diff options
| author | Adrian Johnson <ajohnson@redneon.com> | 2008-03-18 22:29:59 +1030 |
|---|---|---|
| committer | Adrian Johnson <ajohnson@redneon.com> | 2008-03-20 18:15:10 +1030 |
| commit | 158b32b60bc7e0f6488383c1d4f83203ffe97c98 (patch) | |
| tree | 7e79f45f0b0768cadeccf4b439cafa367064b051 | |
| parent | 222041530cd5d7f1ef6b41ea1738bf395ef1678a (diff) | |
PDF: Reduce excess decimals in text position offsets
The numbers output in the TJ array for adjusting the horizontal
position of the next glyph are in 1/1000 of the text space
units. Rounding these numbers to an integer should still provide
sufficient precision.
We use the rounded numbers to update the text position in
pdf-operators so subsequent numbers in the TJ array will compensate
for the rounding error.
| -rw-r--r-- | src/cairo-pdf-operators.c | 26 |
1 files changed, 22 insertions, 4 deletions
diff --git a/src/cairo-pdf-operators.c b/src/cairo-pdf-operators.c index 0c7ec581..9c14d619 100644 --- a/src/cairo-pdf-operators.c +++ b/src/cairo-pdf-operators.c @@ -887,10 +887,28 @@ _cairo_pdf_operators_show_glyphs (cairo_pdf_operators_t *pdf_operators, } else { if (fabs((glyphs[i].x - Tm_x)/scaled_font->scale.xx) > GLYPH_POSITION_TOLERANCE) { double delta = glyphs[i].x - Tm_x; - - _cairo_output_stream_printf (word_wrap_stream, - "> %f <", - -1000.0*delta/scaled_font->scale.xx); + int rounded_delta; + + delta = -1000.0*delta/scaled_font->scale.xx; + /* As the delta is in 1/1000 of a unit of text + * space, rounding to an integer should still + * provide sufficient precision. We round the + * delta before adding to Tm_x so that we keep + * track of the accumulated rounding error in + * the PDF interpreter and compensate for it + * when calculating subsequent deltas. + */ + rounded_delta = _cairo_lround (delta); + if (rounded_delta != 0) { + _cairo_output_stream_printf (word_wrap_stream, + "> %d <", + rounded_delta); + } + + /* Convert the rounded delta back to cairo + * space before adding to the current text + * position. */ + delta = rounded_delta*scaled_font->scale.xx/-1000.0; Tm_x += delta; } _cairo_output_stream_printf (word_wrap_stream, |