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How can I resize animated GIFs in PHP while preserving animation?
How can I resize animated GIFs in PHP while preserving animation?
Nov 07, 2024 pm 09:16 PM
Resizing Animated GIFs with Animation Preservation in PHP
Resizing animated GIFs while maintaining the animation can be achieved using external tools like ImageMagick or through a combination of GD library functions.
ImageMagick Method:
If you have access to ImageMagick, the following commands can resize an animated GIF:
system("convert big.gif -coalesce coalesce.gif");
system("convert -size 200x100 coalesce.gif -resize 200x10 small.gif");
GD Library Method:
For PHP users without ImageMagick access, resizing animated GIFs involves several steps:
1. Detect Image Type:
Determine if the image is an animated GIF using GD.
2. Split into Frames:
Separate the GIF into individual frames using a GD library or third-party class.
3. Resize Frames:
Resize each individual frame using GD library functions.
4. Recomposite Frames:
Reassemble the resized frames into a new animated GIF using GD or a specialized library.
Example Code:
// Get image
$sourceGif = imagecreatefromgif("big.gif");
// Determine if animated
if (gdImageAnimationLen($sourceGif) > 1) {
// Split into frames
$frames = $frames = gdImageSplitAnimation($sourceGif);
// Resize frames
$resizedFrames = [];
foreach ($frames as $frame) {
$resizedFrames[] = gdImageScale($frame, $newWidth, $newHeight);
}
// Recomposite GIF
$newGif = $newGif = gdImageCreateAnimatedGif() ;
foreach ($resizedFrames as $frame) {
gdImageAddGif($newGif, $frame);
}
// Output GIF
imagegif($newGif, "small.gif");
}
Note that this method may produce a larger file size due to the coalescing and deoptimization process. If performance is a concern, consider using ImageMagick instead.
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