Contents
Navigation
Home User Reference Other Resources


The QTPlgVideoPresentation class extends the properties and methods defined into its super class , to provide support for display and or playback of image data.







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.
Anyway, once a new instance of a class derived from QTPlgVideoPresentation is returned, it is good practice to check the class property to be sure that the new object can be used. See the QTPlgVideoPresentation’s validity conditions for more details.

determines whether or not the images will be displayed into the rectangle, contained into the specified area (see the class methods below), that best fits with the original dimensions of the video data. If you do not care to maintain the original video proportions, you can disable this property. By default, this property is set to true
determines the brigthness to apply to the data. The values can range from –100 to +100 with 0 meaning no change
determines the contrast to apply to the data. The values can range from –100 to +100 with 0 meaning no change
specifies the set of graphics transformations to apply to the data being displayed

(w as window, r as )
determines the region of the window where the image data have be displayed. If you pass nil into the r parameter, then will be used the entire window as drawing space. Note that the class will try to conserve the original proportions of image data when using the specified rectangle; that is, if the display region specified does not fit to the original dimensions of the image data (i.e. the region is a square while the images are rectangular), the images will be displayed into the rectangle, contained into the specified area, that best fits with the original images dimensions. If this behavior it is not satisfactorily for you, you can disable it by setting the class property to false. In order to create an offscreen data presentation session, simply set the w parameter to nil
returns nothing. Check the class property for errors
(context as canvas, [r as ])
determines the region of the window where the image data have to be displayed. If you omit the optional r parameter, then will be used the entire canvas as drawing space; otherwise, the data will be displayed into the region of canvas identified by the coordinates specified. Such a coordinates are intended to be expressed as local to the Canvas control. Note that the class will try to conserve the original proportions of image data when using the specified rectangle; that is, if the display region specified does not fit to the original dimensions of the image data (i.e. the region is a square while the images are rectangular), the images will be displayed into the rectangle, contained into the specified area, that best fits with the original images dimensions. If this behavior it is not satisfactorily for you, you can disable it by setting the class property to false
returns nothing. Check the class property for errors
(r as , [handleEvents as boolean=false])
use this function to puts the presentation in full–screen mode; the parameter r defines the area in which display the data. If you pass nil into this parameter the class will set the display boundaries to the entire available screen area. You can choose if handling the presentation by yourself or pass the control of it to the class instance by setting the optional handleEvents parameter; if you set this parameter to true, you can instruct the class to perform some specific action by using the following keyboard keys:
  • Escape: exits from full screen presentation
  • Down Arrow: starts or stops the data playback
  • Left Arrow: stops the data playback, then plays the sample data just before the current sample
  • Right Arrow: stops the data playback, then plays the sample data just after the current sample
  • Page Up: stops the data playback, then rewinds the presentation to the begin
  • Page Down: stops the data playback, then plays the last sample data
returns nothing. Check the class property for errors
()
use this function to terminate a full–screen session began by a call to the class method
returns nothing. Check the class property for errors
(gc as ) as picture
use this method to obtain a picture of the actually played image data; this data are modified according to the graphics transformations specified by the of the class instance passed into the gc parameter. If you want to obtain a picture of the source frame without any modification, pass nil into the gc parameter
returns a picture of the current frame if no error occurs, otherwise returns nil. Check the class property for errors
(gc as , format as ) as
use this method to obtain the raw data counterpart of the actually played image data; this data are modified according to the graphics transformations specified by the of the class instance passed into the gc parameter. If you want to obtain a picture of the source frame without any modification, pass nil into the gc parameter. The original pixel data will be converted according to the specifified
returns a object initialized with the data extracted from the current frame if no error occurs, otherwise returns nil. Check the class property for errors
(gc as ) as picture
use this method to obtain a picture of the actually played image data combining the graphics transformations specified by the of the class instance passed into the gc parameter along with the values of and in use. If you want to obtain a picture that reflects just the brightness and contrast values applied, set the gc parameter to nil
returns a picture of the current frame if no error occurs, otherwise returns nil. Check the class property for errors
(gc as , format as ) as
use this method to obtain the raw data counterpart of the actually played image data; this data are modified by combining the graphics transformations specified by the of the class instance passed into the gc parameter along with the values of and in use. If you want to obtain a picture that reflects just the brightness and contrast values applied, set the gc parameter to nil. The original pixel data will be converted according to the specifified
returns a object initialized with the data extracted from the current frame if no error occurs, otherwise returns nil. Check the class property for errors
()
use this method to force the re–draw of the image data onto the screen
returns nothing. Check the class property for errors
(dst as folderitem, params as , timeRange as )
use this function to "freeze" the current presentation status into the movie file specified by the dst parameter; if the destination file already exists, the method deletes and replaces it with a new one. This method adds a single video track to the destination movie and populates it with the data obtained by playing in sequence all of the images contained into the current presentation; of course, the resulting output will reflect every transformations defined for the presentation. You establish the characteristics of the data output and the details of the compression process by using the of the params parameter. Notably, the values of the , and indicated into the params object, will temporarly override those defined for the current presentation. Finally, you can determine if the entire presentation, or just a portion of it, has to be saved by setting the timeRange parameter appropriately. If you pass nil into this parameter, all of the presentation images are added to the new movie; otherwise, the method adds to the movie only the images falling into the interval defined by the and properties of the timeRange object
returns nothing. Check the class property for errors