Can PNG Image Transparency Be Preserved When Using PHP's GDlib Imagecopyresampled?


Answer :

imagealphablending( $targetImage, false ); imagesavealpha( $targetImage, true );

did it for me. Thanks ceejayoz.

note, the target image needs the alpha settings, not the source image.

Edit: full replacement code. See also answers below and their comments. This is not guaranteed to be be perfect in any way, but did achieve my needs at the time.

$uploadTempFile = $myField[ 'tmp_name' ] list( $uploadWidth, $uploadHeight, $uploadType )    = getimagesize( $uploadTempFile );  $srcImage = imagecreatefrompng( $uploadTempFile );   $targetImage = imagecreatetruecolor( 128, 128 );    imagealphablending( $targetImage, false ); imagesavealpha( $targetImage, true );  imagecopyresampled( $targetImage, $srcImage,                      0, 0,                      0, 0,                      128, 128,                      $uploadWidth, $uploadHeight );  imagepng(  $targetImage, 'out.png', 9 );

Why do you make things so complicated? the following is what I use and so far it has done the job for me.

$im = ImageCreateFromPNG($source); $new_im = imagecreatetruecolor($new_size[0],$new_size[1]); imagecolortransparent($new_im, imagecolorallocate($new_im, 0, 0, 0)); imagecopyresampled($new_im,$im,0,0,0,0,$new_size[0],$new_size[1],$size[0],$size[1]);

I believe this should do the trick:

$srcImage = imagecreatefrompng($uploadTempFile); imagealphablending($srcImage, false); imagesavealpha($srcImage, true);

edit: Someone in the PHP docs claims imagealphablending should be true, not false. YMMV.


Comments

Post a Comment

Popular posts from this blog

C Perror Example

Defined in header <stdio.h> void perror ( const char * s ) ; Prints a textual description of the error code currently stored in the system variable errno to stderr . The description is formed by concatenating the following components: the contents of the null-terminated byte string pointed to by s , followed by ": " (unless s is a null pointer or the character pointed to by s is the null character) implementation-defined error message string describing the error code stored in errno , followed by '\n' . The error message string is identical to the result of strerror ( errno ) . Parameters s - pointer to a null-terminated string with explanatory message Return value (none). Example # include <stdio.h> int main ( void ) { FILE * f = fopen ( "non_existent" , "r" ) ; if ( f == NULL ) { perror ( "fopen() failed" ) ; } else { fclose...
Read more

Converting A String To Int In Groovy

Answer : Use the toInteger() method to convert a String to an Integer , e.g. int value = "99".toInteger() An alternative, which avoids using a deprecated method (see below) is int value = "66" as Integer If you need to check whether the String can be converted before performing the conversion, use String number = "66" if (number.isInteger()) { int value = number as Integer } Deprecation Update In recent versions of Groovy one of the toInteger() methods has been deprecated. The following is taken from org.codehaus.groovy.runtime.StringGroovyMethods in Groovy 2.4.4 /** * Parse a CharSequence into an Integer * * @param self a CharSequence * @return an Integer * @since 1.8.2 */ public static Integer toInteger(CharSequence self) { return Integer.valueOf(self.toString().trim()); } /** * @deprecated Use the CharSequence version * @see #toInteger(CharSequence) */ @Deprecated public static Integer toInteger(String self) { return toInteg...
Read more

"Cannot Create Cache Directory /home//.composer/cache/repo/https---packagist.org/, Or Directory Is Not Writable. Proceeding Without Cache"

Answer : if anyone pass through here, this is shorter solution: sudo chown -R $USER $HOME/.composer it seems to me the group information is missing in your command sudo chown -R <user> /home/<user>/.composer/cache/repo/https---packagist.org Shoud be sudo chown -R <user>:<group> /home/<user>/.composer/cache/repo/https---packagist.org But to avoid other permission issues, I would rather advise: sudo chown -R <user>:<group> /home/<user>/.composer/cache (you'll need access to other folders in there) and sudo chown <user>:<group> /home/<user>/.composer To make sure your user has permissions enough on the global composer folder. Mind the missing recursion so the user don't own keys created by root. If you need to find out the group: groups <user>
Read more