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better line merging

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This commit is contained in:
Lu Wang 2012-08-19 22:30:05 +02:00
parent 6ee3d2b949
commit 3cdde4bce7
1 changed files with 31 additions and 52 deletions
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83
src/HTMLRenderer/state.cc
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@ -182,73 +182,52 @@ void HTMLRenderer::check_state_change(GfxState * state)
// depends: rise & text position & transformation
if(need_recheck_position)
{
bool hope = true;
// do not bother with draw_ctm
if(_tm_equal(cur_ctm, old_ctm)) {
// nothing to do
}
else if (_tm_equal(cur_ctm, old_ctm, 4))
// try to transform the old origin under the new TM
/*
* OldTM * (draw_tx, draw_ty, 1)^T = CurTM * (draw_tx + dx, draw_ty + dy, 1)^T
*
* OldTM[4] = CurTM[0] * dx + CurTM[2] * dy + CurTM[4]
* OldTM[5] = CurTM[1] * dx + CurTM[3] * dy + CurTM[5]
*
* We just care if we can map the origin y to the same new y
* So just let dy = cur_y - old_y, and try to solve dx
*
* TODO, writing mode, set dx and solve dy
*/
double dy = cur_ty + cur_rise - draw_ty;
draw_ty += dy;
double tdx = old_ctm[4] - cur_ctm[4] - cur_ctm[2] * dy;
double tdy = old_ctm[5] - cur_ctm[5] - cur_ctm[3] * dy;
if(_equal(cur_ctm[0] * tdy, cur_ctm[1] * tdx))
{
// try harder,
// try to transform the old origin under the new TM
/*
* OldTM * (draw_tx, draw_ty, 1)^T = CurTM * (draw_tx + dx, draw_ty + dy, 1)^T
*
* OldTM[4] = CurTM[0] * dx + CurTM[2] * dy + CurTM[4]
* OldTM[5] = CurTM[1] * dx + CurTM[3] * dy + CurTM[5]
*
*/
double tdx = old_ctm[4] - cur_ctm[4];
double tdy = old_ctm[5] - cur_ctm[5];
double deter = cur_ctm[0] * cur_ctm[3] - cur_ctm[1] * cur_ctm[2];
if(abs(deter) > EPS)
{
//ok, only one solution
draw_tx += (cur_ctm[3]*tdx - cur_ctm[2]*tdy) / deter;
draw_ty += (-cur_ctm[1]*tdx + cur_ctm[0]*tdy) / deter;
}
if(abs(cur_ctm[0]) > EPS)
draw_tx += tdx / cur_ctm[0];
else if (abs(cur_ctm[1]) > EPS)
draw_tx += tdy / cur_ctm[1];
else
{
//TODO, writing mode?
//prefer the same line, so dy = 0
if(_equal(cur_ctm[0] * old_ctm[5], cur_ctm[1] * old_ctm[4]))
if((abs(tdx) < EPS) && (abs(tdy) < EPS))
{
// just compute dx
if(abs(cur_ctm[0]) > EPS)
draw_tx += old_ctm[4] / cur_ctm[0];
else if (abs(cur_ctm[1]) > EPS)
draw_tx += old_ctm[5] / cur_ctm[1];
else
{
// wo cur_ctm[0] == cur_ctm[1] == 0
// while the first 4 elements of cur/old_ctm are the same, but the last 2 are not
// so give up
hope = false;
}
}
// free
draw_tx = cur_tx;
}
else
{
hope = false;
// fail
new_line_status = max(new_line_status, LineStatus::DIV);
}
}
}
else
{
// ok, have to start a new line
hope = false;
}
// should use the draw_scale here
if(!(hope && (abs((cur_ty + cur_rise) - draw_ty) * draw_scale < param->v_eps)))
{
// no solution
new_line_status = max(new_line_status, LineStatus::DIV);
}
}
// letter space
// depends: draw_scale
if(all_changed || letter_space_changed)