adds support for Acorn GXR style “copy screen to bitmap” command sequence
this is supported on both VDU 23,27,1,n,0,0,0 to define bitmap n from the last two graphics cursor positions, using an 8-bit bitmap ID and also VDU 23,27,&21,n;0; using a 16-bit bitmap/buffer ID
these commands are compatible with the existing VDU 23,27,1 and VDU 23,27,&21 commands - the system can tell the difference as these variants require a zero “height” value
if the buffer specified already exists then it will be deleted/cleared before the new bitmap is created from the screen. the resultant bitmap data will be in vdp-gl’s Bitmap::Native format
the original Acorn command documentation specifies that a few more zeros should be sent. you can safely send additional zeros, as per Acorn’s documentation, as they will just be ignored.
it should be noted that VDU 23,27,&21 when pointing to an existing buffer to set it to be a bitmap also usually expects a format byte, but this isn’t required/supported/needed for copying screen to bitmap, i.e. this command variant requires one less byte to be sent
adds support for Acorn GXR style “copy screen to bitmap” command sequence
this is supported on both
VDU 23,27,1,n,0,0,0to define bitmapnfrom the last two graphics cursor positions, using an 8-bit bitmap ID and alsoVDU 23,27,&21,n;0;using a 16-bit bitmap/buffer IDthese commands are compatible with the existing
VDU 23,27,1andVDU 23,27,&21commands - the system can tell the difference as these variants require a zero “height” valueif the buffer specified already exists then it will be deleted/cleared before the new bitmap is created from the screen. the resultant bitmap data will be in vdp-gl’s
Bitmap::Nativeformatthe original Acorn command documentation specifies that a few more zeros should be sent. you can safely send additional zeros, as per Acorn’s documentation, as they will just be ignored.
it should be noted that
VDU 23,27,&21when pointing to an existing buffer to set it to be a bitmap also usually expects aformatbyte, but this isn’t required/supported/needed for copying screen to bitmap, i.e. this command variant requires one less byte to be sentrequires an updated/custom vdp-gl