Paul Murrell wrote
>
> I think the problem is that I just failed to anticipate this situation
> (i.e., the current documentation and behaviour both assume xlim[1] <
> xlim[2] and ylim[1] < ylim[2]).
>
> Will take a look at where to apply a fix (EITHER allow the API to be
> more flexible [allow negative 'width' and 'height' and 'x' and 'y' to be
> other than left-bottom], which will require complicating the code in
> some devices OR keep the API fixed and complicate the graphics engine
> code instead). The rotation argument adds an interesting twist ...
>
> Thanks for the report!
>
> Paul
>
Thanks for the reply Paul!
This isn't too hard to handle at the device level. For example, all I had to
do to the tikzDevice was add a loop and some logic that re-ordered the
raster vector and re-positioned the coordinate anchor:
int i, j, index, target, row_offset = 0, col_offset = 0, row_trans = 1,
col_trans = 1;
if ( height < 0 ) {
/* Using these parameters, one can cause a loop to "count backwards" */
row_trans = -1;
row_offset = h - 1;
/*
* If a dimension is negative, the (x,y) coordinate no longer references
* the lower left corner of the image. We correct for this and then make
* sure the dimension is positive.
*/
y += height;
height = fabs(height);
}
if ( width < 0 ) {
col_trans = -1;
col_offset = w - 1;
x += width;
width = fabs(width);
}
for ( i = 0; i < h; ++i ) {
for ( j = 0; j < w; ++j ) {
target = i*w + j;
index = (row_trans*i + row_offset)*w + (col_trans*j + col_offset);
INTEGER(red_vec)[target] = R_RED(raster[index]);
INTEGER(green_vec)[target] = R_BLUE(raster[index]);
INTEGER(blue_vec)[target] = R_GREEN(raster[index]);
INTEGER(alpha_vec)[target] = R_ALPHA(raster[index]);
}
}
This gives the device the same behavior as the PDF device. So, the behavior
isn't too difficult to correct on the device end---I was just concerned by
the difference between documentation and behavior and wanted to make sure
the graphics engine was not expecting something different.
-Charlie
-----
Charlie Sharpsteen
Undergraduate-- Environmental Resources Engineering
Humboldt State University
--
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