Add border around png image using imagick PHP

问题

How can I add a border around a png image? Whenever I try to add a border using borderImage function available in imagick it loses its transparency if it is a png image.

<?php

$image = new Imagick();
$image->readImage('tux.png');

$image->BorderImage(new ImagickPixel("red") , 5,5);

// send the result to the browser
header("Content-Type: image/" . $image->getImageFormat());
echo $image;

This is the original image:

and this is after adding a border:

Border color is also applied onto the background. I want to do this using imagick How can I apply a border to a transparent image without losing transparency?

回答1:

If you want to achieve result like this:

then this is it. You can even give padding between border and image if you want!

/** Set source image location. You can use URL here **/
$imageLocation = 'tux.png';

/** Set border format **/
$borderWidth = 10;

// You can use color name, hex code, rgb() or rgba()
$borderColor = 'rgba(255, 0, 0, 1)';

// Padding between image and border. Set to 0 to give none
$borderPadding = 0;


/** Core program **/

// Create Imagick object for source image
$imageSource = new Imagick( $imageLocation );

// Get image width and height, and automatically set it wider than
// source image dimension to give space for border (and padding if set)
$imageWidth = $imageSource->getImageWidth() + ( 2 * ( $borderWidth + $borderPadding ) );
$imageHeight = $imageSource->getImageHeight() + ( 2 * ( $borderWidth + $borderPadding ) );

// Create Imagick object for final image with border
$image = new Imagick();

// Set image canvas
$image->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 );

// Draw border
$border->rectangle(
    $borderWidth / 2 - 1,
    $borderWidth / 2 - 1,
    $imageWidth - ( ($borderWidth / 2) ),
    $imageHeight - ( ($borderWidth / 2) )
);

// Apply drawed border to final image
$image->drawImage( $border );

$image->setImageFormat('png');

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

// Prepare image and publish!
header("Content-type: image/png");
echo $image;

I got this method from here. Basically we just make a rectangle with transparent fill and formatted border using ImagickDraw::rectangle, then we put the image inside the rectangle using Imagick::compositeImage.

Here is the result if you set $borderPadding to 10:

That's it! Hope it helps :)

来源：https://stackoverflow.com/questions/24450999/add-border-around-png-image-using-imagick-php

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