Add text extraction device.

1 files changed, 198 insertions, 0 deletions

diff --git a/fitz/dev_text.c b/fitz/dev_text.c
new file mode 100644
index 00000000..8bcdea7f
--- /dev/null
+++ b/fitz/dev_text.c
@@ -0,0 +1,198 @@
+#include "fitz.h"
+
+#include <ft2build.h>
+#include FT_FREETYPE_H
+
+#if ((FREETYPE_MAJOR == 2) && (FREETYPE_MINOR == 1)) || \
+	((FREETYPE_MAJOR == 2) && (FREETYPE_MINOR == 2)) || \
+	((FREETYPE_MAJOR == 2) && (FREETYPE_MINOR == 3) && (FREETYPE_PATCH < 8))
+
+int FT_Get_Advance(FT_Face face, int gid, int masks, FT_Fixed *out)
+{
+	int fterr;
+	fterr = FT_Load_Glyph(face, gid, masks | FT_LOAD_IGNORE_TRANSFORM);
+	if (fterr)
+		return fterr;
+	*out = face->glyph->advance.x * 1024;
+	return 0;
+}
+
+#else
+
+#include FT_ADVANCES_H
+
+#endif
+
+typedef struct fz_textdevice_s fz_textdevice;
+
+struct fz_textdevice_s
+{
+	fz_point point;
+	fz_textline *line;
+};
+
+fz_textline *
+fz_newtextline(void)
+{
+	fz_textline *line;
+	line = fz_malloc(sizeof(fz_textline));
+	line->len = 0;
+	line->cap = 0;
+	line->text = nil;
+	line->next = nil;
+	return line;
+}
+
+void
+fz_freetextline(fz_textline *line)
+{
+	if (line->next)
+		fz_freetextline(line->next);
+	fz_free(line->text);
+	fz_free(line);
+}
+
+static void
+fz_addtextchar(fz_textline *line, int x, int y, int c)
+{
+	if (line->len + 1 >= line->cap)
+	{
+		line->cap = line->cap ? (line->cap * 3) / 2 : 80;
+		line->text = fz_realloc(line->text, sizeof(fz_textchar) * line->cap);
+	}
+	line->text[line->len].x = x;
+	line->text[line->len].y = y;
+	line->text[line->len].c = c;
+	line->len ++;
+}
+
+void
+fz_debugtextline(fz_textline *line)
+{
+	char buf[10];
+	int c, n, k, i;
+
+	for (i = 0; i < line->len; i++)
+	{
+		c = line->text[i].c;
+		if (c < 128)
+			putchar(c);
+		else
+		{
+			n = runetochar(buf, &c);
+			for (k = 0; k < n; k++)
+				putchar(buf[k]);
+		}
+	}
+	putchar('\n');
+
+	if (line->next)
+		fz_debugtextline(line->next);
+}
+
+static void
+fz_textextractline(fz_textline **line, fz_text *text, fz_point *oldpt)
+{
+	fz_font *font = text->font;
+	fz_matrix ctm = text->ctm;
+	fz_matrix tm = text->trm;
+	fz_matrix inv = fz_invertmatrix(text->trm);
+	fz_matrix trm;
+	float dx, dy;
+	fz_point p;
+	float adv;
+	int i, x, y, fterr;
+
+	if (font->ftface)
+	{
+		FT_Set_Transform(font->ftface, NULL, NULL);
+		fterr = FT_Set_Char_Size(font->ftface, 64, 64, 72, 72);
+		if (fterr)
+			fz_warn("freetype set character size: %s", ft_errorstring(fterr));
+	}
+
+	for (i = 0; i < text->len; i++)
+	{
+		tm.e = text->els[i].x;
+		tm.f = text->els[i].y;
+		trm = fz_concat(tm, ctm);
+		x = trm.e;
+		y = trm.f;
+		trm.e = 0;
+		trm.f = 0;
+
+		p.x = text->els[i].x;
+		p.y = text->els[i].y;
+		p = fz_transformpoint(inv, p);
+		dx = oldpt->x - p.x;
+		dy = oldpt->y - p.y;
+		*oldpt = p;
+
+		/* TODO: flip advance and test for vertical writing */
+
+		if (font->ftface)
+		{
+			FT_Fixed ftadv;
+			fterr = FT_Get_Advance(font->ftface, text->els[i].gid,
+				FT_LOAD_NO_BITMAP | FT_LOAD_NO_HINTING,
+				&ftadv);
+			if (fterr)
+				fz_warn("freetype get advance (gid %d): %s", text->els[i].gid, ft_errorstring(fterr));
+			adv = ftadv / 65536.0;
+			oldpt->x += adv;
+		}
+		else
+		{
+			adv = font->t3widths[text->els[i].gid];
+			oldpt->x += adv;
+		}
+
+		if (fabs(dy) > 0.2)
+		{
+			fz_textline *newline;
+			newline = fz_newtextline();
+			(*line)->next = newline;
+			*line = newline;
+		}
+		else if (fabs(dx) > 0.2)
+		{
+			fz_addtextchar(*line, x, y, ' ');
+		}
+
+		fz_addtextchar(*line, x, y, text->els[i].ucs);
+	}
+}
+
+void fz_textfilltext(void *user, fz_text *text, fz_colorspace *colorspace, float *color, float alpha)
+{
+	fz_textdevice *tdev = user;
+	fz_textextractline(&tdev->line, text, &tdev->point);
+}
+
+void fz_textignoretext(void *user, fz_text *text)
+{
+	fz_textdevice *tdev = user;
+	fz_textextractline(&tdev->line, text, &tdev->point);
+}
+
+fz_device *fz_newtextdevice(fz_textline *root)
+{
+	fz_textdevice *tdev = fz_malloc(sizeof(fz_textdevice));
+	tdev->line = root;
+	tdev->point.x = -1;
+	tdev->point.y = -1;
+
+	fz_device *dev = fz_newdevice(tdev);
+
+	dev->filltext = fz_textfilltext;
+	dev->ignoretext = fz_textignoretext;
+
+	return dev;
+}
+
+void fz_freetextdevice(fz_device *dev)
+{
+	fz_textdevice *tdev = dev->user;
+	fz_free(tdev);
+	fz_free(dev);
+}
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