Png thumbnail program for generating transparent background in php

This article describes how to generate a png thumbnail program with a transparent background in php. to process this in php, we only need to use imagealphablending ($ thumb, false); and imagesavealpha ($ thumb, true); then, let's look at the program.

When a PNG thumbnail is generated, the background is black. Today I wrote another function to make up for it. The code is very simple, that is, imagealphablending ($ thumb, false); and imagesavealpha ($ thumb, true); it is very important to save the alpha value of PNG and do not lose it.

 

The Code is as follows:

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<? PHP /* * $ SourePic: source image path * $ SmallFileName: Specifies the image name. * $ Width: Specifies the width of a thumbnail. * $ Heigh: Small Image Height * Reprinted with www.hzhuti.com */ Function pngthumb ($ sourePic, $ smallFileName, $ width, $ heigh ){ $ Image = imagecreatefrompng ($ sourePic); // PNG Imagesavealpha ($ image, true); // It is important that you do not lose the transparent color of $ sourePic; $ BigWidth = imagesx ($ image); // The width of a large image. $ BigHeigh = imagesy ($ image); // the height of a large image. $ Thumb = imagecreatetruecolor ($ width, $ heigh ); Imagealphablending ($ thumb, false); // It is very important here, meaning that the color is not merged and is directly replaced with the $ img image color, including the transparent color; Imagesavealpha ($ thumb, true); // This is very important, meaning do not lose the transparent color of the $ thumb image; If (imagecopyresampled ($ thumb, $ image, $ width, $ heigh, $ BigWidth, $ BigHeigh )){ Imagepng ($ thumb, $ smallFileName );} Return $ smallFileName; // return the thumbnail path}   Pngthumb ("a.png", "c.png", 300,300); // call ?>

All of the above are built-in functions in php, and no third-party programs are used. If you need them, you can check them out.