/*************************************************************************
** PSPreviewHandler.cpp                                                 **
**                                                                      **
** This file is part of dvisvgm -- a fast DVI to SVG converter          **
** Copyright (C) 2005-2024 Martin Gieseking <martin.gieseking@uos.de>   **
**                                                                      **
** This program is free software; you can redistribute it and/or        **
** modify it under the terms of the GNU General Public License as       **
** published by the Free Software Foundation; either version 3 of       **
** the License, or (at your option) any later version.                  **
**                                                                      **
** This program is distributed in the hope that it will be useful, but  **
** WITHOUT ANY WARRANTY; without even the implied warranty of           **
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the         **
** GNU General Public License for more details.                         **
**                                                                      **
** You should have received a copy of the GNU General Public License    **
** along with this program; if not, see <http://www.gnu.org/licenses/>. **
*************************************************************************/

#include "PSInterpreter.hpp"
#include "PSPreviewHandler.hpp"

using namespace std;

PSPreviewHandler::PSPreviewHandler (PSInterpreter &psi) : _psi(psi) {
}


/** Activates this filter so that the PS code will be redirected through it if
 *  it's hooked into the PSInterpreter. */
void PSPreviewHandler::init () {
	// try to retrieve version string of preview package set in the PS header section
	if (_psi.executeRaw("SDict begin currentdict/preview@version known{preview@version}{0}ifelse end", 1))
		_version = _psi.rawData()[0];
	// check if tightpage option was set
	if (_version != "0" && _psi.executeRaw("SDict begin preview@tightpage end", 1))
		_tightpage = (_psi.rawData()[0] == "true");
	_boxExtents.clear();
}


/** Tries to extract the bounding box information from the PS operand stack.
    @return true on success. */
bool PSPreviewHandler::readDataFromStack () {
	if (!_tightpage)
		return false;

	// Read bounding box information pushed on the operand stack by the preview package.
	// It consists of 7 values in DVI units:
	// adj_left, adj_bottom, adj_right, adj_top, height, depth, width,
	// where the first 4 values are set by \PreviewBorder or \PreviewBbAdjust. They denote
	// the border adjustments to create additional space around the graphics.
	// The baseline of the tight box extends from (0,0) to (tight_width, 0).
	const char *getOperands =
		"count 7 sub neg dup 0 lt{pop 0}if{0}repeat\n"  // ensure 7 operands on the stack
		"7{dup type dup /integertype eq exch /realtype eq or not{pop 0}if cvi 7 1 roll} repeat";  // ensure integer operands
	_psi.executeRaw(getOperands, 7);
	_boxExtents.clear();
	for (const string &str: _psi.rawData())
		_boxExtents.push_back(stoi(str));
	return true;
}


/** Returns the bounding box defined by the preview package. */
bool PSPreviewHandler::getBoundingBox (BoundingBox &bbox) const {
	if (_boxExtents.size() < 7)
		return false;
	const double leftX = _boxExtents[0]*_dvi2bp;
	bbox = BoundingBox(leftX, -height(), width()+leftX, depth());
	return true;
}


/** Returns the box height in PS points, or -1 if no data was found or read yet. */
double PSPreviewHandler::height () const {
	return _boxExtents.size() > 4 ? (_boxExtents[4]+_boxExtents[3])*_dvi2bp : -1;
}


/** Returns the box depth in PS points, or -1 if no data was found or read yet. */
double PSPreviewHandler::depth () const {
	return _boxExtents.size() > 5 ? (_boxExtents[5]-_boxExtents[1])*_dvi2bp : -1;
}


/** Returns the box width in PS points, or -1 if no data was found or read yet. */
double PSPreviewHandler::width () const {
	return _boxExtents.size() > 6 ? (_boxExtents[6]+_boxExtents[2]-_boxExtents[0])*_dvi2bp : -1;
}