textplain.c

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/*
 * Copyright 2006 James Bursa <bursa@users.sourceforge.net>
 * Copyright 2006 Adrian Lees <adrianl@users.sourceforge.net>
 *
 * 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
 *
 * plain text content handling implementation.
 */
 
#include <string.h>
#include <parserutils/input/inputstream.h>
 
#include "utils/errors.h"
#include "utils/corestrings.h"
#include "utils/http.h"
#include "utils/log.h"
#include "utils/messages.h"
#include "utils/utils.h"
#include "utils/utf8.h"
#include "utils/nsoption.h"
#include "netsurf/content.h"
#include "netsurf/keypress.h"
#include "netsurf/browser_window.h"
#include "netsurf/plotters.h"
#include "netsurf/layout.h"
#include "content/content_protected.h"
#include "content/content_factory.h"
#include "content/hlcache.h"
#include "content/textsearch.h"
#include "content/handlers/css/utils.h"
#include "desktop/selection.h"
#include "desktop/gui_internal.h"
 
#include "text/textplain.h"
 
struct textplain_line {
        size_t  start;
        size_t  length;
};
 
/**
 * plain text content
 */
typedef struct textplain_content {
        struct content base;
 
        lwc_string *encoding;
        void *inputstream;
        char *utf8_data;
        size_t utf8_data_size;
        size_t utf8_data_allocated;
        unsigned long physical_line_count;
        struct textplain_line *physical_line;
        int formatted_width;
        struct browser_window *bw;
 
        struct selection *sel; /** Selection state */
 
} textplain_content;
 
 
#define CHUNK 32768 /* Must be a power of 2 */
#define MARGIN 4
 
#define TAB_WIDTH 8  /* must be power of 2 currently */
#define TEXT_SIZE 10 * PLOT_STYLE_SCALE  /* Unscaled text size in pt */
 
static plot_font_style_t textplain_style = {
        .family = PLOT_FONT_FAMILY_MONOSPACE,
        .size = TEXT_SIZE,
        .weight = 400,
        .flags = FONTF_NONE,
        .background = 0xffffff,
        .foreground = 0x000000,
};
 
static int textplain_tab_width = 256;  /* try for a sensible default */
 
static lwc_string *textplain_default_charset;
 
 
/**
 * Clean up after the text content handler
 */
static void textplain_fini(void)
{
        if (textplain_default_charset != NULL) {
                lwc_string_unref(textplain_default_charset);
                textplain_default_charset = NULL;
        }
}
 
 
/**
 * Work around feature in libparserutils
 *
 * if the client provides an encoding up front, but does not provide a
 * charset detection callback, then libparserutils will replace the
 * provided encoding with UTF-8. This breaks our input handling.
 *
 * Avoid this by providing a callback that does precisely nothing,
 * thus preserving whatever charset information we decided on in
 * textplain_create.
 */
static parserutils_error
textplain_charset_hack(const uint8_t *data,
                       size_t len,
                       uint16_t *mibenum,
                       uint32_t *source)
{
        return PARSERUTILS_OK;
}
 
 
/**
 * setup plain text render.
 *
 * \param[in] c content object.
 * \param[in] encoding the encoding of the content.
 * \return NSERROR_OK else appropriate error code.
 */
static nserror
textplain_create_internal(textplain_content *c, lwc_string *encoding)
{
        char *utf8_data;
        parserutils_inputstream *stream;
        parserutils_error error;
 
        textplain_style.size = (nsoption_int(font_size) * PLOT_STYLE_SCALE) / 10;
 
        utf8_data = malloc(CHUNK);
        if (utf8_data == NULL)
                goto no_memory;
 
        error = parserutils_inputstream_create(lwc_string_data(encoding), 0,
                                               textplain_charset_hack, &stream);
        if (error == PARSERUTILS_BADENCODING) {
                /* Fall back to Windows-1252 */
                error = parserutils_inputstream_create("Windows-1252", 0,
                                        textplain_charset_hack, &stream);
        }
        if (error != PARSERUTILS_OK) {
                free(utf8_data);
                goto no_memory;
        }
 
        c->encoding = lwc_string_ref(encoding);
        c->inputstream = stream;
        c->utf8_data = utf8_data;
        c->utf8_data_size = 0;
        c->utf8_data_allocated = CHUNK;
        c->physical_line = 0;
        c->physical_line_count = 0;
        c->formatted_width = 0;
        c->bw = NULL;
        c->sel = selection_create((struct content *)c);
 
        return NSERROR_OK;
 
no_memory:
        content_broadcast_error(&c->base, NSERROR_NOMEM, NULL);
 
        return NSERROR_NOMEM;
}
 
 
/**
 * Create a CONTENT_TEXTPLAIN.
 */
static nserror
textplain_create(const content_handler *handler,
                 lwc_string *imime_type,
                 const struct http_parameter *params,
                 llcache_handle *llcache,
                 const char *fallback_charset,
                 bool quirks,
                 struct content **c)
{
        textplain_content *text;
        nserror error;
        lwc_string *encoding;
 
        text = calloc(1, sizeof(textplain_content));
        if (text == NULL) {
                return NSERROR_NOMEM;
        }
 
        error = content__init(&text->base, handler, imime_type, params,
                              llcache, fallback_charset, quirks);
        if (error != NSERROR_OK) {
                free(text);
                return error;
        }
 
        error = http_parameter_list_find_item(params, corestring_lwc_charset,
                                              &encoding);
        if (error != NSERROR_OK) {
                encoding = lwc_string_ref(textplain_default_charset);
        }
 
        error = textplain_create_internal(text, encoding);
        if (error != NSERROR_OK) {
                lwc_string_unref(encoding);
                free(text);
                return error;
        }
 
        lwc_string_unref(encoding);
 
        *c = (struct content *) text;
 
        return NSERROR_OK;
}
 
 
/**
 * copy utf8 encoded data
 */
static bool
textplain_copy_utf8_data(textplain_content *c, const uint8_t *buf, size_t len)
{
        if (c->utf8_data_size + len >= c->utf8_data_allocated) {
                /* Compute next multiple of chunk above the required space */
                size_t allocated;
                char *utf8_data;
 
                allocated = (c->utf8_data_size + len + CHUNK - 1) & ~(CHUNK - 1);
                utf8_data = realloc(c->utf8_data, allocated);
                if (utf8_data == NULL)
                        return false;
 
                c->utf8_data = utf8_data;
                c->utf8_data_allocated = allocated;
        }
 
        memcpy(c->utf8_data + c->utf8_data_size, buf, len);
        c->utf8_data_size += len;
 
        return true;
}
 
 
/**
 * drain input
 */
static bool
textplain_drain_input(textplain_content *c,
                      parserutils_inputstream *stream,
                      parserutils_error terminator)
{
        static const uint8_t *u_fffd = (const uint8_t *) "\xef\xbf\xbd";
        const uint8_t *ch;
        size_t chlen, offset = 0;
 
        while (parserutils_inputstream_peek(stream, offset, &ch, &chlen) !=
               terminator) {
                /* Replace all instances of NUL with U+FFFD */
                if (chlen == 1 && *ch == 0) {
                        if (offset > 0) {
                                /* Obtain pointer to start of input data */
                                parserutils_inputstream_peek(stream, 0,
                                                             &ch, &chlen);
                                /* Copy from it up to the start of the NUL */
                                if (textplain_copy_utf8_data(c, ch,
                                                             offset) == false)
                                        return false;
                        }
 
                        /* Emit U+FFFD */
                        if (textplain_copy_utf8_data(c, u_fffd, 3) == false)
                                return false;
 
                        /* Advance inputstream past the NUL we just read */
                        parserutils_inputstream_advance(stream, offset + 1);
                        /* Reset the read offset */
                        offset = 0;
                } else {
                        /* Accumulate input */
                        offset += chlen;
 
                        if (offset > CHUNK) {
                                /* Obtain pointer to start of input data */
                                parserutils_inputstream_peek(stream, 0,
                                                             &ch, &chlen);
 
                                /* Emit the data we've read */
                                if (textplain_copy_utf8_data(c, ch,
                                                             offset) == false)
                                        return false;
 
                                /* Advance the inputstream */
                                parserutils_inputstream_advance(stream, offset);
                                /* Reset the read offset */
                                offset = 0;
                        }
                }
        }
 
        if (offset > 0) {
                /* Obtain pointer to start of input data */
                parserutils_inputstream_peek(stream, 0, &ch, &chlen);
                /* Emit any data remaining */
                if (textplain_copy_utf8_data(c, ch, offset) == false)
                        return false;
 
                /* Advance the inputstream past the data we've read */
                parserutils_inputstream_advance(stream, offset);
        }
 
        return true;
}
 
 
/**
 * Process data for CONTENT_TEXTPLAIN.
 */
static bool
textplain_process_data(struct content *c, const char *data, unsigned int size)
{
        textplain_content *text = (textplain_content *) c;
        parserutils_inputstream *stream = text->inputstream;
        parserutils_error error;
 
        error = parserutils_inputstream_append(stream,
                                               (const uint8_t *) data, size);
        if (error != PARSERUTILS_OK) {
                goto no_memory;
        }
 
        if (textplain_drain_input(text, stream, PARSERUTILS_NEEDDATA) == false)
                goto no_memory;
 
        return true;
 
no_memory:
        content_broadcast_error(c, NSERROR_NOMEM, NULL);
        return false;
}
 
 
/**
 * Convert a CONTENT_TEXTPLAIN for display.
 */
static bool textplain_convert(struct content *c)
{
        textplain_content *text = (textplain_content *) c;
        parserutils_inputstream *stream = text->inputstream;
        parserutils_error error;
 
        error = parserutils_inputstream_append(stream, NULL, 0);
        if (error != PARSERUTILS_OK) {
                return false;
        }
 
        if (textplain_drain_input(text, stream, PARSERUTILS_EOF) == false)
                return false;
 
        parserutils_inputstream_destroy(stream);
        text->inputstream = NULL;
 
        content_set_ready(c);
        content_set_done(c);
        content_set_status(c, messages_get("Done"));
 
        return true;
}
 
 
/**
 * Calculate the line height, in pixels
 *
 * \return Line height, in pixels
 */
static float textplain_line_height(void)
{
        /* Size is in points, so convert to pixels.
         * Then use a constant line height of 1.2 x font size.
         */
        return FIXTOFLT(FDIV((FMUL(FLTTOFIX(1.2), FMUL(nscss_screen_dpi, INTTOFIX((textplain_style.size / PLOT_STYLE_SCALE))))), F_72));
}
 
 
/**
 * Reformat a CONTENT_TEXTPLAIN to a new width.
 */
static void textplain_reformat(struct content *c, int width, int height)
{
        textplain_content *text = (textplain_content *) c;
        char *utf8_data = text->utf8_data;
        size_t utf8_data_size = text->utf8_data_size;
        unsigned long line_count = 0;
        struct textplain_line *line = text->physical_line;
        struct textplain_line *line1;
        size_t i, space, col;
        size_t columns = 80;
        int character_width;
        size_t line_start;
        nserror res;
 
        NSLOG(netsurf, INFO, "content %p w:%d h:%d", c, width, height);
 
        /* compute available columns (assuming monospaced font) - use 8
         * characters for better accuracy
         */
        res = guit->layout->width(&textplain_style,
                                  "ABCDEFGH", 8,
                                  &character_width);
        if (res != NSERROR_OK) {
                return;
        }
 
        columns = (width - MARGIN - MARGIN) * 8 / character_width;
        textplain_tab_width = (TAB_WIDTH * character_width) / 8;
 
        text->formatted_width = width;
 
        text->physical_line_count = 0;
 
        if (!line) {
                text->physical_line = line =
                        malloc(sizeof(struct textplain_line) * (1024 + 3));
                if (!line)
                        goto no_memory;
        }
 
        line[line_count++].start = line_start = 0;
        space = 0;
        i = 0;
        col = 0;
        while (i < utf8_data_size) {
                size_t csize; /* number of bytes in character */
                uint32_t chr;
                bool term;
                size_t next_col;
                parserutils_error perror;
 
                perror = parserutils_charset_utf8_to_ucs4((const uint8_t *)utf8_data + i, utf8_data_size - i, &chr, &csize);
                if (perror != PARSERUTILS_OK) {
                        chr = 0xfffd;
                }
 
                term = (chr == '\n' || chr == '\r');
 
                next_col = col + 1;
 
                if (chr == '\t') {
                        next_col = (next_col + TAB_WIDTH - 1) & ~(TAB_WIDTH - 1);
                }
 
                if (term || next_col >= columns) {
                        if (line_count % 1024 == 0) {
                                line1 = realloc(line,
                                                sizeof(struct textplain_line) *
                                                (line_count + 1024 + 3));
                                if (!line1)
                                        goto no_memory;
                                text->physical_line = line = line1;
                        }
 
                        if (term) {
                                line[line_count-1].length = i - line_start;
 
                                /* skip second char of CR/LF or LF/CR pair */
                                if (i + 1 < utf8_data_size &&
                                    utf8_data[i+1] != utf8_data[i] &&
                                    (utf8_data[i+1] == '\n' ||
                                     utf8_data[i+1] == '\r')) {
                                        i++;
                                }
                        } else {
                                if (space) {
                                        /* break at last space in line */
                                        i = space;
                                        line[line_count-1].length = (i + 1) - line_start;
                                } else
                                        line[line_count-1].length = i - line_start;
                        }
 
                        line[line_count++].start = line_start = i + 1;
                        col = 0;
                        space = 0;
                } else {
                        col++;
                        if (chr == ' ')
                                space = i;
                }
                i += csize;
        }
        line[line_count-1].length = i - line[line_count-1].start;
        line[line_count].start = utf8_data_size;
 
        text->physical_line_count = line_count;
        c->width = width;
        c->height = line_count * textplain_line_height() + MARGIN + MARGIN;
 
        return;
 
no_memory:
        NSLOG(netsurf, INFO, "out of memory (line_count %lu)", line_count);
        return;
}
 
 
/**
 * Destroy a CONTENT_TEXTPLAIN and free all resources it owns.
 */
 
static void textplain_destroy(struct content *c)
{
        textplain_content *text = (textplain_content *) c;
 
        lwc_string_unref(text->encoding);
 
        if (text->inputstream != NULL) {
                parserutils_inputstream_destroy(text->inputstream);
        }
 
        if (text->physical_line != NULL) {
                free(text->physical_line);
        }
 
        if (text->utf8_data != NULL) {
                free(text->utf8_data);
        }
 
        if (text->sel != NULL) {
                selection_destroy(text->sel);
        }
}
 
 
static nserror textplain_clone(const struct content *old, struct content **newc)
{
        const textplain_content *old_text = (textplain_content *) old;
        textplain_content *text;
        nserror error;
        const uint8_t *data;
        size_t size;
 
        text = calloc(1, sizeof(textplain_content));
        if (text == NULL)
                return NSERROR_NOMEM;
 
        error = content__clone(old, &text->base);
        if (error != NSERROR_OK) {
                content_destroy(&text->base);
                return error;
        }
 
        /* Simply replay create/process/convert */
        error = textplain_create_internal(text, old_text->encoding);
        if (error != NSERROR_OK) {
                content_destroy(&text->base);
                return error;
        }
 
        data = content__get_source_data(&text->base, &size);
        if (size > 0) {
                if (textplain_process_data(&text->base,
                                           (const char *)data,
                                           size) == false) {
                        content_destroy(&text->base);
                        return NSERROR_NOMEM;
                }
        }
 
        if (old->status == CONTENT_STATUS_READY ||
            old->status == CONTENT_STATUS_DONE) {
                if (textplain_convert(&text->base) == false) {
                        content_destroy(&text->base);
                        return NSERROR_CLONE_FAILED;
                }
        }
 
        return NSERROR_OK;
}
 
 
static content_type textplain_content_type(void)
{
        return CONTENT_TEXTPLAIN;
}
 
 
/**
 * Return byte offset within UTF8 textplain content.
 *
 * given the co-ordinates of a point within a textplain content. 'dir'
 * specifies the direction in which to search (-1 = above-left, +1 =
 * below-right) if the co-ordinates are not contained within a line.
 *
 * \param[in] c   content of type CONTENT_TEXTPLAIN
 * \param[in] x   x ordinate of point
 * \param[in] y   y ordinate of point
 * \param[in] dir direction of search if not within line
 * \return byte offset of character containing (or nearest to) point
 */
static size_t
textplain_offset_from_coords(struct content *c, int x, int y, int dir)
{
        textplain_content *textc = (textplain_content *) c;
        float line_height = textplain_line_height();
        struct textplain_line *line;
        const char *text;
        unsigned nlines;
        size_t length;
        int idx;
 
        assert(c != NULL);
 
        y = (int)((float)(y - MARGIN) / line_height);
        x -= MARGIN;
 
        nlines = textc->physical_line_count;
        if (!nlines)
                return 0;
 
        if (y <= 0) y = 0;
        else if ((unsigned)y >= nlines)
                y = nlines - 1;
 
        line = &textc->physical_line[y];
        text = textc->utf8_data + line->start;
        length = line->length;
        idx = 0;
 
        while (x > 0) {
                size_t next_offset = 0;
                int width = INT_MAX;
 
                while (next_offset < length && text[next_offset] != '\t') {
                        next_offset = utf8_next(text, length, next_offset);
                }
 
                if (next_offset < length) {
                        guit->layout->width(&textplain_style,
                                            text,
                                            next_offset,
                                            &width);
                }
 
                if (x <= width) {
                        int pixel_offset;
                        size_t char_offset;
 
                        guit->layout->position(&textplain_style,
                                               text, next_offset, x,
                                               &char_offset, &pixel_offset);
 
                        idx += char_offset;
                        break;
                }
 
                x -= width;
                length -= next_offset;
                text += next_offset;
                idx += next_offset;
 
                /* check if it's within the tab */
                width = textplain_tab_width - (width % textplain_tab_width);
                if (x <= width) break;
 
                x -= width;
                length--;
                text++;
                idx++;
        }
 
        return line->start + idx;
}
 
 
/**
 * Handle mouse clicks and movements in a TEXTPLAIN content window.
 *
 * \param c       content of type textplain
 * \param bw      browser window
 * \param mouse  mouse state on action
 * \param x       coordinate of mouse
 * \param y       coordinate of mouse
 */
static nserror
textplain_mouse_action(struct content *c,
                       struct browser_window *bw,
                       browser_mouse_state mouse,
                       int x, int y)
{
        textplain_content *text = (textplain_content *) c;
        browser_pointer_shape pointer = BROWSER_POINTER_DEFAULT;
        union content_msg_data msg_data;
        const char *status = 0;
        size_t idx;
        int dir = 0;
 
        browser_window_set_drag_type(bw, DRAGGING_NONE, NULL);
 
        idx = textplain_offset_from_coords(c, x, y, dir);
        if (selection_click(text->sel, text->bw, mouse, idx)) {
 
                if (selection_dragging(text->sel)) {
                        browser_window_set_drag_type(bw,
                                                     DRAGGING_SELECTION, NULL);
                        status = messages_get("Selecting");
                }
 
        } else {
                if (mouse & (BROWSER_MOUSE_DRAG_1 | BROWSER_MOUSE_DRAG_2)) {
                        browser_window_page_drag_start(bw, x, y);
                        pointer = BROWSER_POINTER_MOVE;
                }
        }
 
        msg_data.explicit_status_text = status;
        content_broadcast(c, CONTENT_MSG_STATUS, &msg_data);
 
        msg_data.pointer = pointer;
        content_broadcast(c, CONTENT_MSG_POINTER, &msg_data);
 
        return NSERROR_OK;
}
 
 
/**
 * Handle mouse tracking (including drags) in a TEXTPLAIN content window.
 *
 * \param  c      content of type textplain
 * \param  bw     browser window
 * \param  mouse  state of mouse buttons and modifier keys
 * \param  x      coordinate of mouse
 * \param  y      coordinate of mouse
 */
static nserror
textplain_mouse_track(struct content *c,
                      struct browser_window *bw,
                      browser_mouse_state mouse,
                      int x, int y)
{
        textplain_content *text = (textplain_content *) c;
 
        if (browser_window_get_drag_type(bw) == DRAGGING_SELECTION && !mouse) {
                int dir = -1;
                size_t idx;
 
                if (selection_dragging_start(text->sel))
                        dir = 1;
 
                idx = textplain_offset_from_coords(c, x, y, dir);
                selection_track(text->sel, mouse, idx);
 
                browser_window_set_drag_type(bw, DRAGGING_NONE, NULL);
        }
 
        switch (browser_window_get_drag_type(bw)) {
 
        case DRAGGING_SELECTION: {
                int dir = -1;
                size_t idx;
 
                if (selection_dragging_start(text->sel)) dir = 1;
 
                idx = textplain_offset_from_coords(c, x, y, dir);
                selection_track(text->sel, mouse, idx);
        }
                break;
 
        default:
                textplain_mouse_action(c, bw, mouse, x, y);
                break;
        }
 
        return NSERROR_OK;
}
 
 
/**
 * Handle keypresses.
 *
 * \param  c    content of type CONTENT_TEXTPLAIN
 * \param  key  The UCS4 character codepoint
 * \return true if key handled, false otherwise
 */
static bool textplain_keypress(struct content *c, uint32_t key)
{
        textplain_content *text = (textplain_content *) c;
        struct selection *sel = text->sel;
 
        switch (key) {
        case NS_KEY_COPY_SELECTION:
                selection_copy_to_clipboard(sel);
                return true;
 
        case NS_KEY_CLEAR_SELECTION:
                selection_clear(sel, true);
                return true;
 
        case NS_KEY_SELECT_ALL:
                selection_select_all(sel);
                return true;
 
        case NS_KEY_ESCAPE:
                /* if there's no selection, leave Escape for the caller */
                return selection_clear(sel, true);
        }
 
        return false;
}
 
 
/**
 * Redraw a text string with highlighting
 * (for selection/search)
 *
 * \param utf8_text pointer to UTF-8 text string
 * \param utf8_len  length of string, in bytes
 * \param offset    byte offset within textual representation
 * \param x         x ordinate at which to plot text
 * \param y         y ordinate at which to plot text
 * \param clip      pointer to current clip rectangle
 * \param height    height of text string
 * \param scale     current display scale (1.0 = 100%)
 * \param text      Content being redrawn.
 * \param sel       Selection context
 * \param search    Search context
 * \param ctx       current redraw context
 * \return true iff successful and redraw should proceed
 */
static bool
text_draw(const char *utf8_text,
            size_t utf8_len,
            size_t offset,
            int x,
            int y,
            const struct rect *clip,
            int height,
            float scale,
            textplain_content *text,
            const struct selection *sel,
            const struct redraw_context *ctx)
{
        bool highlighted = false;
        plot_font_style_t plot_fstyle;
        nserror res;
 
        /* Need scaled text size to pass to plotters */
        plot_fstyle = textplain_style;
        plot_fstyle.size *= scale;
 
        /* is this box part of a selection? */
        if (ctx->interactive == true) {
                unsigned len = utf8_len;
                unsigned start_idx;
                unsigned end_idx;
 
                /* first try the browser window's current selection */
                if (selection_highlighted(sel,
                                          offset,
                                          offset + len,
                                          &start_idx,
                                          &end_idx)) {
                        highlighted = true;
                }
 
                /* what about the current search operation, if any? */
                if (!highlighted &&
                    (text->base.textsearch.context != NULL) &&
                    content_textsearch_ishighlighted(text->base.textsearch.context,
                                                     offset,
                                                     offset + len,
                                                     &start_idx,
                                                     &end_idx)) {
                        highlighted = true;
                }
 
                /* \todo make search terms visible within selected text */
                if (highlighted) {
                        struct rect r;
                        unsigned endtxt_idx = end_idx;
                        bool clip_changed = false;
                        bool text_visible = true;
                        int startx, endx;
                        plot_style_t pstyle_fill_hback = *plot_style_fill_white;
                        plot_font_style_t fstyle_hback = plot_fstyle;
 
                        if (end_idx > utf8_len) {
                                /* adjust for trailing space, not present in
                                 * utf8_text
                                 */
                                assert(end_idx == utf8_len + 1);
                                endtxt_idx = utf8_len;
                        }
 
                        res = guit->layout->width(&textplain_style,
                                                  utf8_text,
                                                  start_idx,
                                                  &startx);
                        if (res != NSERROR_OK) {
                                startx = 0;
                        }
 
                        res = guit->layout->width(&textplain_style,
                                                  utf8_text,
                                                  endtxt_idx,
                                                  &endx);
                        if (res != NSERROR_OK) {
                                endx = 0;
                        }
 
                        if (scale != 1.0) {
                                startx *= scale;
                                endx *= scale;
                        }
 
                        /* draw any text preceding highlighted portion */
                        if (start_idx > 0) {
                                res = ctx->plot->text(ctx,
                                              &plot_fstyle,
                                              x,
                                              y + (int)(height * 0.75 * scale),
                                              utf8_text,
                                              start_idx);
                                if (res != NSERROR_OK) {
                                        return false;
                                }
                        }
 
                        pstyle_fill_hback.fill_colour = textplain_style.foreground;
 
                        /* highlighted portion */
                        r.x0 = x + startx;
                        r.y0 = y;
                        r.x1 = x + endx;
                        r.y1 = y + height * scale;
                        res = ctx->plot->rectangle(ctx, &pstyle_fill_hback, &r);
                        if (res != NSERROR_OK) {
                                return false;
                        }
 
                        if (start_idx > 0) {
                                int px0 = max(x + startx, clip->x0);
                                int px1 = min(x + endx, clip->x1);
 
                                if (px0 < px1) {
                                        r.x0 = px0;
                                        r.y0 = clip->y0;
                                        r.x1 = px1;
                                        r.y1 = clip->y1;
                                        res = ctx->plot->clip(ctx, &r);
                                        if (res != NSERROR_OK) {
                                                return false;
                                        }
 
                                        clip_changed = true;
                                } else {
                                        text_visible = false;
                                }
                        }
 
                        fstyle_hback.background =
                                pstyle_fill_hback.fill_colour;
                        fstyle_hback.foreground = colour_to_bw_furthest(
                                pstyle_fill_hback.fill_colour);
 
                        if (text_visible &&
                            (ctx->plot->text(ctx,
                                             &fstyle_hback,
                                             x,
                                             y + (int)(height * 0.75 * scale),
                                             utf8_text,
                                             endtxt_idx) != NSERROR_OK)) {
                                return false;
                        }
 
                        /* draw any text succeeding highlighted portion */
                        if (endtxt_idx < utf8_len) {
                                int px0 = max(x + endx, clip->x0);
                                if (px0 < clip->x1) {
 
                                        r.x0 = px0;
                                        r.y0 = clip->y0;
                                        r.x1 = clip->x1;
                                        r.y1 = clip->y1;
                                        res = ctx->plot->clip(ctx, &r);
                                        if (res != NSERROR_OK) {
                                                return false;
                                        }
 
                                        clip_changed = true;
 
                                        res = ctx->plot->text(ctx,
                                                              &plot_fstyle,
                                                              x,
                                                              y + (int)(height * 0.75 * scale),
                                                              utf8_text,
                                                              utf8_len);
                                        if (res != NSERROR_OK) {
                                                return false;
                                        }
                                }
                        }
 
                        if (clip_changed &&
                            (ctx->plot->clip(ctx, clip) != NSERROR_OK)) {
                                return false;
                        }
                }
        }
 
        if (!highlighted) {
                res = ctx->plot->text(ctx,
                                      &plot_fstyle,
                                      x,
                                      y + (int) (height * 0.75 * scale),
                                      utf8_text,
                                      utf8_len);
                if (res != NSERROR_OK) {
                        return false;
                }
        }
        return true;
}
 
 
/**
 * Draw a CONTENT_TEXTPLAIN using the current set of plotters (plot).
 *
 * x, y, clip_[xy][01] are in target coordinates.
 *
 * \param  c     content of type CONTENT_TEXTPLAIN
 * \param  data  redraw data for this content redraw
 * \param  clip  current clip region
 * \param  ctx   current redraw context
 * \return true if successful, false otherwise
 */
static bool
textplain_redraw(struct content *c,
                 struct content_redraw_data *data,
                 const struct rect *clip,
                 const struct redraw_context *ctx)
{
        textplain_content *text = (textplain_content *) c;
        struct browser_window *bw = text->bw;
        char *utf8_data = text->utf8_data;
        long lineno;
        int x = data->x;
        int y = data->y;
        unsigned long line_count = text->physical_line_count;
        float line_height = textplain_line_height();
        float scaled_line_height = line_height * data->scale;
        long line0 = (clip->y0 - y * data->scale) / scaled_line_height - 1;
        long line1 = (clip->y1 - y * data->scale) / scaled_line_height + 1;
        struct textplain_line *line = text->physical_line;
        size_t length;
        plot_style_t *plot_style_highlight;
        nserror res;
 
        if (line0 < 0)
                line0 = 0;
        if (line1 < 0)
                line1 = 0;
        if (line_count < (unsigned long) line0)
                line0 = line_count;
        if (line_count < (unsigned long) line1)
                line1 = line_count;
        if (line1 < line0)
                line1 = line0;
 
        res = ctx->plot->rectangle(ctx, plot_style_fill_white, clip);
        if (res != NSERROR_OK) {
                return false;
        }
 
        if (!line)
                return true;
 
        /* choose a suitable background colour for any highlighted text */
        if ((data->background_colour & 0x808080) == 0x808080)
                plot_style_highlight = plot_style_fill_black;
        else
                plot_style_highlight = plot_style_fill_white;
 
        /* Set up font plot style */
        textplain_style.background = data->background_colour;
 
        x = (x + MARGIN) * data->scale;
        y = (y + MARGIN) * data->scale;
        for (lineno = line0; lineno != line1; lineno++) {
                const char *text_d = utf8_data + line[lineno].start;
                int tab_width = textplain_tab_width * data->scale;
                size_t offset = 0;
                int tx = x;
 
                if (!tab_width) tab_width = 1;
 
                length = line[lineno].length;
                if (!length)
                        continue;
 
                while (offset < length) {
                        size_t next_offset = offset;
                        int width;
                        int ntx;
                        nserror res;
 
                        while ((next_offset < length) &&
                               (text_d[next_offset] != '\t')) {
                                next_offset = utf8_next(text_d,
                                                        length,
                                                        next_offset);
                        }
 
                        if (!text_draw(text_d + offset,
                                       next_offset - offset,
                                       line[lineno].start + offset,
                                       tx,
                                       y + (lineno * scaled_line_height),
                                       clip,
                                       line_height,
                                       data->scale,
                                       text,
                                       text->sel,
                                       ctx)) {
                                return false;
                        }
 
                        if (next_offset >= length)
                                break;
 
                        res = guit->layout->width(&textplain_style,
                                                  &text_d[offset],
                                                  next_offset - offset,
                                                  &width);
                        /* locate end of string and align to next tab position */
                        if (res == NSERROR_OK) {
                                tx += (int)(width * data->scale);
                        }
 
                        ntx = x + ((1 + (tx - x) / tab_width) * tab_width);
 
                        /* if the tab character lies within the
                         *  selection, if any, then we must draw it as
                         *  a filled rectangle so that it's consistent
                         *  with background of the selected text
                         */
 
                        if (bw) {
                                unsigned tab_ofst = line[lineno].start + next_offset;
                                struct selection *sel = text->sel;
                                bool highlighted = false;
 
                                unsigned start_idx, end_idx;
                                if (selection_highlighted(sel,
                                                          tab_ofst,
                                                          tab_ofst + 1,
                                                          &start_idx,
                                                          &end_idx)) {
                                        highlighted = true;
                                }
 
 
                                if (!highlighted &&
                                    (c->textsearch.context != NULL)) {
                                        unsigned start_idx, end_idx;
                                        if (content_textsearch_ishighlighted(
                                                    c->textsearch.context,
                                                    tab_ofst,
                                                    tab_ofst + 1,
                                                    &start_idx,
                                                    &end_idx)) {
                                                highlighted = true;
                                        }
                                }
 
                                if (highlighted) {
                                        struct rect rect;
                                        rect.x0 = tx;
                                        rect.y0 = y + (lineno * scaled_line_height);
                                        rect.x1 = ntx;
                                        rect.y1 = rect.y0 + scaled_line_height;
                                        res = ctx->plot->rectangle(ctx,
                                                                   plot_style_highlight,
                                                                   &rect);
                                        if (res != NSERROR_OK) {
                                                return false;
                                        }
                                }
                        }
 
                        offset = next_offset + 1;
                        tx = ntx;
                }
        }
 
        return true;
}
 
 
/**
 * Handle a window containing a CONTENT_TEXTPLAIN being opened.
 */
static nserror
textplain_open(struct content *c,
               struct browser_window *bw,
               struct content *page,
               struct object_params *params)
{
        textplain_content *text = (textplain_content *) c;
 
        text->bw = bw;
 
        /* text selection */
        selection_init(text->sel);
 
        return NSERROR_OK;
}
 
 
/**
 * Handle a window containing a CONTENT_TEXTPLAIN being closed.
 */
static nserror textplain_close(struct content *c)
{
        textplain_content *text = (textplain_content *) c;
 
        text->bw = NULL;
 
        return NSERROR_OK;
}
 
 
/**
 * Return an textplain content's selection context
 */
static char *textplain_get_selection(struct content *c)
{
        textplain_content *text = (textplain_content *) c;
 
        return selection_get_copy(text->sel);
}
 
 
/**
 * Convert a character offset within a line of text into the
 * horizontal co-ordinate
 *
 * The conversion takes into account the font being used and any tabs
 * in the text
 *
 * \param  text    line of text
 * \param  offset  char offset within text
 * \param  length  line length
 * \return x ordinate
 */
static int
textplain_coord_from_offset(const char *text, size_t offset, size_t length)
{
        int x = 0;
 
        while (offset > 0) {
                size_t next_offset = 0;
                int tx;
 
                while (next_offset < offset && text[next_offset] != '\t') {
                        next_offset = utf8_next(text, length, next_offset);
                }
 
                guit->layout->width(&textplain_style, text, next_offset, &tx);
 
                x += tx;
 
                if (next_offset >= offset)
                        break;
 
                /* align to next tab boundary */
                next_offset++;
                x = (1 + (x / textplain_tab_width)) * textplain_tab_width;
                offset -= next_offset;
                text += next_offset;
                length -= next_offset;
        }
 
        return x;
}
 
 
/**
 * Retrieve number of lines in content
 *
 * \param[in] c Content to retrieve line count from
 * \return Number of lines
 */
static unsigned long textplain_line_count(struct content *c)
{
        textplain_content *text = (textplain_content *) c;
 
        assert(c != NULL);
 
        return text->physical_line_count;
}
 
 
/**
 * Return a pointer to the requested line of text.
 *
 * \param[in] c        content of type CONTENT_TEXTPLAIN
 * \param[in] lineno   line number
 * \param[out] poffset receives byte offset of line start within text
 * \param[out] plen    receives length of returned line
 * \return pointer to text, or NULL if invalid line number
 */
static char *
textplain_get_line(struct content *c,
                   unsigned lineno,
                   size_t *poffset,
                   size_t *plen)
{
        textplain_content *text = (textplain_content *) c;
        struct textplain_line *line;
 
        assert(c != NULL);
 
        if (lineno >= text->physical_line_count)
                return NULL;
        line = &text->physical_line[lineno];
 
        *poffset = line->start;
        *plen = line->length;
        return text->utf8_data + line->start;
}
 
 
/**
 * Find line number of byte in text
 *
 * Given a byte offset within the text, return the line number
 * of the line containing that offset.
 *
 * \param[in] c       content of type CONTENT_TEXTPLAIN
 * \param[in] offset  byte offset within textual representation
 * \return line number, or -1 if offset invalid (larger than size)
 */
static int textplain_find_line(struct content *c, unsigned offset)
{
        textplain_content *text = (textplain_content *) c;
        struct textplain_line *line;
        int nlines;
        int lineno = 0;
 
        assert(c != NULL);
 
        line = text->physical_line;
        nlines = text->physical_line_count;
 
        if (offset > text->utf8_data_size) {
                return -1;
        }
 
/* \todo - implement binary search here */
        while (lineno < nlines && line[lineno].start < offset) {
                lineno++;
        }
        if (line[lineno].start > offset) {
                lineno--;
        }
 
        return lineno;
}
 
 
/**
 * Finds all occurrences of a given string in a textplain content
 *
 * \param c the content to be searched
 * \param context The search context to add the entry to.
 * \param pattern the string pattern to search for
 * \param p_len pattern length
 * \param case_sens whether to perform a case sensitive search
 * \return NSERROR_OK on success else error code on faliure
 */
static nserror
textplain_textsearch_find(struct content *c,
                          struct textsearch_context *context,
                          const char *pattern,
                          int p_len,
                          bool case_sens)
{
        int nlines = textplain_line_count(c);
        int line;
        nserror res = NSERROR_OK;
 
        for(line = 0; line < nlines; line++) {
                size_t offset, length;
                const char *text;
 
                text = textplain_get_line(c, line, &offset, &length);
                if (text) {
                        while (length > 0) {
                                unsigned match_length;
                                size_t start_idx;
                                const char *new_text;
                                const char *pos;
 
                                pos = content_textsearch_find_pattern(
                                                text,
                                                length,
                                                pattern,
                                                p_len,
                                                case_sens,
                                                &match_length);
                                if (!pos)
                                        break;
 
                                /* found string in line => add to list */
                                start_idx = offset + (pos - text);
                                res = content_textsearch_add_match(context,
                                                start_idx,
                                                start_idx + match_length,
                                                NULL,
                                                NULL);
                                if (res != NSERROR_OK) {
                                        return res;
                                }
 
                                new_text = pos + match_length;
                                offset += (new_text - text);
                                length -= (new_text - text);
                                text = new_text;
                        }
                }
        }
 
        return res;
}
 
 
/**
 * Given a range of byte offsets within a UTF8 textplain content,
 * return a box that fully encloses the text
 *
 * \param[in] c     content of type CONTENT_TEXTPLAIN
 * \param[in] start byte offset of start of text range
 * \param[in] end   byte offset of end
 * \param[out] r    rectangle to be completed
 */
static void
textplain_coords_from_range(struct content *c,
                            unsigned start,
                            unsigned end,
                            struct rect *r)
{
        textplain_content *text = (textplain_content *) c;
        float line_height = textplain_line_height();
        char *utf8_data;
        struct textplain_line *line;
        unsigned lineno = 0;
        unsigned nlines;
 
        assert(c != NULL);
        assert(start <= end);
        assert(end <= text->utf8_data_size);
 
        utf8_data = text->utf8_data;
        nlines = text->physical_line_count;
        line = text->physical_line;
 
        /* find start */
        lineno = textplain_find_line(c, start);
 
        r->y0 = (int)(MARGIN + lineno * line_height);
 
        if (lineno + 1 <= nlines || line[lineno + 1].start >= end) {
                /* \todo - it may actually be more efficient just to
                 *   run forwards most of the time
                 */
 
                /* find end */
                lineno = textplain_find_line(c, end);
 
                r->x0 = 0;
                r->x1 = text->formatted_width;
        } else {
                /* single line */
                const char *text = utf8_data + line[lineno].start;
 
                r->x0 = textplain_coord_from_offset(text,
                                                    start - line[lineno].start,
                                                    line[lineno].length);
 
                r->x1 = textplain_coord_from_offset(text,
                                                    end - line[lineno].start,
                                                    line[lineno].length);
        }
 
        r->y1 = (int)(MARGIN + (lineno + 1) * line_height);
}
 
 
/**
 * Return a pointer to the raw UTF-8 data, as opposed to the reformatted
 * text to fit the window width. Thus only hard newlines are preserved
 * in the saved/copied text of a selection.
 *
 * \param[in] c     content of type CONTENT_TEXTPLAIN
 * \param[in] start starting byte offset within UTF-8 text
 * \param[in] end   ending byte offset
 * \param[out] plen receives validated length
 * \return pointer to text, or NULL if no text
 */
static char *
textplain_get_raw_data(struct content *c,
                       unsigned start,
                       unsigned end,
                       size_t *plen)
{
        textplain_content *text = (textplain_content *) c;
        size_t utf8_size;
 
        assert(c != NULL);
 
        utf8_size = text->utf8_data_size;
 
        /* any text at all? */
        if (!utf8_size) return NULL;
 
        /* clamp to valid offset range */
        if (start >= utf8_size) start = utf8_size;
        if (end >= utf8_size) end = utf8_size;
 
        *plen = end - start;
 
        return text->utf8_data + start;
}
 
 
/**
 * get bounds of a free text search match
 */
static nserror
textplain_textsearch_bounds(struct content *c,
                            unsigned start_idx,
                            unsigned end_idx,
                            struct box *start_box,
                            struct box *end_box,
                            struct rect *bounds)
{
        textplain_coords_from_range(c, start_idx, end_idx, bounds);
 
        return NSERROR_OK;
}
 
 
/**
 * invalidate a region based on offsets into the text cauing a redraw
 */
static nserror
textplain_textselection_redraw(struct content *c,
                               unsigned start_idx,
                               unsigned end_idx)
{
        struct rect r;
 
        if (end_idx <= start_idx) {
                return NSERROR_BAD_PARAMETER;
        }
 
        textplain_coords_from_range(c, start_idx, end_idx, &r);
 
        content__request_redraw(c, r.x0, r.y0, r.x1 - r.x0, r.y1 - r.y0);
 
        return NSERROR_OK;
}
 
static nserror
textplain_textselection_copy(struct content *c,
                             unsigned start_idx,
                             unsigned end_idx,
                             struct selection_string *selstr)
{
        const char *text;
        size_t length;
        bool res = false;
 
        text = textplain_get_raw_data(c, start_idx, end_idx, &length);
        if (text != NULL) {
                res = selection_string_append(text, length, false, NULL, selstr);
        }
        if (res == false) {
                return NSERROR_NOMEM;
        }
        return NSERROR_OK;
}
 
 
/**
 * Retrieve the index of the end of the text
 *
 * \param[in] c Content to retrieve size of
 * \return Size, in bytes, of data
 */
static nserror
textplain_textselection_get_end(struct content *c, unsigned *end_idx)
{
        textplain_content *text = (textplain_content *)c;
 
        *end_idx = text->utf8_data_size;
        return NSERROR_OK;
}
 
 
/**
 * plain text content handler table
 */
static const content_handler textplain_content_handler = {
        .fini = textplain_fini,
        .create = textplain_create,
        .process_data = textplain_process_data,
        .data_complete = textplain_convert,
        .reformat = textplain_reformat,
        .destroy = textplain_destroy,
        .mouse_track = textplain_mouse_track,
        .mouse_action = textplain_mouse_action,
        .keypress = textplain_keypress,
        .redraw = textplain_redraw,
        .open = textplain_open,
        .close = textplain_close,
        .get_selection = textplain_get_selection,
        .clone = textplain_clone,
        .type = textplain_content_type,
        .textsearch_find = textplain_textsearch_find,
        .textsearch_bounds = textplain_textsearch_bounds,
        .textselection_redraw = textplain_textselection_redraw,
        .textselection_copy = textplain_textselection_copy,
        .textselection_get_end = textplain_textselection_get_end,
        .no_share = true,
};
 
 
/* exported interface documented in html/textplain.h */
nserror textplain_init(void)
{
        lwc_error lerror;
        nserror error;
 
        lerror = lwc_intern_string("Windows-1252",
                                   SLEN("Windows-1252"),
                                   &textplain_default_charset);
        if (lerror != lwc_error_ok) {
                return NSERROR_NOMEM;
        }
 
        error = content_factory_register_handler("text/plain",
                                                 &textplain_content_handler);
        if (error != NSERROR_OK) {
                lwc_string_unref(textplain_default_charset);
        }
 
        error = content_factory_register_handler("application/json",
                                                 &textplain_content_handler);
        if (error != NSERROR_OK) {
                lwc_string_unref(textplain_default_charset);
        }
 
        return error;
}