Changes between Version 7 and Version 8 of TEXT_MODEL_REDESIGN

Timestamp:

03/24/10 15:29:46 (15 years ago)

Author:

kyli

Comment:

--

TEXT_MODEL_REDESIGN

@@ -47 +47 @@
 
 = Design =
--TEXT MODEL PART-
 
-The idea of the new text design is to remove the existing stable poses with unstable indexes.
+== TEXT MODEL PART ==
+
+ The idea of the new text design is to remove the existing stable poses with unstable indexes.
+ 
 In order to achieve this functionality the following changes have been made:
- * Rename HotIndexInterval in org.sophie2.base.model.text.smart.position package with HotTextInterval.
- *  From org.sophie2.base.model.text.smart.position remove HotInterval and replace all of its usage
- in Sophie with HotTextInterval.
- * Remove HotPos class.
- * Remove HotPos persister class. 
+
+ * Rename HotIndexInterval in org.sophie2.base.model.text.smart.position package to HotTextInterval.
+
+ *  From org.sophie2.base.model.text.smart.position remove HotInterval and replace its usage with HotTextInterval.
+
+ * Remove the HotPos class.
+
+ * Remove the HotPos persister class. 
+
  * In HotTextInterval add a comparator for intervals.
+
  * In org.sophie2.base.model.text.smart package add new class named TextUnit - this class represents a
  single text unit in sophie text. This class is needed mostly to hold the styled value of every single text
@@ -63 +70 @@
    * Add getUnitStyle function in the class to get the unit style.
    * Add getUnitChar function to get the char.
+
  * In org.sophie2.base.model.text.smart add ImmText interface - the interface of the new sophie text.
   * Hash getStyledHash() - Returns the styled hash of the text.
@@ -77 +85 @@
   * int getEnd() - Gets the end of the text. 
   * ImmText subText(HotTextInterval interval) - Creates a new sub text of the given text. 
- * In ImmHotText class remove all the existing fields and add ImmList<TextUnit> textUnits .
+
+ * In ImmHotText class remove all the existing fields and add ImmList<TextUnit> textUnits.
+
  * Make the ImmHotText class implement the ImmText interface and implement the functions of the interface.
- * Make HotStyleDef class implement Hashable and intern the HotStyleDef's values(add field with the used styles
+
+ * Make HotStyleDef class implement Hashable and intern the HotStyleDef's values(add static field with the used styles
  till now and when creating a new HotStyleDef object if the map contains the object take the containing object
  else add the object in the map).
+
  * In HotStyleDef class add replaceDerive function that concatenates only the non default values from this 
  style and the given one and constructs a new HotStyleDef with this values.
+
  * In HotStyleDef class add getAllAttr function that returns list of all the CommonAttr's values.
+
  * In CommonAttr add two new values: HotAttr<String> LINK_ATTRIBUTE - represents the link id's for the text and
  HotAttr<ImmList<String>> ATTACHMENT_ATTRIBUTE - represents the text attachments
 (without text links(anchors and so on)).
+
  * In LinkAttachment class add String linkId attribute - this is a random final value that is unique for every
  link in the text and is genetared in the constructor of the class. Add a getter method for the value.
+
  * In HotTextResourceR4 class add Key<ImmMap<String, LinkAttachment>> KEY_TEXT_LINK_MAP key that
  holds all the the text link attachments' ids to the link attachment itself(this is used in the ligics for adding
  and removing text links).
- * The new logic for adding/removing link is as follows:first applying style to the text with the map consisting
+
+ * The new logic for adding/removing link is as follows: first applying style to the text with the map consisting
  of LINK_ATTRIBUTE with value equal to the added link id's(the default LINK_ATTRIBUTE's value if removed),
  second we change the map of the current hottextresource to a new one(with one added or removed value).
+
  * In TextViewFlow add abstract Prop<ImmMap<HotTextInterval, Attachment>> attachmentMap() - Property, holding map
- of intervals to link attachments. it holds all the links that are not none-refs(it is called attachmentMap
+ of intervals to link attachments. It holds all the links that are not none-refs(it is called attachmentMap
  not linkAttachmentMap because it will hold all the link attachments and the other attachments  in the future).
+
  * In org.sophie2.base.model.text.smart add new utility class ImmTextUtils that has:
   * ImmText empty() - Creates an empty text.
@@ -111 +130 @@
   * getStyleValue - Retrieves a specific text attribute's value at a specific position of the given text.
  
--TEXT LAYOUT PART-
+== TEXT LAYOUT PART ==
 
+=== Text Layout ===
+
+ Why should TextLayout be removed from our code:
+
+ * We only use the nextLayout() method,  get the line metrics and get the text hit info (determine which char hits a concrete Point2D) from it. Drawing with TextLayout is actually problematic, since it causes the baseline zig-zagging problem. Thus we use tons of reflection, which I suppose is not good.
+
+ * TextLayout is constructed by a LineBreakMeasurer, which demands AttributedCharacterIterator to be made out of the HotText. In the current situation, this could cause some performance problems with large texts and many styles. On the other hand, LineBreakMeasurers need to be cached in order to have better performance (so says the JavaDoc), but they are statefull. So, simultaneous usage is quite undetermined (this could happen with the backgound thread which is used by the lazy layout).
+
+ What to use instead:
+
+ * '''Definition''': a TextRun is a sequence of characters with equal styles. 
+
+ * :)
+ 
+ * The HotText will provide us the longest possible TextRun, starting from a concrete position. The method would look like this: TextRun getRun(int charIndex); This method will be fast enough with the new HotText design.
+
+ * TextRuns can be cached, because they are immutable. They hold enough information for creating a Font object (it needs CharSequence and AttributeMap), which can create a GlyphVector. The font can also create FontMetrics, which gives additional information.
+
+ * For calculating the line height of a paragraph, we get all the text runs from it, retrieve their font metrics and sum the ascent and descent values. Then we return the largest value from these.
+
+ * For laying out a paragraph text, we get the words one by one and create glyph vectors subsequently, then using their getLogicalBounds methods, we determine the sum of the widths of the vectors. If a vector does not fit in the space left, the whole word will be removed from the segment. If no words are laid out in the current segment, we try to lay out as many text runs as possible. If no runs can be laid out, we split the current TextRun and try again. This logic implements the common line-breaking policy in LineBreakMeasurer, which we currently use.
+
+ * Drawing a TextRun: the vector generated from the run has getOutline() method, which returns a shape. The run attributes hold the foreground and backgound colors, so we fill the shape with the first and the rest with the second. Note: all the glyph vectors in a paragraph must be drawn on the same baseline offset. The baseline offset for a paragraph can be calculated together with the line height.
+
+ * Decoration: the Font class can work with Font Family, Font Size, Bold and Italics attributes. Underline and Strikethrough will be implemented by drawing lines respectively on the underline and strikethrough offsets (retrieved from the font metrics). Other decorations (highlights, caret, spellcheck undrelining and others) will be implemented in another task. 
+
+ * Tabbed text: tabs can be calculated when creating the segment layouts. First of all, we must ensure that if the HotText breaks the text runs if a tab is met (e.g. a tab can only be in the end of a run). Next, put a constant in SegmentLayout which defines the max tab width (the logical width). Then we determine the actual tab width with the formula ''tabSize = MAX_TAB_WIDTH - tabXPos % MAX_TAB_WIDTH''. We add the calculated value as an offset between the current glyph vector and the next one. This way, in a rectangular area, the tabbed text will be aligned and will look cool. 
+
+=== Positioning ===
+
+ * Since the HotPos will be removed, HotLayout should not use it. So simply replace all the HotPos-related methods with int-related ones.
+
+
+
+== Tests ==
+
+ * We should make all the current text and layout-related tests to work again.
+ * New tests: [branches/private/kyli/2344/modules/org.sophie2.base.model.text/src/test/java/org/sophie2/base/model/text/smart/TextPerformanceTest.java Performance test], [branches/private/kyli/2344/modules/org.sophie2.base.model.text/src/test/java/org/sophie2/base/model/text/smart/ImmTextTest.java]
 
 = Implementation =