IMAGE DRAWING/DISPLAYING DEVICE

摘要

A flag memory is provided which stores a flag indicating whether or not a corresponding pixel is in the initial state. When writing has been performed on an image memory by a drawing unit, a value of the flag of a corresponding pixel is changed from a first value indicating that the pixel is in the initial state to a second value indicating that the pixel is not in the initial state. When a display unit reads a pixel value from the image memory, a flag corresponding to the pixel is read from the flag memory, and if the flag still has the first value, an initial pixel value is supplied to the display unit, and otherwise, a pixel value read from the image memory is supplied to the display unit.

主权项

1. An image drawing/displaying device comprising:
an image memory configured to store data of an image to be displayed on a screen; an initial pixel value storage unit configured to store an initial pixel value; a flag memory configured to store a flag indicating whether or not a corresponding one of pixels of the screen is in an initial state; a drawing unit configured to write data of an image to be drawn to the image memory; a non-initialization unit configured to, when writing has been performed on the image memory, changes a value of the flag of a corresponding pixel in the flag memory from a first value indicating that the pixel is in the initial state to a second value indicating that the pixel is not in the initial state; a display unit configured to read a pixel value from the image memory to display an image on the screen; and a flag determination unit configured to, when the display unit reads a pixel value from the image memory, read the flag corresponding to the pixel from the flag memory to determine whether or not the pixel is in the initial state, and if the flag still has the first value, supply the initial pixel value stored in the initial pixel value storage unit to the display unit, and otherwise, read the pixel value from the image memory and supplying the pixel value to the display unit.