(Advanced) PHP image processing technology-GD Library

(Advanced) PHP image processing technology-GD Library details. if you need it, refer to section 1. start GD extension.

Extension = php_gd2.dll

Apache restart

2. example:

Scenario:

Create a green image of 500x300

① Create a canvas

Canvas, a type of resource-based data. Operational image resources.

Create a canvas (new)

ImageCreate (width and height) to create a canvas based on the color palette.

ImageCreateTrueColor (width, height); create a true color canvas.

Create a canvas (open) based on the image)

ImageCreateFromJPEG (image address );

ImageCreateFromPNG (image address );

ImageCreateFromGIF (image address );

② Operating canvas

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

Function:

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

Color representation:

RGB

③ Fill the canvas: fill (replace) the filled points that are continuous and of the same color)

Function:

ImageFill (canvas, fill position x, fill position Y, color logo) complete

Coordinates are used for location management:

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

To the right, the X axis increases, and the downward Y axis increases.

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

④ Output canvas

Output the processed image information in the canvas.

Typical:

1. output to the image file.

2. direct output.

Function:

ImagePNG (canvas [, file address]):

ImageJPEG ();

ImageGIF ();

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

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

Use the command Content-type;

A canvas can be output multiple times and in various formats

⑤ Destroy canvas resources

ImageDestroy ()

Sample code:

 

Sample code:
  
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