Re: unicode, rendering, and a minor doc typeo patch

[martine cs washington edu (Evan Martin)]

On Thu, Jan 24, 2002 at 04:51:32PM -0500, Owen Taylor wrote:
> > It seems the easy (and probably naive and slow) way to render fonts is
> > like this (in the expose event): 
> > 	layout = gtk_widget_create_pango_layout(widget, text);
> > 	gdk_draw_layout(window, 
> > 		widget->style->fg_gc[widget->state],
> > 		10, 10, 
> > 		layout); 
> > 	g_object_unref(G_OBJECT(layout));
> > 
> > When I try this with my sample file (sample.u8, displayed in the above
> > screenshot), my text displays correctly, but I get this warning:
> > 	fb (pid:17955): ** WARNING **: pango_default_break(): the array
> > 	of PangoLogAttr passed in must have at least N+1 elements, if
> > 	there are N characters in the text being broken
> > 
> > Here's a backtrace (using --g-fatal-warnings):
> > #2  0x4044401e in pango_default_break () from /usr/lib/libpango-0.23.so
> > #3  0x404456b6 in pango_break () from /usr/lib/libpango-0.23.so
> > #4  0x404506ab in pango_layout_get_pixel_size () from /usr/lib/libpango-0.23.so
> > #5  0x404509c9 in pango_layout_get_pixel_size () from /usr/lib/libpango-0.23.so
> > #6  0x40451fa3 in pango_layout_get_iter () from /usr/lib/libpango-0.23.so
> > #7  0x4024400b in gdk_draw_layout_with_colors () from /usr/lib/libgdk-x11-1.3.so.12
> > #8  0x402442a0 in gdk_draw_layout () from /usr/lib/libgdk-x11-1.3.so.12
> > #9  0x080491e0 in expose_event ()
> > 
> > 
> > Am I going about this the wrong way?
> 
> It sounds reasonable. I think there I may have heard about some
> problems with one-character layouts, though I can't reproduce that in
> some quick tests. If you can produce a test case that exhibits the
> problem, I'll take a look.

Actually, this is using a small (45 byte) UTF-8 file.

Attached test case and file.

-- 
      Evan Martin
martine cs washington edu
  http://neugierig.org

/* vim: set ts=4 sw=4 : */

#include <gtk/gtk.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>

GString*
string_from_file(char *filename) {
	int fd;
	char buf[1024];
	GString *str;
	size_t size;

	str = g_string_new(NULL);
	if ((fd = open(filename, 0)) < 0)
		perror("open");
	/* a loop is overkill for this test case, 
	 * but this code is more correct. */
	do {
		size = read(fd, buf, 1024);
		if (size < 0)
			perror("read");
		g_string_append_len(str, buf, size);
	} while (size > 0);
	close(fd);

	return str;
}

gboolean
expose_event(GtkWidget *widget, GdkEventExpose *event, gpointer data) {
	GdkWindow *window = GTK_LAYOUT(widget)->bin_window;
	static GString* text = NULL;
	PangoLayout *layout;

	if (text == NULL)
		text = string_from_file("sample.u8");

	gdk_window_clear_area(window,
			event->area.x, event->area.y,
			event->area.width, event->area.height);
	gdk_gc_set_clip_rectangle(widget->style->fg_gc[widget->state],
			&event->area);

	layout = gtk_widget_create_pango_layout(widget, text->str);

	/* 
	 * providing the string length doesn't fix it, either.
	layout = pango_layout_new(gtk_widget_get_pango_context(widget));
	pango_layout_set_text(layout, text->str, text->len);
	*/

	gdk_draw_layout(window,
			widget->style->fg_gc[widget->state],
			10, 10,
			layout);
	g_object_unref(G_OBJECT(layout));

	gdk_gc_set_clip_rectangle(widget->style->fg_gc[widget->state],
			NULL);

	return TRUE;
}

GtkWidget*
make_contents() {
	GtkWidget *layout, *scroll;
	PangoFontDescription *font_desc;

	layout = gtk_layout_new(NULL, NULL);
	font_desc = pango_font_description_from_string("Bitstream Cyberbit 18");
	gtk_widget_modify_font(layout, font_desc);
	pango_font_description_free(font_desc);
	gtk_signal_connect(GTK_OBJECT(layout), "expose-event",
			GTK_SIGNAL_FUNC(expose_event), NULL);

	scroll = gtk_scrolled_window_new(NULL, NULL);
	gtk_scrolled_window_set_policy(GTK_SCROLLED_WINDOW(scroll), 
			GTK_POLICY_AUTOMATIC,
			GTK_POLICY_AUTOMATIC);
	gtk_container_add(GTK_CONTAINER(scroll), layout);
	return scroll;
}

int main(int argc, char* argv[]) {
	GtkWidget *dlg, *contents;

	gtk_init(&argc, &argv);

	dlg = gtk_dialog_new_with_buttons("Test Case", NULL, 0,
			GTK_STOCK_CLOSE, GTK_STOCK_CLOSE, NULL);
	gtk_window_set_default_size(GTK_WINDOW(dlg), 400, 200);
	gtk_window_set_position(GTK_WINDOW(dlg), GTK_WIN_POS_CENTER);

	contents = make_contents();
	gtk_box_pack_start(GTK_BOX(GTK_DIALOG(dlg)->vbox),
			contents, TRUE, TRUE, 0);
	gtk_widget_show_all(contents);

	gtk_dialog_run(GTK_DIALOG(dlg));

	return 0;
}

テストです。

だいがく / 大学。