Dynamic image processing - php (34), dynamic image processing php34_PHP tutorial

Dynamic image processing - php (34), dynamic image processing php34

1 Use of GD library in PHP

PHP is not limited to just producing HTML output, but can also create and manipulate image files in a variety of different formats. PHP provides some built-in image information functions, and you can also use the GD function library to create new images or process existing images. Currently the GD2 library supports JPEG, PNG and WBMP formats. But the GIF format is no longer supported.

• JPEG is the name of a compression standard commonly used to store photos or images with rich colors and color gradations. This format uses lossy compression.

• PNG is a portable web image that uses a lossless compression standard for images.

• WBMP is a file format specially designed for wireless communication devices. But it has not been widely used.

2 Image generation steps

Creating an image in PHP should complete the 4 steps shown below:
1. Create a background image (also called canvas), and subsequent operations will be based on this background image.
2. Draw an image outline or enter text on the background.
3. Output the final graphics
4. Release resources

<span><?<span>php
</span><span>//</span><span> 创建背景图像</span>
$height = <span>200</span><span>;
$width </span>= <span>200</span><span>;
$im </span>= ImageCreateTrueColor($width, $height); <span>//</span><span>建立空白背景</span>
$white = ImageColorAllocate ($im, <span>255</span>, <span>255</span>, <span>255</span>);<span>//</span><span>设置绘图颜色</span>
$blue = ImageColorAllocate ($im, <span>0</span>, <span>0</span>, <span>64</span><span>);
imageFill($im, </span><span>0</span>, <span>0</span>, $blue);<span>//</span><span>绘制背景</span>
imageLine($im, <span>0</span>, <span>0</span>, $width, $height, $white); <span>//</span><span>画线</span>
imageString($im, <span>4</span>, <span>50</span>, <span>150</span>, <span>'</span><span>Sales</span><span>'</span>, $white); <span>//</span><span>添加字串</span>
header(<span>'</span><span>Content-type: image/png</span><span>'</span><span>);
imagePng($im); </span><span>//</span><span>以PNG 格式将图像输出</span>
<span>imageDestroy($im);
</span>?></span>

3 Canvas Management

imagecreate--Create a new palette-based image

http://www.bkjia.com/PHPjc/1007363.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/1007363.htmlTechArticleDynamic image processing - php (34), dynamic image processing php34 1 The use of GD library in PHP PHP is not limited to only Generate HTML output, and can also create and manipulate image files in many different formats...