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1 : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2 : /*
3 : * This file is part of the LibreOffice project.
4 : *
5 : * This Source Code Form is subject to the terms of the Mozilla Public
6 : * License, v. 2.0. If a copy of the MPL was not distributed with this
7 : * file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 : */
9 : #ifndef INCLUDED_STARMATH_INC_CARET_HXX
10 : #define INCLUDED_STARMATH_INC_CARET_HXX
11 :
12 : #include "node.hxx"
13 :
14 : /** Representation of caret position with an equation */
15 : struct SmCaretPos{
16 0 : SmCaretPos(SmNode* selectedNode = NULL, int iIndex = 0) {
17 0 : pSelectedNode = selectedNode;
18 0 : Index = iIndex;
19 0 : }
20 : /** Selected node */
21 : SmNode* pSelectedNode;
22 : /** Index within the selected node
23 : *
24 : * 0: Position in front of a node
25 : * 1: Position after a node or after first char in SmTextNode
26 : * n: Position after n char in SmTextNode
27 : *
28 : * Notice how there's special cases for SmTextNode.
29 : */
30 : //TODO: Special cases for SmBlankNode is needed
31 : //TODO: Consider forgetting about the todo above... As it's really unpleasant.
32 : int Index;
33 : /** True, if this is a valid caret position */
34 0 : bool IsValid() const { return pSelectedNode != NULL; }
35 : bool operator!=(SmCaretPos pos) const {
36 : return pos.pSelectedNode != pSelectedNode || Index != pos.Index;
37 : }
38 0 : bool operator==(SmCaretPos pos) const {
39 0 : return pos.pSelectedNode == pSelectedNode && Index == pos.Index;
40 : }
41 : /** Get the caret position after pNode, regardless of pNode
42 : *
43 : * Gets the caret position following pNode, this is SmCaretPos(pNode, 1).
44 : * Unless pNode is an instance of SmTextNode, then the index is the text length.
45 : */
46 0 : static SmCaretPos GetPosAfter(SmNode* pNode) {
47 0 : if(pNode && pNode->GetType() == NTEXT)
48 0 : return SmCaretPos(pNode, ((SmTextNode*)pNode)->GetText().getLength());
49 0 : return SmCaretPos(pNode, 1);
50 : }
51 : };
52 :
53 : /** A line that represents a caret */
54 : class SmCaretLine{
55 : public:
56 0 : SmCaretLine(long left = 0, long top = 0, long height = 0) {
57 0 : _top = top;
58 0 : _left = left;
59 0 : _height = height;
60 0 : }
61 0 : long GetTop() const {return _top;}
62 0 : long GetLeft() const {return _left;}
63 0 : long GetHeight() const {return _height;}
64 0 : long SquaredDistanceX(SmCaretLine line) const{
65 0 : return (GetLeft() - line.GetLeft()) * (GetLeft() - line.GetLeft());
66 : }
67 0 : long SquaredDistanceX(Point pos) const{
68 0 : return (GetLeft() - pos.X()) * (GetLeft() - pos.X());
69 : }
70 0 : long SquaredDistanceY(SmCaretLine line) const{
71 0 : long d = GetTop() - line.GetTop();
72 0 : if(d < 0)
73 0 : d = (d * -1) - GetHeight();
74 : else
75 0 : d = d - line.GetHeight();
76 0 : if(d < 0)
77 0 : return 0;
78 0 : return d * d;
79 : }
80 0 : long SquaredDistanceY(Point pos) const{
81 0 : long d = GetTop() - pos.Y();
82 0 : if(d < 0)
83 0 : d = (d * -1) - GetHeight();
84 0 : if(d < 0)
85 0 : return 0;
86 0 : return d * d;
87 : }
88 : private:
89 : long _top;
90 : long _left;
91 : long _height;
92 : };
93 :
94 : // SmCaretPosGraph
95 :
96 : /** An entry in SmCaretPosGraph */
97 : struct SmCaretPosGraphEntry{
98 0 : SmCaretPosGraphEntry(SmCaretPos pos = SmCaretPos(),
99 : SmCaretPosGraphEntry* left = NULL,
100 0 : SmCaretPosGraphEntry* right = NULL){
101 0 : CaretPos = pos;
102 0 : Left = left;
103 0 : Right = right;
104 0 : }
105 : /** Caret position */
106 : SmCaretPos CaretPos;
107 : /** Entry to the left visually */
108 : SmCaretPosGraphEntry* Left;
109 : /** Entry to the right visually */
110 : SmCaretPosGraphEntry* Right;
111 0 : void SetRight(SmCaretPosGraphEntry* right){
112 0 : Right = right;
113 0 : }
114 0 : void SetLeft(SmCaretPosGraphEntry* left){
115 0 : Left = left;
116 0 : }
117 : };
118 :
119 : /** Define SmCaretPosGraph to be less than one page 4096 */
120 : #define SmCaretPosGraphSize 255
121 :
122 : class SmCaretPosGraph;
123 :
124 : /** Iterator for SmCaretPosGraph */
125 : class SmCaretPosGraphIterator{
126 : public:
127 0 : SmCaretPosGraphIterator(SmCaretPosGraph* graph){
128 0 : pGraph = graph;
129 0 : nOffset = 0;
130 0 : pEntry = NULL;
131 0 : }
132 : /** Get the next entry, NULL if none */
133 : SmCaretPosGraphEntry* Next();
134 : /** Get the current entry, NULL if none */
135 0 : SmCaretPosGraphEntry* Current(){
136 0 : return pEntry;
137 : }
138 : /** Get the current entry, NULL if none */
139 0 : SmCaretPosGraphEntry* operator->(){
140 0 : return pEntry;
141 : }
142 : private:
143 : /** Next entry to return */
144 : int nOffset;
145 : /** Current graph */
146 : SmCaretPosGraph* pGraph;
147 : /** Current entry */
148 : SmCaretPosGraphEntry* pEntry;
149 : };
150 :
151 :
152 : /** A graph over all caret positions
153 : * @remarks Graphs can only grow, entries cannot be removed!
154 : */
155 : class SmCaretPosGraph{
156 : public:
157 0 : SmCaretPosGraph(){
158 0 : pNext = NULL;
159 0 : nOffset = 0;
160 0 : }
161 : ~SmCaretPosGraph();
162 : /** Add a caret position
163 : * @remarks If Left and/or Right are set NULL, they will point back to the entry.
164 : */
165 : SmCaretPosGraphEntry* Add(SmCaretPosGraphEntry entry);
166 : /** Add a caret position
167 : * @remarks If left and/or right are set NULL, they will point back to the entry.
168 : */
169 0 : SmCaretPosGraphEntry* Add(SmCaretPos pos,
170 : SmCaretPosGraphEntry* left = NULL,
171 : SmCaretPosGraphEntry* right = NULL){
172 : SAL_WARN_IF( pos.Index < 0, "starmath", "Index shouldn't be -1!" );
173 0 : return Add(SmCaretPosGraphEntry(pos, left, right));
174 : }
175 : /** Get an iterator for this graph */
176 0 : SmCaretPosGraphIterator GetIterator(){
177 0 : return SmCaretPosGraphIterator(this);
178 : }
179 : friend class SmCaretPosGraphIterator;
180 : private:
181 : /** Next graph, to be used when this graph is full */
182 : SmCaretPosGraph* pNext;
183 : /** Next free entry in graph */
184 : int nOffset;
185 : /** Entries in this graph segment */
186 : SmCaretPosGraphEntry Graph[SmCaretPosGraphSize];
187 : };
188 :
189 : /** \page visual_formula_editing Visual Formula Editing
190 : * A visual formula editor allows users to easily edit formulas without having to learn and
191 : * use complicated commands. A visual formula editor is a WYSIWYG editor. For OpenOffice Math
192 : * this essentially means that you can click on the formula image, to get a caret, which you
193 : * can move with arrow keys, and use to modify the formula by entering text, clicking buttons
194 : * or using shortcuts.
195 : *
196 : * \subsection formula_trees Formula Trees
197 : * A formula in OpenOffice Math is a tree of nodes, take for instance the formula
198 : * "A + {B cdot C} over D", it looks like this
199 : * \f$ \mbox{A} + \frac{\mbox{B} \cdot \mbox{C}}{\mbox{D}} \f$. The tree for this formula
200 : * looks like this:
201 : *
202 : * \dot
203 : * digraph {
204 : * labelloc = "t";
205 : * label= "Equation: \"A + {B cdot C} over D\"";
206 : * size = "9,9";
207 : * n0 [label="SmTableNode (1)"];
208 : * n0 -> n1 [label="0"];
209 : * n1 [label="SmLineNode (2)"];
210 : * n1 -> n2 [label="0"];
211 : * n2 [label="SmExpressionNode (3)"];
212 : * n2 -> n3 [label="0"];
213 : * n3 [label="SmBinHorNode (4)"];
214 : * n3 -> n4 [label="0"];
215 : * n4 [label="SmTextNode: A (5)"];
216 : * n3 -> n5 [label="1"];
217 : * n5 [label="SmMathSymbolNode: (6)"];
218 : * n3 -> n6 [label="2"];
219 : * n6 [label="SmBinVerNode (7)"];
220 : * n6 -> n7 [label="0"];
221 : * n7 [label="SmExpressionNode (8)"];
222 : * n7 -> n8 [label="0"];
223 : * n8 [label="SmBinHorNode (9)"];
224 : * n8 -> n9 [label="0"];
225 : * n9 [label="SmTextNode: B (10)"];
226 : * n8 -> n10 [label="1"];
227 : * n10 [label="SmMathSymbolNode: ⋅ (11)"];
228 : * n8 -> n11 [label="2"];
229 : * n11 [label="SmTextNode: C (12)"];
230 : * n6 -> n12 [label="1"];
231 : * n12 [label="SmRectangleNode (13)"];
232 : * n6 -> n13 [label="2"];
233 : * n13 [label="SmTextNode: D (14)"];
234 : * }
235 : * \enddot
236 : *
237 : * The vertices are nodes, their label says what kind of node and the number in parentheses is
238 : * the identifier of the node (In practices a pointer is used instead of the id). The direction
239 : * of the edges tells which node is parent and which is child. The label of the edges are the
240 : * child node index number, given to SmNode::GetSubNode() of the parent to get the child node.
241 : *
242 : *
243 : * \subsection visual_lines Visual Lines
244 : *
245 : * Inorder to do caret movement in visual lines, we need a definition of caret position and
246 : * visual line. In a tree such as the above there are three visual lines. There's the outer most
247 : * line, with entries such as
248 : * \f$\mbox{A}\f$, \f$ + \f$ and \f$ \frac{\mbox{B} \cdot \mbox{C}}{\mbox{D}} \f$. Then there's
249 : * the numerator line of the fraction it has entries \f$ \mbox{B} \f$, \f$ \cdot \f$ and \f$ \mbox{C} \f$.
250 : * And last by not least there's the denominator line of the fraction it's only entry is \f$ \mbox{D} \f$.
251 : *
252 : * For visual editing it should be possible to place a caret on both sides of any line entry,
253 : * consider a line entry a character or construction that in a line is treated as a character.
254 : * Imagine the caret is placed to the right of the plus sign (id: 6), now if user presses
255 : * backspace this should delete the plus sign (id: 6), and if the user presses delete this
256 : * should delete the entire fraction (id: 7). This is because the caret is in the outer most
257 : * line where the fraction is considered a line entry.
258 : *
259 : * However, inorder to prevent users from accidentally deleting large subtrees, just because
260 : * they logically placed there caret a in the wrong line, require that complex constructions
261 : * such as a fraction is selected before it is deleted. Thus in this case it wouldn't be
262 : * deleted, but only selected and then deleted if the user hit delete again. Anyway, this is
263 : * slightly off topic for now.
264 : *
265 : * Important about visual lines is that they don't always have an SmExpressionNode as root
266 : * and the entries in a visual line is all the nodes of a subtree ordered left to right that
267 : * isn't either an SmExpressionNode, SmBinHorNode or SmUnHorNode.
268 : *
269 : *
270 : * \subsection caret_positions Caret Positions
271 : *
272 : * A caret position in OpenOffice Math is representated by an instance of SmCaretPos.
273 : * That is a caret position is a node and an index related to this node. For most nodes the
274 : * index 0, means caret is in front of this node, the index 1 means caret is after this node.
275 : * For SmTextNode the index is the caret position after the specified number of characters,
276 : * imagine an SmTextNode with the number 1337. The index 3 in such SmTextNode would mean a
277 : * caret placed right before 7, e.g. "133|7".
278 : *
279 : * For SmExpressionNode, SmBinHorNode and SmUnHorNode the only legal index is 0, which means
280 : * in front of the node. Actually the index 0 may only because for the first caret position
281 : * in a visual line. From the example above, consider the following subtree that constitutes
282 : * a visual line:
283 : *
284 : * \dot
285 : * digraph {
286 : * labelloc = "t";
287 : * label= "Subtree that constitutes a visual line";
288 : * size = "7,5";
289 : * n7 [label="SmExpressionNode (8)"];
290 : * n7 -> n8 [label="0"];
291 : * n8 [label="SmBinHorNode (9)"];
292 : * n8 -> n9 [label="0"];
293 : * n9 [label="SmTextNode: B (10)"];
294 : * n8 -> n10 [label="1"];
295 : * n10 [label="SmMathSymbolNode: ⋅ (11)"];
296 : * n8 -> n11 [label="2"];
297 : * n11 [label="SmTextNode: C (12)"];
298 : * }
299 : * \enddot
300 : * Here the caret positions are:
301 : *
302 : * <TABLE>
303 : * <TR><TD><B>Caret position:</B></TD><TD><B>Example:</B></TD>
304 : * </TR><TR>
305 : * <TD>{id: 8, index: 0}</TD>
306 : * <TD>\f$ \mid \mbox{C} \cdot \mbox{C} \f$</TD>
307 : * </TR><TR>
308 : * <TD>{id: 10, index: 1}</TD>
309 : * <TD>\f$ \mbox{C} \mid \cdot \mbox{C} \f$</TD>
310 : * </TR><TR>
311 : * <TD>{id: 11, index: 1}</TD>
312 : * <TD>\f$ \mbox{C} \cdot \mid \mbox{C} \f$</TD>
313 : * </TR><TR>
314 : * <TD>{id: 12, index: 1}</TD>
315 : * <TD>\f$ \mbox{C} \cdot \mbox{C} \mid \f$</TD>
316 : * </TR><TR>
317 : * </TABLE>
318 : *
319 : * Where \f$ \mid \f$ is used to denote caret position.
320 : *
321 : * With these exceptions included in the definition the id and index: {id: 11, index: 0} does
322 : * \b not constitute a caret position in the given context. Note the method
323 : * SmCaretPos::IsValid() does not check if this invariant holds true, but code in SmCaret,
324 : * SmSetSelectionVisitor and other places depends on this invariant to hold.
325 : *
326 : *
327 : * \subsection caret_movement Caret Movement
328 : *
329 : * As the placement of caret positions depends very much on the context within which a node
330 : * appears it is not trivial to find all caret positions and determine which follows which.
331 : * In OpenOffice Math this is done by the SmCaretPosGraphBuildingVisitor. This visitor builds
332 : * graph (an instnce of SmCaretPosGraph) over the caret positions. For details on how this
333 : * graph is build, and how new methods should be implemented see SmCaretPosGraphBuildingVisitor.
334 : *
335 : * The result of the SmCaretPosGraphBuildingVisitor is a graph over the caret positions in a
336 : * formula, representated by an instance of SmCaretPosGraph. Each entry (instances of SmCaretPosGraphEntry)
337 : * has a pointer to the entry to the left and right of itself. This way we can easily find
338 : * the caret position to a right or left of a given caret position. Note each caret position
339 : * only appears once in this graph.
340 : *
341 : * When searching for a caret position after a left click on the formula this map is also used.
342 : * We simply iterate over all entries, uses the SmCaretPos2LineVisitor to find a line for each
343 : * caret position. Then the distance from the click to the line is computed and we choose the
344 : * caret position closest to the click.
345 : *
346 : * For up and down movement, we also iterator over all caret positions and use SmCaretPos2LineVisitor
347 : * to find a line for each caret position. Then we compute the distance from the current
348 : * caret position to every other caret position and chooses the one closest that is either
349 : * above or below the current caret position, depending on whether we're doing up or down movement.
350 : *
351 : * This result of this approach to caret movement is that we have logically predictable
352 : * movement for left and right, whilst leftclick, up and down movement depends on the sizes
353 : * and placement of all node and may be less logically predictable. This solution also means
354 : * that we only have one complex visitor generating the graph, imagine the nightmare if we
355 : * had a visitor for movement in each direction.
356 : *
357 : * Making up and down movement independent of node sizes and placement wouldn't necessarily
358 : * be a good thing either. Consider the formula \f$ \frac{1+2+3+4+5}{6} \f$, if the caret is
359 : * placed as displayed here: \f$ \frac{1+2+3+4+5}{6 \mid} \f$, up movement should move to right
360 : * after "3": \f$ \frac{1+2+3|+4+5}{6} \f$. However, such a move depends on the sizes and placement
361 : * of all nodes in the fraction.
362 : *
363 : *
364 : * \subsubsection caretpos_graph_example Example of Caret Position Graph
365 : *
366 : * If we consider the formula
367 : * \f$ \mbox{A} + \frac{\mbox{B} \cdot \mbox{C}}{\mbox{D}} \f$ from \ref formula_trees.
368 : * It has the following caret positions:
369 : *
370 : * <TABLE>
371 : * <TR>
372 : * <TD><B>Caret position:</B></TD>
373 : * <TD><B>Example:</B></TD>
374 : * </TR><TR>
375 : * <TD>{id: 3, index: 0}</TD>
376 : * <TD>\f$ \mid\mbox{A} + \frac{\mbox{B} \cdot \mbox{C}}{\mbox{D}} \f$</TD>
377 : * </TR><TR>
378 : * <TD>{id: 5, index: 1}</TD>
379 : * <TD>\f$ \mbox{A}\mid + \frac{\mbox{B} \cdot \mbox{C}}{\mbox{D}} \f$</TD>
380 : * </TR><TR>
381 : * <TD>{id: 6, index: 1}</TD>
382 : * <TD>\f$ \mbox{A} + \mid \frac{\mbox{B} \cdot \mbox{C}}{\mbox{D}} \f$</TD>
383 : * </TR><TR>
384 : * <TD>{id: 8, index: 0}</TD>
385 : * <TD>\f$ \mbox{A} + \frac{ \mid \mbox{B} \cdot \mbox{C}}{\mbox{D}} \f$</TD>
386 : * </TR><TR>
387 : * <TD>{id: 10, index: 1}</TD>
388 : * <TD>\f$ \mbox{A} + \frac{\mbox{B} \mid \cdot \mbox{C}}{\mbox{D}} \f$</TD>
389 : * </TR><TR>
390 : * <TD>{id: 11, index: 1}</TD>
391 : * <TD>\f$ \mbox{A} + \frac{\mbox{B} \cdot \mid \mbox{C}}{\mbox{D}} \f$</TD>
392 : * </TR><TR>
393 : * <TD>{id: 12, index: 1}</TD>
394 : * <TD>\f$ \mbox{A} + \frac{\mbox{B} \cdot \mbox{C} \mid}{\mbox{D}} \f$</TD>
395 : * </TR><TR>
396 : * <TD>{id: 14, index: 0}</TD>
397 : * <TD>\f$ \mbox{A} + \frac{\mbox{B} \cdot \mbox{C}}{\mid \mbox{D}} \f$</TD>
398 : * </TR><TR>
399 : * <TD>{id: 14, index: 1}</TD>
400 : * <TD>\f$ \mbox{A} + \frac{\mbox{B} \cdot \mbox{C}}{\mbox{D} \mid} \f$</TD>
401 : * </TR><TR>
402 : * <TD>{id: 7, index: 1}</TD>
403 : * <TD>\f$ \mbox{A} + \frac{\mbox{B} \cdot \mbox{C}}{\mbox{D}} \mid \f$</TD>
404 : * </TR>
405 : * </TABLE>
406 : *
407 : * Below is a directed graph over the caret postions and how you can move between them.
408 : * \dot
409 : * digraph {
410 : * labelloc = "t";
411 : * label= "Caret Position Graph";
412 : * size = "4,6";
413 : * p0 [label = "{id: 3, index: 0}"];
414 : * p0 -> p1 [fontsize = 10.0, label = "right"];
415 : * p1 [label = "{id: 5, index: 1}"];
416 : * p1 -> p0 [fontsize = 10.0, label = "left"];
417 : * p1 -> p2 [fontsize = 10.0, label = "right"];
418 : * p2 [label = "{id: 6, index: 1}"];
419 : * p2 -> p1 [fontsize = 10.0, label = "left"];
420 : * p2 -> p3 [fontsize = 10.0, label = "right"];
421 : * p3 [label = "{id: 8, index: 0}"];
422 : * p3 -> p2 [fontsize = 10.0, label = "left"];
423 : * p3 -> p4 [fontsize = 10.0, label = "right"];
424 : * p4 [label = "{id: 10, index: 1}"];
425 : * p4 -> p3 [fontsize = 10.0, label = "left"];
426 : * p4 -> p5 [fontsize = 10.0, label = "right"];
427 : * p5 [label = "{id: 11, index: 1}"];
428 : * p5 -> p4 [fontsize = 10.0, label = "left"];
429 : * p5 -> p6 [fontsize = 10.0, label = "right"];
430 : * p6 [label = "{id: 12, index: 1}"];
431 : * p6 -> p5 [fontsize = 10.0, label = "left"];
432 : * p6 -> p9 [fontsize = 10.0, label = "right"];
433 : * p7 [label = "{id: 14, index: 0}"];
434 : * p7 -> p2 [fontsize = 10.0, label = "left"];
435 : * p7 -> p8 [fontsize = 10.0, label = "right"];
436 : * p8 [label = "{id: 14, index: 1}"];
437 : * p8 -> p7 [fontsize = 10.0, label = "left"];
438 : * p8 -> p9 [fontsize = 10.0, label = "right"];
439 : * p9 [label = "{id: 7, index: 1}"];
440 : * p9 -> p6 [fontsize = 10.0, label = "left"];
441 : * }
442 : * \enddot
443 : */
444 :
445 : /* TODO: Write documentation about the following keywords:
446 : *
447 : * Visual Selections:
448 : * - Show images
449 : * - Talk about how the visitor does this
450 : *
451 : * Modifying a Visual Line:
452 : * - Find top most non-compo of the line (e.g. The subtree that constitutes a line)
453 : * - Make the line into a list
454 : * - Edit the list, add/remove/modify nodes
455 : * - Parse the list back into a subtree
456 : * - Insert the new subtree where the old was taken
457 : */
458 :
459 : #endif // INCLUDED_STARMATH_INC_CARET_HXX
460 :
461 : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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