从中心 PHP 裁剪图像
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Crop Image From Center PHP
提问by June
I want to crop an image from the center in the size 200 * 130 the image to be cropped may vary in size, if the image is smaller we wont crop it i know how to this part where i can check height and with of image but kind of struck into the thing of cropping from the middle of the image As i cant figure it out how to keep the center as crop point and than outward crop it
我想从中心裁剪 200 * 130 大小的图像，要裁剪的图像大小可能会有所不同，如果图像较小，我们不会裁剪它，我知道如何在这部分检查图像的高度和图像，但是有点影响从图像中间裁剪的东西 因为我不知道如何将中心保持为裁剪点而不是向外裁剪它
回答by Phil
GD comes bundled with all PHP installations from version 4.3.6 onwards so chances are, you have it.
从 4.3.6 版开始，GD 与所有 PHP 安装捆绑在一起，所以您有机会拥有它。
Here's the steps you need to take...
这是您需要采取的步骤...
- Create an image resource using one of the GD
imagecreatefrom*()functions. The one you use depends on the type of image you're dealing with - Determine the image dimensions using
imagesx()andimagesy() - Determine your crop coordinates using the following algorithm and crop using
imagecopy()
- 使用 GD
imagecreatefrom*()函数之一创建图像资源。您使用的那个取决于您正在处理的图像类型 - 使用
imagesx()和确定图像尺寸imagesy() - 使用以下算法确定您的裁剪坐标并使用裁剪
imagecopy()
Find crop coordinates
查找裁剪坐标
$width = imagesx($img);
$height = imagesy($img);
$centreX = round($width / 2);
$centreY = round($height / 2);
$cropWidth = 200;
$cropHeight = 130;
$cropWidthHalf = round($cropWidth / 2); // could hard-code this but I'm keeping it flexible
$cropHeightHalf = round($cropHeight / 2);
$x1 = max(0, $centreX - $cropWidthHalf);
$y1 = max(0, $centreY - $cropHeightHalf);
$x2 = min($width, $centreX + $cropWidthHalf);
$y2 = min($height, $centreY + $cropHeightHalf);
Feel free to use my image manipulation class, it should make some aspects much easier - https://gist.github.com/880506
随意使用我的图像处理类，它应该使某些方面更容易 - https://gist.github.com/880506
$im = new ImageManipulator('/path/to/image');
$centreX = round($im->getWidth() / 2);
$centreY = round($im->getHeight() / 2);
$x1 = $centreX - 100;
$y1 = $centreY - 65;
$x2 = $centreX + 100;
$y2 = $centreY + 65;
$im->crop($x1, $y1, $x2, $y2); // takes care of out of boundary conditions automatically
$im->save('/path/to/cropped/image');
回答by totymedli
Image crop with configurable alignment
具有可配置对齐的图像裁剪
Here is a native implementation of a function (called cropAlign) that can crop an image to a given width and height with alignto the 9 standard points (4 edges, 4 corners, 1 center).
这是一个函数（称为cropAlign）的本机实现，它可以将图像裁剪为给定的宽度和高度，并对齐9 个标准点（4 个边、4 个角、1 个中心）。
Just pass the image, the desired size of the crop, and the alignment on the two axis (you can use left, center, rightor top, middle, bottomirregardless from the axis) for the cropAlignfunction.
只需传递图像、所需的裁剪尺寸以及两个轴上的对齐（您可以使用left, center,right或top, middle，bottom不管轴是否来自该cropAlign函数）。
Specification
规格
Description
cropAlign(resource $image, int $width, int $height, string $horizontalAlign = 'center', string $verticalAlign = 'middle')Parameters
image: An image resource, returned by one of the image creation functions, such asimagecreatetruecolor().width: Width of the final cropped image.height: Height of the final cropped image.horizontalAlign: Where the crop should be aligned along the horizontal axis. Possible values are:left/top,center/middle,right/bottom.verticalAlign: Where the crop should be aligned along the vertical axis. Possible values are:left/top,center/middle,right/bottom.Return Values
Return cropped image resource on success or
FALSEon failure. This comes fromimagecrop().
描述
cropAlign(resource $image, int $width, int $height, string $horizontalAlign = 'center', string $verticalAlign = 'middle')参数
image：图像资源，由图像创建函数之一返回，例如imagecreatetruecolor().width：最终裁剪图像的宽度。height：最终裁剪图像的高度。horizontalAlign：裁剪应沿水平轴对齐的位置。可能的值为：left/top、center/middle、right/bottom。verticalAlign：裁剪应沿垂直轴对齐的位置。可能的值为：left/top、center/middle、right/bottom。返回值
成功或
FALSE失败时返回裁剪的图像资源。这来自imagecrop().
Source code
源代码
function cropAlign($image, $cropWidth, $cropHeight, $horizontalAlign = 'center', $verticalAlign = 'middle') {
$width = imagesx($image);
$height = imagesy($image);
$horizontalAlignPixels = calculatePixelsForAlign($width, $cropWidth, $horizontalAlign);
$verticalAlignPixels = calculatePixelsForAlign($height, $cropHeight, $verticalAlign);
return imageCrop($image, [
'x' => $horizontalAlignPixels[0],
'y' => $verticalAlignPixels[0],
'width' => $horizontalAlignPixels[1],
'height' => $verticalAlignPixels[1]
]);
}
function calculatePixelsForAlign($imageSize, $cropSize, $align) {
switch ($align) {
case 'left':
case 'top':
return [0, min($cropSize, $imageSize)];
case 'right':
case 'bottom':
return [max(0, $imageSize - $cropSize), min($cropSize, $imageSize)];
case 'center':
case 'middle':
return [
max(0, floor(($imageSize / 2) - ($cropSize / 2))),
min($cropSize, $imageSize),
];
default: return [0, $imageSize];
}
}
Example usage
示例用法
Here are some crop examples using this imageof the Utah teapot.
$im = imagecreatefrompng('https://i.stack.imgur.com/NJcML.png');
imagePng(cropAlign($im, 200, 250, 'center', 'middle'));
imagePng(cropAlign($im, 300, 150, 'left', 'top'));
imagePng(cropAlign($im, 1000, 250, 'right', 'middle'));
Input
输入
Output
输出
cropAlign($im, 200, 250, 'center', 'middle')
cropAlign($im, 300, 150, 'left', 'top')
cropAlign($im, 1000, 250, 'right', 'middle')
回答by Ethan SK
Jeez, why are you doing it the hard way? Just simply set the x and y positions as the amount to crop / 2
天哪，你为什么要这么艰难？只需简单地将 x 和 y 位置设置为要裁剪的数量 / 2
$imageSize = getimagesize('thumbnail.png');
$croppedImage = imagecrop(imagecreatefrompng('thumbnail.png'), ['x' => 0, 'y' => ($imageSize[1]-$imageSize[0]*(9/16))/2, 'width' => $imageSize[0], 'height' => $imageSize[0]*(9/16)]);
notice how I used my $imageSize[0]*(9/16), which is the amount i am cropping by in the y direction, and i subtracted that from the original image height to find crop amount, then divided by 2. If you want to do the same for width, simply follow the same steps.
请注意我如何使用 $imageSize[0]*(9/16)，这是我在 y 方向上裁剪的数量，我从原始图像高度中减去它以找到裁剪数量，然后除以 2。如果你想对宽度做同样的事情，只需按照相同的步骤。
回答by P. R. Ribeiro
This might help you.
这可能对你有帮助。
function cropCentered($img, $w, $h)
{
$cx = $img->getWidth() / 2;
$cy = $img->getHeight() / 2;
$x = $cx - $w / 2;
$y = $cy - $h / 2;
if ($x < 0) $x = 0;
if ($y < 0) $y = 0;
return $img->crop($x, $y, $w, $h);
}
I'm assuming you're using the GD library. $img is a GD image, $w and $h are width and height, respectively, you want your new image to have. In your case, $w = 200, $h = 130.
我假设您正在使用 GD 库。$img 是 GD 图像，$w 和 $h 分别是宽度和高度，您希望新图像具有。在您的情况下，$w = 200，$h = 130。
