Perforce Chronicle supplies a set of drivers for commonly used image libraries, but
developers may want to create their own drivers.
A custom driver typically implements P4Cms_Image_Driver_Interface
and extends from P4Cms_Image_Driver_Abstract, which provides
infrastructure for image transformations and driver management, plus a uniform strategy for
invoking transformation methods: a transformation called 'transform' will
be invoked by calling the _transform() method.
For example, when a developer wants to create a new image driver using the
foo extension that implements the 'scale',
'sharpen' and 'rotate' transformations, the driver
class might look like this:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 | <?phpclass P4Cms_Image_Driver_Foo extends P4Cms_Image_Driver_Abstract{ /** * @var string The name of the extension required for this driver to function. */ protected $_requiredExtension = 'foo'; /** * @var array The list of transformations this driver implements. */ protected $_supportedTransforms = array( 'scale', 'sharpen', 'rotate' ); /** * Set the image data. * * @param string|null $data optional - image data * @return P4Cms_Image_Driver_Foo provides fluent interface */ public function setData($data = null) { // set image data return $this; } /** * Return binary image data. * * @param string $type optional - the image format (will return image data * in the same format as input if not provided) * @return string|null binary image data or null if no image data were set */ public function getData($type = null) { // early exit if there is no image data if (!$this->hasData()) { return null; } // get image data into $data return $data; } /** * Check if there is image data to operate with. * * @return bool true if there has been image data set, false otherwise. */ public function hasData() { // check if there is image data return $data ? true : false; } /** * Check if given image type is supported. * * @param string $type image type to check for * @return bool true if given image type is supported, false otherwise */ public function isSupportedType($type) { // check if image type is supported return $supported ? true : false; } /** * Scale the image to the given size. * * @param int $width the width in pixels * @param int $height the height in pixels */ protected function _scale($width, $height) { // implement image scaling } /** * Sharpen the image. */ protected function _sharpen() { // implement image sharpening } /** * Rotate the image. * * @param float $degrees the rotation angle */ protected function _rotate($degrees) { // implement image rotate } /** * Return image width in pixels. * * @return int image width in pixels */ protected function _getImageWidth() { // get image width return $width } /** * Return image height in pixels. * * @return int image height in pixels */ protected function _getImageHeight() { // get image height return $height; }} |
