PHP实现图片裁剪与缩放的几种方法

图片指定大小然后由php相关函数来实现图片裁剪功能,前段的js效果在这里就不介绍了,大家可以到网上找有很多这类代码,我只整理了php操作部份.

方法一,代码如下,图片裁剪缩放函数,支持方位裁剪和自定义坐标裁剪.

  1. /**
  2. * 图片裁剪函数,支持指定定点裁剪和方位裁剪两种裁剪模式
  3. * @param <string> $src_file 原图片路径
  4. * @param <int> $new_width 裁剪后图片宽度(当宽度超过原图片宽度时,去原图片宽度)
  5. * @param <int> $new_height 裁剪后图片高度(当宽度超过原图片宽度时,去原图片高度)
  6. * @param <int> $type 裁剪方式,1-方位模式裁剪;0-定点模式裁剪。
  7. * @param <int> $pos 方位模式裁剪时的起始方位(当选定点模式裁剪时,此参数不起作用)
  8. * 1为顶端居左,2为顶端居中,3为顶端居右;
  9. * 4为中部居左,5为中部居中,6为中部居右;
  10. * 7为底端居左,8为底端居中,9为底端居右;
  11. * @param <int> $start_x 起始位置X (当选定方位模式裁剪时,此参数不起作用)
  12. * @param <int> $start_y 起始位置Y(当选定方位模式裁剪时,此参数不起作用)
  13. * @return <string> 裁剪图片存储路径
  14. */
  15. function thumb($src_file, $new_width, $new_height, $type = 1, $pos = 5, $start_x = 0, $start_y = 0) {
  16. $pathinfo = pathinfo($src_file);
  17. $dst_file = $pathinfo['dirname'] . '/' . $pathinfo['filename'] .'_'. $new_width . 'x' . $new_height . '.' . $pathinfo['extension'];
  18. if (!file_exists($dst_file)) {
  19. if ($new_width < 1 || $new_height < 1) {
  20. echo "params width or height error !";
  21. exit();
  22. }
  23. if (!file_exists($src_file)) {
  24. echo $src_file . " is not exists !";
  25. exit();
  26. }
  27. // 图像类型
  28. $img_type = exif_imagetype($src_file);
  29. $support_type = array(IMAGETYPE_JPEG, IMAGETYPE_PNG, IMAGETYPE_GIF);
  30. if (!in_array($img_type, $support_type, true)) {
  31. echo "只支持jpg、png、gif格式图片裁剪";
  32. exit();
  33. }
  34. /* 载入图像 */
  35. switch ($img_type) {
  36. case IMAGETYPE_JPEG :
  37. $src_img = imagecreatefromjpeg($src_file);
  38. break;
  39. case IMAGETYPE_PNG :
  40. $src_img = imagecreatefrompng($src_file);
  41. break;
  42. case IMAGETYPE_GIF :
  43. $src_img = imagecreatefromgif($src_file);
  44. break;
  45. default:
  46. echo "载入图像错误!";
  47. exit();
  48. }
  49. /* 获取源图片的宽度和高度 */
  50. $src_width = imagesx($src_img);
  51. $src_height = imagesy($src_img);
  52. /* 计算剪切图片的宽度和高度 */
  53. $mid_width = ($src_width < $new_width) ? $src_width : $new_width;
  54. $mid_height = ($src_height < $new_height) ? $src_height : $new_height;
  55. /* 初始化源图片剪切裁剪的起始位置坐标 */
  56. switch ($pos * $type) {
  57. case 1://1为顶端居左
  58. $start_x = 0;
  59. $start_y = 0;
  60. break;
  61. case 2://2为顶端居中
  62. $start_x = ($src_width - $mid_width) / 2;
  63. $start_y = 0;
  64. break;
  65. case 3://3为顶端居右
  66. $start_x = $src_width - $mid_width;
  67. $start_y = 0;
  68. break;
  69. case 4://4为中部居左
  70. $start_x = 0;
  71. $start_y = ($src_height - $mid_height) / 2;
  72. break;
  73. case 5://5为中部居中
  74. $start_x = ($src_width - $mid_width) / 2;
  75. $start_y = ($src_height - $mid_height) / 2;
  76. break;
  77. case 6://6为中部居右
  78. $start_x = $src_width - $mid_width;
  79. $start_y = ($src_height - $mid_height) / 2;
  80. break;
  81. case 7://7为底端居左
  82. $start_x = 0;
  83. $start_y = $src_height - $mid_height;
  84. break;
  85. case 8://8为底端居中
  86. $start_x = ($src_width - $mid_width) / 2;
  87. $start_y = $src_height - $mid_height;
  88. break;
  89. case 9://9为底端居右
  90. $start_x = $src_width - $mid_width;
  91. $start_y = $src_height - $mid_height;
  92. break;
  93. default://随机
  94. break;
  95. }
  96. // 为剪切图像创建背景画板
  97. $mid_img = imagecreatetruecolor($mid_width, $mid_height);
  98. //拷贝剪切的图像数据到画板,生成剪切图像
  99. imagecopy($mid_img, $src_img, 0, 0, $start_x, $start_y, $mid_width, $mid_height);
  100. // 为裁剪图像创建背景画板
  101. $new_img = imagecreatetruecolor($new_width, $new_height);
  102. //拷贝剪切图像到背景画板,并按比例裁剪
  103. imagecopyresampled($new_img, $mid_img, 0, 0, 0, 0, $new_width, $new_height, $mid_width, $mid_height);
  104. /* 按格式保存为图片 */
  105. switch ($img_type) {
  106. case IMAGETYPE_JPEG :
  107. imagejpeg($new_img, $dst_file, 100);
  108. break;
  109. case IMAGETYPE_PNG :
  110. imagepng($new_img, $dst_file, 9);
  111. break;
  112. case IMAGETYPE_GIF :
  113. imagegif($new_img, $dst_file, 100);
  114. break;
  115. default:
  116. break;
  117. }
  118. }
  119. return ltrim($dst_file, '.');
  120. }

附件是一个有样例图片的测试demo,不过,这个函数不支持动态gif图片的裁剪缩放.

方法二,代码如下:

  1. <?php
  2. list($src_w,$src_h)=getimagesize($src_img); // 获取原图尺寸
  3. $dst_scale = $dst_h/$dst_w; //目标图像长宽比
  4. $src_scale = $src_h/$src_w; // 原图长宽比
  5. if($src_scale>=$dst_scale)
  6. {
  7. // 过高
  8. $w = intval($src_w);
  9. $h = intval($dst_scale*$w);
  10. $x = 0;
  11. $y = ($src_h - $h)/3;
  12. }
  13. else
  14. {
  15. // 过宽
  16. $h = intval($src_h);
  17. $w = intval($h/$dst_scale);
  18. $x = ($src_w - $w)/2;
  19. $y = 0;
  20. }
  21. // 剪裁
  22. $source=imagecreatefromjpeg($src_img);
  23. $croped=imagecreatetruecolor($w, $h);
  24. imagecopy($croped,$source,0,0,$x,$y,$src_w,$src_h);
  25. // 缩放
  26. $scale = $dst_w/$w;
  27. $target = imagecreatetruecolor($dst_w, $dst_h);
  28. $final_w = intval($w*$scale);
  29. $final_h = intval($h*$scale);
  30. imagecopysampled($target,$croped,0,0,0,0,$final_w,$final_h,$w,$h);
  31. // 保存
  32. $timestamp = time();
  33. imagejpeg($target, "$timestamp.jpg");
  34. imagedestroy($target);
  35. ?>

方法三:根据自定义的目标图,按目标图高宽比裁剪、缩放源图.传入参数,代码如下:

  1. $source_path string 源图路径
  2. $target_width integer 目标图宽度
  3. $target_height integer 目标图高度
  4. 支持图片类型: image/gif, image/jpeg, image/png.
  5. function imagecropper($source_path, $target_width, $target_height)
  6. {
  7. $source_info = getimagesize($source_path);
  8. $source_width = $source_info[0];
  9. $source_height = $source_info[1];
  10. $source_mime = $source_info['mime'];
  11. $source_ratio = $source_height / $source_width;
  12. $target_ratio = $target_height / $target_width;
  13. // 源图过高
  14. if ($source_ratio > $target_ratio)
  15. {
  16. $cropped_width = $source_width;
  17. $cropped_height = $source_width * $target_ratio;
  18. $source_x = 0;
  19. $source_y = ($source_height - $cropped_height) / 2;
  20. }
  21. // 源图过宽
  22. elseif ($source_ratio < $target_ratio)
  23. {
  24. $cropped_width = $source_height / $target_ratio;
  25. $cropped_height = $source_height;
  26. $source_x = ($source_width - $cropped_width) / 2;
  27. $source_y = 0;
  28. }
  29. // 源图适中
  30. else
  31. {
  32. $cropped_width = $source_width;
  33. $cropped_height = $source_height;
  34. $source_x = 0;
  35. $source_y = 0;
  36. }
  37. switch ($source_mime)
  38. {
  39. case 'image/gif':
  40. $source_image = imagecreatefromgif($source_path);
  41. break;
  42. case 'image/jpeg':
  43. $source_image = imagecreatefromjpeg($source_path);
  44. break;
  45. case 'image/png':
  46. $source_image = imagecreatefrompng($source_path);
  47. break;
  48. default:
  49. return false;
  50. break;
  51. }
  52. $target_image = imagecreatetruecolor($target_width, $target_height);
  53. $cropped_image = imagecreatetruecolor($cropped_width, $cropped_height);
  54. // 裁剪
  55. imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);
  56. // 缩放
  57. imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height);
  58. header('Content-Type: image/jpeg');
  59. imagejpeg($target_image);
  60. imagedestroy($source_image);
  61. imagedestroy($target_image);
  62. imagedestroy($cropped_image);
  63. }