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Diffstat (limited to 'bk_paper.c')
| -rw-r--r-- | bk_paper.c | 884 |
1 files changed, 884 insertions, 0 deletions
diff --git a/bk_paper.c b/bk_paper.c new file mode 100644 index 0000000..0bf3ce1 --- /dev/null +++ b/bk_paper.c @@ -0,0 +1,884 @@ +/* + * Paper printing pre-backend for Halibut. + * + * This module does all the processing common to both PostScript + * and PDF output: selecting fonts, line wrapping and page breaking + * in accordance with font metrics, laying out the contents and + * index pages, generally doing all the page layout. After this, + * bk_ps.c and bk_pdf.c should only need to do linear translations + * into their literal output format. + */ + +/* + * To be done: + * + * - Text wrapping is suspicious in both PS and PDF: the space + * adjust seems to be _approximately_ working, but not exactly. + * I bet some rounding error compensation is required. + * + * - set up contents section now we know what sections begin on + * which pages + * + * - do cross-reference rectangles + * + * - do PDF outline + * + * - all the missing features in text rendering (code paragraphs, + * list bullets, indentation, section heading styles) + * + * - index + * + * That should bring us to the same level of functionality that + * original-Halibut had, and the same in PDF plus the obvious + * interactive navigation features. After that, in future work: + * + * - linearised PDF, perhaps? + * + * - I'm uncertain of whether I need to include a ToUnicode CMap + * in each of my font definitions in PDF. Currently things (by + * which I mean cut and paste out of acroread) seem to be + * working fairly happily without it, but I don't know. + * + * - configurability + * + * - title pages + */ + +#include <assert.h> +#include <stdio.h> + +#include "halibut.h" +#include "paper.h" + +static font_data *make_std_font(font_list *fontlist, char const *name); +static void wrap_paragraph(para_data *pdata, word *words, + int w, int i1, int i2); +static page_data *page_breaks(line_data *first, line_data *last, + int page_height); +static void render_line(line_data *ldata, int left_x, int top_y); + +void *paper_pre_backend(paragraph *sourceform, keywordlist *keywords, + indexdata *idx) { + paragraph *p; + document *doc; + int indent, extra_indent, firstline_indent; + para_data *pdata; + line_data *ldata, *firstline, *lastline; + font_data *tr, *ti, *cr; + page_data *pages; + font_list *fontlist; + + /* + * FIXME: All these things ought to become configurable. + */ + int paper_width = 595 * 4096; + int paper_height = 841 * 4096; + int left_margin = 72 * 4096; + int top_margin = 72 * 4096; + int right_margin = 72 * 4096; + int bottom_margin = 108 * 4096; + int indent_list_bullet = 6 * 4096; + int indent_list = 24 * 4096; + int indent_quote = 18 * 4096; + int base_leading = 4096; + int base_para_spacing = 10 * 4096; + + int base_width = paper_width - left_margin - right_margin; + int page_height = paper_height - top_margin - bottom_margin; + + IGNORE(keywords); /* FIXME */ + IGNORE(idx); /* FIXME */ + IGNORE(indent_list_bullet); /* FIXME */ + + /* + * First, set up some font structures. + */ + fontlist = mknew(font_list); + fontlist->head = fontlist->tail = NULL; + tr = make_std_font(fontlist, "Times-Roman"); + ti = make_std_font(fontlist, "Times-Italic"); + cr = make_std_font(fontlist, "Courier"); + + /* + * Go through and break up each paragraph into lines. + */ + indent = 0; + firstline = lastline = NULL; + for (p = sourceform; p; p = p->next) { + p->private_data = NULL; + + switch (p->type) { + /* + * These paragraph types are either invisible or don't + * define text in the normal sense. Either way, they + * don't require wrapping. + */ + case para_IM: + case para_BR: + case para_Rule: + case para_Biblio: + case para_NotParaType: + case para_Config: + case para_VersionID: + case para_NoCite: + break; + + /* + * These paragraph types don't require wrapping, but + * they do affect the line width to which we wrap the + * rest of the paragraphs, so we need to pay attention. + */ + case para_LcontPush: + indent += indent_list; break; + case para_LcontPop: + indent -= indent_list; assert(indent >= 0); break; + case para_QuotePush: + indent += indent_quote; break; + case para_QuotePop: + indent -= indent_quote; assert(indent >= 0); break; + + /* + * This paragraph type is special. Process it + * specially. + */ + case para_Code: + /* FIXME */ + break; + + /* + * All of these paragraph types require wrapping in the + * ordinary way. So we must supply a set of fonts, a + * line width and auxiliary information (e.g. bullet + * text) for each one. + */ + case para_Chapter: + case para_Appendix: + case para_UnnumberedChapter: + case para_Heading: + case para_Subsect: + case para_Normal: + case para_BiblioCited: + case para_Bullet: + case para_NumberedList: + case para_DescribedThing: + case para_Description: + case para_Copyright: + case para_Title: + pdata = mknew(para_data); + + /* + * FIXME: Subsidiary switch on paragraph type to decide + * what font set to use for this paragraph. + */ + pdata->fonts[FONT_NORMAL] = tr; + pdata->sizes[FONT_NORMAL] = 12; + pdata->fonts[FONT_EMPH] = ti; + pdata->sizes[FONT_EMPH] = 12; + pdata->fonts[FONT_CODE] = cr; + pdata->sizes[FONT_CODE] = 12; + + /* + * FIXME: Also select an indentation level depending on + * the paragraph type (list paragraphs other than + * para_DescribedThing need extra indent). + * + * Perhaps at some point we might even arrange for the + * user to be able to request indented first lines in + * paragraphs. + */ + extra_indent = 0; + firstline_indent = 0; + + wrap_paragraph(pdata, p->words, base_width, + indent + firstline_indent, + indent + extra_indent); + + /* + * FIXME: Also find the auxiliary data for this + * paragraph. For para_Bullet it's a bullet; for + * para_NumberedList it's the number; for some section + * headings (depending on the style of section heading + * selected) it's the section number. + * + * Assign into pdata->first->aux_*. + */ + + p->private_data = pdata; + + /* + * Set the line spacing for each line in this paragraph. + */ + for (ldata = pdata->first; ldata; ldata = ldata->next) { + if (ldata == pdata->first) + ldata->space_before = base_para_spacing / 2; + else + ldata->space_before = base_leading / 2; + if (ldata == pdata->last) + ldata->space_after = base_para_spacing / 2; + else + ldata->space_after = base_leading / 2; + ldata->page_break = FALSE; + } + + /* + * FIXME: some kinds of section heading do require a + * page break before them. + */ + + break; + } + + /* + * Link all line structures together into a big list. + */ + if (p->private_data) { + pdata = (para_data *)p->private_data; + if (pdata->first) { + if (lastline) { + lastline->next = pdata->first; + pdata->first->prev = lastline; + } else { + firstline = pdata->first; + pdata->first->prev = NULL; + } + lastline = pdata->last; + } + } + } + + /* + * Now we have an enormous linked list of every line of text in + * the document. Break it up into pages. + */ + pages = page_breaks(firstline, lastline, page_height); + + /* + * Now we're ready to actually lay out the pages. We do this by + * looping over _paragraphs_, since we may need to track cross- + * references between lines and even across pages. + */ + for (p = sourceform; p; p = p->next) { + pdata = (para_data *)p->private_data; + + if (pdata) { + for (ldata = pdata->first; ldata; ldata = ldata->next) { + render_line(ldata, left_margin, paper_height - top_margin); + if (ldata == pdata->last) + break; + } + } + } + + doc = mknew(document); + doc->fonts = fontlist; + doc->pages = pages; + doc->paper_width = paper_width; + doc->paper_height = paper_height; + return doc; +} + +static font_encoding *new_font_encoding(font_data *font) +{ + font_encoding *fe; + int i; + + fe = mknew(font_encoding); + fe->next = NULL; + + if (font->list->tail) + font->list->tail->next = fe; + else + font->list->head = fe; + font->list->tail = fe; + + fe->font = font; + fe->free_pos = 0x21; + + for (i = 0; i < 256; i++) { + fe->vector[i] = NULL; + fe->indices[i] = -1; + fe->to_unicode[i] = 0xFFFF; + } + + return fe; +} + +static font_data *make_std_font(font_list *fontlist, char const *name) +{ + const int *widths; + int nglyphs; + font_data *f; + font_encoding *fe; + int i; + + widths = ps_std_font_widths(name); + if (!widths) + return NULL; + + for (nglyphs = 0; ps_std_glyphs[nglyphs] != NULL; nglyphs++); + + f = mknew(font_data); + + f->list = fontlist; + f->name = name; + f->nglyphs = nglyphs; + f->glyphs = ps_std_glyphs; + f->widths = widths; + f->subfont_map = mknewa(subfont_map_entry, nglyphs); + + /* + * Our first subfont will contain all of US-ASCII. This isn't + * really necessary - we could just create custom subfonts + * precisely as the whim of render_string dictated - but + * instinct suggests that it might be nice to have the text in + * the output files look _marginally_ recognisable. + */ + fe = new_font_encoding(f); + fe->free_pos = 0xA1; /* only the top half is free */ + f->latest_subfont = fe; + + for (i = 0; i < (int)lenof(f->bmp); i++) + f->bmp[i] = 0xFFFF; + + for (i = 0; i < nglyphs; i++) { + wchar_t ucs; + ucs = ps_glyph_to_unicode(f->glyphs[i]); + assert(ucs != 0xFFFF); + f->bmp[ucs] = i; + if (ucs >= 0x20 && ucs <= 0x7E) { + fe->vector[ucs] = f->glyphs[i]; + fe->indices[ucs] = i; + fe->to_unicode[ucs] = ucs; + f->subfont_map[i].subfont = fe; + f->subfont_map[i].position = ucs; + } else { + /* + * This character is not yet assigned to a subfont. + */ + f->subfont_map[i].subfont = NULL; + f->subfont_map[i].position = 0; + } + } + + return f; +} + +static int string_width(font_data *font, wchar_t const *string, int *errs) +{ + int width = 0; + + if (errs) + *errs = 0; + + for (; *string; string++) { + int index; + + index = font->bmp[(unsigned short)*string]; + if (index == 0xFFFF) { + if (errs) + *errs = 1; + } else { + width += font->widths[index]; + } + } + + return width; +} + +static int paper_width(void *vctx, word *word); + +struct paper_width_ctx { + int minspacewidth; + para_data *pdata; +}; + +static int paper_width_list(void *vctx, word *text, word *end) { + int w = 0; + while (text) { + w += paper_width(vctx, text); + if (text == end) + break; + text = text->next; + } + return w; +} + +static int paper_width(void *vctx, word *word) +{ + struct paper_width_ctx *ctx = (struct paper_width_ctx *)vctx; + int style, type, findex, width, errs; + wchar_t *str; + + switch (word->type) { + case word_HyperLink: + case word_HyperEnd: + case word_UpperXref: + case word_LowerXref: + case word_XrefEnd: + case word_IndexRef: + return 0; + } + + style = towordstyle(word->type); + type = removeattr(word->type); + + findex = (style == word_Normal ? FONT_NORMAL : + style == word_Emph ? FONT_EMPH : + FONT_CODE); + + if (type == word_Normal) { + str = word->text; + } else if (type == word_WhiteSpace) { + if (findex != FONT_CODE) + return ctx->minspacewidth; + else + str = L" "; + } else /* if (type == word_Quote) */ { + if (word->aux == quote_Open) + str = L"\x2018"; /* FIXME: configurability! */ + else + str = L"\x2019"; /* FIXME: configurability! */ + } + + width = string_width(ctx->pdata->fonts[findex], str, &errs); + + if (errs && word->alt) + return paper_width_list(vctx, word->alt, NULL); + else + return ctx->pdata->sizes[findex] * width; +} + +static void wrap_paragraph(para_data *pdata, word *words, + int w, int i1, int i2) +{ + wrappedline *wrapping, *p; + int spacewidth; + struct paper_width_ctx ctx; + int line_height; + + /* + * We're going to need to store the line height in every line + * structure we generate. + */ + { + int i; + line_height = 0; + for (i = 0; i < NFONTS; i++) + if (line_height < pdata->sizes[i]) + line_height = pdata->sizes[i]; + line_height *= 4096; + } + + spacewidth = (pdata->sizes[FONT_NORMAL] * + string_width(pdata->fonts[FONT_NORMAL], L" ", NULL)); + if (spacewidth == 0) { + /* + * A font without a space?! Disturbing. I hope this never + * comes up, but I'll make a random guess anyway and set my + * space width to half the point size. + */ + spacewidth = pdata->sizes[FONT_NORMAL] * 4096 / 2; + } + + /* + * I'm going to set the _minimum_ space width to 3/5 of the + * standard one, and use the standard one as the optimum. + */ + ctx.minspacewidth = spacewidth * 3 / 5; + ctx.pdata = pdata; + + wrapping = wrap_para(words, w - i1, w - i2, paper_width, &ctx, spacewidth); + + /* + * Having done the wrapping, we now concoct a set of line_data + * structures. + */ + pdata->first = pdata->last = NULL; + + for (p = wrapping; p; p = p->next) { + line_data *ldata; + word *wd; + int len, wid, spaces; + + ldata = mknew(line_data); + + ldata->pdata = pdata; + ldata->first = p->begin; + ldata->last = p->end; + ldata->line_height = line_height; + + ldata->xpos = (p == wrapping ? i1 : i2); + + if (pdata->last) { + pdata->last->next = ldata; + ldata->prev = pdata->last; + } else { + pdata->first = ldata; + ldata->prev = NULL; + } + ldata->next = NULL; + pdata->last = ldata; + + len = paper_width_list(&ctx, ldata->first, ldata->last); + wid = (p == wrapping ? w - i1 : w - i2); + spaces = 0; + wd = ldata->first; + while (wd) { +#if 0 + switch (wd->type) { + case word_HyperLink: + case word_HyperEnd: + case word_UpperXref: + case word_LowerXref: + case word_XrefEnd: + case word_IndexRef: + break; + + default: + if (removeattr(wd->type) == word_Normal) + printf("%ls", wd->text); + else if (removeattr(wd->type) == word_WhiteSpace) + printf(" "); + else if (removeattr(wd->type) == word_Quote) + printf(wd->aux == quote_Open ? "`" : "'"); + break; + } +#endif + if (removeattr(wd->type) == word_WhiteSpace) + spaces++; + if (wd == ldata->last) + break; + wd = wd->next; + } + + if (spaces) { + ldata->space_adjust = (wid - len) / spaces; + /* + * This tells us how much the space width needs to + * change from _min_spacewidth. But we want to store + * its difference from the _natural_ space width, to + * make the text rendering easier. + */ + ldata->space_adjust += ctx.minspacewidth; + ldata->space_adjust -= spacewidth; + /* + * Special case: on the last line of a paragraph, we + * never stretch spaces. + */ + if (ldata->space_adjust > 0 && !p->next) + ldata->space_adjust = 0; + } else { + ldata->space_adjust = 0; + } + + ldata->aux_text = NULL; + ldata->aux_left_indent = 0; + } + +} + +static page_data *page_breaks(line_data *first, line_data *last, + int page_height) +{ + line_data *l, *m; + page_data *ph, *pt; + + /* + * Page breaking is done by a close analogue of the optimal + * paragraph wrapping algorithm used by wrap_para(). We work + * backwards from the end of the document line by line; for + * each line, we contemplate every possible number of lines we + * could put on a page starting with that line, determine a + * cost function for each one, add it to the pre-computed cost + * function for optimally page-breaking everything after that + * page, and pick the best option. + * + * Since my line_data structures are only used for this + * purpose, I might as well just store the algorithm data + * directly in them. + */ + + for (l = last; l; l = l->prev) { + int minheight, text = 0, space = 0; + int cost; + + l->bestcost = -1; + for (m = l; m; m = m->next) { + if (m != l && m->page_break) + break; /* we've gone as far as we can */ + + if (m != l) + space += m->prev->space_after; + if (m != l || m->page_break) + space += m->space_before; + text += m->line_height; + minheight = text + space; + + if (m != l && minheight > page_height) + break; + + /* + * Compute the cost of this arrangement, as the square + * of the amount of wasted space on the page. + * Exception: if this is the last page before a + * mandatory break or the document end, we don't + * penalise a large blank area. + */ + if (m->next && !m->next->page_break) + { + int x = page_height - minheight; + int xf; + + xf = x & 0xFF; + x >>= 8; + + cost = x*x; + cost += (x * xf) >> 8; + } else + cost = 0; + + /* + * FIXME: here I should introduce penalties for + * breaking in mid-paragraph, particularly very close + * to one end of a paragraph and particularly in code + * paragraphs. + */ + + if (m->next && !m->next->page_break) + cost += m->next->bestcost; + + if (l->bestcost == -1 || l->bestcost > cost) { + /* + * This is the best option yet for this starting + * point. + */ + l->bestcost = cost; + if (m->next && !m->next->page_break) + l->shortfall = page_height - minheight; + else + l->shortfall = 0; + l->text = text; + l->space = space; + l->page_last = m; + } + } + } + + /* + * Now go through the line list forwards and assemble the + * actual pages. + */ + ph = pt = NULL; + + l = first; + while (l) { + page_data *page; + int text, space; + + page = mknew(page_data); + page->next = NULL; + page->prev = pt; + if (pt) + pt->next = page; + else + ph = page; + pt = page; + + page->first_line = l; + page->last_line = l->page_last; + + page->first_text = page->last_text = NULL; + + /* + * Now assign a y-coordinate to each line on the page. + */ + text = space = 0; + for (l = page->first_line; l; l = l->next) { + if (l != page->first_line) + space += l->prev->space_after; + if (l != page->first_line || l->page_break) + space += l->space_before; + text += l->line_height; + + l->page = page; + l->ypos = text + space + + space * (float)page->first_line->shortfall / + page->first_line->space; + + if (l == page->last_line) + break; + } + + l = page->last_line->next; + } + + return ph; +} + +static void add_string_to_page(page_data *page, int x, int y, + font_encoding *fe, int size, char *text) +{ + text_fragment *frag; + + frag = mknew(text_fragment); + frag->next = NULL; + + if (page->last_text) + page->last_text->next = frag; + else + page->first_text = frag; + page->last_text = frag; + + frag->x = x; + frag->y = y; + frag->fe = fe; + frag->fontsize = size; + frag->text = dupstr(text); +} + +/* + * Returns the updated x coordinate. + */ +static int render_string(page_data *page, font_data *font, int fontsize, + int x, int y, wchar_t *str) +{ + char *text; + int textpos, textwid, glyph; + font_encoding *subfont = NULL, *sf; + + text = mknewa(char, 1 + ustrlen(str)); + textpos = textwid = 0; + + while (*str) { + glyph = font->bmp[*str]; + + if (glyph == 0xFFFF) + continue; /* nothing more we can do here */ + + /* + * Find which subfont this character is going in. + */ + sf = font->subfont_map[glyph].subfont; + + if (!sf) { + int c; + + /* + * This character is not yet in a subfont. Assign one. + */ + if (font->latest_subfont->free_pos >= 0x100) + font->latest_subfont = new_font_encoding(font); + + c = font->latest_subfont->free_pos++; + if (font->latest_subfont->free_pos == 0x7F) + font->latest_subfont->free_pos = 0xA1; + + font->subfont_map[glyph].subfont = font->latest_subfont; + font->subfont_map[glyph].position = c; + font->latest_subfont->vector[c] = font->glyphs[glyph]; + font->latest_subfont->indices[c] = glyph; + font->latest_subfont->to_unicode[c] = *str; + + sf = font->latest_subfont; + } + + if (!subfont || sf != subfont) { + if (subfont) { + text[textpos] = '\0'; + add_string_to_page(page, x, y, subfont, fontsize, text); + x += textwid; + } else { + assert(textpos == 0); + } + textpos = 0; + subfont = sf; + } + + text[textpos++] = font->subfont_map[glyph].position; + textwid += font->widths[glyph] * fontsize; + + str++; + } + + if (textpos > 0) { + text[textpos] = '\0'; + add_string_to_page(page, x, y, subfont, fontsize, text); + x += textwid; + } + + return x; +} + +/* + * Returns the updated x coordinate. + */ +static int render_text(page_data *page, para_data *pdata, int x, int y, + word *text, word *text_end, int space_adjust) +{ + while (text) { + int style, type, findex, errs; + wchar_t *str; + + switch (text->type) { + case word_HyperLink: + case word_HyperEnd: + case word_UpperXref: + case word_LowerXref: + case word_XrefEnd: + case word_IndexRef: + goto nextword; + /* + * FIXME: we should do something with all of these! + * Hyperlinks and xrefs have meaning in PDF, and this + * is probably the right place to nail down the index + * references too. + */ + } + + style = towordstyle(text->type); + type = removeattr(text->type); + + findex = (style == word_Normal ? FONT_NORMAL : + style == word_Emph ? FONT_EMPH : + FONT_CODE); + + if (type == word_Normal) { + str = text->text; + } else if (type == word_WhiteSpace) { + x += pdata->sizes[findex] * + string_width(pdata->fonts[findex], L" ", NULL); + x += space_adjust; + goto nextword; + } else /* if (type == word_Quote) */ { + if (text->aux == quote_Open) + str = L"\x2018"; /* FIXME: configurability! */ + else + str = L"\x2019"; /* FIXME: configurability! */ + } + + (void) string_width(pdata->fonts[findex], str, &errs); + + if (errs && text->alt) + x = render_text(page, pdata, x, y, text->alt, NULL, space_adjust); + else + x = render_string(page, pdata->fonts[findex], + pdata->sizes[findex], x, y, str); + + nextword: + if (text == text_end) + break; + text = text->next; + } + + return x; +} + +static void render_line(line_data *ldata, int left_x, int top_y) +{ + if (ldata->aux_text) + render_text(ldata->page, ldata->pdata, left_x + ldata->aux_left_indent, + top_y - ldata->ypos, ldata->aux_text, NULL, 0); + render_text(ldata->page, ldata->pdata, left_x + ldata->xpos, + top_y - ldata->ypos, ldata->first, ldata->last, + ldata->space_adjust); +} |