Question

我正在尝试调整大小并裁剪图像，@imagecopyresampled保持原始宽高比。

这个想法是： 1）我修复了缩略图的尺寸（f.e. 300x40） 2）裁剪开始到高度的中心

enter image description here

我试图在stackoverflow上阅读文档和很多其他问题，但没有结果。谁能帮帮我？我的实际代码如下：

//$img_height, $img_width [original size of the image]

$thumb_width  = 300;
$thumb_height = 40;
$new_img = @imagecreatetruecolor($thumb_width, $thumb_height);
$middle = floor($img_height/2);

$src_x = 0;
$src_y = $middle-($thumb_width/2);

$src_w = $img_width;
$aspectRatio = $img_width/$thumb_width;

//$src_h = ?????

$imgCopyRes = @imagecopyresampled(
                  $new_img, $src_img,
                  0, 0, 
                  $src_x, $src_y, 
                  $thumb_width, $thumb_height, 
                  $src_w, $src_h);

编辑：

非常感谢@Joshua Burns，阅读课程并编辑代码我找到了解决方案而不包括整个文件。

代码：

$target_width  = 300;
$target_height = 40;
$new_img = @imagecreatetruecolor($target_width, $target_height);

$width_ratio  = $target_width  / $img_width;
$height_ratio = $target_height / $img_height;
if($width_ratio > $height_ratio) {
    $resized_width  = $target_width;
    $resized_height = $img_height * $width_ratio;
} else {
    $resized_height = $target_height;
    $resized_width  = $img_width * $height_ratio;
}
// Drop decimal values
$resized_width  = round($resized_width);
$resized_height = round($resized_height);

// Calculations for centering the image
$offset_width  = round(($target_width  - $resized_width) / 2);
$offset_height = round(($target_height - $resized_height) / 2);

$imgCopyRes = @imagecopyresampled(
                  $new_img, $src_img, 
                  $offset_width, $offset_height, 
                  0, 0, 
                  $resized_width, $resized_height, 
                  $img_width, $img_height);

Answer 1

好吧，这对你的需求来说可能有点臃肿，但是它完成了工作并且很好地完成了它。

首先，将此类包含或粘贴到您的PHP代码中：http://pastebin.com/dnmiUVmk

然后，使用与以下类似的类：

<?php
// Replace 'picture' w/ whatever the name of the file upload.
// Alternately, specify an absolute path to an image already on the server.
$upload_image_tmp_filename = $_FILES['picture']['tmp_name'];
$saveas_image_filename = 'my_resized_image.png';
$max_width = 300;
$max_height = 40;

// If there was a problem, an exception is thrown.
try {
    // Load the image
    $picture = New Image($upload_image_tmp_filename);
    // Save the image, resized.
    $picture->saveFile($saveas_image_filename, $max_width, $max_height, True);
} catch(Exception $e) {
    print $e->getMessage();
}

Answer 2

使用Imagick（http://www.php.net/manual/en/class.imagick.php）

//instantiate the image magick class
$image = new Imagick($image_path);

//crop and resize the image
$image->cropThumbnailImage(100,100);

// save
$image->writeImage($your_file);

Answer 3

您可以使用以下代码计算裁剪参数：

$target_width = 300;
$target_height = 40;
$test_case = array(
    array(233,350),
    array(350,233),
    array(300,40)
);
foreach ($test_case as $test) {
    list($source_width, $source_height) = $test;
    $source_ar = $source_width / $source_height;
    $target_ar = $target_width / $target_height;
    if ($source_ar > $target_ar) {
        $temp_height = $target_height;
        $temp_width = (int) ($target_height * $source_ar);
    } else {
        $temp_width = $target_width;
        $temp_height = (int) ($target_width / $source_ar);
    }
    $temp_crop_hori = (int) (($temp_width - $target_width) / 2);
    $temp_crop_vert = (int) (($temp_height - $target_height) / 2);
    echo "==================
source image: ${source_width}x${source_height}
temp image:   ${temp_width}x${temp_height}
target image: crop ${target_width}x${target_height} from ${temp_crop_hori}, ${temp_crop_vert}
";
}

打印：

==================
source image: 233x350
temp image:   300x450
target image: crop 300x40 from 0, 205
==================
source image: 350x233
temp image:   300x199
target image: crop 300x40 from 0, 79
==================
source image: 300x40
temp image:   300x40
target image: crop 300x40 from 0, 0

您可以在以下网址中使用此信息：

imagecopyresampled将 233x350 图片调整为 300x450 图片
imagecopy从 0,205

300x450

300x40

PHP：创建一个裁剪的矩形缩略图

3 个答案: