In order to make the painting support more movement, four layers of containers are used in combination. . Image carrier class diagram. Carrier carrying relationship diagram The logic of container carrying is everywhere in life: biscuits are sealed into packaging bags, then packed together into boxes, boxes are loaded into transport vehicles, vehicles are on the earth, the earth is in the universe... When using containers to carry, it is necessary to specify a coordinate system for the container to determine the position relationship of the carried objects. For example, a bag holds biscuits and a cup holds water.
This kind of carrying is very intuitive. coordinate system, such lebanon dialing code as the longitude and latitude coordinate system of the earth. In the computer world, everything needs to be constructed manually, so all containers need to declare coordinate systems. From small values to large objects, modules, and applications, with the development of software, the tasks of direct memory coding are more handed over to computer software for automatic execution. The core framework logic of the drawing tool is sorted out.
4. Single coordinate system composition. Although it is common for containers to be packed layer by layer, the relationship between each container is not equal. For example, although biscuits are packaged in several layers, only the biscuits themselves are the ultimate carrier of nutrition. The purpose of all other containers such as plastic packaging, box packaging, box packaging, and car compartments is to facilitate the storage, trading, and transportation of biscuits. The status of these four packaging containers is like the significance of biscuits to box, box, and car compartment packaging. It is the core of the container.