Scrolling Viewports

[kevin]

 Scrolling Viewports

    The following shows a few different ways of creating a scrolling area in the screen.  


  Using Viewport to limit the draw area.

PlayBASIC Code: [Select]

   size=32

   //make a block
   pad=4
   boxc 0,0,size,size,true,$008000   
   boxc Pad,pad,size-pad,size-pad,true,$00ff00   
   boxc 0,0,size-1,size-1,false,$ffffff   
   getimage 1,0,0,size,size


   loadFont "arial",1,48


   Do
      c1=rgb(20,80,50)
      c2=rgb(82,40,20)
      ShadeBox 0,0,800,600,c1,c1,c2,c2


      ; screen Viewport to a reduce area of the screen
      ScreenViewport 100,100,700,500
      tileimage 1,xpos,ypos,false
      xpos=mod(xpos+1,size)
      ypos=mod(ypos+1,size)

      ; Restore to original size
      ScreenViewport 0,0,800,600
      centertext 400,10,"Scrolling Viewport"   
      sync   
   loop

 
  Using Image  to limit the draw area.

PlayBASIC Code: [Select]

   // Load the 
   loadFont "arial",1,48
   

   //make a block
   size=32
   pad=4
   boxc 0,0,size,size,true,$008000   
   boxc Pad,pad,size-pad,size-pad,true,$00ff00   
   boxc 0,0,size-1,size-1,false,$ffffff   
   getimage 1,0,0,size,size



   // Create image to represent the scrolling screen
   ScrollingScreen=NewImage(600,400)


   // main loop of program.
   
   Do
      c1=rgb(20,80,50)
      c2=rgb(82,40,20)
      ShadeBox 0,0,800,600,c1,c1,c2,c2


      ; screen Viewport to a reduce area of the screen
      rendertoimage ScrollingSCreen
      tileimage 1,xpos,ypos,false
      xpos=mod(xpos+1,size)
      ypos=mod(ypos+1,size)


      ; Restore rendering back to the screen
      rendertoscreen

      ; draw scrolling screen to the display
      drawimage ScrollingScreen,100,100,false

      ; display the heading message
      centertext 400,10,"Scrolling Using Images"   

      sync   
   loop