Gtk4-tutorial/src/sec3.src.md

# Widgets (2)

## GtkTextView, GtkTextbuffer and GtkScrolledWindow

### GtkTextView and GtkTextBuffer

GtkTextview is a widget for multiline text editing.
GtkTextBuffer is a text buffer which is connected to GtkTextView.
See a sample program `tfv1.c` below.

@@@ tfv1.c

Look at line 25.
GtkTextView is generated and its pointer is assigned to `tv`.
When GtkTextView is generated, the connected GtkTextBuffer is also generated automatically.
In the next line, the pointer to the buffer is got and assigned to `tb`.
Then, the text from line 10 to 20 is assigned to the buffer.

GtkTextView has a wrap mode.
When `GTK_WRAP_WORD_CHAR` is set, text wraps in between words, or if that is not enough, also between graphemes.

In line 30, `tv` is set to `win` as a child.

Now compile and run it.

![GtkTextView](../image/screenshot_tfv1.png)

There's an I-beam pointer in the window.
You can add or delete any character on GtkTextview.
And your change is kept in GtkTextBuffer.
If you add more characters than the limit of the window, the height of the window extends.
If the height gets bigger than the height of the display screen, you won't be able to control the size of the window back to the original size.
It's a problem.
You can solve it by putting GtkScrolledWindow between GtkApplicationWindow and GtkTextView.

### GtkScrolledWindow

What we need to do is:

- Generate GtkScrolledWindow and set it as a child of GtkApplicationWindow.
- Set GtkTextVies as a child of GtkScrolledWindow.

Modify `tfv1.c` and save it as `tfv2.c`.
The difference between these two files is very little.

$$$
diff tfv1.c tfv2.c
$$$

Though you can modify the source file by this diff output, It's good for you to show `tfv2.c`.

@@@ tfv2.c

Now compile and run it.
This time the window doesn't extend even if you type a lot of characters.
It just scrolls.