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php实现图片缩略图的方法

发布:smiling 来源: PHP粉丝网  添加日期:2021-07-22 11:33:44 浏览: 评论:0 

本文使用php实现的图片缩略图,支持jpg,jpeg,gif,png,bmp图片格式,支持按原图片的比例进行缩放,可以选择在图片缩放的过程中是否需要对图片进行裁切,加入了图片质量控制,可以实现缩略图片质量最高化,需要的朋友可以参考下本段代码。

本段代码实现功能有这些:

支持jpg,jpeg,gif,png,bmp图片格式,支持按原图片的比例进行缩放,可以选择在图片缩放的过程中是否需要对图片进行裁切,加入了图片质量控制,可以实现缩略图片质量最高化。

完整类的代码如下:

  1. <?php 
  2. /** 
  3. * 功能:php生成缩略图片的类 
  4. */ 
  5. class ResizeImage{ 
  6. public $type;//图片类型 
  7. public $width;//实际宽度 
  8. public $height;//实际高度 
  9. public $resize_width;//改变后的宽度 
  10. public $resize_height;//改变后的高度 
  11. public $cut;//是否裁图 
  12. public $srcimg;//源图象  
  13. public $dstimg;//目标图象地址 
  14. public $im;//临时创建的图象 
  15. public $quality;//图片质量 
  16. function resizeimage($img,$wid,$hei,$c,$dstpath,$quality=100){ 
  17. $this->srcimg=$img
  18. $this->resize_width=$wid
  19. $this->resize_height=$hei
  20. $this->cut=$c
  21. $this->quality=$quality
  22. $this->type=strtolower(substr(strrchr($this->srcimg,'.'),1));//图片的类型 
  23. $this->initi_img();//初始化图象 
  24. $this -> dst_img($dstpath);//目标图象地址 
  25. @$this->width=imagesx($this->im); 
  26. @$this->height=imagesy($this->im); 
  27. $this->newimg();//生成图象 
  28. @ImageDestroy($this->im); 
  29. function newimg(){ 
  30. $resize_ratio=($this->resize_width)/($this->resize_height);//改变后的图象的比例 
  31. @$ratio=($this->width)/($this->height);//实际图象的比例 
  32. if(($this->cut)=='1'){//裁图 
  33. if($img_func==='imagepng'&&(str_replace('.','',PHP_VERSION)>=512)){ //针对php版本大于5.12参数变化后的处理情况 
  34. $quality=9; 
  35. if($ratio>=$resize_ratio){//高度优先 
  36. $newimg=imagecreatetruecolor($this->resize_width,$this->resize_height); 
  37. imagecopyresampled($newimg,$this->im,0,0,0,0,$this->resize_width,$this->resize_height,(($this->height)*$resize_ratio),$this->height); 
  38. imagejpeg($newimg,$this->dstimg,$this->quality); 
  39. if($ratio<$resize_ratio){//宽度优先 
  40. $newimg=imagecreatetruecolor($this->resize_width,$this->resize_height); 
  41. imagecopyresampled($newimg,$this->im,0,0,0,0,$this->resize_width,$this->resize_height,$this->width,(($this->width)/$resize_ratio)); 
  42. imagejpeg($newimg,$this->dstimg,$this->quality); 
  43. }else{//不裁图 
  44. if($ratio>=$resize_ratio){ 
  45. $newimg=imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio); 
  46. imagecopyresampled($newimg,$this->im,0,0,0,0,$this->resize_width,($this->resize_width)/$ratio,$this->width,$this->height); 
  47. imagejpeg($newimg,$this->dstimg,$this->quality); 
  48. if($ratio<$resize_ratio){ 
  49. @$newimg=imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height); 
  50. @imagecopyresampled($newimg,$this->im,0,0,0,0,($this->resize_height)*$ratio,$this->resize_height,$this->width,$this->height); 
  51. @imagejpeg($newimg,$this->dstimg,$this->quality); 
  52. function initi_img(){//初始化图象 
  53. if($this->type=='jpg' || $this->type=='jpeg'){ 
  54. $this->im=imagecreatefromjpeg($this->srcimg); 
  55. if($this->type=='gif'){ 
  56. $this->im=imagecreatefromgif($this->srcimg); 
  57. if($this->type=='png'){ 
  58. $this->im=imagecreatefrompng($this->srcimg); 
  59. if($this->type=='wbm'){ 
  60. @$this->im=imagecreatefromwbmp($this->srcimg); 
  61. if($this->type=='bmp'){ 
  62. $this->im=$this->ImageCreateFromBMP($this->srcimg); 
  63. function dst_img($dstpath){//图象目标地址 
  64. $full_length=strlen($this->srcimg); 
  65. $type_length=strlen($this->type); 
  66. $name_length=$full_length-$type_length
  67. $name=substr($this->srcimg,0,$name_length-1); 
  68. $this->dstimg=$dstpath
  69. //echo $this->dstimg; 
  70. function ImageCreateFromBMP($filename){ //自定义函数处理bmp图片 
  71. if(!$f1=fopen($filename,"rb"))returnFALSE; 
  72. $FILE=unpack("vfile_type/Vfile_size/Vreserved/Vbitmap_offset",fread($f1,14)); 
  73. if($FILE['file_type']!=19778)returnFALSE; 
  74. $BMP=unpack('Vheader_size/Vwidth/Vheight/vplanes/vbits_per_pixel'
  75. '/Vcompression/Vsize_bitmap/Vhoriz_resolution'
  76. '/Vvert_resolution/Vcolors_used/Vcolors_important',fread($f1,40)); 
  77. $BMP['colors']=pow(2,$BMP['bits_per_pixel']); 
  78. if($BMP['size_bitmap']==0)$BMP['size_bitmap']=$FILE['file_size']-$FILE['bitmap_offset']; 
  79. $BMP['bytes_per_pixel']=$BMP['bits_per_pixel']/8; 
  80. $BMP['bytes_per_pixel2']=ceil($BMP['bytes_per_pixel']); 
  81. $BMP['decal']=($BMP['width']*$BMP['bytes_per_pixel']/4); 
  82. $BMP['decal']-=floor($BMP['width']*$BMP['bytes_per_pixel']/4); 
  83. $BMP['decal']=4-(4*$BMP['decal']); 
  84. if($BMP['decal']==4)$BMP['decal']=0; 
  85. $PALETTE=array(); 
  86. if($BMP['colors']<16777216) 
  87. $PALETTE=unpack('V'.$BMP['colors'],fread($f1,$BMP['colors']*4)); 
  88. $IMG=fread($f1,$BMP['size_bitmap']); 
  89. $VIDE=chr(0); 
  90. $res=imagecreatetruecolor($BMP['width'],$BMP['height']); 
  91. $P=0; 
  92. $Y=$BMP['height']-1; 
  93. while($Y>=0) 
  94. $X=0; 
  95. while($X<$BMP['width']) 
  96. if($BMP['bits_per_pixel']==24) 
  97. $COLOR=unpack("V",substr($IMG,$P,3).$VIDE); 
  98. elseif($BMP['bits_per_pixel']==16) 
  99. $COLOR=unpack("n",substr($IMG,$P,2)); 
  100. $COLOR[1]=$PALETTE[$COLOR[1]+1]; 
  101. elseif($BMP['bits_per_pixel']==8) 
  102. $COLOR=unpack("n",$VIDE.substr($IMG,$P,1)); 
  103. $COLOR[1]=$PALETTE[$COLOR[1]+1]; 
  104. elseif($BMP['bits_per_pixel']==4) 
  105. $COLOR=unpack("n",$VIDE.substr($IMG,floor($P),1)); 
  106. if(($P*2)%2==0)$COLOR[1]=($COLOR[1]>>4);else$COLOR[1]=($COLOR[1]&0x0F); 
  107. $COLOR[1]=$PALETTE[$COLOR[1]+1]; 
  108. elseif($BMP['bits_per_pixel']==1) 
  109. $COLOR=unpack("n",$VIDE.substr($IMG,floor($P),1)); 
  110. if(($P*8)%8==0)$COLOR[1]=$COLOR[1]>>7; 
  111. elseif(($P*8)%8==1)$COLOR[1]=($COLOR[1]&0x40)>>6; 
  112. elseif(($P*8)%8==2)$COLOR[1]=($COLOR[1]&0x20)>>5; 
  113. elseif(($P*8)%8==3)$COLOR[1]=($COLOR[1]&0x10)>>4; 
  114. elseif(($P*8)%8==4)$COLOR[1]=($COLOR[1]&0x8)>>3; 
  115. elseif(($P*8)%8==5)$COLOR[1]=($COLOR[1]&0x4)>>2; 
  116. elseif(($P*8)%8==6)$COLOR[1]=($COLOR[1]&0x2)>>1; 
  117. elseif(($P*8)%8==7)$COLOR[1]=($COLOR[1]&0x1); 
  118. $COLOR[1]=$PALETTE[$COLOR[1]+1]; 
  119. else 
  120. returnFALSE; 
  121. imagesetpixel($res,$X,$Y,$COLOR[1]); 
  122. $X++; 
  123. $P+=$BMP['bytes_per_pixel']; 
  124. $Y--; 
  125. $P+=$BMP['decal']; 
  126. fclose($f1); 
  127. return$res
  128. ?> 

使用方法很简单代码如下:

$resizeimage=new ResizeImage('upload/abc.bmp', '120', '90', '0', 'upload/xabc.bmp');

以上代码是小编给大家分享的php实现图片缩略图的方法,希望对大家有所帮助!

Tags: php图片缩略图

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