PHP繪制漸變顏色圖片

使用范例如下,基本函數封裝在gd-gradient-fill.php中,

1. require_once('/path/to/gd-gradient-fill.php');
2. $image = new gd_gradient_fill($width,$height,$direction,$startcolor,$endcolor,$step);

1. integer $width
   Width of the image
2. integer $height
   Height of the image
3. string $direction
   The shape or direction of the gradient, which can be any of : vertical, horizontal, ellipse, ellipse2, circle, circle2, rectangle, diamond.
4. string $startcolor
   Gradient start color, 3 or 6 digit hexadecimal ("#ff0" or "#dd4578")
5. string $endcolor
   Gradient end color
6. Optional : $step
   Breaks the gradient smooth blending

下面是一些實例,顏色從#101040漸變到#a1a1ff, 漸變方向不同, 鼠標移動到圖片上可看到提示信息.

另外, 這個函數處理非矩形圖片一樣可以.

附函數源碼如下:

1. <?php
2. /*
3. Script Name: GD Gradient Fill
4. Script URI: http://planetozh.com/blog/my-projects/images-php-gd-gradient-fill/
5. Description: Creates a gradient fill of any shape (rectangle, ellipse, vertical, horizontal, diamond)
6. Author: Ozh
7. Version: 1.1
8. Author URI: http://planetozh.com/
9. */
11. /* Release history :
12. * 1.1
13. * - changed : more nicely packaged as a class
14. * - fixed : not displaying proper gradient colors with image dimension greater than 255 (because of a limitation in imagecolorallocate)
15. * - added : optional parameter 'step', more options for 'direction'
16. * 1.0
17. * - initial release
18. */
20. /* Usage :
21. *
22. * require_once('/path/to/gd-gradient-fill.php');
23. * $image = new gd_gradient_fill($width,$height,$direction,$startcolor,$endcolor,$step);
24. *
25. * Parameters :
26. * - width and height : integers, dimesions of your image.
27. * - direction : string, shape of the gradient.
28. * Can be : vertical, horizontal, rectangle (or square), ellipse, ellipse2, circle, circle2, diamond.
29. * - startcolor : string, start color in 3 or 6 digits hexadecimal.
30. * - endcolor : string, end color in 3 or 6 digits hexadecimal.
31. * - step : integer, optional, default to 0. Step that breaks the smooth blending effect.
32. * Returns a resource identifier.
33. *
34. * Examples :
35. *
36. * 1.
37. * require_once('/home/ozh/www/includes/gd-gradient-fill.php');
38. * $image = new gd_gradient_fill(200,200,'horizontal','#fff','#f00');
39. *
40. * 2.
41. * require_once('c:/iis/inet/include/gd-gradient-fill.php');
42. * $myimg = new gd_gradient_fill(80,20,'diamond','#ff0010','#303060');
43. *
44. */
47. // Test it :
48. // $image = new gd_gradient_fill(400,200,'ellipse','#f00','#000',0);
50. class gd_gradient_fill {
52. // Constructor. Creates, fills and returns an image
53. function gd_gradient_fill($w,$h,$d,$s,$e,$step=0) {
54. $this->width = $w;
55. $this->height = $h;
56. $this->direction = $d;
57. $this->startcolor = $s;
58. $this->endcolor = $e;
59. $this->step = intval(abs($step));
61. // Attempt to create a blank image in true colors, or a new palette based image if this fails
62. if (function_exists('imagecreatetruecolor')) {
63. $this->image = imagecreatetruecolor($this->width,$this->height);
64. } elseif (function_exists('imagecreate')) {
65. $this->image = imagecreate($this->width,$this->height);
66. } else {
67. die('Unable to create an image');
68. }
70. // Fill it
71. $this->fill($this->image,$this->direction,$this->startcolor,$this->endcolor);
73. // Show it
74. $this->display($this->image);
76. // Return it
77. return $this->image;
78. }
81. // Displays the image with a portable function that works with any file type
82. // depending on your server software configuration
83. function display ($im) {
84. if (function_exists("imagepng")) {
85. header("Content-type: image/png");
86. imagepng($im);
87. }
88. elseif (function_exists("imagegif")) {
89. header("Content-type: image/gif");
90. imagegif($im);
91. }
92. elseif (function_exists("imagejpeg")) {
93. header("Content-type: image/jpeg");
94. imagejpeg($im, "", 0.5);
95. }
96. elseif (function_exists("imagewbmp")) {
97. header("Content-type: image/vnd.wap.wbmp");
98. imagewbmp($im);
99. } else {
100. die("Doh ! No graphical functions on this server ?");
101. }
102. return true;
103. }
106. // The main function that draws the gradient
107. function fill($im,$direction,$start,$end) {
109. switch($direction) {
110. case 'horizontal':
111. $line_numbers = imagesx($im);
112. $line_width = imagesy($im);
113. list($r1,$g1,$b1) = $this->hex2rgb($start);
114. list($r2,$g2,$b2) = $this->hex2rgb($end);
115. break;
116. case 'vertical':
117. $line_numbers = imagesy($im);
118. $line_width = imagesx($im);
119. list($r1,$g1,$b1) = $this->hex2rgb($start);
120. list($r2,$g2,$b2) = $this->hex2rgb($end);
121. break;
122. case 'ellipse':
123. $width = imagesx($im);
124. $height = imagesy($im);
125. $rh=$height>$width?1:$width/$height;
126. $rw=$width>$height?1:$height/$width;
127. $line_numbers = min($width,$height);
128. $center_x = $width/2;
129. $center_y = $height/2;
130. list($r1,$g1,$b1) = $this->hex2rgb($end);
131. list($r2,$g2,$b2) = $this->hex2rgb($start);
132. imagefill($im, 0, 0, imagecolorallocate( $im, $r1, $g1, $b1 ));
133. break;
134. case 'ellipse2':
135. $width = imagesx($im);
136. $height = imagesy($im);
137. $rh=$height>$width?1:$width/$height;
138. $rw=$width>$height?1:$height/$width;
139. $line_numbers = sqrt(pow($width,2)+pow($height,2));
140. $center_x = $width/2;
141. $center_y = $height/2;
142. list($r1,$g1,$b1) = $this->hex2rgb($end);
143. list($r2,$g2,$b2) = $this->hex2rgb($start);
144. break;
145. case 'circle':
146. $width = imagesx($im);
147. $height = imagesy($im);
148. $line_numbers = sqrt(pow($width,2)+pow($height,2));
149. $center_x = $width/2;
150. $center_y = $height/2;
151. $rh = $rw = 1;
152. list($r1,$g1,$b1) = $this->hex2rgb($end);
153. list($r2,$g2,$b2) = $this->hex2rgb($start);
154. break;
155. case 'circle2':
156. $width = imagesx($im);
157. $height = imagesy($im);
158. $line_numbers = min($width,$height);
159. $center_x = $width/2;
160. $center_y = $height/2;
161. $rh = $rw = 1;
162. list($r1,$g1,$b1) = $this->hex2rgb($end);
163. list($r2,$g2,$b2) = $this->hex2rgb($start);
164. imagefill($im, 0, 0, imagecolorallocate( $im, $r1, $g1, $b1 ));
165. break;
166. case 'square':
167. case 'rectangle':
168. $width = imagesx($im);
169. $height = imagesy($im);
170. $line_numbers = max($width,$height)/2;
171. list($r1,$g1,$b1) = $this->hex2rgb($end);
172. list($r2,$g2,$b2) = $this->hex2rgb($start);
173. break;
174. case 'diamond':
175. list($r1,$g1,$b1) = $this->hex2rgb($end);
176. list($r2,$g2,$b2) = $this->hex2rgb($start);
177. $width = imagesx($im);
178. $height = imagesy($im);
179. $rh=$height>$width?1:$width/$height;
180. $rw=$width>$height?1:$height/$width;
181. $line_numbers = min($width,$height);
182. break;
183. default:
184. }
186. for ( $i = 0; $i < $line_numbers; $i=$i+1+$this->step ) {
187. // old values :
188. $old_r=$r;
189. $old_g=$g;
190. $old_b=$b;
191. // new values :
192. $r = ( $r2 - $r1 != 0 ) ? intval( $r1 + ( $r2 - $r1 ) * ( $i / $line_numbers ) ): $r1;
193. $g = ( $g2 - $g1 != 0 ) ? intval( $g1 + ( $g2 - $g1 ) * ( $i / $line_numbers ) ): $g1;
194. $b = ( $b2 - $b1 != 0 ) ? intval( $b1 + ( $b2 - $b1 ) * ( $i / $line_numbers ) ): $b1;
195. // if new values are really new ones, allocate a new color, otherwise reuse previous color.
196. // There's a "feature" in imagecolorallocate that makes this function
197. // always returns '-1' after 255 colors have been allocated in an image that was created with
198. // imagecreate (everything works fine with imagecreatetruecolor)
199. if ( "$old_r,$old_g,$old_b" != "$r,$g,$b")
200. $fill = imagecolorallocate( $im, $r, $g, $b );
201. switch($direction) {
202. case 'vertical':
203. imagefilledrectangle($im, 0, $i, $line_width, $i+$this->step, $fill);
204. break;
205. case 'horizontal':
206. imagefilledrectangle( $im, $i, 0, $i+$this->step, $line_width, $fill );
207. break;
208. case 'ellipse':
209. case 'ellipse2':
210. case 'circle':
211. case 'circle2':
212. imagefilledellipse ($im,$center_x, $center_y, ($line_numbers-$i)*$rh, ($line_numbers-$i)*$rw,$fill);
213. break;
214. case 'square':
215. case 'rectangle':
216. imagefilledrectangle ($im,$i*$width/$height,$i*$height/$width,$width-($i*$width/$height), $height-($i*$height/$width),$fill);
217. break;
218. case 'diamond':
219. imagefilledpolygon($im, array (
220. $width/2, $i*$rw-0.5*$height,
221. $i*$rh-0.5*$width, $height/2,
222. $width/2,1.5*$height-$i*$rw,
223. 1.5*$width-$i*$rh, $height/2 ), 4, $fill);
224. break;
225. default:
226. }
227. }
228. }
230. // #ff00ff -> array(255,0,255) or #f0f -> array(255,0,255)
231. function hex2rgb($color) {
232. $color = str_replace('#','',$color);
233. $s = strlen($color) / 3;
234. $rgb[]=hexdec(str_repeat(substr($color,0,$s),2/$s));
235. $rgb[]=hexdec(str_repeat(substr($color,$s,$s),2/$s));
236. $rgb[]=hexdec(str_repeat(substr($color,2*$s,$s),2/$s));
237. return $rgb;
238. }
239. }
240. ?>