294 lines
6.7 KiB
C++
294 lines
6.7 KiB
C++
/*
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* Copyright © 2022 Behdad Esfahbod
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*
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* This is part of HarfBuzz, a text shaping library.
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*
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* Permission is hereby granted, without written agreement and without
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* license or royalty fees, to use, copy, modify, and distribute this
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* software and its documentation for any purpose, provided that the
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* above copyright notice and the following two paragraphs appear in
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* all copies of this software.
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*
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* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
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* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
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* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
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* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
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* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
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* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*/
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#ifndef HB_PAINT_EXTENTS_HH
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#define HB_PAINT_EXTENTS_HH
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#include "hb.hh"
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#include "hb-paint.h"
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typedef struct hb_extents_t
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{
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hb_extents_t () {}
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hb_extents_t (float xmin, float ymin, float xmax, float ymax) :
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xmin (xmin), ymin (ymin), xmax (xmax), ymax (ymax) {}
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bool is_empty () const { return xmin >= xmax || ymin >= ymax; }
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bool is_void () const { return xmin > xmax; }
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void union_ (const hb_extents_t &o)
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{
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xmin = hb_min (xmin, o.xmin);
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ymin = hb_min (ymin, o.ymin);
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xmax = hb_max (xmax, o.xmax);
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ymax = hb_max (ymax, o.ymax);
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}
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void intersect (const hb_extents_t &o)
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{
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xmin = hb_max (xmin, o.xmin);
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ymin = hb_max (ymin, o.ymin);
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xmax = hb_min (xmax, o.xmax);
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ymax = hb_min (ymax, o.ymax);
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}
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void
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add_point (float x, float y)
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{
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if (unlikely (is_void ()))
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{
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xmin = xmax = x;
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ymin = ymax = y;
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}
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else
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{
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xmin = hb_min (xmin, x);
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ymin = hb_min (ymin, y);
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xmax = hb_max (xmax, x);
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ymax = hb_max (ymax, y);
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}
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}
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float xmin = 0.f;
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float ymin = 0.f;
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float xmax = -1.f;
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float ymax = -1.f;
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} hb_extents_t;
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typedef struct hb_transform_t
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{
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hb_transform_t () {}
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hb_transform_t (float xx, float yx,
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float xy, float yy,
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float x0, float y0) :
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xx (xx), yx (yx), xy (xy), yy (yy), x0 (x0), y0 (y0) {}
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void multiply (const hb_transform_t &o)
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{
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/* Copied from cairo, with "o" being "a" there and "this" being "b" there. */
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hb_transform_t r;
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r.xx = o.xx * xx + o.yx * xy;
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r.yx = o.xx * yx + o.yx * yy;
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r.xy = o.xy * xx + o.yy * xy;
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r.yy = o.xy * yx + o.yy * yy;
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r.x0 = o.x0 * xx + o.y0 * xy + x0;
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r.y0 = o.x0 * yx + o.y0 * yy + y0;
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*this = r;
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}
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void transform_distance (float &dx, float &dy) const
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{
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float new_x = xx * dx + xy * dy;
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float new_y = yx * dx + yy * dy;
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dx = new_x;
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dy = new_y;
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}
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void transform_point (float &x, float &y) const
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{
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transform_distance (x, y);
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x += x0;
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y += y0;
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}
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void transform_extents (hb_extents_t &extents) const
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{
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float quad_x[4], quad_y[4];
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quad_x[0] = extents.xmin;
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quad_y[0] = extents.ymin;
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quad_x[1] = extents.xmin;
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quad_y[1] = extents.ymax;
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quad_x[2] = extents.xmax;
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quad_y[2] = extents.ymin;
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quad_x[3] = extents.xmax;
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quad_y[3] = extents.ymax;
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extents = hb_extents_t {};
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for (unsigned i = 0; i < 4; i++)
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{
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transform_point (quad_x[i], quad_y[i]);
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extents.add_point (quad_x[i], quad_y[i]);
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}
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}
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float xx = 1.f;
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float yx = 0.f;
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float xy = 0.f;
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float yy = 1.f;
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float x0 = 0.f;
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float y0 = 0.f;
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} hb_transform_t;
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typedef struct hb_bounds_t
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{
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enum status_t {
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UNBOUNDED,
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BOUNDED,
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EMPTY,
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};
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hb_bounds_t (status_t status) : status (status) {}
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hb_bounds_t (const hb_extents_t &extents) :
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status (extents.is_empty () ? EMPTY : BOUNDED), extents (extents) {}
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void union_ (const hb_bounds_t &o)
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{
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if (o.status == UNBOUNDED)
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status = UNBOUNDED;
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else if (o.status == BOUNDED)
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{
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if (status == EMPTY)
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*this = o;
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else if (status == BOUNDED)
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extents.union_ (o.extents);
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}
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}
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void intersect (const hb_bounds_t &o)
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{
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if (o.status == EMPTY)
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status = EMPTY;
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else if (o.status == BOUNDED)
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{
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if (status == UNBOUNDED)
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*this = o;
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else if (status == BOUNDED)
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{
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extents.intersect (o.extents);
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if (extents.is_empty ())
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status = EMPTY;
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}
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}
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}
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status_t status;
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hb_extents_t extents;
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} hb_bounds_t;
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typedef struct hb_paint_extents_context_t hb_paint_extents_context_t;
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struct hb_paint_extents_context_t
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{
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hb_paint_extents_context_t ()
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{
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transforms.push (hb_transform_t{});
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clips.push (hb_bounds_t{hb_bounds_t::UNBOUNDED});
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groups.push (hb_bounds_t{hb_bounds_t::EMPTY});
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}
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hb_extents_t get_extents ()
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{
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return groups.tail().extents;
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}
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bool is_bounded ()
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{
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return groups.tail().status != hb_bounds_t::UNBOUNDED;
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}
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void push_transform (const hb_transform_t &trans)
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{
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hb_transform_t t = transforms.tail ();
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t.multiply (trans);
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transforms.push (t);
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}
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void pop_transform ()
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{
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transforms.pop ();
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}
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void push_clip (hb_extents_t extents)
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{
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/* Transform extents and push a new clip. */
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const hb_transform_t &t = transforms.tail ();
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t.transform_extents (extents);
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clips.push (hb_bounds_t {extents});
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}
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void pop_clip ()
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{
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clips.pop ();
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}
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void push_group ()
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{
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groups.push (hb_bounds_t {hb_bounds_t::EMPTY});
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}
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void pop_group (hb_paint_composite_mode_t mode)
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{
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const hb_bounds_t src_bounds = groups.pop ();
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hb_bounds_t &backdrop_bounds = groups.tail ();
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// https://learn.microsoft.com/en-us/typography/opentype/spec/colr#format-32-paintcomposite
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switch ((int) mode)
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{
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case HB_PAINT_COMPOSITE_MODE_CLEAR:
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backdrop_bounds.status = hb_bounds_t::EMPTY;
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break;
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case HB_PAINT_COMPOSITE_MODE_SRC:
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case HB_PAINT_COMPOSITE_MODE_SRC_OUT:
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backdrop_bounds = src_bounds;
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break;
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case HB_PAINT_COMPOSITE_MODE_DEST:
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case HB_PAINT_COMPOSITE_MODE_DEST_OUT:
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break;
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case HB_PAINT_COMPOSITE_MODE_SRC_IN:
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case HB_PAINT_COMPOSITE_MODE_DEST_IN:
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backdrop_bounds.intersect (src_bounds);
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break;
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default:
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backdrop_bounds.union_ (src_bounds);
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break;
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}
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}
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void paint ()
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{
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const hb_bounds_t &clip = clips.tail ();
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hb_bounds_t &group = groups.tail ();
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group.union_ (clip);
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}
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protected:
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hb_vector_t<hb_transform_t> transforms;
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hb_vector_t<hb_bounds_t> clips;
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hb_vector_t<hb_bounds_t> groups;
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};
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HB_INTERNAL hb_paint_funcs_t *
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hb_paint_extents_get_funcs ();
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#endif /* HB_PAINT_EXTENTS_HH */
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