RFXCOM RFXtrx433 Especificaciones descargar pdf (Pagina 71)

Chapter 4. Implementation 64

The internal structure of the scene menu is similar to the structure of the visualization menu,

except that no QHash containers were used, as the scenes contain usually less than 30 elements.

Only the handling of the background image was optimized in order to prevent lags between scene

changes. All scenes are saved in a memory based database as shown in ﬁgure 4.25.

name1: scene1

name2: scene2

nameN: sceneN

QHash<name, sceneStruct>

sceneStruct

string background_path

float background_scale

QList<elementStruct> list

elementStruct

int pos_x

int pos_y

string type

string name

Scene list

Figure 4.25.: The structure of the scene database.

The scene database is a single QHash list with scene names as keys and scene structures as values.

A scene structure is composed of a path to the background image, the scaling factor and a list of

element structures that contain the x-y-position within the background image, their device type

and their name. Whenever a scene is selected in the scene selection box, the corresponding scene

structure is loaded into the QGraphicsScene and rendered by a QGraphicsView class. The scene

menu is connected via two signals to the device manager class: a device state change notiﬁcation

and a database change notiﬁcation. Both signals will only cause single elements to be redrawn

in the current scene, which make scenes faster than the visualization menu, as the number of

displayed elements is smaller. The number of database accesses is low, as the accesses occur

primarily scene changes and the scenes usually only have a small number of elements. In order to

maintain the memory-based database, it is saved in a XML ﬁle when shutting down the node and

loaded when starting the node. The following code illustrates the scene database for the example

shown in listing B.2 on page 77. An example database is shown in appendix B on page 77.

1 2 ... 66 67 68 69 70 71 72 73 74 75 76 ... 94 95

Sin comentarios

RFXCOM RFXtrx433 Especificaciones Pagina 71