在保持宽高比的同时用GD调整图像大小和裁剪图像 [英] Resizing and cropping image with GD while retaining aspect ratio

问题描述

我目前正在基于Uploadify编写一个上载程序脚本。现在，我调整给定图像的大小，并给其中一种尺寸加水印。一切正常，但是我需要脚本来调整高度大小，然后裁剪宽度，以免长宽比弄乱。

I'm currently coding an uploader script based on Uploadify. Right now I resize the given image and watermark one of the sizes. It all works well, but I need the script to resize the height and then crop the width so that the aspect ratio does not get messed up.

这是我的代码，因此远：

This is my code so far:

if ($fileExtension == "jpg" || 
        $fileExtension == "jpeg" || 
        $fileExtension == "png" || 
        $fileExtension == "gif"){

        // GD variables:
        list($width, $height, $type) = GetImageSize($uploadedFile['tmp_name']);

        // Image sizes:
        $bigImage = array(800, 453);
        $mediumImage = array(410, 231);
        $listImage = array(120, 68);
        $thumbnail = array(90, 51);

        $sourceAspect = $width / $height;
        $bigAspect = $bigImage[0] / $bigImage[1];
        $mediumAspect = $mediumImage[0] / $mediumImage[1];
        $listAspect = $listImage[0] / $listImage[1];
        $thumbnailAspect = $thumbnail[0] / $thumbnail[1];

        // Image is PNG:
        if ($type == IMAGETYPE_PNG){
            $image = imagecreatefrompng($uploadedFile['tmp_name']);
            $valid = true;
        }

        // Image is JPEG:
        else if ($type == IMAGETYPE_JPEG){
            $image = imagecreatefromjpeg($uploadedFile['tmp_name']);
            $valid = true;
        }

        // Image is GIF:
        else if ($type == IMAGETYPE_GIF){
            $image = imagecreatefromgif($uploadedFile['tmp_name']);
            $valid = true;
        }

        // Format not allowed:
        else {
            $valid = false;
        }

        // Start creating images:
        if ($valid){

            // Get size:
            $imageSize = getimagesize($uploadedFile['tmp_name']);

            // Generate canvas:
            $bCanvas = imagecreatetruecolor($bigImage[0], $bigImage[1]);
            $mCanvas = imagecreatetruecolor($mediumImage[0], $mediumImage[1]);
            $lCanvas = imagecreatetruecolor($listImage[0], $listImage[1]);
            $tCanvas = imagecreatetruecolor($thumbnail[0], $thumbnail[1]);

            // Copy content:
            imagecopyresampled($bCanvas, $image, 0, 0, 0, 0, ($bigImage[0] * $sourceAspect), ($bigImage[1] / $sourceAspect), $imageSize[0], $imageSize[1]);
            imagecopyresampled($mCanvas, $image, 0, 0, 0, 0, $mediumImage[0], $mediumImage[1], $imageSize[0], $imageSize[1]);
            imagecopyresampled($lCanvas, $image, 0, 0, 0, 0, $listImage[0], $listImage[1], $imageSize[0], $imageSize[1]);
            imagecopyresampled($tCanvas, $image, 0, 0, 0, 0, $thumbnail[0], $thumbnail[1], $imageSize[0], $imageSize[1]);

            // Save images:
            $saveB = imagejpeg($bCanvas, $targetFile.'_big.jpg', 90);
            $saveM = imagejpeg($mCanvas, $targetFile.'_medium.jpg', 90);
            $saveT = imagejpeg($lCanvas, $targetFile.'_list.jpg', 90);
            $saveT = imagejpeg($tCanvas, $targetFile.'_thumb.jpg', 90);

            // Destroy images:
            imagedestroy($image);
            imagedestroy($bCanvas);
            imagedestroy($mCanvas);
            imagedestroy($lCanvas);
            imagedestroy($tCanvas);

            // Watermark images:
            $mark = imagecreatefrompng("logo.png");
            list($mwidth, $mheight) = getimagesize("logo.png");
            $img = imagecreatefromjpeg($targetFile.'_big.jpg');

            list($bwidth, $bheight) = getimagesize($targetFile.'_big.jpg');
            imagecopy($img, $mark, $bwidth-$mwidth-25, $bheight-$mheight-25, 0, 0, $mwidth, $mheight);
            imagejpeg($img, $targetFile.'_big.jpg', 100);
            imagedestroy($img);

        } else {
            echo "0";
        }

    } else {
        move_uploaded_file($tempFile,$targetFile.'.'.$fileExtension);
    }

如果有人可以帮助我解决这个问题，我将非常高兴。我一直在尝试几种方法，但似乎都无法正常工作。正如您在顶部看到的那样，我已经在变量 bigImage， mediumImage， listImage和 thumbnail中定义了要使用的画布大小。

I would be really happy if someone could help me solve this. I've been trying several methods but none of them seemed to work properly. As you can see in the top I have already defined the canvas sizes that I want to use in the variables "bigImage", "mediumImage", "listImage" and "thumbnail".

提前谢谢！ //
Jonathan

Thanks in advance! // Jonathan

推荐答案

有多种方法可以调整图像大小。我会为您拼写出来：

There is more than one way to resize an image. I'll spell them out for you:

• 拉伸以适合-图像的尺寸调整为所需的尺寸而忽略了宽高比


• 缩放以适合-调整图像的大小，以使一个尺寸（宽度或高度）具有所需的尺寸，而另一个尺寸则保持相同或更短，同时保持宽高比（可能需要执行一个额外的步骤才能用实色填充较短的一面）


• 裁剪以适合-调整图像的大小，以使一个尺寸（宽度或高度）具有所需的尺寸，而另一个尺寸则保持相同或更长，同时保持宽高比（需要额外的步骤来修剪外部区域） ）

• Stretch to fit -- the image is resized to the desired size ignoring aspect ratio
• Scale to fit -- the image is resized so that one dimension (width or height) has the desired size while the other is same or shorter while maintaining aspect ratio (one extra step may be required to fill the shorter side with solid color)
• Crop to fit -- the image is resized so that one dimension (width or height) has the desired size while the other is same or longer while maintaining aspect ratio (one extra step is required to trim the outside region)

PS：这两篇文章都是我写的。

PS: both articles were written by me.

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