16 The following diagram shows a less efficient technique for applying format |
16 The following diagram shows a less efficient technique for applying format |
17 layering to text. The inefficiency arises because each format layer stores |
17 layering to text. The inefficiency arises because each format layer stores |
18 not only the new attribute which it introduces, but also every attribute which |
18 not only the new attribute which it introduces, but also every attribute which |
19 it inherits from the preceding format layer. </p> |
19 it inherits from the preceding format layer. </p> |
20 <fig id="GUID-DBA21807-9BC8-5FFB-962A-4CDCD9A72359"> |
20 <fig id="GUID-DBA21807-9BC8-5FFB-962A-4CDCD9A72359"> |
21 <image href="GUID-CFD3CD78-D99A-57B8-80EB-8C67899E5D27_d0e427545_href.png" placement="inline"/> |
21 <image href="GUID-CFD3CD78-D99A-57B8-80EB-8C67899E5D27_d0e427383_href.png" placement="inline"/> |
22 </fig> |
22 </fig> |
23 <p>The Symbian platform avoids this inefficiency by using the system of <keyword>based-on |
23 <p>The Symbian platform avoids this inefficiency by using the system of <keyword>based-on |
24 links</keyword>. Here, each new layer adds attributes in a natural way without |
24 links</keyword>. Here, each new layer adds attributes in a natural way without |
25 restating all attributes previously set. A based-on link is a pointer to the |
25 restating all attributes previously set. A based-on link is a pointer to the |
26 format layer whose attributes are inherited by another layer. For example, |
26 format layer whose attributes are inherited by another layer. For example, |
33 therefore based upon any other layer.</p> |
33 therefore based upon any other layer.</p> |
34 <p>This method is demonstrated in the following two diagrams, in which each |
34 <p>This method is demonstrated in the following two diagrams, in which each |
35 arrow represents a based-on link.</p> |
35 arrow represents a based-on link.</p> |
36 <fig id="GUID-3BE6B9A3-D8DB-543C-AA88-DD519B991B62"> |
36 <fig id="GUID-3BE6B9A3-D8DB-543C-AA88-DD519B991B62"> |
37 <title>Format layering</title> |
37 <title>Format layering</title> |
38 <image href="GUID-52743192-B1E0-5B71-B85B-43487F18F412_d0e427565_href.png" placement="inline"/> |
38 <image href="GUID-52743192-B1E0-5B71-B85B-43487F18F412_d0e427403_href.png" placement="inline"/> |
39 </fig> |
39 </fig> |
40 <p>The following diagram demonstrates the system of based-on links when attributes |
40 <p>The following diagram demonstrates the system of based-on links when attributes |
41 are applied to different parts of text rather than added on top of existing |
41 are applied to different parts of text rather than added on top of existing |
42 attribute layers.</p> |
42 attribute layers.</p> |
43 <fig id="GUID-1E0E17F0-BE93-5403-8474-ED612E118C8F"> |
43 <fig id="GUID-1E0E17F0-BE93-5403-8474-ED612E118C8F"> |
44 <image href="GUID-F99938E9-9E06-53C0-B762-2CE51BC5F1E2_d0e427573_href.png" placement="inline"/> |
44 <image href="GUID-F99938E9-9E06-53C0-B762-2CE51BC5F1E2_d0e427411_href.png" placement="inline"/> |
45 </fig> |
45 </fig> |
46 <p>In this case, several format layers are required, all of which are based |
46 <p>In this case, several format layers are required, all of which are based |
47 on the normal layer.</p> |
47 on the normal layer.</p> |
48 </conbody></concept> |
48 </conbody></concept> |