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---
Title: Complex layout
---
# Complex layout
The central object in high-level Pango API is [class@Pango2.Layout].
It is well-suited for breaking text into lines that fill a rectangular
area, since that is commonly how paragraphs are formatted in books.
But in real-life situations, text does not always fit in a box.
Examples of more complicated requirements are fitting text around
an image, or flowing text between multiple frames.
For cases like these, it is better to use [class@Pango2.LineBreaker]
directly instead of `Pango2Layout` (`Pango2Layout` is using a line
breaker internally). The way `Pango2LineBreaker` works is to let
applications access the formatted result one line at a time, place
it, and change parameters such as the line width before requesting
the next one.
The following example shows how to use `Pango2LineBreaker` to
produce an unusually shaped paragraph with a hole in the middle.
## Using Pango2LineBreaker
```
#include <pango2/pangocairo.h>
static Pango2Lines *
format_text (const char *text)
{
Pango2Context *context;
Pango2LineBreaker *breaker;
Pango2Lines *lines;
int x, y, width;
int inc, m, w, w2;
context = pango2_context_new ();
breaker = pango2_line_breaker_new (context);
pango2_line_breaker_add_text (breaker, text, -1, NULL);
lines = pango2_lines_new ();
m = 200;
w = 10;
w2 = -200;
inc = 40;
y = 40 * PANGO2_SCALE;
x = (m - w / 2) * PANGO2_SCALE;
width = w * PANGO2_SCALE;
while (pango2_line_breaker_has_line (breaker))
{
Pango2Line *line;
Pango2Rectangle ext;
gboolean ltr;
line = pango2_line_breaker_next_line (breaker,
x, width,
PANGO2_WRAP_CHAR,
PANGO2_ELLIPSIZE_NONE);
pango2_line_get_extents (line, NULL, &ext);
line = pango2_line_justify (line, width);
pango2_lines_add_line (lines, line, x, y - ext.y);
ltr = pango2_line_breaker_get_direction (breaker) == PANGO2_DIRECTION_LTR;
if (w2 > 0 && ltr && x <= m * PANGO2_SCALE)
x = (m + w2 / 2) * PANGO2_SCALE;
else if (w2 > 0 && !ltr && x > m * PANGO2_SCALE)
x = (m - w2 / 2) * PANGO2_SCALE;
else
{
y += ext.height;
w += inc;
w2 += inc;
if (w + inc >= 340 || w + inc < 0)
inc = - inc;
if (w2 > 0)
width = ((w - w2) / 2) * PANGO2_SCALE;
else
width = w * PANGO2_SCALE;
if (ltr)
x = (m - w / 2) * PANGO2_SCALE;
else
x = (m + w / 2) * PANGO2_SCALE;
}
}
g_object_unref (breaker);
g_object_unref (context);
return lines;
}
static void
draw_lines (cairo_t *cr, Pango2Lines *lines)
{
for (int i = 0; i < pango2_lines_get_line_count (lines); i++)
{
Pango2Line *line = pango2_lines_get_lines (lines)[i];
int x, y;
pango2_lines_get_line_position (lines, i, &x, &y);
cairo_save (cr);
cairo_move_to (cr, x / (double)PANGO2_SCALE, y / (double)PANGO2_SCALE);
pango2_cairo_show_line (cr, line);
cairo_restore (cr);
}
}
int
main (int argc, char *argv[])
{
const char *filename;
Pango2Lines *lines;
cairo_surface_t *surface;
cairo_t *cr;
char *text;
gsize length;
GError *error = NULL;
cairo_status_t status;
if (argc != 3)
{
g_printerr ("Usage: %s INPUT_FILENAME OUTPUT_FILENAME\n", argv[0]);
return 1;
}
if (!g_file_get_contents (argv[1], &text, &length, &error))
{
g_printerr ("%s\n", error->message);
return 1;
}
filename = argv[2];
surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 400, 600);
cr = cairo_create (surface);
cairo_set_source_rgb (cr, 1, 1, 1);
cairo_paint (cr);
cairo_set_source_rgb (cr, 0, 0, 0);
lines = format_text (text);
draw_lines (cr, lines);
g_object_unref (lines);
#ifdef CAIRO_HAS_PNG_FUNCTIONS
status = cairo_surface_write_to_png (surface, filename);
#else
status = CAIRO_STATUS_PNG_ERROR; /* Not technically correct, but... */
#endif
if (status != CAIRO_STATUS_SUCCESS)
g_printerr ("Could not save png to '%s'\n", filename);
else
g_print ("Output written to %s\n", filename);
cairo_surface_destroy (surface);
cairo_destroy (cr);
return 0;
}
```
Once you build and run the example code above, you should see the
following result:
|
