cache.md

Cache operations

Reference

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

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

// 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.