PHP Image Processing-PNG transparent scaling and Gray Image Generation

Not to mention nonsense.Code:

 

If (move_uploaded_file ($ arrfile ['tmp _ name'], $ strpicname )){

Switch ($ fileext ){

Case ". GIF": // GIF

$ Im = imagecreatefromgif ($ strpicname );

Break;

Case ". PNG": // PNG

$ Im = imagecreatefrompng ($ strpicname );

Break;

Default: // JPG

$ Im = imagecreatefromjpeg ($ strpicname );

Break;

}

// Obtain image information

$ Imageinfo = $ this-> getinfo ($ strpicname );

 

// Create a new canvas for zooming and transparency

If (function_exists ("imagecreatetruecolor") {// gd2.0.1

$ New = imagecreatetruecolor (150, 80 );

$ This-> addtranbylistimage ($ fileext, $ new );

Imagecopyresampled ($ new, $ im, 0, 0, 0, 0,150, 80, $ imageinfo ["width"], $ imageinfo ["height"]);

} Else {

$ New = imagecreate (150, 80 );

$ This-> addtranbylistimage ($ fileext, $ new );

Imagecopyresized ($ new, $ im, 0, 0, 0, 0,150, 80, $ imageinfo ["width"], $ imageinfo ["height"]);

}

// Generate a thumbnail

Switch ($ fileext ){

Case ". GIF": // GIF

Imagegif ($ new, $ strpicname );

Break;

Case ". PNG": // PNG

Imagepng ($ new, $ strpicname );

Break;

Default: // JPG

Imagejpeg ($ new, $ strpicname );

Break;

}

// Generate a gray chart

If ($ New & imagefilter ($ new, img_filter_grayscale )){

Imagepng ($ new, $ strpicname. "_grey.png ");

Return $ strphoto;

} Else {

Check: alertexit ('Gray Graph Generation failed! ',-1 );

}

} Else {

Check: alertexit ($ strpicname. 'file upload error! ',-1 );

}

 

The above code will not be re-written. We will start from move_uploaded_file.

After the file is uploaded, get the $ im object according to the file path, that is, the imagecreatexxx object. $ Fileext is the suffix of the obtained image. Other content annotations should also be clearly written. Let's take a look at these two methods: $ this-> getinfo ($ strpicname); and $ this-> addtranbylistimage ($ fileext, $ new );

 

$ This-> getinfo (); actually, it's easy to get the image information:

 

Function getinfo ($ file ){

$ DATA = getimagesize ($ file );

$ Imageinfo ["width"] = $ data [0];

$ Imageinfo ["height"] = $ data [1];

$ Imageinfo ["type"] = $ data [2];

$ Imageinfo ["name"] = basename ($ file );

Return $ imageinfo;

}

 

$ This-> addtranbylistimage () is our focus today:

 

Function addtranbylistimage ($ fileext, $ IMG ){

Switch ($ fileext ){

Case ". GIF": // GIF

Case ". PNG": // PNG

Imagealphablending ($ IMG, true );

Imagesavealpha ($ IMG, true );

$ Trans_colour = imagecolorallocatealpha ($ IMG, 0, 0, 0,127 );

Imagefill ($ IMG, 0, 0, $ trans_colour );

Break;

Default: // JPG

Break;

}

}

 

In fact, it is also a very simple method. I just found it on Baidu and added itProgramAnd the test is completed. Under normal circumstances, after the uploaded transparent PNG image with a background is scaled or some operations are performed, the transparent background of the image becomes black, the Code is the key statement to ensure that the background is still transparent.

 

As for the gray image, the imagefilter method is simpler. The following parameters are all constants.

 

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