diff options
Diffstat (limited to 'content/handlers/html/textselection.c')
-rw-r--r-- | content/handlers/html/textselection.c | 547 |
1 files changed, 547 insertions, 0 deletions
diff --git a/content/handlers/html/textselection.c b/content/handlers/html/textselection.c new file mode 100644 index 000000000..9b83e73ec --- /dev/null +++ b/content/handlers/html/textselection.c @@ -0,0 +1,547 @@ +/* + * Copyright 2020 Vincent Sanders <vince@netsurf-browser.org> + * + * This file is part of NetSurf, http://www.netsurf-browser.org/ + * + * NetSurf is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * NetSurf is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +/** + * \file + * implementation of text selection for a HTML content. + */ + +#include <stdlib.h> + +#include "utils/errors.h" +#include "utils/utils.h" +#include "netsurf/types.h" +#include "netsurf/plot_style.h" +#include "desktop/selection.h" +#include "desktop/save_text.h" + +#include "html/private.h" +#include "html/box.h" +#include "html/box_inspect.h" +#include "html/font.h" +#include "html/textselection.h" + +#define SPACE_LEN(b) ((b->space == 0) ? 0 : 1) + +struct rdw_info { + bool inited; + struct rect r; +}; + + +/** + * Tests whether a text box lies partially within the given range of + * byte offsets, returning the start and end indexes of the bytes + * that are enclosed. + * + * \param box box to be tested + * \param start_idx byte offset of start of range + * \param end_idx byte offset of end of range + * \param start_offset receives the start offset of the selected part + * \param end_offset receives the end offset of the selected part + * \return true iff the range encloses at least part of the box + */ +static bool +selected_part(struct box *box, + unsigned start_idx, + unsigned end_idx, + unsigned *start_offset, + unsigned *end_offset) +{ + size_t box_length = box->length + SPACE_LEN(box); + + if (box_length > 0) { + if ((box->byte_offset >= start_idx) && + (box->byte_offset + box_length <= end_idx)) { + + /* fully enclosed */ + *start_offset = 0; + *end_offset = box_length; + return true; + } else if ((box->byte_offset + box_length > start_idx) && + (box->byte_offset < end_idx)) { + /* partly enclosed */ + int offset = 0; + int len; + + if (box->byte_offset < start_idx) { + offset = start_idx - box->byte_offset; + } + + len = box_length - offset; + + if (box->byte_offset + box_length > end_idx) { + len = end_idx - (box->byte_offset + offset); + } + + *start_offset = offset; + *end_offset = offset + len; + + return true; + } + } + return false; +} + + +/** + * Traverse the given box subtree adding the boxes inside the + * selection to the coordinate range. + * + * \param box box subtree + * \param start_idx start of range within textual representation (bytes) + * \param end_idx end of range + * \param rdwi redraw range to fill in + * \param do_marker whether deal enter any marker box + * \return NSERROR_OK on success else error code + */ +static nserror +coords_from_range(struct box *box, + unsigned start_idx, + unsigned end_idx, + struct rdw_info *rdwi, + bool do_marker) +{ + struct box *child; + nserror res; + + assert(box); + + /* If selection starts inside marker */ + if (box->parent && + box->parent->list_marker == box && + !do_marker) { + /* set box to main list element */ + box = box->parent; + } + + /* If box has a list marker */ + if (box->list_marker) { + /* do the marker box before continuing with the rest of the + * list element */ + res = coords_from_range(box->list_marker, + start_idx, + end_idx, + rdwi, + true); + if (res != NSERROR_OK) { + return res; + } + } + + /* we can prune this subtree, it's after the selection */ + if (box->byte_offset >= end_idx) { + return NSERROR_OK; + } + + /* read before calling the handler in case it modifies the tree */ + child = box->children; + + if ((box->type != BOX_BR) && + !((box->type == BOX_FLOAT_LEFT || + box->type == BOX_FLOAT_RIGHT) && + !box->text)) { + unsigned start_off; + unsigned end_off; + + if (selected_part(box, start_idx, end_idx, &start_off, &end_off)) { + int width, height; + int x, y; + + /** + * \todo it should be possible to reduce the redrawn + * area using the offsets + */ + box_coords(box, &x, &y); + + width = box->padding[LEFT] + box->width + box->padding[RIGHT]; + height = box->padding[TOP] + box->height + box->padding[BOTTOM]; + + if ((box->type == BOX_TEXT) && + (box->space != 0)) { + width += box->space; + } + + if (rdwi->inited) { + if (x < rdwi->r.x0) { + rdwi->r.x0 = x; + } + if (y < rdwi->r.y0) { + rdwi->r.y0 = y; + } + if (x + width > rdwi->r.x1) { + rdwi->r.x1 = x + width; + } + if (y + height > rdwi->r.y1) { + rdwi->r.y1 = y + height; + } + } else { + rdwi->inited = true; + rdwi->r.x0 = x; + rdwi->r.y0 = y; + rdwi->r.x1 = x + width; + rdwi->r.y1 = y + height; + } + } + } + + /* find the first child that could lie partially within the selection; + * this is important at the top-levels of the tree for pruning subtrees + * that lie entirely before the selection */ + + if (child) { + struct box *next = child->next; + + while (next && next->byte_offset < start_idx) { + child = next; + next = child->next; + } + + while (child) { + /* read before calling the handler in case it modifies + * the tree */ + struct box *next = child->next; + + res = coords_from_range(child, + start_idx, + end_idx, + rdwi, + false); + if (res != NSERROR_OK) { + return res; + } + + child = next; + } + } + + return NSERROR_OK; +} + + +/** + * Append the contents of a box to a selection along with style information + * + * \param text pointer to text being added, or NULL for newline + * \param length length of text to be appended (bytes) + * \param box pointer to text box, or NULL if from textplain + * \param unit_len_ctx Length conversion context + * \param handle selection string to append to + * \param whitespace_text whitespace to place before text for formatting + * may be NULL + * \param whitespace_length length of whitespace_text + * \return NSERROR_OK iff successful and traversal should continue else error code + */ +static nserror +selection_copy_box(const char *text, + size_t length, + struct box *box, + const css_unit_ctx *unit_len_ctx, + struct selection_string *handle, + const char *whitespace_text, + size_t whitespace_length) +{ + bool add_space = false; + plot_font_style_t style; + plot_font_style_t *pstyle = NULL; + + /* add any whitespace which precedes the text from this box */ + if (whitespace_text != NULL && + whitespace_length > 0) { + if (!selection_string_append(whitespace_text, + whitespace_length, + false, + pstyle, + handle)) { + return NSERROR_NOMEM; + } + } + + if (box != NULL) { + /* HTML */ + add_space = (box->space != 0); + + if (box->style != NULL) { + /* Override default font style */ + font_plot_style_from_css(unit_len_ctx, box->style, &style); + pstyle = &style; + } else { + /* If there's no style, there must be no text */ + assert(box->text == NULL); + } + } + + /* add the text from this box */ + if (!selection_string_append(text, length, add_space, pstyle, handle)) { + return NSERROR_NOMEM; + } + + return NSERROR_OK; +} + + +/** + * Traverse the given box subtree, calling selection copy for all + * boxes that lie (partially) within the given range + * + * \param box box subtree + * \param unit_len_ctx Length conversion context. + * \param start_idx start of range within textual representation (bytes) + * \param end_idx end of range + * \param handler handler function to call + * \param handle handle to pass + * \param before type of whitespace to place before next encountered text + * \param first whether this is the first box with text + * \param do_marker whether deal enter any marker box + * \return NSERROR_OK on sucess else error code + */ +static nserror +selection_copy(struct box *box, + const css_unit_ctx *unit_len_ctx, + unsigned start_idx, + unsigned end_idx, + struct selection_string *selstr, + save_text_whitespace *before, + bool *first, + bool do_marker) +{ + nserror res; + struct box *child; + const char *whitespace_text = ""; + size_t whitespace_length = 0; + + assert(box); + + /* If selection starts inside marker */ + if (box->parent && + box->parent->list_marker == box && + !do_marker) { + /* set box to main list element */ + box = box->parent; + } + + /* If box has a list marker */ + if (box->list_marker) { + /* do the marker box before continuing with the rest of the + * list element */ + res = selection_copy(box->list_marker, + unit_len_ctx, + start_idx, + end_idx, + selstr, + before, + first, + true); + if (res != NSERROR_OK) { + return res; + } + } + + /* we can prune this subtree, it's after the selection */ + if (box->byte_offset >= end_idx) { + return NSERROR_OK; + } + + /* read before calling the handler in case it modifies the tree */ + child = box->children; + + /* If nicely formatted output of the selected text is required, work + * out what whitespace should be placed before the next bit of text */ + if (before) { + save_text_solve_whitespace(box, + first, + before, + &whitespace_text, + &whitespace_length); + } else { + whitespace_text = NULL; + } + + if ((box->type != BOX_BR) && + !((box->type == BOX_FLOAT_LEFT || + box->type == BOX_FLOAT_RIGHT) && + !box->text)) { + unsigned start_off; + unsigned end_off; + + if (selected_part(box, start_idx, end_idx, &start_off, &end_off)) { + res = selection_copy_box(box->text + start_off, + min(box->length, end_off) - start_off, + box, + unit_len_ctx, + selstr, + whitespace_text, + whitespace_length); + if (res != NSERROR_OK) { + return res; + } + if (before) { + *first = false; + *before = WHITESPACE_NONE; + } + } + } + + /* find the first child that could lie partially within the selection; + * this is important at the top-levels of the tree for pruning subtrees + * that lie entirely before the selection */ + + if (child) { + struct box *next = child->next; + + while (next && next->byte_offset < start_idx) { + child = next; + next = child->next; + } + + while (child) { + /* read before calling the handler in case it modifies + * the tree */ + struct box *next = child->next; + + res = selection_copy(child, + unit_len_ctx, + start_idx, + end_idx, + selstr, + before, + first, + false); + if (res != NSERROR_OK) { + return res; + } + + child = next; + } + } + + return NSERROR_OK; +} + + +/** + * Label each text box in the given box subtree with its position + * in a textual representation of the content. + * + * \param box The box at root of subtree + * \param idx current position within textual representation + * \return updated position + */ +static unsigned selection_label_subtree(struct box *box, unsigned idx) +{ + struct box *child; + + assert(box != NULL); + + child = box->children; + + box->byte_offset = idx; + + if (box->text) { + idx += box->length + SPACE_LEN(box); + } + + while (child) { + if (child->list_marker) { + idx = selection_label_subtree(child->list_marker, idx); + } + + idx = selection_label_subtree(child, idx); + child = child->next; + } + + return idx; +} + + +/* exported interface documented in html/textselection.h */ +nserror +html_textselection_redraw(struct content *c, + unsigned start_idx, + unsigned end_idx) +{ + nserror res; + html_content *html = (html_content *)c; + struct rdw_info rdw; + + if (html->layout == NULL) { + return NSERROR_INVALID; + } + + rdw.inited = false; + + res = coords_from_range(html->layout, start_idx, end_idx, &rdw, false); + if (res != NSERROR_OK) { + return res; + } + + if (rdw.inited) { + content__request_redraw(c, + rdw.r.x0, + rdw.r.y0, + rdw.r.x1 - rdw.r.x0, + rdw.r.y1 - rdw.r.y0); + } + + return NSERROR_OK; +} + + +/* exported interface documented in html/textselection.h */ +nserror +html_textselection_copy(struct content *c, + unsigned start_idx, + unsigned end_idx, + struct selection_string *selstr) +{ + html_content *html = (html_content *)c; + save_text_whitespace before = WHITESPACE_NONE; + bool first = true; + + if (html->layout == NULL) { + return NSERROR_INVALID; + } + + return selection_copy(html->layout, + &html->unit_len_ctx, + start_idx, + end_idx, + selstr, + &before, + &first, + false); +} + + +/* exported interface documented in html/textselection.h */ +nserror +html_textselection_get_end(struct content *c, unsigned *end_idx) +{ + html_content *html = (html_content *)c; + unsigned root_idx; + + if (html->layout == NULL) { + return NSERROR_INVALID; + } + + root_idx = 0; + + *end_idx = selection_label_subtree(html->layout, root_idx); + + return NSERROR_OK; +} |