What should you pay attention to when dynamically generating images in gif format? _PHP Tutorial

If you use
int imagecreatefromgif(string filename);
to take out a GIF format graphic and use it as a background or basic canvas sample to draw graphics on it, please note:
If there is no such file of pigments you will not be able to use.


As a solution, you can use
int imagecreate(int x_size, int y_size);
to create a completely empty graphic. Draw graphics on it. Use black as the transparent color.
The newly created graphic should be the same size and absolute position as the original graphic. Just place it above the original graphic.


Original graphic file


Empty file photo.php

Photo.php code:
Header("Content- type: image/gif");
$im = imagecreate(200,300);
$black = ImageColorAllocate($im, 0,0,0);
$red = ImageColorAllocate($im, 255, 0,0);
$blue = ImageColorAllocate($im, 0,0,255);

imagerectangle($im,100,200,150,200,$red);
imagestring($im,2,120,150,"aaaaaaaa ",$blue);

imagecolortransparent($im,$black);
//Use black as transparent color

ImageGif($im);
ImageDestroy($im ;



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