1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
|
<?xml version="1.0"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd">
<refentry id="gwymodule-tutorial-process" revision="$Id: module-tutorial-process.xml 20682 2017-12-18 18:39:00Z yeti-dn $">
<refmeta>
<refentrytitle>Data Processing Modules</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>Gwyddion</refmiscinfo>
</refmeta>
<refnamediv>
<refname>Data Processing Modules</refname>
<refpurpose>
More about data processing modules
</refpurpose>
</refnamediv>
<refsect1>
<title>Run Modes</title>
<para>
<link linkend="GwyRunType">Run modes</link> specify how a module function
can be run. Data processing functions have two possible run modes.
</para>
<para>
If the function presents a (modal) dialog in which the user can for
instance adjust parameter values or make selections, include
%GWY_RUN_INTERACTIVE flag in its run modes.
If it makes sense to be run without asking, include %GWY_RUN_IMMEDIATE
flag in its run modes. When a function is run in immediate mode, it
should fetch the last used parameter values from settings as if it is
run interactively.
</para>
<para>
Many functions allow both modes and behave according to the mode
they were called in. The logic typically looks as follows:
</para>
<informalexample><programlisting>
static void
function(GwyContainer *data, GwyRunType run)
{
FunctionArgs args;
GwyDataField *data_field;
GQuark quark;
gboolean ok;
/* Check run mode */
g_return_if_fail(run & FUNCTION_RUN_MODES);
/* Get data field to operate on */
gwy_app_data_browser_get_current(GWY_APP_DATA_FIELD_KEY, &quark,
GWY_APP_DATA_FIELD, &data_field,
0);
g_return_if_fail(data_field && quark);
load_args(gwy_app_settings_get(), &args);
/* Present a GUI in interactive mode, quit if cancelled */
if (run == GWY_RUN_INTERACTIVE) {
ok = function_dialog(&args);
save_args(gwy_app_settings_get(), &args);
if (!ok)
return;
}
/* Perform the processing in immediate mode, or after user confirmation */
function_do(data, data_field, quark, &args);
}
</programlisting></informalexample>
</refsect1>
<refsect1>
<title>Masks</title>
<para>
To highlight some areas in the data (like the grain modules do) you may
want to use a mask. Masks are data fields too, differing only by a few
things from the ordinary ones. Standalone masks do not exist in the
container, they are always associated with some channel data. Mask data
field units are irrelevant – the value range is always from 0 to 1;
0 being fully transparent and 1 the mask color set by user (may not be
fully opaque). It should be noted that values different from 0 and 1 at
present do not have a well-defined meaning and current modules generally
produce and handle only values 0 and 1.
</para>
<para>
To attach a mask to a data field with id <symbol>id</symbol>, just create
a new data field and put it to the container at the appropriate key which
can be obtained with gwy_app_get_mask_key_for_id().
</para>
<informalexample><programlisting><![CDATA[
GwyDataField *mask_field;
GQuark quark;
mask_field = gwy_data_field_new_alike(data_field, TRUE);
/* Fill mask_field with the mask */
...
quark = gwy_app_get_mask_key_for_id(id);
gwy_container_set_object(container, quark, mask_field);
g_object_unref(mask_field);
]]></programlisting></informalexample>
<para>
If you functions takes a mask as an input (e.g., as Grain Statistics
does), it should add %GWY_MENU_FLAG_DATA_MASK to its sensitivity flags.
The application will then make its menu item and/or toolbox button
insensitive when no mask is available.
</para>
<para>
The mask of current channel and its key can be obtained with
gwy_app_data_browser_get_current() as usual.
</para>
<informalexample><programlisting>
gwy_app_data_browser_get_current(GWY_APP_MASK_FIELD, &mask_field,
GWY_APP_MASK_FIELD_KEY, &quark,
0);
</programlisting></informalexample>
<para>
The function will set <symbol>mask_field</symbol> to %NULL and
<symbol>quark</symbol> to 0 if the mask does not exist.
</para>
</refsect1>
<refsect1>
<title>Presentations</title>
<para>
Presentations are means to display some data derived from channel data
(or even completely unrelated data) to the user instead of the actual
data, while all other processing methods and tools still can see and work
on the real data. An example is Shader module.
</para>
<para>
Working with presentations is similar to masks. One only uses
gwy_app_get_show_key_for_id() instead of gwy_app_get_mask_key_for_id()
(most functions working with presentations have <literal>show</literal>
in their name for <literal>presentation</literal> is just too long) to
obtain the presentation key, and uses %GWY_APP_SHOW_FIELD and
%GWY_APP_SHOW_FIELD_KEY when requesting the current presentation and its
key. Likewise one should add %GWY_MENU_FLAG_DATA_SHOW to menu
sensitivity flags of a function which processes presentations (this is
seldom needed as most functions only create presentations).
</para>
</refsect1>
<refsect1>
<title>Data Previews</title>
<para>
Data previews in module dialogs are best realized with #GwyDataView
widget which is used for two-dimensional data displays everywhere else
in <application>Gwyddion</application>. This widget is a bit complex,
but we can often simplify things a lot in a module dialog. The basic
scheme is following:
</para>
<orderedlist>
<listitem>
Create a local #GwyContainer that will hold the objects to display.
On rare occasions we can directly display data from the application's
data container, but normally we are going to modify the data and
therefore a local object is needed.
</listitem>
<listitem>
Fill it with objects. If our function does not change a data field
it is easier and more efficient to just put it to the private container
too, modifiable objects have to be duplicated. Since the container is
private, we are free to put anything anywhere, but to take advantage
of convenience data browser functions, we rather keep the application's
naming scheme and make the data field the 0th channel.
</listitem>
<listitem>
Construct the #GwyDataView. We have to put at least one layer there,
namely #GwyLayerBasic and set it up to display our data field.
To display mask we must add #GwyLayerMask too, and for interactive
selections a <link linkend="standard-vector-layers">vector layer</link>
must be added.
</listitem>
<listitem>
When the data of a displayed data field changes, we call
gwy_data_field_data_changed() to notify its users.
</listitem>
</orderedlist>
<informalexample><programlisting>
GtkWidget *data_view;
GwyPixmapLayer *layer;
GwyContainer *mydata;
gdouble zoomval;
/* Create new container */
mydata = gwy_container_new();
/* Fill it with objects and auxiliary data, dfield and id were obtained
* before. */
gwy_container_set_object_by_name(mydata, "/0/data", dfield);
gwy_app_sync_data_items(data, mydata, id, 0, FALSE,
GWY_DATA_ITEM_PALETTE,
GWY_DATA_ITEM_MASK_COLOR,
GWY_DATA_ITEM_RANGE,
0);
/* Create the data view and its layers */
data_view = gwy_data_view_new(mydata);
layer = gwy_layer_basic_new<!--x-->();
gwy_pixmap_layer_set_data_key(layer, "/0/data");
gwy_layer_basic_set_gradient_key(GWY_LAYER_BASIC(layer), "/0/base/palette");
gwy_data_view_set_base_layer(GWY_DATA_VIEW(data_view), layer);
/* Calculate preview size */
zoomval = PREVIEW_SIZE/(gdouble)MAX(gwy_data_field_get_xres(dfield),
gwy_data_field_get_yres(dfield));
gwy_data_view_set_zoom(GWY_DATA_VIEW(data_view), zoomval);
/* Pack data_view somewhere... */
</programlisting></informalexample>
<para>
The foregoing example uses raw data keys as <literal>"/0/data"</literal>.
Assuming we keep the standard naming scheme we can partially avoid this
with functions like gwy_app_get_data_key_for_id() and
g_quark_to_string(). However, such helper functions do not exist for all
objects that can appear in a container therefore some knowledge of
the naming scheme is usually necessary.
</para>
</refsect1>
</refentry>
|
