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# Cache operations
[Reference](http://wiki.pchart.net/doc.pcache.pcache.html)
To speed up the process of creating charts, you can store them in the cache files
using the `CpChart\Cache` class. It will create two files - `cache.db` and
`index.db` in a dedicated directory (`app\cache` by default, relative to the library's
root directory), but you can change these using the `$settings` array passed
to the object's constructor.
Should you decide to use the cache component, the following sections describe
how you can do that.
## Using cache to store and retrieve chart data
```php
require '/path/to/your/vendor/autoload.php';
use CpChart\Cache;
use CpChart\Data;
use CpChart\Image;
// Standard chart creation
$data = new Data();
$data->addPoints([1, 3, 4, 3, 5]);
$image = new Image(700, 230, $data);
$image->setFontProperties(["FontName" => "Forgotte.ttf", "FontSize" => 11]);
$image->setGraphArea(60, 40, 670, 190);
$image->drawScale();
$image->drawSplineChart();
$image->drawGradientArea(0, 0, 700, 20, DIRECTION_VERTICAL, [
"StartR" => 0,
"StartG" => 0,
"StartB" => 0,
"EndR" => 50,
"EndG" => 50,
"EndB" => 50,
"Alpha" => 100
]);
$image->setFontProperties(["FontName" => "Silkscreen.ttf", "FontSize" => 6]);
$image->drawText(10, 13, "Test of the pCache class", ["R" => 255, "G" => 255, "B" => 255]);
// Create a cache object and store the chart in it
$cache = new Cache([
// Optionally change the default directory and file names
'CacheFolder' => 'path/to/your/cache/directory',
'CacheIndex' => 'name_of_the_index_file.db',
'CacheDB' => 'name_of_the_database_file.db'
]);
$chartHash = $cache->getHash($data); // Chart dentifier in the cache
$cache->writeToCache($chartHash, $image);
// Create an image file from cache
$cache->saveFromCache($chartHash, "example.drawCachedSpline.png");
// Directly stroke the saved data to the browser
$cache->strokeFromCache($chartHash)
// Automatically choose a way to output stored data
$cache->autoOutput($chartHash)
```
## Removal operations
```php
// Assuming we have $chartHash and $cache variables from the previous example
// This will remove the chart by it's hash
$cache->remove($chartHash);
// This will remove every chart in cache older than the amount of seconds passed
// into the argument's parameter
$cache->removeOlderThan(60 * 60 * 24); // Remove data older than 24 hours
// This flushes the cache completely and regenerates the .db files
$cache->flush();
```
There is also the function called `CpChart\Cache::dbRemoval(array $settings)`,
but it only covers two use cases - removing by chart hash and age. Since there
are dedicated methods for each of them (`remove` and `removeOlderThan`, respectively),
there is no reason to cover it any further.
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