NAME
BitMapScale -- Perform raster scaling on a bit map. (V36)
SYNOPSIS
BitMapScale(bitScaleArgs)
A0
void BitMapScale(struct BitScaleArgs *);Links: BitScaleArgs
FUNCTION
Scale a source bit map to a non-overlapping destination bit map.
INPUTS
bitScaleArgs - structure of parameters describing scale: bsa_SrcX, bsa_SrcY - origin of the source bits. bsa_SrcWidth, bsa_SrcHeight - number of bits to scale from in x and y. bsa_DestX, bsa_DestY - origin of the destination. bsa_DestWidth, bsa_DestHeight - resulting number of bits in x and y. NOTE: these values are set by this function. bsa_XSrcFactor:bsa_XDestFactor - equivalant to the ratio srcWidth:destWidth, but not necessarily the same numbers. Each must be in the range 1..16383. bsa_YSrcFactor:bsa_YDestFactor - equivalant to the ratio srcHeight:destHeight, but not necessarily the same numbers. Each must be in the range 1..16383. bsa_SrcBitMap - source of the bits to scale. bsa_DestBitMap - destination for the bits to scale. This had better be big enough! bsa_Flags - future scaling options. Set it to zero! bsa_XDDA, bsa_YDDA - for future use. Need not be set by user. bsa_Reserved1, bsa_Reserved2 - for future use. Need not be set.
RESULT The destWidth, destHeight fields are set by this function as described above.
NOTES o This function may use the blitter. o Overlapping source and destination bit maps are not supported. o No check is made to ensure destBitMap is big enough: use ScalerDiv to calculate a destination dimension.
BUGS o This function does not use the HighRes Agnus 'Big Blit' facility. You should not use XSrcFactor == XDestFactor, where SrcWidth or DestWidth > 1024.
o Also, the blitter is used when expanding in the Y direction. You should not expand in the Y direction if ((DestX & 0xf) + DestWidth) >= 1024 pixels. (Up to 1008 pixels is always safe).
SEE ALSO