Abstract: An online electronic whiteboard content synchronization and sharing system includes an electronic whiteboard server and a plurality of clients, wherein an electronic whiteboard is installed in each client. The electronic whiteboard comprises a first layer, a second layer, a third layer and a fourth layer, which are sequentially stacked together, wherein the first layer is used to set a background color; the second layer is used to set a background picture; the third layer is used to draw received drawing data, which is transmitted from a network side; and the fourth layer is used to draw graphics on a local side. By means of the system, drawing data sent from network sides at the same time does not interfere with drawing data on a local side, such that a high real-time performance is achieved.

Abstract: Disclosed is a lamp having a dynamic starry sky effect. The lamp includes a lamp frame, and a first light source, optical integrating lenses, a roller beam splitter, a starry sky laser assembly and a starry sky mirror disc, where the optical integrating lenses are configured to focus light emitted by the first light source into strip-shaped light spots and transmit the strip-shaped light spots formed through focusing to the roller beam splitter at a front part in a shining direction; the roller beam splitter is configured to form the light into nonlinear dynamic strip-shaped light spots during rotation; the starry sky laser assembly includes a second light source; the starry sky mirror disc is configured to reflect light generated by the second light source; and the light dots and the strip-shaped light spots are superposed and combined together to form the dynamic starry sky effect.