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php+js实现裁剪任意形状图片

2019年05月29日  | 移动技术网IT编程  | 我要评论

最近做到相关的项目，由于项目使用html2canvas，但是不支持css mask属性，故，利用php后台来裁剪。

准备两张图片，一张是镂空png图案，一张是任意纯色图片。

便能够在纯色图片上裁剪出镂空的图案为png文件。

见下图。

首先两张png图片：

生成图片

 js片段：

html2canvas($(".head1pic"), {
     onrendered: function(canvas) { 
     url = canvas.todataurl("image/png", 1.0);
       sourcepic = "assets/images/demo.png";
       maskpic = "assets/images/jinmao.png";
          croppicname = "cropdog1";
          // ajax php截图
          $.ajax({
          type: 'post',
           url: 'getpicture',
          data: {
            "sourcepic": sourcepic,
            "maskpic": maskpic,
            "croppicname": croppicname
            },
         success: function(data) {
             $(".page2bg")[0].setattribute("src", "assets/images/crop/cropdog1.png"); 
            },
         error: function(data) {
              console.log(data)
              }
            });
       }
 });

php的片段：

 public function actiongetpicture()
  {  
     $request = yii::$app->request;
    $sourcepic=$request->post('sourcepic');
    $maskpic=$request->post('maskpic'); 
    $croppicname=$request->post('croppicname'); 
 
    // $sourcepic="http://bings.local.com/bi_ngs2_2/assets/images/yinpian1/page2bg4.png";
    // $maskpic="http://bings.local.com/bi_ngs2_2/assets/images/jinmao.png";
    $source = imagecreatefrompng( $sourcepic );
    $mask = imagecreatefrompng( $maskpic); 
    // apply mask to source
    // imagealphamask( $source, $mask );
    $this->imagealphamask ($source, $mask );
    // output
    header( "content-type: image/png"); 
    // 生成截取后的图片并保存在本地
    imagepng( $source,"assets/images/crop/".$croppicname.".png" );
    //销毁图片内存
    imagedestroy($source);
      
  }
 
  public function imagealphamask( &$picture, $mask ) {
    // 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, 100, 100, 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 ) );
        //small mod to extract alpha, if using a black(transparent) and white
        //mask file instead change the following line back to jules's original:
        // $alpha = 127 - floor($alpha['black'] / 2);
        //or a white(transparent) and black mask file:
        // $alpha = floor($alpha['black'] / 2);
        $alpha = $alpha['alpha'];
        $color = imagecolorsforindex( $picture, imagecolorat( $picture, $x, $y ) );
        //preserve alpha by comparing the two values
        if ($color['alpha'] > $alpha)
          $alpha = $color['alpha'];
        //kill data for fully transparent pixels
        if ($alpha == 127) {
          $color['red'] = 0;
          $color['blue'] = 0;
          $color['green'] = 0;
        }
        imagesetpixel( $newpicture, $x, $y, imagecolorallocatealpha( $newpicture, $color[ 'red' ], $color[ 'green' ], $color[ 'blue' ], $alpha ) );
      }
    }
 
    // copy back to original picture
    imagedestroy( $picture );
    $picture = $newpicture;
  }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。

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