text: Add reset requets to protocol

Add a reset request to the text_model interface and a reset event to the
input_method_context interface. Use it to reset the pre-edit buffers in
the example keyboard when the cursor is moved in the example editor
client.

Signed-off-by: Jan Arne Petersen <jpetersen@openismus.com>

clients/editor.c

@@ -548,6 +548,8 @@ text_entry_set_cursor_position(struct text_entry *entry,
 {
 	entry->cursor = text_layout_xy_to_index(entry->layout, x, y);
 
+	text_model_reset(entry->model);
+
 	if (entry->cursor >= entry->preedit_cursor) {
 		entry->cursor -= entry->preedit_cursor;
 	}

clients/keyboard.c

@@ -303,8 +303,26 @@ input_method_context_surrounding_text(void *data,
 	fprintf(stderr, "Surrounding text updated: %s\n", text);
 }
 
+static void
+input_method_context_reset(void *data,
+			   struct input_method_context *context)
+{
+	struct virtual_keyboard *keyboard = data;
+
+	fprintf(stderr, "Reset pre-edit buffer\n");
+
+	if (strlen(keyboard->preedit_string)) {
+		input_method_context_preedit_string(context,
+						    "",
+						    0);
+		free(keyboard->preedit_string);
+		keyboard->preedit_string = strdup("");
+	}
+}
+
 static const struct input_method_context_listener input_method_context_listener = {
 	input_method_context_surrounding_text,
+	input_method_context_reset
 };
 
 static void