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Icons and Blocks

If you want to draw the Block at a new position, then add the new x,y-coordinates for the It left-hand corner, after the Block number.

The Amiga's screen is divided into segments known as "bit-planes", and Blocks are normally displayed using all the available screen bit-planes, which is a bit-pattern of %111111. Re-setting these bit-planes can create numerous special effects, and various settings are dealt with at the beginning of Chapter 6.2.

instruction: delete a screen Block
Del Block
Del Block number

To delete all new screen Blocks, the DEL BLOCK command is used. The memory these Blocks used is returned to the main program automatically. If you only want to get rid of a single Block, follow the command with that Block's identification number.

instruction: flip a Block horizontally
Hrev Block number

This command reverses any numbered Block, by flipping it over its own horizontal axis.

instruction: flip a Block vertically
Vrev Block number

Similarly, VREV BLOCK is used to flip a block over its own vertical axis.

Compacted blocks
If you need reminding about the screen compaction memory-saving techniques, please refer to SPACK and PACK, which are fully explained at the end of Chapter 6.2. The compaction system used for the following commands is designed for speed as opposed to efficiency. They save less memory than SPACK and PACK, but they are a lot faster!

instruction: save and compact a screen Block
Get Cblock number,x,y,width,height

The GET CBLOCK command is used to save and compact a rectangular area of graphics from the screen. These Blocks are often used to grab the area underneath dialogue boxes, so that after the dialogue has been completed, the screen can be rapidly restored to its original state.

Specify the Block number from 1 to 65535, followed by the x,y-coordinates of its top left-hand corner. Then define the Block by giving its width and height, in pixels. Note that the x- coordinate, and the width of the Block will be rounded to the nearest multiple of eight pixels.

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