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使用PHP裁剪png图像,删除空白透明度

php-gd image php

saperlipopette · 技术社区 · 7 年前

现在我想修改PNG图片的大小。下面是我想要调整大小的PNG示例:

虚线代表PNG的边界,背景是透明的,我只在一个大空间的中间丢失了一颗星。我想裁剪这颗星,得到一个简单的恒星正方形(即使新背景变为空白,也没关系)。

<?php

$file = "./crop.png";

$ext = pathinfo($file, PATHINFO_EXTENSION);

$image;

switch ($ext){
case 'png':
    $image = imagecreatefrompng($file);
    break;

case 'jpeg':
case 'jpg':
    $image = imagecreatefromjpeg($file);
    break;

case 'gif':
    $image = imagecreatefromgif($file);
    break;
}

$cropped = imagecropauto($image, IMG_CROP_DEFAULT);

    if ($cropped !== false) { // in case a new image resource was returned
        echo "=> Cropping needed\n";
        imagedestroy($image);    // we destroy the original image
        $image = $cropped;       // and assign the cropped image to $im
    }

    imagepng($image, "./cropped.png");
    imagedestroy($image);

2 回复 | 直到 7 年前

Christos Lytras 7 年前

如果你阅读并遵循 php php-gd imagecropauto 这正是你想要的,它修剪图像的alpha通道。

$im = imagecreatefrompng("./star-with-alpha.png");
$cropped = imagecropauto($im, IMG_CROP_DEFAULT);

if ($cropped !== false) { // in case a new image resource was returned
    imagedestroy($im);    // we destroy the original image
    $im = $cropped;       // and assign the cropped image to $im
}

imagepng($im, "./star-with-alpha-crop.png");
imagedestroy($im);

<body>

<img src="star-with-alpha.png">

<?php 

$im = imagecreatefrompng("./star-with-alpha.png");
$cropped = imagecropauto($im, IMG_CROP_DEFAULT);

if ($cropped !== false) { // in case a new image resource was returned
    imagedestroy($im);    // we destroy the original image
    $im = $cropped;       // and assign the cropped image to $im
}

imagepng($im, "./star-with-alpha-crop.png");
imagedestroy($im);

?>

<img src="star-with-alpha-crop.png">

</body>

http://zikro.gr/dbg/php/crop-png/

informer 4 年前

[这是ubuntu 12的] 唯一的问题是 imagecropauto 由于现在大多数服务器都使用ubuntu/debain,这个功能没有用。下面是我编写的示例代码,它正是这样做的:

    //Add background transmparent
    $background = 'none';
    $image = new Imagick($path);
    $image->trimImage(0);
   
    //add transparent border
    //border add start
    /** Set border format **/
    $borderWidth = 20;
    $borderColor = 'none';
    $borderPadding = 10;


    $imageWidth = $image->getImageWidth() + ( 2 * ( $borderWidth + 
    $borderPadding ) );
    $imageHeight = $image->getImageHeight() + ( 2 * ( $borderWidth + 
    $borderPadding ) );

    $imageWithBorder = new Imagick();
    // Set image canvas
    $imageWithBorder->newImage( $imageWidth, $imageHeight, new ImagickPixel( 
    'none' ));
    // Create ImagickDraw object to draw border
    $border = new ImagickDraw();
    // Set fill color to transparent
    $border->setFillColor( 'none' );
    // Set border format
    $border->setStrokeColor( new ImagickPixel( $borderColor ) );
    $border->setStrokeWidth( $borderWidth );
    $border->setStrokeAntialias( false );

绘制边框

    $border->rectangle(
        $borderWidth / 2 - 1,
        $borderWidth / 2 - 1,
        $imageWidth - ( ($borderWidth / 2) ),
        $imageHeight - ( ($borderWidth / 2) )
    );
    // Apply drawed border to final image
    $imageWithBorder->drawImage( $border );
    $imageWithBorder->setImageFormat('png');

保存图像

    // Put source image to final image
    $imageWithBorder->compositeImage(
            $image, Imagick::COMPOSITE_DEFAULT,
            $borderWidth + $borderPadding,
            $borderWidth + $borderPadding
    );
    
    $imageWithBorder->writeImage($path);

    $imageWithBorder->scaleImage(FINAL_WIDTH, FINAL_HEIGHT, true);
    $imageWithBorder->setImageBackgroundColor($background);
    $w = $imageWithBorder->getImageWidth();
    $h = $imageWithBorder->getImageHeight();
    $imageWithBorder->extentImage(FINAL_WIDTH, FINAL_HEIGHT, ($w  - 
    FINAL_WIDTH) / 2, ($h - FINAL_HEIGHT)/ 2);
    $imageWithBorder->writeImage($path);

希望有帮助。干杯