PHP/GD - 图片裁剪和大小调整

Question

我编写了一个函数，可以将图像裁剪为给定的宽高比，最后将其调整大小并输出为JPG格式：

<?php

function Image($image, $crop = null, $size = null)
{
    $image = ImageCreateFromString(file_get_contents($image));

    if (is_resource($image) === true)
    {
        $x = 0;
        $y = 0;
        $width = imagesx($image);
        $height = imagesy($image);

        /*
        CROP (Aspect Ratio) Section
        */

        if (is_null($crop) === true)
        {
            $crop = array($width, $height);
        }

        else
        {
            $crop = array_filter(explode(':', $crop));

            if (empty($crop) === true)
            {
                $crop = array($width, $height);
            }

            else
            {
                if ((empty($crop[0]) === true) || (is_numeric($crop[0]) === false))
                {
                    $crop[0] = $crop[1];
                }

                else if ((empty($crop[1]) === true) || (is_numeric($crop[1]) === false))
                {
                    $crop[1] = $crop[0];
                }
            }

            $ratio = array
            (
                0 => $width / $height,
                1 => $crop[0] / $crop[1],
            );

            if ($ratio[0] > $ratio[1])
            {
                $width = $height * $ratio[1];
                $x = (imagesx($image) - $width) / 2;
            }

            else if ($ratio[0] < $ratio[1])
            {
                $height = $width / $ratio[1];
                $y = (imagesy($image) - $height) / 2;
            }

            /*
            How can I skip (join) this operation
            with the one in the Resize Section?
            */

            $result = ImageCreateTrueColor($width, $height);

            if (is_resource($result) === true)
            {
                ImageSaveAlpha($result, true);
                ImageAlphaBlending($result, false);
                ImageFill($result, 0, 0, ImageColorAllocateAlpha($result, 255, 255, 255, 127));

                ImageCopyResampled($result, $image, 0, 0, $x, $y, $width, $height, $width, $height);

                $image = $result;
            }
        }

        /*
        Resize Section
        */

        if (is_null($size) === true)
        {
            $size = array(imagesx($image), imagesy($image));
        }

        else
        {
            $size = array_filter(explode('x', $size));

            if (empty($size) === true)
            {
                $size = array(imagesx($image), imagesy($image));
            }

            else
            {
                if ((empty($size[0]) === true) || (is_numeric($size[0]) === false))
                {
                    $size[0] = round($size[1] * imagesx($image) / imagesy($image));
                }

                else if ((empty($size[1]) === true) || (is_numeric($size[1]) === false))
                {
                    $size[1] = round($size[0] * imagesy($image) / imagesx($image));
                }
            }
        }

        $result = ImageCreateTrueColor($size[0], $size[1]);

        if (is_resource($result) === true)
        {
            ImageSaveAlpha($result, true);
            ImageAlphaBlending($result, true);
            ImageFill($result, 0, 0, ImageColorAllocate($result, 255, 255, 255));
            ImageCopyResampled($result, $image, 0, 0, 0, 0, $size[0], $size[1], imagesx($image), imagesy($image));

            header('Content-Type: image/jpeg');

            ImageInterlace($result, true);
            ImageJPEG($result, null, 90);
        }
    }

    return false;
}

?>

这个函数的功能符合预期，但我正在创建一个非必需的GD图像资源，我该怎么解决？我尝试了将两个调用合并，但我一定做错了一些计算。

<?php

/*
Usage Examples
*/

Image('http://upload.wikimedia.org/wikipedia/commons/4/47/PNG_transparency_demonstration_1.png', '1:1', '600x');
Image('http://upload.wikimedia.org/wikipedia/commons/4/47/PNG_transparency_demonstration_1.png', '2:1', '600x');
Image('http://upload.wikimedia.org/wikipedia/commons/4/47/PNG_transparency_demonstration_1.png', '2:', '250x300');

?>

任何帮助都非常感激，谢谢。

- Alix Axel

Answer 1

您需要修改缩放代码，使其不基于剪裁后的图像开始。由于您希望在一次操作中完成剪裁和缩放，因此需要独立计算。

<?php
function Image($image, $crop = ':', $size = null) {

    $image = ImageCreateFromString(file_get_contents($image));

    if (is_resource($image)) {

        $x = 0;
        $y = 0;
        $width = imagesx($image);
        $height = imagesy($image);

        // CROP (Aspect Ratio) Section
        $crop = array_filter(explode(':', $crop));

        if (empty($crop)) {

            $crop = [$width, $height];

        } else {

            $crop[0] = $crop[0] ?: $crop[1];
            $crop[1] = $crop[1] ?: $crop[0];

        }

        $ratio = [$width / $height, $crop[0] / $crop[1]];

        if ($ratio[0] > $ratio[1]) {

            $width = $height * $ratio[1];
            $x = (imagesx($image) - $width) / 2;

        } else {

            $height = $width / $ratio[1];
            $y = (imagesy($image) - $height) / 2;

        }


        // Resize Section    
        if (is_null($size)) {

            $size = [$width, $height];

        } else {

            $size = array_filter(explode('x', $size));

            if (empty($size)) {

                $size = [imagesx($image), imagesy($image)];

            } else {

                $size[0] = $size[0] ?: round($size[1] * $width / $height);
                $size[1] = $size[1] ?: round($size[0] * $height / $width);

            }
        }

        $result = ImageCreateTrueColor($size[0], $size[1]);

        if (is_resource($result)) {

            ImageSaveAlpha($result, true);
            ImageAlphaBlending($result, true);
            ImageFill($result, 0, 0, ImageColorAllocate($result, 255, 255, 255));
            ImageCopyResampled($result, $image, 0, 0, $x, $y, $size[0], $size[1], $width, $height);

            ImageInterlace($result, true);
            ImageJPEG($result, null, 90);

        }
    }

    return false;
}

header('Content-Type: image/jpeg');
Image('http://upload.wikimedia.org/wikipedia/commons/4/47/PNG_transparency_demonstration_1.png', '1:1', '600x');

?>

- monowerker

---

谢谢，现在它运行得很好，只有一个问题，当它说$size = array(imagesx($image), imagesy($image));时，它不应该是$size = array($width, $height);吗？ - Alix Axel

是的，我错过了那个。所有的 imagesx($image)、imagesy($image) 都被更改为新计算出的宽度和高度了。 - monowerker