Contents
Navigation
Home User Reference Other Resources


The QTPlgCompressionDialog is an abstract class that defines base services for any class of the QTPlugin class hierarchy that use the services provided by the standard image–compression dialog.

Because the standard image–compression dialog is a component, the any subclass will use the Component Manager to open and close a connection to the component; QTPlugin developers do not worry about it, cause the QTPlgCompressionDialog classes take care about the details of opening and closing a connection to the standard image–compression dialog component.

You can use the QTPlgCompressionDialog class hierarchy to obtain compression parameters from the user (or set them by yourself) and to manage the process of compressing the images,video and audio. You can follow several ways to control the different steps involved into the compression process.

The simplest way is to use the standard image–compression dialog component dialog box. The dialog box presents a consistent interface to the user; the QTPlgCompressionDialog class hierarchy eliminates the need for you to worry about the details of managing this dialog box. Also, provided that the requirements are met, this class features the class method as well. Once you have collected the parameter information from the user, you can use the class to instruct the Image Compression Manager to perform the compression of data. Again, the class manages the details for you.

Alternatively, you can use the methods the class provides you with to examine or modify the parameters to be used during the compression process. This way allows you to perform the compression without using any user interface.
Whatever way you follow, the class allows you to store the compression parameters you have set into files and restore them later.







The class has not constructor at all (you can always use the Realbasic common constructor syntax, of course, but you will obtain an usless object). Its destructor, will be implicitly invoked every time one of its derived classes will be destroyed. The class destructor will also close the connection to the component in use if any.

specifies the active settings that will be applied to the compression process. The type of class that can be used to manage settings depends on the data you are going to compress. For this property accepts objects, for you have to provide instances of the class and, for , objects. In case of visual data compression, if you want to compress the entire source image, you should let the and properties set to 0 and the property to an empty rectangle
if you specify either a valid region of interest (the property) or a scale (by using the and properties) or both, the class will apply them during the compression using the following order: first will be used the roi to delimit the original image area to compress, then the resulting image will be scaled as appropriate
determines whether the dialog window includes a "best depth" entry in the pop-up menu for pixel depth. If you set this property to true, the component includes a "best depth" entry in the pop–up menu. If you set this property to false, the component does not include a "best depth" entry in the pop–up menu. The user must select a depth from among the other available choices. This property is not used by the derived class
determines whether the standard compression dialog is a movable or a stationary dialog
specifies a test image. The component uses this image to display the effect of the user’s image-compression settings. In this manner, the user can experiment with different settings and see the results of those settings immediately. This property is not used by the derived class