IF you are familiar with the screen concepts set out in the last Chapter, this is where you make AMOS Professional screens come alive. This Chapter explains how to manipulate your screens, and we have provided ready-made demonstrations of the techniques on disc, complete with led notes in their listings.
Copying screens
Any rectangular part of a screen can be copied and moved on the current screen or to any other
screen, time and time again, at great speed. Copying between the "physical" and "logical"
screens is fully discussed in Chapter 7.2, along with detailed explanations of double buffering.
SCREEN COPY
instruction: copy an area of a screen
Screen Copy source number To destination number
Screen Copy source number,x1,y1,x2,y2 To destination number,x3,y3
Screen Copy source number,x1 ,y1 ,x2,y2 To destination number,x3,y3,mode
SCREEN COPY is the most important screen command of all. It can be used to achieve classic screen techniques like "wiping" from one screen to another, as well as providing all sorts of special effects. At its simplest level, use this command to copy the whole contents of one screen to another screen. Simply give the number of the source screen that holds the image to be copied, which can be a logical or physical screen. Then determine the number of the destination screen, which is where you want the image copied to. For example:
X> Screen Copy 1 To 2
Exact sections of screens can be copied by giving the coordinates of the top left-hand and bottom right-hand corners of the areas to be copied, followed by the number of the destination screen and the coordinates where the copy's top left-hand corner should be placed. If the destination screen number is omitted, the copied image will appear at the new coordinates on the current screen. For example:
X> Circle 50,50,10 : Wait 50 Screen Copy 0,20,20,70,70 To 0,100,100
Note that there are no limits to these coordinates, and any parts of the image that fall outside of the current visible screen area will be clipped automatically.
There is also an optional parameter which selects one of 255 possible blitter modes for the copying operation. These modes affect how the source and destination areas are combined together on the screen, and are set using a bit-pattern in the following format:
Mode Bit Source Bit Destination Bit 4 0 0 5 0 1 6 1 0 7 1 1