeight(500);

$image->saveAs('新高度图片1.jpg');

$image->resizeToHeight(200);

$image->saveAs('新高度图片2.jpg');

```

你可以轻松地调整图片的高度，同时保持其等比缩放。

按比例，缩放至50%

```php

引入SimpleImage魔法棒

$image = new SimpleImage();

$image->load('原始图片.jpg');

$image->scale(50);

$image->saveAs('半尺寸图片.jpg');

```

只需调用scale方法，即可将图片缩放到原始大小的50%。

缩放后直接输出到屏幕

```php

设置内容类型为JPEG图像

引入SimpleImage魔法棒

$image = new SimpleImage();

$image->load('原始图片.jpg');

$image->resizeToWidth(150);

$image->outputToBrowser();

```

如果你想将处理后的图片直接显示在网页上，这个示例将帮助你实现这一目标。

实用例子分享

假设你正在为狼蚁网站的SEO优化忙碌。你可以使用SimpleImage来处理从网络下载的图片。以下是一个简单的实例：

```php

```php

function downloadImage($url) {

$httpContext = array();

$headerPrefix = "

if ($headerPrefix) {

$httpContext['header'] = $headerPrefix;

}

$httpContext['timeout'] = 50;

$context = stream_context_create($httpContext);

$content = @file_get_contents($url, false, $context);

sleep(1); // Pause for 1 second

if (!$content) {

return false; // Return false if unable to fetch the content

}

$tempfile = createTempFile(); // Generate a temporary file name

file_put_contents($tempfile, $content); // Save the content to the temporary file

return $tempfile; // Return the temporary file path

}

function createTempFile() {

$path = __DIR__; // Current directory path

$subPath = '/spider/' . date('Ymd') . '/' . date('His') . '-' . (int)(time() / 300); // Generate a unique sub-directory path based on current date and time

if (!file_exists($path . $subPath)) { // If the sub-directory doesn't exist, create it with full permissions

mkdir($path . $subPath, 0777, true);

}

do { // Generate a unique file name within the sub-directory until a non-existing file name is found

$file = $path . $subPath . '/' . dechex(mt_rand()); // Create a random file name with hexadecimal representation of a random number

} while (file_exists($file)); // Check if the file already exists, and loop until a unique file name is found

touch($file); // Create an empty file with the specified name

return $file; // Return the generated temporary file path

}

```

```php

class SimpleImage { // Class definition for SimpleImage with methods to manipulate images

private $image; // Variable to hold the image resource

private $image_type; // Variable to hold the image type (JPEG, GIF, PNG)

// Method to load an image from a filename and initialize image resource and type accordingly

public function load($filename) { // Load an image from a given filename and initialize properties accordingly

$image_info = getimagesize($filename); // Get image information from the filename

$this->image_type = $image_info[2]; // Set the image type based on the information retrieved from getimagesize() function

switch ($this->image_type) { // Load the image resource based on its type (JPEG, GIF, PNG) using appropriate PHP functions like imagecreatefromjpeg(), imagecreatefromgif(), imagecreatefrompng() respectively

case IMAGETYPE_JPEG: // Case for JPEG images

$this->image = @imagecreatefromjpeg($filename); // Create an image resource from JPEG file using imagecreatefromjpeg() function and assign it to $this->image variable of this class instance

break; // Break out of switch statement for JPEG case processing completion and continue to next case or exit switch if it's the last case or no more cases are available.

case IMAGETYPE_GIF: // Case for GIF images similar to JPEG case above with different function call for GIF images using imagecreatefromgif() function instead of imagecreatefromjpeg() function.

$this->image = @imagecreatefromgif($filename); // Create an image resource from GIF file using imagecreatefromgif() function and assign it to $this->image variable of this class instance

break; // Break out of switch statement for GIF case processing completion and continue to next case or exit switch if it's the last case or no more cases are available.

case IMAGETYPE_PNG: // Case for PNG images similar to above cases with different function call for PNG images using imagecreatefrompng() function instead of previous functions.

$this->image = @imagecreatefrompng($filename); // Create an image resource from PNG file using imagecreatefrompng() function and assign it to $this->image variable of this class instance

break; // Break out of switch statement for PNG case processing completion and continue to next case or exit switch if it's the last case or no