Question

请看这个问题：PHP GD Use one image to mask another image, including transparency - 这里的规则说用户可以创建新问题而不是重新访问旧问题并寻求支持

我一直在使用这个脚本来启用透明屏蔽 - （可能）区别在于源图像具有透明度，但似乎下面的代码仅在输入PNG没有透明度时才有效。有人可以看看我是否做错了什么？

我在下面尝试做什么： 1.获取$源图像 2.调整大小并将其保存在本地pjg.png，保持透明度（这可行） 3.用另一个PNG掩盖结果图像。

的信息：

image.png具有透明度。
mask1.png是黑色背景上的白色椭圆形，没有透明度

最终保存的图像上有黑色，此时应始终保持透明度。

<?php
$data       = file_get_contents('assets/img/image.png');
$source     = imagecreatefromstring( $data);


// Set the percentage resize

$percent = 0.5;

// Get new dimensions
list($width, $height) = getimagesize('assets/img/image.png');
$new_width = $width * $percent;
$new_height = $height * $percent;

$image_p = imagecreatetruecolor($new_width, $new_height);
imagealphablending($image_p, false);
imagesavealpha( $image_p, true );

imagecopyresampled($image_p, $source, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

imagepng($image_p, "assets/img/pjg.png");

$mask_id = 1;


create_mask( $image_p, $mask_id ); 


function create_mask( &$picture, $mask_id) {
// Image masking using PHP
// https://stackoverflow.com/questions/7203160/php-gd-use-one-image-to-mask-another-image-including-transparency

$mask = imagecreatefrompng( 'assets/img/masks/mask'.$mask_id.'.png' );   // The mask is a white-on-black png



// Get sizes and set up new picture
$xSize = imagesx( $picture );
$ySize = imagesy( $picture );
$newPicture = imagecreatetruecolor( $xSize, $ySize );

imagesavealpha($newPicture, true);  
imagefill( $newPicture, 0, 0, imagecolorallocatealpha( $newPicture, 0, 0, 0, 127 ) );


// Resize mask if necessary
if( $xSize != imagesx( $mask ) || $ySize != imagesy( $mask ) ) {
    $tempPic = imagecreatetruecolor( $xSize, $ySize );
    imagecopyresampled( $tempPic, $mask, 0, 0, 0, 0, $xSize, $ySize, imagesx( $mask ), imagesy( $mask ) );
    imagedestroy( $mask );
    $mask = $tempPic;
}

// Perform pixel-based alpha map application
for( $x = 0; $x < $xSize; $x++ ) {
    for( $y = 0; $y < $ySize; $y++ ) {
        $alpha = imagecolorsforindex( $mask, imagecolorat( $mask, $x, $y ) );
        $alpha = 127 - floor( $alpha[ 'red' ] / 2 );
        $color = imagecolorsforindex( $picture, imagecolorat( $picture, $x, $y ) );
        imagesetpixel( $newPicture, $x, $y, imagecolorallocatealpha( $newPicture, $color[ 'red' ], $color[ 'green' ], $color[ 'blue' ], $alpha ) );
    }
}

$salt = random_string('alnum', 8); // Another function generating a string, not important
$now = time();
$new_filename = $now."_".$salt .".png";

// Save it Locally using a unique name
imagepng($newPicture, "assets/img/uploads/cropped/".$new_filename);


// Copy back to original picture
imagedestroy( $picture );
$picture = $newPicture;

}

如果有人能指出为什么输出图像没有保持其透明度，那么就会有适合你的冰镇啤酒。

谢谢！

PJG

Answer 1

我已经解决了。原始脚本没有检查源图像的透明度。下面的脚本检查源图像的像素透明度，并相应地采取行动。下面的脚本在PNG图像上预先形成一个shap蒙版，并保持源图像的透明度。

<?php
$data       = file_get_contents('assets/img/image.png');
$source     = imagecreatefromstring( $data);


// Set the percentage resize

$percent = 0.5;

// Get new dimensions
list($width, $height) = getimagesize('assets/img/image.png');
$new_width = $width * $percent;
$new_height = $height * $percent;

$image_p = imagecreatetruecolor($new_width, $new_height);
imagealphablending($image_p, false);
imagesavealpha( $image_p, true );

imagecopyresampled($image_p, $source, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

imagepng($image_p, "assets/img/pjg.png");

$mask_id = 1;


create_mask( $image_p, $mask_id ); 


function create_mask( &$picture, $mask_id) {
// Image masking using PHP
// http://stackoverflow.com/questions/7203160/php-gd-use-one-image-to-mask-another-image-including-transparency

$mask = imagecreatefrompng( 'assets/img/masks/mask'.$mask_id.'.png' );   // The mask is a white-on-black png



// Get sizes and set up new picture
$xSize = imagesx( $picture );
$ySize = imagesy( $picture );
$newPicture = imagecreatetruecolor( $xSize, $ySize );

imagesavealpha($newPicture, true);  
imagefill( $newPicture, 0, 0, imagecolorallocatealpha( $newPicture, 0, 0, 0, 127 ) );


// Resize mask if necessary
if( $xSize != imagesx( $mask ) || $ySize != imagesy( $mask ) ) {
    $tempPic = imagecreatetruecolor( $xSize, $ySize );
    imagecopyresampled( $tempPic, $mask, 0, 0, 0, 0, $xSize, $ySize, imagesx( $mask ), imagesy( $mask ) );
    imagedestroy( $mask );
    $mask = $tempPic;
}

// Perform pixel-based alpha map application
for( $x = 0; $x < $xSize; $x++ ) {
    for( $y = 0; $y < $ySize; $y++ ) {
         $alpha = imagecolorsforindex( $mask, imagecolorat( $mask, $x, $y ) );

            if(($alpha['red'] == 0) && ($alpha['green'] == 0) && ($alpha['blue'] == 0) && ($alpha['alpha'] == 0))
            {
                // It's a black part of the mask
                imagesetpixel( $newPicture, $x, $y, imagecolorallocatealpha( $newPicture, 0, 0, 0, 127 ) ); // Stick a black, but totally transparent, pixel in.
            }
            else
            {

                // Check the alpha state of the corresponding pixel of the image we're dealing with.    
                $alphaSource = imagecolorsforindex( $picture, imagecolorat( $picture, $x, $y ) );

                if(($alphaSource['alpha'] == 127))
                {
                    imagesetpixel( $newPicture, $x, $y, imagecolorallocatealpha( $newPicture, 0, 0, 0, 127 ) ); // Stick a black, but totally transparent, pixel in.
                } 
                else
                {
                    $color = imagecolorsforindex( $picture, imagecolorat( $picture, $x, $y ) );
                    imagesetpixel( $newPicture, $x, $y, imagecolorallocatealpha( $newPicture, $color[ 'red' ], $color[ 'green' ], $color[ 'blue' ], $color['alpha'] ) ); // Stick the pixel from the source image in
                }


            }
    }
}

$salt = random_string('alnum', 8); // Another function generating a string, not important
$now = time();
$new_filename = $now."_".$salt .".png";

// Save it Locally using a unique name
imagepng($newPicture, "assets/img/uploads/cropped/".$new_filename);


// Copy back to original picture
imagedestroy( $picture );
$picture = $newPicture;

}
?>

欢呼阅读 - 看起来我以后会给自己买啤酒：）

PG

使用PHP GD屏蔽一个图像与另一个图像

1 个答案: