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flutter/third_party/harfbuzz/refs/heads/variable-glyph-experiment/./src/hb-vector-paint-pdf.cc
blob: a9f365777e8590e05ec79525c6e2e17ee1041dcf [file] [edit]
/*
* Copyright © 2026 Behdad Esfahbod
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Author(s): Behdad Esfahbod
*/
#include "hb.hh"
#include "hb-vector-paint.hh"
#include "hb-vector-draw.hh"
#include "hb-paint.hh"
#include <math.h>
#include <stdio.h>
#ifdef HAVE_ZLIB
#include <zlib.h>
#endif
/* PDF paint backend for COLRv0/v1 color font rendering.
*
* Supports:
* - Solid colors with alpha (via ExtGState)
* - Glyph and rectangle clipping
* - Affine transforms
* - Groups (save/restore)
* - Linear gradients (PDF Type 2 axial shading)
* - Radial gradients (PDF Type 3 radial shading)
* - Sweep gradients (approximated via solid fallback)
*/
/* ---- PDF object collector ---- */
struct hb_pdf_obj_t
{
hb_vector_buf_t data;
};
/* Collects extra PDF objects (shadings, functions, ExtGState)
* during painting. Referenced from the content stream by name
* (e.g. /SH0, /GS0) and emitted at render time. */
static bool
hb_pdf_build_indexed_smask (hb_vector_buf_t *out,
const char *idat_data, unsigned idat_len,
unsigned width, unsigned height,
const uint8_t *trns, unsigned trns_len);
struct hb_pdf_resources_t
{
hb_vector_t<hb_pdf_obj_t> objects; /* extra objects, starting at id 5 */
hb_vector_buf_t extgstate_dict; /* /GS0 5 0 R /GS1 6 0 R ... */
hb_vector_buf_t shading_dict; /* /SH0 7 0 R ... */
hb_vector_buf_t xobject_dict; /* /Im0 8 0 R ... */
unsigned extgstate_count = 0;
unsigned shading_count = 0;
unsigned xobject_count = 0;
unsigned add_object (hb_vector_buf_t &&obj_data)
{
unsigned id = 5 + objects.length; /* objects 1-4 are fixed */
hb_pdf_obj_t obj;
obj.data = std::move (obj_data);
objects.push (std::move (obj));
return id;
}
/* Add ExtGState for fill opacity, return resource name index. */
unsigned add_extgstate_alpha (float alpha)
{
unsigned idx = extgstate_count++;
hb_vector_buf_t obj;
obj.append_str ("<< /Type /ExtGState /ca ");
obj.append_num (alpha, 4);
obj.append_str (" >>");
unsigned obj_id = add_object (std::move (obj));
extgstate_dict.append_str ("/GS");
extgstate_dict.append_unsigned (idx);
extgstate_dict.append_c (' ');
extgstate_dict.append_unsigned (obj_id);
extgstate_dict.append_str (" 0 R ");
return idx;
}
/* Add ExtGState for blend mode, return resource name index. */
unsigned add_extgstate_blend (const char *bm)
{
unsigned idx = extgstate_count++;
hb_vector_buf_t obj;
obj.append_str ("<< /Type /ExtGState /BM /");
obj.append_str (bm);
obj.append_str (" >>");
unsigned obj_id = add_object (std::move (obj));
extgstate_dict.append_str ("/GS");
extgstate_dict.append_unsigned (idx);
extgstate_dict.append_c (' ');
extgstate_dict.append_unsigned (obj_id);
extgstate_dict.append_str (" 0 R ");
return idx;
}
/* Add ExtGState with an SMask (soft mask) referencing a Form XObject
* that paints a DeviceGray shading. Returns the ExtGState resource index. */
unsigned add_extgstate_smask (unsigned alpha_shading_id,
float bbox_x, float bbox_y,
float bbox_w, float bbox_h,
unsigned precision)
{
/* Form XObject: transparency group painting the alpha shading. */
hb_vector_buf_t form_stream;
form_stream.append_str ("/SHa sh\n");
hb_vector_buf_t form;
form.append_str ("<< /Type /XObject /Subtype /Form\n");
form.append_str ("/BBox [");
form.append_num (bbox_x, precision);
form.append_c (' ');
form.append_num (bbox_y, precision);
form.append_c (' ');
form.append_num (bbox_x + bbox_w, precision);
form.append_c (' ');
form.append_num (bbox_y + bbox_h, precision);
form.append_str ("]\n/Group << /S /Transparency /CS /DeviceGray >>\n");
form.append_str ("/Resources << /Shading << /SHa ");
form.append_unsigned (alpha_shading_id);
form.append_str (" 0 R >> >>\n");
form.append_str ("/Length ");
form.append_unsigned (form_stream.length);
form.append_str (" >>\nstream\n");
form.append_len (form_stream.arrayZ, form_stream.length);
form.append_str ("endstream");
unsigned form_id = add_object (std::move (form));
/* ExtGState with luminosity soft mask. */
unsigned idx = extgstate_count++;
hb_vector_buf_t gs;
gs.append_str ("<< /Type /ExtGState\n");
gs.append_str ("/SMask << /Type /Mask /S /Luminosity /G ");
gs.append_unsigned (form_id);
gs.append_str (" 0 R >> >>");
unsigned gs_id = add_object (std::move (gs));
extgstate_dict.append_str ("/GS");
extgstate_dict.append_unsigned (idx);
extgstate_dict.append_c (' ');
extgstate_dict.append_unsigned (gs_id);
extgstate_dict.append_str (" 0 R ");
return idx;
}
/* Add a shading, return resource name index. */
unsigned add_shading (hb_vector_buf_t &&shading_data)
{
unsigned obj_id = add_object (std::move (shading_data));
return add_shading_by_id (obj_id);
}
/* Register an already-allocated object as a shading resource. */
unsigned add_shading_by_id (unsigned obj_id)
{
unsigned idx = shading_count++;
shading_dict.append_str ("/SH");
shading_dict.append_unsigned (idx);
shading_dict.append_c (' ');
shading_dict.append_unsigned (obj_id);
shading_dict.append_str (" 0 R ");
return idx;
}
/* Add an XObject image, return resource name index.
* idat_data/idat_len is the concatenated PNG IDAT payload (zlib data).
* colors is 1 (gray), 3 (RGB), or 4 (RGBA); for indexed, pass colors=1.
* plte/plte_len is the PLTE chunk data for indexed images (may be null). */
unsigned add_xobject_png_image (const char *idat_data, unsigned idat_len,
unsigned width, unsigned height,
unsigned colors, bool has_alpha,
const uint8_t *plte = nullptr,
unsigned plte_len = 0,
const uint8_t *trns = nullptr,
unsigned trns_len = 0)
{
unsigned idx = xobject_count++;
hb_vector_buf_t obj;
obj.append_str ("<< /Type /XObject /Subtype /Image\n");
obj.append_str ("/Width ");
obj.append_unsigned (width);
obj.append_str (" /Height ");
obj.append_unsigned (height);
obj.append_str ("\n/BitsPerComponent 8\n");
if (plte && plte_len >= 3)
{
/* Indexed color: /ColorSpace [/Indexed /DeviceRGB N <hex palette>] */
unsigned n_entries = plte_len / 3;
obj.append_str ("/ColorSpace [/Indexed /DeviceRGB ");
obj.append_unsigned (n_entries - 1);
obj.append_str (" <");
for (unsigned i = 0; i < n_entries * 3; i++)
{
obj.append_c ("0123456789ABCDEF"[plte[i] >> 4]);
obj.append_c ("0123456789ABCDEF"[plte[i] & 0xF]);
}
obj.append_str (">]\n");
}
else
{
obj.append_str ("/ColorSpace ");
unsigned color_channels = has_alpha ? colors - 1 : colors;
obj.append_str (color_channels == 1 ? "/DeviceGray" : "/DeviceRGB");
obj.append_c ('\n');
}
/* Build SMask for indexed images with tRNS transparency. */
unsigned smask_id = 0;
if (plte && trns && trns_len)
{
hb_vector_buf_t smask_stream;
if (hb_pdf_build_indexed_smask (&smask_stream, idat_data, idat_len,
width, height, trns, trns_len))
{
hb_vector_buf_t smask_obj;
smask_obj.append_str ("<< /Type /XObject /Subtype /Image\n");
smask_obj.append_str ("/Width ");
smask_obj.append_unsigned (width);
smask_obj.append_str (" /Height ");
smask_obj.append_unsigned (height);
smask_obj.append_str ("\n/ColorSpace /DeviceGray /BitsPerComponent 8\n");
smask_obj.append_str ("/Length ");
smask_obj.append_unsigned (smask_stream.length);
smask_obj.append_str (" >>\nstream\n");
smask_obj.append_len (smask_stream.arrayZ, smask_stream.length);
smask_obj.append_str ("\nendstream");
smask_id = add_object (std::move (smask_obj));
}
}
if (smask_id)
{
obj.append_str ("/SMask ");
obj.append_unsigned (smask_id);
obj.append_str (" 0 R\n");
}
obj.append_str ("/Filter /FlateDecode\n");
obj.append_str ("/DecodeParms << /Predictor 15 /Colors ");
obj.append_unsigned (colors);
obj.append_str (" /BitsPerComponent 8 /Columns ");
obj.append_unsigned (width);
obj.append_str (" >>\n");
obj.append_str ("/Length ");
obj.append_unsigned (idat_len);
obj.append_str (" >>\nstream\n");
obj.append_len (idat_data, idat_len);
obj.append_str ("\nendstream");
(void) has_alpha;
unsigned obj_id = add_object (std::move (obj));
xobject_dict.append_str ("/Im");
xobject_dict.append_unsigned (idx);
xobject_dict.append_c (' ');
xobject_dict.append_unsigned (obj_id);
xobject_dict.append_str (" 0 R ");
return idx;
}
};
/* Store resources pointer in the paint struct's defs buffer
* (repurposed — defs is unused for PDF). */
static hb_pdf_resources_t *
hb_pdf_get_resources (hb_vector_paint_t *paint)
{
if (!paint->defs.length)
{
/* First call: allocate and store. */
auto *res = (hb_pdf_resources_t *) hb_calloc (1, sizeof (hb_pdf_resources_t));
if (unlikely (!res)) return nullptr;
new (res) hb_pdf_resources_t ();
if (unlikely (!paint->defs.resize (sizeof (void *))))
{
res->~hb_pdf_resources_t ();
hb_free (res);
return nullptr;
}
memcpy (paint->defs.arrayZ, &res, sizeof (void *));
}
hb_pdf_resources_t *res;
memcpy (&res, paint->defs.arrayZ, sizeof (void *));
return res;
}
void
hb_vector_paint_pdf_free_resources (hb_vector_paint_t *paint)
{
if (paint->defs.length >= sizeof (void *))
{
hb_pdf_resources_t *res;
memcpy (&res, paint->defs.arrayZ, sizeof (void *));
if (res)
{
res->~hb_pdf_resources_t ();
hb_free (res);
}
}
paint->defs.clear ();
}
/* ---- helpers ---- */
/* Emit a glyph outline as PDF path operators into buf. */
static void
hb_pdf_emit_glyph_path (hb_vector_paint_t *paint,
hb_font_t *font,
hb_codepoint_t glyph,
hb_vector_buf_t *buf)
{
hb_vector_path_sink_t sink = {&paint->path, paint->get_precision (),
paint->x_scale_factor, paint->y_scale_factor};
paint->path.clear ();
hb_font_draw_glyph (font, glyph,
hb_vector_pdf_path_draw_funcs_get (),
&sink);
buf->append_len (paint->path.arrayZ, paint->path.length);
paint->path.clear ();
}
/* ---- paint callbacks ---- */
static void
hb_pdf_paint_push_transform (hb_paint_funcs_t *,
void *paint_data,
float xx, float yx,
float xy, float yy,
float dx, float dy,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
auto &body = paint->current_body ();
unsigned sprec = body.scale_precision ();
body.append_str ("q\n");
body.append_num (xx, sprec);
body.append_c (' ');
body.append_num (yx, sprec);
body.append_c (' ');
body.append_num (xy, sprec);
body.append_c (' ');
body.append_num (yy, sprec);
body.append_c (' ');
body.append_num (paint->sx (dx));
body.append_c (' ');
body.append_num (paint->sy (dy));
body.append_str (" cm\n");
}
static void
hb_pdf_paint_pop_transform (hb_paint_funcs_t *,
void *paint_data,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
paint->current_body ().append_str ("Q\n");
}
static void
hb_pdf_paint_fill_glyph (hb_paint_funcs_t *,
void *paint_data,
hb_codepoint_t glyph,
hb_font_t *font,
hb_bool_t,
hb_color_t c,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
float r = hb_color_get_red (c) / 255.f;
float g = hb_color_get_green (c) / 255.f;
float b = hb_color_get_blue (c) / 255.f;
float a = hb_color_get_alpha (c) / 255.f;
if (a < 1.f / 255.f)
return;
auto &body = paint->current_body ();
bool scoped = false;
/* Set alpha via ExtGState if needed, scoped so it does not leak
* into later paints. */
if (a < 1.f - 1.f / 512.f)
{
auto *res = hb_pdf_get_resources (paint);
if (res)
{
unsigned gs_idx = res->add_extgstate_alpha (a);
body.append_str ("q\n");
scoped = true;
body.append_str ("/GS");
body.append_unsigned (gs_idx);
body.append_str (" gs\n");
}
}
body.append_num (r, 4);
body.append_c (' ');
body.append_num (g, 4);
body.append_c (' ');
body.append_num (b, 4);
body.append_str (" rg\n");
hb_pdf_emit_glyph_path (paint, font, glyph, &body);
body.append_str ("f\n");
if (scoped)
body.append_str ("Q\n");
}
static void
hb_pdf_paint_push_clip_glyph (hb_paint_funcs_t *,
void *paint_data,
hb_codepoint_t glyph,
hb_font_t *font,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
auto &body = paint->current_body ();
body.append_str ("q\n");
hb_pdf_emit_glyph_path (paint, font, glyph, &body);
body.append_str ("W n\n");
}
static void
hb_pdf_paint_push_clip_rectangle (hb_paint_funcs_t *,
void *paint_data,
float xmin, float ymin,
float xmax, float ymax,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
auto &body = paint->current_body ();
body.append_str ("q\n");
body.append_num (paint->sx (xmin));
body.append_c (' ');
body.append_num (paint->sy (ymin));
body.append_c (' ');
body.append_num (paint->sx (xmax - xmin));
body.append_c (' ');
body.append_num (paint->sy (ymax - ymin));
body.append_str (" re W n\n");
}
static hb_draw_funcs_t *
hb_pdf_paint_push_clip_path_start (hb_paint_funcs_t *,
void *paint_data,
void **draw_data,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
{
*draw_data = nullptr;
return nullptr;
}
auto &body = paint->current_body ();
body.append_str ("q\n");
/* Stream path operators straight into the body; end() seals
* the path with "W n" to turn it into the clip region.
* Coordinates arrive in font-scale; the sink divides by
* scale_factor so they land in output space. */
paint->clip_path_sink = {&body, paint->get_precision (),
paint->x_scale_factor,
paint->y_scale_factor};
*draw_data = &paint->clip_path_sink;
return hb_vector_pdf_path_draw_funcs_get ();
}
static void
hb_pdf_paint_push_clip_path_end (hb_paint_funcs_t *,
void *paint_data,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
paint->current_body ().append_str ("W n\n");
}
static void
hb_pdf_paint_pop_clip (hb_paint_funcs_t *,
void *paint_data,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
paint->current_body ().append_str ("Q\n");
}
/* Paint a solid color, including alpha via ExtGState. */
static void
hb_pdf_paint_solid_color (hb_vector_paint_t *paint, hb_color_t c)
{
auto &body = paint->current_body ();
float r = hb_color_get_red (c) / 255.f;
float g = hb_color_get_green (c) / 255.f;
float b = hb_color_get_blue (c) / 255.f;
float a = hb_color_get_alpha (c) / 255.f;
if (a < 1.f / 255.f)
return;
/* Set alpha via ExtGState if needed. */
if (a < 1.f - 1.f / 512.f)
{
auto *res = hb_pdf_get_resources (paint);
if (res)
{
unsigned gs_idx = res->add_extgstate_alpha (a);
body.append_str ("/GS");
body.append_unsigned (gs_idx);
body.append_str (" gs\n");
}
}
/* Set fill color. */
body.append_num (r, 4);
body.append_c (' ');
body.append_num (g, 4);
body.append_c (' ');
body.append_num (b, 4);
body.append_str (" rg\n");
/* Paint a huge rect (will be clipped). */
body.append_str ("-32767 -32767 65534 65534 re f\n");
}
static void
hb_pdf_paint_color (hb_paint_funcs_t *,
void *paint_data,
hb_bool_t,
hb_color_t color,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
hb_pdf_paint_solid_color (paint, color);
}
/* Build an uncompressed alpha mask from indexed PNG IDAT data + tRNS.
* Decompresses IDAT, un-filters PNG rows, maps palette indices to alpha. */
static bool
hb_pdf_build_indexed_smask (hb_vector_buf_t *out,
const char *idat_data, unsigned idat_len,
unsigned width, unsigned height,
const uint8_t *trns, unsigned trns_len)
{
#ifndef HAVE_ZLIB
(void) out; (void) idat_data; (void) idat_len;
(void) width; (void) height; (void) trns; (void) trns_len;
return false;
#else
/* Guard the size arithmetic below against 32-bit overflow. width/height come
* from the attacker-controlled PNG IHDR; without this, (width + 1) * height or
* width * height can wrap and under-size buffers that are then indexed per
* pixel (raw + y * (width + 1), out->arrayZ[y * width + x]). */
unsigned raw_len, mask_len;
if (!width || !height ||
width == 0xFFFFFFFFu ||
hb_unsigned_mul_overflows (width + 1, height, &raw_len) ||
hb_unsigned_mul_overflows (width, height, &mask_len))
return false;
/* Decompress IDAT (zlib). */
/* raw_len = (width + 1) * height: 1 filter byte per row + width bytes. */
uint8_t *raw = (uint8_t *) hb_malloc (raw_len);
if (!raw) return false;
HB_SCOPE_GUARD (hb_free (raw));
z_stream stream = {};
stream.next_in = (Bytef *) idat_data;
stream.avail_in = idat_len;
stream.next_out = (Bytef *) raw;
stream.avail_out = raw_len;
if (inflateInit (&stream) != Z_OK)
return false;
int status = inflate (&stream, Z_FINISH);
unsigned long total_out = stream.total_out;
inflateEnd (&stream);
if (status != Z_STREAM_END || total_out != raw_len)
return false;
/* Un-filter and map to alpha. */
if (!out->resize (mask_len))
return false;
uint8_t *unfiltered = (uint8_t *) hb_malloc (width);
if (!unfiltered)
return false;
HB_SCOPE_GUARD (hb_free (unfiltered));
uint8_t *prev_unfiltered = (uint8_t *) hb_calloc (width, 1);
if (!prev_unfiltered)
return false;
HB_SCOPE_GUARD (hb_free (prev_unfiltered));
for (unsigned y = 0; y < height; y++)
{
uint8_t *row = raw + y * (width + 1);
uint8_t filter = row[0];
uint8_t *pixels = row + 1;
for (unsigned x = 0; x < width; x++)
{
uint8_t a = (x > 0) ? unfiltered[x - 1] : 0;
uint8_t b = prev_unfiltered[x];
uint8_t c = (x > 0) ? prev_unfiltered[x - 1] : 0;
uint8_t val = pixels[x];
switch (filter)
{
case 0: unfiltered[x] = val; break; /* None */
case 1: unfiltered[x] = val + a; break; /* Sub */
case 2: unfiltered[x] = val + b; break; /* Up */
case 3: unfiltered[x] = val + (uint8_t) (((unsigned) a + b) / 2); break; /* Average */
case 4: /* Paeth */
{
int p = (int) a + (int) b - (int) c;
int pa = abs (p - (int) a);
int pb = abs (p - (int) b);
int pc = abs (p - (int) c);
uint8_t pr = (pa <= pb && pa <= pc) ? a : (pb <= pc) ? b : c;
unfiltered[x] = val + pr;
break;
}
default: unfiltered[x] = val; break;
}
/* Map palette index to alpha. */
uint8_t idx = unfiltered[x];
out->arrayZ[y * width + x] = (idx < trns_len) ? trns[idx] : 0xFF;
}
/* Swap buffers. */
uint8_t *tmp = prev_unfiltered;
prev_unfiltered = unfiltered;
unfiltered = tmp;
}
return true;
#endif
}
/* Read a big-endian uint32 from a byte pointer. */
static inline uint32_t
hb_pdf_png_u32 (const uint8_t *p)
{
return ((uint32_t) p[0] << 24) | ((uint32_t) p[1] << 16) |
((uint32_t) p[2] << 8) | (uint32_t) p[3];
}
static hb_bool_t
hb_pdf_paint_image (hb_paint_funcs_t *,
void *paint_data,
hb_blob_t *image,
unsigned width,
unsigned height,
hb_tag_t format,
float slant HB_UNUSED,
hb_glyph_extents_t *extents,
void *)
{
if (format != HB_TAG ('p','n','g',' '))
return false;
if (!extents || !width || !height)
return false;
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return false;
auto *res = hb_pdf_get_resources (paint);
if (unlikely (!res))
return false;
unsigned len = 0;
const uint8_t *data = (const uint8_t *) hb_blob_get_data (image, &len);
if (!data || len < 8)
return false;
/* Verify PNG signature. */
static const uint8_t png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
if (hb_memcmp (data, png_sig, 8) != 0)
return false;
/* Parse PNG chunks: extract IHDR and concatenate IDAT payloads. */
unsigned png_w = 0, png_h = 0;
unsigned colors = 3; /* default RGB */
uint8_t color_type = 2;
bool has_alpha = false;
const uint8_t *plte_data = nullptr;
unsigned plte_len = 0;
const uint8_t *trns_data = nullptr;
unsigned trns_len = 0;
hb_vector_buf_t idat;
unsigned pos = 8;
/* Invariant: pos <= len (len >= 8 checked above). All bounds checks below
* are written to avoid 32-bit wrapping: a malicious chunk_len must not be
* able to wrap pos + 12 + chunk_len past the end of the buffer. */
while (len - pos >= 12)
{
uint32_t chunk_len = hb_pdf_png_u32 (data + pos);
uint32_t chunk_type = hb_pdf_png_u32 (data + pos + 4);
if (chunk_len > len - pos - 12)
break;
const uint8_t *chunk_data = data + pos + 8;
if (chunk_type == 0x49484452u) /* IHDR */
{
if (chunk_len < 13) return false;
png_w = hb_pdf_png_u32 (chunk_data);
png_h = hb_pdf_png_u32 (chunk_data + 4);
uint8_t bit_depth = chunk_data[8];
color_type = chunk_data[9];
if (bit_depth != 8) return false; /* only 8-bit supported */
switch (color_type)
{
case 0: colors = 1; has_alpha = false; break; /* Grayscale */
case 2: colors = 3; has_alpha = false; break; /* RGB */
case 3: colors = 1; has_alpha = false; break; /* Indexed */
case 4: colors = 2; has_alpha = true; break; /* Gray+Alpha */
case 6: colors = 4; has_alpha = true; break; /* RGBA */
default: return false;
}
}
else if (chunk_type == 0x504C5445u) /* PLTE */
{
plte_data = chunk_data;
plte_len = chunk_len;
}
else if (chunk_type == 0x74524E53u) /* tRNS */
{
trns_data = chunk_data;
trns_len = chunk_len;
}
else if (chunk_type == 0x49444154u) /* IDAT */
{
idat.append_len ((const char *) chunk_data, chunk_len);
}
else if (chunk_type == 0x49454E44u) /* IEND */
break;
pos += 12 + chunk_len;
}
if (!png_w || !png_h || !idat.length)
return false;
unsigned im_idx = res->add_xobject_png_image (idat.arrayZ, idat.length,
png_w, png_h,
colors, has_alpha,
plte_data, plte_len,
trns_data, trns_len);
/* Emit: save state, set CTM to map image (0,0)-(1,1) to extents, paint. */
auto &body = paint->current_body ();
body.append_str ("q\n");
/* Image space: (0,0) at bottom-left, (1,1) at top-right.
* We need to map to extents (x_bearing, y_bearing+height) .. (x_bearing+width, y_bearing).
* Since font coords are Y-up like PDF, y_bearing is the top. */
float ix = (float) extents->x_bearing;
float iy = (float) extents->y_bearing + (float) extents->height;
float iw = (float) extents->width;
float ih = (float) -extents->height; /* negative because image Y goes up but height is negative in extents */
body.append_num (paint->sx (iw));
body.append_str (" 0 0 ");
body.append_num (paint->sy (ih));
body.append_c (' ');
body.append_num (paint->sx (ix));
body.append_c (' ');
body.append_num (paint->sy (iy));
body.append_str (" cm\n");
body.append_str ("/Im");
body.append_unsigned (im_idx);
body.append_str (" Do\nQ\n");
return true;
}
/* ---- Gradient helpers ---- */
static bool
hb_pdf_gradient_needs_alpha (hb_array_t<const hb_color_stop_t> stops)
{
for (const auto &s : stops)
if (hb_color_get_alpha (s.color) != 255)
return true;
return false;
}
/* Build a PDF Type 2 (exponential interpolation) function for
* a single alpha stop pair (DeviceGray, scalar output). */
static void
hb_pdf_build_alpha_interpolation_function (hb_vector_buf_t *obj,
float a0, float a1)
{
obj->append_str ("<< /FunctionType 2 /Domain [0 1] /N 1\n");
obj->append_str ("/C0 [");
obj->append_num (a0, 4);
obj->append_str ("]\n/C1 [");
obj->append_num (a1, 4);
obj->append_str ("] >>");
}
/* Build a stitching function (Type 3) for the alpha channel of
* pre-populated paint->color_stops_scratch (already sorted+normalized). */
static unsigned
hb_pdf_build_alpha_gradient_function_from_stops (hb_pdf_resources_t *res,
hb_vector_paint_t *paint)
{
unsigned count = paint->color_stops_scratch.length;
if (count < 2)
{
float a = count ? hb_color_get_alpha (paint->color_stops_scratch.arrayZ[0].color) / 255.f : 1.f;
hb_vector_buf_t obj;
hb_pdf_build_alpha_interpolation_function (&obj, a, a);
return res->add_object (std::move (obj));
}
if (count == 2)
{
hb_vector_buf_t obj;
hb_pdf_build_alpha_interpolation_function (&obj,
hb_color_get_alpha (paint->color_stops_scratch.arrayZ[0].color) / 255.f,
hb_color_get_alpha (paint->color_stops_scratch.arrayZ[1].color) / 255.f);
return res->add_object (std::move (obj));
}
hb_vector_t<unsigned> sub_func_ids;
for (unsigned i = 0; i + 1 < count; i++)
{
hb_vector_buf_t sub;
hb_pdf_build_alpha_interpolation_function (&sub,
hb_color_get_alpha (paint->color_stops_scratch.arrayZ[i].color) / 255.f,
hb_color_get_alpha (paint->color_stops_scratch.arrayZ[i + 1].color) / 255.f);
sub_func_ids.push (res->add_object (std::move (sub)));
}
hb_vector_buf_t obj;
obj.append_str ("<< /FunctionType 3 /Domain [0 1]\n");
obj.append_str ("/Functions [");
for (unsigned i = 0; i < sub_func_ids.length; i++)
{
if (i) obj.append_c (' ');
obj.append_unsigned (sub_func_ids.arrayZ[i]);
obj.append_str (" 0 R");
}
obj.append_str ("]\n/Bounds [");
for (unsigned i = 1; i + 1 < count; i++)
{
if (i > 1) obj.append_c (' ');
obj.append_num (paint->color_stops_scratch.arrayZ[i].offset, 4);
}
obj.append_str ("]\n/Encode [");
for (unsigned i = 0; i + 1 < count; i++)
{
if (i) obj.append_c (' ');
obj.append_str ("0 1");
}
obj.append_str ("] >>");
return res->add_object (std::move (obj));
}
/* Build a PDF Type 2 (exponential interpolation) function for
* a single color stop pair. */
static void
hb_pdf_build_interpolation_function (hb_vector_buf_t *obj,
hb_color_t c0, hb_color_t c1)
{
obj->append_str ("<< /FunctionType 2 /Domain [0 1] /N 1\n");
obj->append_str ("/C0 [");
obj->append_num (hb_color_get_red (c0) / 255.f, 4);
obj->append_c (' ');
obj->append_num (hb_color_get_green (c0) / 255.f, 4);
obj->append_c (' ');
obj->append_num (hb_color_get_blue (c0) / 255.f, 4);
obj->append_str ("]\n/C1 [");
obj->append_num (hb_color_get_red (c1) / 255.f, 4);
obj->append_c (' ');
obj->append_num (hb_color_get_green (c1) / 255.f, 4);
obj->append_c (' ');
obj->append_num (hb_color_get_blue (c1) / 255.f, 4);
obj->append_str ("] >>");
}
/* Build a stitching function (Type 3) from pre-populated
* paint->color_stops_scratch (already sorted+normalized). */
static unsigned
hb_pdf_build_gradient_function_from_stops (hb_pdf_resources_t *res,
hb_vector_paint_t *paint)
{
unsigned count = paint->color_stops_scratch.length;
if (count < 2)
{
/* Single stop: constant function. */
hb_color_t c = count ? paint->color_stops_scratch.arrayZ[0].color
: HB_COLOR (0, 0, 0, 255);
hb_vector_buf_t obj;
hb_pdf_build_interpolation_function (&obj, c, c);
return res->add_object (std::move (obj));
}
/* Sort by offset. */
paint->color_stops_scratch.as_array ().qsort (
[] (const hb_color_stop_t &a, const hb_color_stop_t &b)
{ return (a.offset > b.offset) - (a.offset < b.offset); });
if (count == 2)
{
/* Two stops: single interpolation function. */
hb_vector_buf_t obj;
hb_pdf_build_interpolation_function (&obj,
paint->color_stops_scratch.arrayZ[0].color,
paint->color_stops_scratch.arrayZ[1].color);
return res->add_object (std::move (obj));
}
/* Multiple stops: create sub-functions and stitch. */
hb_vector_t<unsigned> sub_func_ids;
for (unsigned i = 0; i + 1 < count; i++)
{
hb_vector_buf_t sub;
hb_pdf_build_interpolation_function (&sub,
paint->color_stops_scratch.arrayZ[i].color,
paint->color_stops_scratch.arrayZ[i + 1].color);
sub_func_ids.push (res->add_object (std::move (sub)));
}
/* Stitching function (Type 3). */
hb_vector_buf_t obj;
obj.append_str ("<< /FunctionType 3 /Domain [0 1]\n");
/* Functions array. */
obj.append_str ("/Functions [");
for (unsigned i = 0; i < sub_func_ids.length; i++)
{
if (i) obj.append_c (' ');
obj.append_unsigned (sub_func_ids.arrayZ[i]);
obj.append_str (" 0 R");
}
obj.append_str ("]\n");
/* Bounds. */
obj.append_str ("/Bounds [");
for (unsigned i = 1; i + 1 < count; i++)
{
if (i > 1) obj.append_c (' ');
obj.append_num (paint->color_stops_scratch.arrayZ[i].offset, 4);
}
obj.append_str ("]\n");
/* Encode array. */
obj.append_str ("/Encode [");
for (unsigned i = 0; i + 1 < count; i++)
{
if (i) obj.append_c (' ');
obj.append_str ("0 1");
}
obj.append_str ("] >>");
return res->add_object (std::move (obj));
}
static void
hb_pdf_paint_linear_gradient (hb_paint_funcs_t *,
void *paint_data,
hb_color_line_t *color_line,
float x0, float y0,
float x1, float y1,
float x2 HB_UNUSED, float y2 HB_UNUSED,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
auto *res = hb_pdf_get_resources (paint);
if (unlikely (!res))
return;
/* Fetch, normalize stops to [0,1], and adjust coordinates. */
if (!paint->fetch_color_stops (color_line))
return;
hb_vector_t<hb_color_stop_t> &stops = paint->color_stops_scratch;
float mn, mx;
hb_paint_normalize_color_line (stops.arrayZ, stops.length, &mn, &mx);
float gx0 = x0 + mn * (x1 - x0);
float gy0 = y0 + mn * (y1 - y0);
float gx1 = x0 + mx * (x1 - x0);
float gy1 = y0 + mx * (y1 - y0);
unsigned func_id = hb_pdf_build_gradient_function_from_stops (res, paint);
hb_paint_extend_t extend = hb_color_line_get_extend (color_line);
const char *extend_str = (extend == HB_PAINT_EXTEND_PAD)
? "/Extend [true true]\n" : "";
/* Build Type 2 (axial) shading — color only. */
hb_vector_buf_t sh;
sh.append_str ("<< /ShadingType 2 /ColorSpace /DeviceRGB\n");
sh.append_str ("/Coords [");
sh.append_num (paint->sx (gx0));
sh.append_c (' ');
sh.append_num (paint->sy (gy0));
sh.append_c (' ');
sh.append_num (paint->sx (gx1));
sh.append_c (' ');
sh.append_num (paint->sy (gy1));
sh.append_str ("]\n/Function ");
sh.append_unsigned (func_id);
sh.append_str (" 0 R\n");
sh.append_str (extend_str);
sh.append_str (">>");
unsigned sh_idx = res->add_shading (std::move (sh));
auto &body = paint->current_body ();
bool needs_alpha = hb_pdf_gradient_needs_alpha (stops);
if (needs_alpha)
{
unsigned alpha_func_id = hb_pdf_build_alpha_gradient_function_from_stops (res, paint);
hb_vector_buf_t ash;
ash.append_str ("<< /ShadingType 2 /ColorSpace /DeviceGray\n");
ash.append_str ("/Coords [");
ash.append_num (paint->sx (gx0));
ash.append_c (' ');
ash.append_num (paint->sy (gy0));
ash.append_c (' ');
ash.append_num (paint->sx (gx1));
ash.append_c (' ');
ash.append_num (paint->sy (gy1));
ash.append_str ("]\n/Function ");
ash.append_unsigned (alpha_func_id);
ash.append_str (" 0 R\n");
ash.append_str (extend_str);
ash.append_str (">>");
unsigned alpha_sh_id = res->add_object (std::move (ash));
unsigned gs_idx = res->add_extgstate_smask (alpha_sh_id,
paint->sx (gx0), paint->sy (gy0),
paint->sx (gx1 - gx0), paint->sy (gy1 - gy0),
paint->get_precision ());
body.append_str ("/GS");
body.append_unsigned (gs_idx);
body.append_str (" gs\n");
}
body.append_str ("/SH");
body.append_unsigned (sh_idx);
body.append_str (" sh\n");
}
static void
hb_pdf_paint_radial_gradient (hb_paint_funcs_t *,
void *paint_data,
hb_color_line_t *color_line,
float x0, float y0, float r0,
float x1, float y1, float r1,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
auto *res = hb_pdf_get_resources (paint);
if (unlikely (!res))
return;
/* Fetch, normalize stops to [0,1], and adjust coordinates. */
if (!paint->fetch_color_stops (color_line))
return;
hb_vector_t<hb_color_stop_t> &stops = paint->color_stops_scratch;
float mn, mx;
hb_paint_normalize_color_line (stops.arrayZ, stops.length, &mn, &mx);
float gx0 = x0 + mn * (x1 - x0);
float gy0 = y0 + mn * (y1 - y0);
float gr0 = r0 + mn * (r1 - r0);
float gx1 = x0 + mx * (x1 - x0);
float gy1 = y0 + mx * (y1 - y0);
float gr1 = r0 + mx * (r1 - r0);
unsigned func_id = hb_pdf_build_gradient_function_from_stops (res, paint);
hb_paint_extend_t extend = hb_color_line_get_extend (color_line);
const char *extend_str = (extend == HB_PAINT_EXTEND_PAD)
? "/Extend [true true]\n" : "";
/* Build Type 3 (radial) shading — color only. */
hb_vector_buf_t sh;
sh.append_str ("<< /ShadingType 3 /ColorSpace /DeviceRGB\n");
sh.append_str ("/Coords [");
sh.append_num (paint->sx (gx0));
sh.append_c (' ');
sh.append_num (paint->sy (gy0));
sh.append_c (' ');
sh.append_num (paint->sx (gr0));
sh.append_c (' ');
sh.append_num (paint->sx (gx1));
sh.append_c (' ');
sh.append_num (paint->sy (gy1));
sh.append_c (' ');
sh.append_num (paint->sx (gr1));
sh.append_str ("]\n/Function ");
sh.append_unsigned (func_id);
sh.append_str (" 0 R\n");
sh.append_str (extend_str);
sh.append_str (">>");
unsigned sh_idx = res->add_shading (std::move (sh));
auto &body = paint->current_body ();
bool needs_alpha = hb_pdf_gradient_needs_alpha (stops);
if (needs_alpha)
{
unsigned alpha_func_id = hb_pdf_build_alpha_gradient_function_from_stops (res, paint);
hb_vector_buf_t ash;
ash.append_str ("<< /ShadingType 3 /ColorSpace /DeviceGray\n");
ash.append_str ("/Coords [");
ash.append_num (paint->sx (gx0));
ash.append_c (' ');
ash.append_num (paint->sy (gy0));
ash.append_c (' ');
ash.append_num (paint->sx (gr0));
ash.append_c (' ');
ash.append_num (paint->sx (gx1));
ash.append_c (' ');
ash.append_num (paint->sy (gy1));
ash.append_c (' ');
ash.append_num (paint->sx (gr1));
ash.append_str ("]\n/Function ");
ash.append_unsigned (alpha_func_id);
ash.append_str (" 0 R\n");
ash.append_str (extend_str);
ash.append_str (">>");
unsigned alpha_sh_id = res->add_object (std::move (ash));
/* BBox: enclosing square of the outer circle. */
float cx = (gr1 >= gr0) ? gx1 : gx0;
float cy = (gr1 >= gr0) ? gy1 : gy0;
float rr = hb_max (gr0, gr1);
unsigned gs_idx = res->add_extgstate_smask (alpha_sh_id,
paint->sx (cx - rr), paint->sy (cy - rr),
paint->sx (2 * rr), paint->sy (2 * rr),
paint->get_precision ());
body.append_str ("/GS");
body.append_unsigned (gs_idx);
body.append_str (" gs\n");
}
body.append_str ("/SH");
body.append_unsigned (sh_idx);
body.append_str (" sh\n");
}
/* Encode a 16-bit big-endian unsigned value into buf. */
static void
hb_pdf_encode_u16 (hb_vector_buf_t *buf, uint16_t v)
{
char bytes[2] = {(char) (v >> 8), (char) (v & 0xFF)};
buf->append_len (bytes, 2);
}
/* Encode a coordinate as 16-bit value relative to Decode range. */
static void
hb_pdf_encode_coord (hb_vector_buf_t *buf,
float val, float lo, float hi)
{
float t = (val - lo) / (hi - lo);
t = hb_clamp (t, 0.f, 1.f);
hb_pdf_encode_u16 (buf, (uint16_t) (t * 65535.f + 0.5f));
}
/* Encode RGB from hb_color_t as 3 bytes. */
static void
hb_pdf_encode_color_rgb (hb_vector_buf_t *buf, hb_color_t c)
{
char rgb[3] = {(char) hb_color_get_red (c),
(char) hb_color_get_green (c),
(char) hb_color_get_blue (c)};
buf->append_len (rgb, 3);
}
/* Encode alpha from hb_color_t as 1 byte (gray). */
static void
hb_pdf_encode_color_alpha (hb_vector_buf_t *buf, hb_color_t c)
{
char a = (char) hb_color_get_alpha (c);
buf->append_len (&a, 1);
}
/* Encode one Coons patch control point. */
static void
hb_pdf_encode_point (hb_vector_buf_t *buf,
float x, float y,
float xlo, float xhi,
float ylo, float yhi)
{
hb_pdf_encode_coord (buf, x, xlo, xhi);
hb_pdf_encode_coord (buf, y, ylo, yhi);
}
/* Emit one Coons patch sector into the mesh stream(s).
* Splits large arcs into sub-patches of max 90°.
* If alpha_mesh is non-null, emits a parallel DeviceGray
* patch with the alpha channel. */
static void
hb_pdf_add_sweep_patch (hb_vector_buf_t *mesh,
hb_vector_buf_t *alpha_mesh,
float cx, float cy,
float xlo, float xhi, float ylo, float yhi,
float a0, hb_color_t c0_in,
float a1, hb_color_t c1_in)
{
const float R = 32767.f;
const float eps = 0.5f;
const float MAX_SECTOR = (float) M_PI / 2.f;
int num_splits = (int) ceilf (fabsf (a1 - a0) / MAX_SECTOR);
if (num_splits < 1) num_splits = 1;
for (int s = 0; s < num_splits; s++)
{
float k0 = (float) s / num_splits;
float k1 = (float) (s + 1) / num_splits;
float sa0 = a0 + k0 * (a1 - a0);
float sa1 = a0 + k1 * (a1 - a0);
hb_color_t sc0 = hb_color_lerp (c0_in, c1_in, k0);
hb_color_t sc1 = hb_color_lerp (c0_in, c1_in, k1);
float da = sa1 - sa0;
float kappa = (4.f / 3.f) * tanf (da / 4.f);
float cos0 = cosf (sa0), sin0 = sinf (sa0);
float cos1 = cosf (sa1), sin1 = sinf (sa1);
float p0x = cx + eps * cos0, p0y = cy + eps * sin0;
float p3x = cx + R * cos0, p3y = cy + R * sin0;
float p6x = cx + R * cos1, p6y = cy + R * sin1;
float p9x = cx + eps * cos1, p9y = cy + eps * sin1;
/* Edge 1: p0→p3, radial straight line. */
float e1_1x = p0x + (p3x - p0x) / 3.f;
float e1_1y = p0y + (p3y - p0y) / 3.f;
float e1_2x = p0x + 2.f * (p3x - p0x) / 3.f;
float e1_2y = p0y + 2.f * (p3y - p0y) / 3.f;
/* Edge 2: p3→p6, outer arc. */
float e2_1x = p3x + kappa * R * (-sin0);
float e2_1y = p3y + kappa * R * ( cos0);
float e2_2x = p6x - kappa * R * (-sin1);
float e2_2y = p6y - kappa * R * ( cos1);
/* Edge 3: p6→p9, radial straight line. */
float e3_1x = p6x + (p9x - p6x) / 3.f;
float e3_1y = p6y + (p9y - p6y) / 3.f;
float e3_2x = p6x + 2.f * (p9x - p6x) / 3.f;
float e3_2y = p6y + 2.f * (p9y - p6y) / 3.f;
/* Edge 4: p9→p0, inner arc. */
float e4_1x = p9x + kappa * eps * (-sin1);
float e4_1y = p9y + kappa * eps * ( cos1);
float e4_2x = p0x - kappa * eps * (-sin0);
float e4_2y = p0y - kappa * eps * ( cos0);
mesh->append_c ('\0'); /* flag = 0, new patch */
hb_pdf_encode_point (mesh, p0x, p0y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, e1_1x, e1_1y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, e1_2x, e1_2y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, p3x, p3y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, e2_1x, e2_1y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, e2_2x, e2_2y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, p6x, p6y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, e3_1x, e3_1y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, e3_2x, e3_2y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, p9x, p9y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, e4_1x, e4_1y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (mesh, e4_2x, e4_2y, xlo, xhi, ylo, yhi);
hb_pdf_encode_color_rgb (mesh, sc0); /* inner start */
hb_pdf_encode_color_rgb (mesh, sc0); /* outer start */
hb_pdf_encode_color_rgb (mesh, sc1); /* outer end */
hb_pdf_encode_color_rgb (mesh, sc1); /* inner end */
if (alpha_mesh)
{
alpha_mesh->append_c ('\0');
hb_pdf_encode_point (alpha_mesh, p0x, p0y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, e1_1x, e1_1y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, e1_2x, e1_2y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, p3x, p3y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, e2_1x, e2_1y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, e2_2x, e2_2y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, p6x, p6y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, e3_1x, e3_1y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, e3_2x, e3_2y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, p9x, p9y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, e4_1x, e4_1y, xlo, xhi, ylo, yhi);
hb_pdf_encode_point (alpha_mesh, e4_2x, e4_2y, xlo, xhi, ylo, yhi);
hb_pdf_encode_color_alpha (alpha_mesh, sc0);
hb_pdf_encode_color_alpha (alpha_mesh, sc0);
hb_pdf_encode_color_alpha (alpha_mesh, sc1);
hb_pdf_encode_color_alpha (alpha_mesh, sc1);
}
}
}
/* Callback context + trampoline for hb_paint_sweep_gradient_tiles. */
struct hb_pdf_sweep_ctx_t {
hb_vector_buf_t *mesh;
hb_vector_buf_t *alpha_mesh;
float cx, cy, xlo, xhi, ylo, yhi;
};
static void
hb_pdf_sweep_emit_patch (float a0, hb_color_t c0,
float a1, hb_color_t c1,
void *user_data)
{
auto *ctx = (hb_pdf_sweep_ctx_t *) user_data;
hb_pdf_add_sweep_patch (ctx->mesh, ctx->alpha_mesh,
ctx->cx, ctx->cy,
ctx->xlo, ctx->xhi, ctx->ylo, ctx->yhi,
a0, c0, a1, c1);
}
static void
hb_pdf_paint_sweep_gradient (hb_paint_funcs_t *,
void *paint_data,
hb_color_line_t *color_line,
float cx, float cy,
float start_angle,
float end_angle,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
auto *res = hb_pdf_get_resources (paint);
if (unlikely (!res))
return;
/* Get and sort color stops. */
if (!paint->fetch_color_stops (color_line))
return;
hb_vector_t<hb_color_stop_t> &stops = paint->color_stops_scratch;
stops.as_array ().qsort (
[] (const hb_color_stop_t &a, const hb_color_stop_t &b)
{ return (a.offset > b.offset) - (a.offset < b.offset); });
hb_paint_extend_t extend = hb_color_line_get_extend (color_line);
const float R = 32767.f;
float scx = paint->sx (cx), scy = paint->sy (cy);
float xlo = scx - R - 1, xhi = scx + R + 1;
float ylo = scy - R - 1, yhi = scy + R + 1;
bool needs_alpha = hb_pdf_gradient_needs_alpha (stops);
hb_vector_buf_t mesh;
hb_vector_buf_t alpha_mesh;
mesh.alloc (256);
if (needs_alpha)
alpha_mesh.alloc (256);
hb_pdf_sweep_ctx_t ctx { &mesh, needs_alpha ? &alpha_mesh : nullptr,
scx, scy, xlo, xhi, ylo, yhi };
hb_paint_sweep_gradient_tiles (stops.arrayZ, stops.length, extend,
start_angle, end_angle,
hb_pdf_sweep_emit_patch, &ctx);
if (!mesh.length)
return;
auto hb_pdf_build_mesh_shading = [&] (hb_vector_buf_t &m,
const char *cs,
const char *decode_suffix) -> unsigned
{
hb_vector_buf_t sh;
sh.append_str ("<< /ShadingType 6 /ColorSpace /");
sh.append_str (cs);
sh.append_str ("\n/BitsPerCoordinate 16 /BitsPerComponent 8 /BitsPerFlag 8\n");
sh.append_str ("/Decode [");
sh.append_num (xlo, 2);
sh.append_c (' ');
sh.append_num (xhi, 2);
sh.append_c (' ');
sh.append_num (ylo, 2);
sh.append_c (' ');
sh.append_num (yhi, 2);
sh.append_str (decode_suffix);
sh.append_str ("]\n/Length ");
sh.append_unsigned (m.length);
sh.append_str (" >>\nstream\n");
sh.append_len (m.arrayZ, m.length);
sh.append_str ("\nendstream");
return res->add_object (std::move (sh));
};
unsigned sh_obj_id = hb_pdf_build_mesh_shading (mesh, "DeviceRGB",
" 0 1 0 1 0 1");
unsigned sh_idx = res->add_shading_by_id (sh_obj_id);
auto &body = paint->current_body ();
if (needs_alpha && alpha_mesh.length)
{
unsigned alpha_sh_id = hb_pdf_build_mesh_shading (alpha_mesh, "DeviceGray",
" 0 1");
unsigned gs_idx = res->add_extgstate_smask (alpha_sh_id,
xlo, ylo,
xhi - xlo, yhi - ylo,
paint->get_precision ());
body.append_str ("/GS");
body.append_unsigned (gs_idx);
body.append_str (" gs\n");
}
body.append_str ("/SH");
body.append_unsigned (sh_idx);
body.append_str (" sh\n");
}
static const char *
hb_pdf_blend_mode_name (hb_paint_composite_mode_t mode)
{
switch (mode)
{
case HB_PAINT_COMPOSITE_MODE_MULTIPLY: return "Multiply";
case HB_PAINT_COMPOSITE_MODE_SCREEN: return "Screen";
case HB_PAINT_COMPOSITE_MODE_OVERLAY: return "Overlay";
case HB_PAINT_COMPOSITE_MODE_DARKEN: return "Darken";
case HB_PAINT_COMPOSITE_MODE_LIGHTEN: return "Lighten";
case HB_PAINT_COMPOSITE_MODE_COLOR_DODGE: return "ColorDodge";
case HB_PAINT_COMPOSITE_MODE_COLOR_BURN: return "ColorBurn";
case HB_PAINT_COMPOSITE_MODE_HARD_LIGHT: return "HardLight";
case HB_PAINT_COMPOSITE_MODE_SOFT_LIGHT: return "SoftLight";
case HB_PAINT_COMPOSITE_MODE_DIFFERENCE: return "Difference";
case HB_PAINT_COMPOSITE_MODE_EXCLUSION: return "Exclusion";
case HB_PAINT_COMPOSITE_MODE_HSL_HUE: return "Hue";
case HB_PAINT_COMPOSITE_MODE_HSL_SATURATION: return "Saturation";
case HB_PAINT_COMPOSITE_MODE_HSL_COLOR: return "Color";
case HB_PAINT_COMPOSITE_MODE_HSL_LUMINOSITY: return "Luminosity";
/* Porter-Duff modes have no PDF blend-mode equivalent; approximate
* the two that have a plausible color-blend analog, and let the
* rest fall through to Normal (SRC_OVER). */
case HB_PAINT_COMPOSITE_MODE_PLUS: return "Screen";
case HB_PAINT_COMPOSITE_MODE_XOR: return "Difference";
case HB_PAINT_COMPOSITE_MODE_CLEAR:
case HB_PAINT_COMPOSITE_MODE_SRC:
case HB_PAINT_COMPOSITE_MODE_DEST:
case HB_PAINT_COMPOSITE_MODE_SRC_OVER:
case HB_PAINT_COMPOSITE_MODE_DEST_OVER:
case HB_PAINT_COMPOSITE_MODE_SRC_IN:
case HB_PAINT_COMPOSITE_MODE_DEST_IN:
case HB_PAINT_COMPOSITE_MODE_SRC_OUT:
case HB_PAINT_COMPOSITE_MODE_DEST_OUT:
case HB_PAINT_COMPOSITE_MODE_SRC_ATOP:
case HB_PAINT_COMPOSITE_MODE_DEST_ATOP:
default: return nullptr; /* Normal */
}
}
static void
hb_pdf_paint_push_group (hb_paint_funcs_t *,
void *paint_data,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
paint->current_body ().append_str ("q\n");
}
static void
hb_pdf_paint_push_group_for (hb_paint_funcs_t *,
void *paint_data,
hb_paint_composite_mode_t mode,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
auto &body = paint->current_body ();
body.append_str ("q\n");
const char *bm = hb_pdf_blend_mode_name (mode);
if (bm)
{
auto *res = hb_pdf_get_resources (paint);
if (likely (res))
{
unsigned gs_idx = res->add_extgstate_blend (bm);
body.append_str ("/GS");
body.append_unsigned (gs_idx);
body.append_str (" gs\n");
}
}
}
static void
hb_pdf_paint_pop_group (hb_paint_funcs_t *,
void *paint_data,
hb_paint_composite_mode_t mode HB_UNUSED,
void *)
{
auto *paint = (hb_vector_paint_t *) paint_data;
if (unlikely (!paint->ensure_initialized ()))
return;
paint->current_body ().append_str ("Q\n");
}
/* ---- lazy loader for paint funcs ---- */
static inline void free_static_pdf_paint_funcs ();
static struct hb_pdf_paint_funcs_lazy_loader_t
: hb_paint_funcs_lazy_loader_t<hb_pdf_paint_funcs_lazy_loader_t>
{
static hb_paint_funcs_t *create ()
{
hb_paint_funcs_t *funcs = hb_paint_funcs_create ();
hb_paint_funcs_set_push_transform_func (funcs, (hb_paint_push_transform_func_t) hb_pdf_paint_push_transform, nullptr, nullptr);
hb_paint_funcs_set_pop_transform_func (funcs, (hb_paint_pop_transform_func_t) hb_pdf_paint_pop_transform, nullptr, nullptr);
hb_paint_funcs_set_fill_glyph_func (funcs, (hb_paint_fill_glyph_func_t) hb_pdf_paint_fill_glyph, nullptr, nullptr);
hb_paint_funcs_set_push_clip_glyph_func (funcs, (hb_paint_push_clip_glyph_func_t) hb_pdf_paint_push_clip_glyph, nullptr, nullptr);
hb_paint_funcs_set_push_clip_rectangle_func (funcs, (hb_paint_push_clip_rectangle_func_t) hb_pdf_paint_push_clip_rectangle, nullptr, nullptr);
hb_paint_funcs_set_push_clip_path_start_func (funcs, (hb_paint_push_clip_path_start_func_t) hb_pdf_paint_push_clip_path_start, nullptr, nullptr);
hb_paint_funcs_set_push_clip_path_end_func (funcs, (hb_paint_push_clip_path_end_func_t) hb_pdf_paint_push_clip_path_end, nullptr, nullptr);
hb_paint_funcs_set_pop_clip_func (funcs, (hb_paint_pop_clip_func_t) hb_pdf_paint_pop_clip, nullptr, nullptr);
hb_paint_funcs_set_color_func (funcs, (hb_paint_color_func_t) hb_pdf_paint_color, nullptr, nullptr);
hb_paint_funcs_set_image_func (funcs, (hb_paint_image_func_t) hb_pdf_paint_image, nullptr, nullptr);
hb_paint_funcs_set_linear_gradient_func (funcs, (hb_paint_linear_gradient_func_t) hb_pdf_paint_linear_gradient, nullptr, nullptr);
hb_paint_funcs_set_radial_gradient_func (funcs, (hb_paint_radial_gradient_func_t) hb_pdf_paint_radial_gradient, nullptr, nullptr);
hb_paint_funcs_set_sweep_gradient_func (funcs, (hb_paint_sweep_gradient_func_t) hb_pdf_paint_sweep_gradient, nullptr, nullptr);
hb_paint_funcs_set_push_group_func (funcs, (hb_paint_push_group_func_t) hb_pdf_paint_push_group, nullptr, nullptr);
hb_paint_funcs_set_push_group_for_func (funcs, (hb_paint_push_group_for_func_t) hb_pdf_paint_push_group_for, nullptr, nullptr);
hb_paint_funcs_set_pop_group_func (funcs, (hb_paint_pop_group_func_t) hb_pdf_paint_pop_group, nullptr, nullptr);
hb_paint_funcs_make_immutable (funcs);
hb_atexit (free_static_pdf_paint_funcs);
return funcs;
}
} static_pdf_paint_funcs;
static inline void
free_static_pdf_paint_funcs ()
{
static_pdf_paint_funcs.free_instance ();
}
hb_paint_funcs_t *
hb_vector_paint_pdf_funcs_get ()
{
return static_pdf_paint_funcs.get_unconst ();
}
/* ---- render ---- */
hb_blob_t *
hb_vector_paint_render_pdf (hb_vector_paint_t *paint)
{
if (!paint->has_extents)
return nullptr;
if (!paint->group_stack.length ||
!paint->group_stack.arrayZ[0].length)
return nullptr;
hb_vector_buf_t &content = paint->group_stack.arrayZ[0];
hb_pdf_resources_t *res = hb_pdf_get_resources (paint);
float ex = paint->extents.x;
float ey = paint->extents.y;
float ew = paint->extents.width;
float eh = paint->extents.height;
unsigned num_extra = res ? res->objects.length : 0;
unsigned total_objects = 4 + num_extra; /* 1-based: 1..total_objects */
/* Build PDF. */
hb_vector_buf_t out;
hb_buf_recover_recycled (paint->recycled_blob, &out);
out.alloc (content.length + num_extra * 128 + 1024);
hb_vector_t<unsigned> offsets;
if (unlikely (!offsets.resize (total_objects)))
return nullptr;
out.append_str ("%PDF-1.4\n%\xC0\xC1\xC2\xC3\n");
/* Object 1: Catalog */
offsets.arrayZ[0] = out.length;
out.append_str ("1 0 obj\n<< /Type /Catalog /Pages 2 0 R >>\nendobj\n");
/* Object 2: Pages */
offsets.arrayZ[1] = out.length;
out.append_str ("2 0 obj\n<< /Type /Pages /Kids [3 0 R] /Count 1 >>\nendobj\n");
/* Object 3: Page */
offsets.arrayZ[2] = out.length;
out.append_str ("3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [");
out.append_num (ex);
out.append_c (' ');
out.append_num (ey);
out.append_c (' ');
out.append_num (ex + ew);
out.append_c (' ');
out.append_num (ey + eh);
out.append_str ("]\n/Contents 4 0 R");
/* Resources. */
bool has_resources = res &&
(res->extgstate_dict.length || res->shading_dict.length || res->xobject_dict.length);
if (has_resources)
{
out.append_str ("\n/Resources <<");
if (res->extgstate_dict.length)
{
out.append_str (" /ExtGState << ");
out.append_len (res->extgstate_dict.arrayZ, res->extgstate_dict.length);
out.append_str (">>");
}
if (res->shading_dict.length)
{
out.append_str (" /Shading << ");
out.append_len (res->shading_dict.arrayZ, res->shading_dict.length);
out.append_str (">>");
}
if (res->xobject_dict.length)
{
out.append_str (" /XObject << ");
out.append_len (res->xobject_dict.arrayZ, res->xobject_dict.length);
out.append_str (">>");
}
out.append_str (" >>");
}
out.append_str (" >>\nendobj\n");
/* Build content stream: optional background rect + glyph content. */
hb_vector_buf_t bg_prefix;
if (hb_color_get_alpha (paint->background))
{
float r = hb_color_get_red (paint->background) / 255.f;
float g = hb_color_get_green (paint->background) / 255.f;
float b = hb_color_get_blue (paint->background) / 255.f;
float a = hb_color_get_alpha (paint->background) / 255.f;
if (a < 1.f - 1.f / 512.f)
{
if (res)
{
unsigned gs_idx = res->add_extgstate_alpha (a);
bg_prefix.append_str ("/GS");
bg_prefix.append_unsigned (gs_idx);
bg_prefix.append_str (" gs\n");
}
}
bg_prefix.append_num (r, 4);
bg_prefix.append_c (' ');
bg_prefix.append_num (g, 4);
bg_prefix.append_c (' ');
bg_prefix.append_num (b, 4);
bg_prefix.append_str (" rg\n");
bg_prefix.append_num (ex);
bg_prefix.append_c (' ');
bg_prefix.append_num (ey);
bg_prefix.append_c (' ');
bg_prefix.append_num (ew);
bg_prefix.append_c (' ');
bg_prefix.append_num (eh);
bg_prefix.append_str (" re f\n");
}
unsigned stream_len = bg_prefix.length + content.length;
/* Object 4: Content stream */
offsets.arrayZ[3] = out.length;
out.append_str ("4 0 obj\n<< /Length ");
out.append_unsigned (stream_len);
out.append_str (" >>\nstream\n");
out.append_len (bg_prefix.arrayZ, bg_prefix.length);
out.append_len (content.arrayZ, content.length);
out.append_str ("endstream\nendobj\n");
/* Extra objects (functions, shadings, ExtGState). */
for (unsigned i = 0; i < num_extra; i++)
{
offsets.arrayZ[4 + i] = out.length;
out.append_unsigned (5 + i);
out.append_str (" 0 obj\n");
auto &obj = res->objects.arrayZ[i];
out.append_len (obj.data.arrayZ, obj.data.length);
out.append_str ("\nendobj\n");
}
/* Cross-reference table */
unsigned xref_offset = out.length;
out.append_str ("xref\n0 ");
out.append_unsigned (total_objects + 1);
out.append_str ("\n0000000000 65535 f \n");
for (unsigned i = 0; i < total_objects; i++)
{
char tmp[21];
snprintf (tmp, sizeof (tmp), "%010u 00000 n \n", offsets.arrayZ[i]);
out.append_len (tmp, 20);
}
/* Trailer */
out.append_str ("trailer\n<< /Size ");
out.append_unsigned (total_objects + 1);
out.append_str (" /Root 1 0 R >>\nstartxref\n");
out.append_unsigned (xref_offset);
out.append_str ("\n%%EOF\n");
hb_blob_t *blob = hb_buf_blob_from (&paint->recycled_blob, &out);
hb_vector_paint_clear (paint);
return blob;
}