(Advanced) PHP image processing technology-GD library

1. Enable GD extension

extension=php_gd2.dll

Apache restart

2. Example:

Scenario:

Make a 500×300 green picture

①Create canvas

Canvas, a kind of resource data. Image resources that can be manipulated.

Create a new canvas (new)

ImageCreate(width, height), create a canvas based on the palette.

imageCreateTrueColor(width, height); Create a true color canvas.

Create canvas based on image (open)

imageCreateFromJPEG(image address);

imageCreateFromPNG(image address);

imageCreateFromGIF(image address);

②Operation canvas

Assign color: If you need to use a certain color on the canvas, you should assign the color to the canvas first.

Use function:

Color identification = imageColorAllocate(canvas, R, G, B);

Color representation:

RGB

③Fill the canvas: Fill (replace) the filling points with consecutive points with the same color

Use the function:

imageFill(canvas, filling position x, filling position Y, color Logo) Complete

The position is managed using coordinates:

Origin: 0, 0, the upper left corner of the canvas.

To the right, the x-axis increases, and down the Y-axis increases.

Coordinates of the lower right corner: width-1, height-1

④Output canvas

Output the processed pattern information in the canvas.

Typical:

1Output to image file.

2Direct output.

Use function:

imagePNG(canvas[, file address]):

imageJPEG();

imageGIF();

If there is no second parameter, it means direct output.

Note: If it is output directly to the browser, you need to inform the browser that the type of response data should be a PNG format image:

Use the command Content-type;

a The canvas can be output multiple times in various formats

⑤Destroy canvas resources

imageDestroy()

Sample code:

<?php
//例如：制作500×300的绿色图片
$width=500;
$height=300;
//创建真彩色的画布
$img=imageCreateTrueColor($width,$height);
// var_dump($img);    //测试结果： resource(2) of type (gd)   $img是一个资源类型
//使用函数imageColorAllocate(画布，R，G，B)分配颜色，颜色的表示方式：R  G  B
$green=imageColorAllocate($img, 0x0, 0xff, 0x0);
//填充画布，原点：0，0,画布的左上角，imageFill(画布, 填充位置x， 填充位置Y，颜色标识)完成
imageFill($img,0,0,$green);
//输出画布，直接输出到当前路径下为图片文件，格式有PNG、JPEG、GIF
//imagePNG($img,&#39;./green.png&#39;);  //如果没有第二个参数，表示直接输出
//如果直接输出到浏览器，需要告知浏览器，响应数据的类型应该是PNG格式的图片：使用指令Content-type
header(&#39;Content-Type:image/png;&#39;);
imagePNG($img);
//注：一个画布可以输出多次，输出为各种格式
//销毁画布资源
imageDestroy($img);

Sample code:

<?php
//例如：制作500×300的绿色图片
$width=500;
$height=300;
//创建真彩色的画布
$img=imageCreateTrueColor($width,$height);
// var_dump($img);    //测试结果： resource(2) of type (gd)   $img是一个资源类型
//使用函数imageColorAllocate(画布，R，G，B)分配颜色，颜色的表示方式：R  G  B
$green=imageColorAllocate($img, 0x0, 0xff, 0x0);
//填充画布，原点：0，0,画布的左上角，imageFill(画布, 填充位置x， 填充位置Y，颜色标识)完成
imageFill($img,0,0,$green);
//输出画布，直接输出到当前路径下为图片文件，格式有PNG、JPEG、GIF
//imagePNG($img,&#39;./green.png&#39;);  //如果没有第二个参数，表示直接输出
//如果直接输出到浏览器，需要告知浏览器，响应数据的类型应该是PNG格式的图片：使用指令Content-type
header(&#39;Content-Type:image/png;&#39;);
imagePNG($img);
//注：一个画布可以输出多次，输出为各种格式
//销毁画布资源
imageDestroy($img);

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