Pokiri Movie Download Tamil Font
Phyllis Sterlin
Please note: This document reflects the changes made in 2005 recommendations for Indic-script OpenType font and shaping-engine implementations. While Indic fonts made according to the earlier recommendations will still function properly in the new versions of Uniscribe, font developers may choose to update their fonts, particularly if they wish to avoid certain limitations of the earlier implementation.
This document presents information that will help font developers create or support OpenType fonts for the Telugu script covered by the Unicode Standard. The Telugu script is used to write the Telugu language of Andhra Pradesh, India, as well as the minority languages Gondi and Lambadi.
This document targets developers implementing Indic shaping behavior compatible with Microsoft OpenType specification for Indic scripts. It contains information about terminology, font features and behavior of the Indic shaping engine in regards to the Telugu script. While it does not contain instructions for creating Telugu fonts, it will help font developers understand how the Indic shaping engine processes Indic text. In addition, registered features of the Telugu script are defined and illustrated with examples.
The new Indic shaping engine allows for variations in typographic conventions, giving a font developer control over shaping by the choice of designation of glyphs to certain OpenType features. For example, the location where the reph and pre-pended matra are re-ordered within a syllable cluster is affected by the presence of a half form. See illustrations below.
Akhand ligatures - Required consonant ligatures that may appear anywhere in the syllable, and may or may not involve the base glyph. Akhand ligatures have the highest priority and are formed first; some languages include them in their alphabets.
Base glyph - The only consonant or consonant conjunct in the orthographic syllable that is written in its "full" (nominal) form. In Devanagari, the last consonant of the syllable (except for syllables ending with letter "Ra") usually forms the base glyph. In "degenerate" syllables that have no vowel (last letter of a word), the last consonant in halant form serves as the base consonant and is mapped as the base glyph. Layout operations are defined in terms of a base glyph, not a base character, since the base can often be a ligature.
Below-base form of consonants - A variant form of a consonant that appears below the base glyph. In Devanagari, only the consonant Ra has a below-base form. In the glyph sequence, the below-base form comes after the consonant(s) that form the base glyph. Below-base forms are represented by a non-spacing mark glyph.
Consonant - Each represents a single consonant sound. Consonants may exist in different contextual forms and have an inherent vowel (usually, the short vowel "a"). For example, "Ka" and "Ta", rather than just "K" or "T."
Halant form of consonants - The form produced by adding the Virama to the nominal shape. The Halant form is used in syllables that have no vowel or as the half form when no distinct shape for the half form exists.
Halant form of consonants - The form produced by adding the halant (virama) to the nominal shape. The Halant form is used in syllables that have no vowel or as the half form when no distinct shape for the half form exists.
Half form of consonants (pre-base form) - A variant form of consonants which appear to the left of the base consonant, if they do not participate in a ligature. Consonants in their half form precede the ones forming the base glyph. Some Indic scripts, like Devanagari have distinctly shaped half forms for most of the consonants. If not distinct shape exists, the full form will display with an explicit Virama (same shape as the halant form).
Matra (Dependent Vowel) - Used to represent a vowel sound that is not inherent to the consonant. Dependent vowels are referred to as "matras" in Sanskrit. They are always depicted in combination with a single consonant, or with a consonant cluster. The greatest variation among different Indian scripts is found in the rules for attaching dependent vowels to base characters.
New shaping behavior - Shaping behavior defined in this version of the Indic OpenType Font Specification. Information in this document relates primarily to the new implementation model. Old behavior may be mentioned in comments about compatibility.
Pre-base form of consonants - A variant form of a consonant that appears to the left of the base glyph. Note that most pre-base consonant forms are logically as well as visually before the base consonant. Half forms are examples of this kind of pre-base form. In some scripts, though, a pre-base Ra may logically follow the base consonant (that is, it follows it phonetically and in the character sequence of the text), even though it is presented visually before the base. The shaping engine detects such cases dynamically using the 'pref' feature and re-orders the pre-base-form glyph as needed.
Split Matra - A matra that is decomposed into pieces for rendering. Usually the different pieces appear in different positions relative to the base. For instance, part of the matra may be placed at the beginning of the cluster and another part at the end of the cluster.
Syllable - A single unit of Indic text processing. Shaping of Indic text is performed independently for each syllable. Process of identifying boundaries of each syllable is described below.
Telugu syllable - Effective orthographic "unit" of Telugu writing systems, consisting of a consonant and a vowel core, and optionally preceded by one or more consonants. Syllables are composed of consonant letters, independent vowels, and dependant vowels. In a text sequence, these characters are stored in phonetic order (although they may not be represented in phonetic order when displayed). Once a syllable is shaped, it is indivisible. The cursor cannot be positioned within the syllable. Transformations discussed in this document do not cross syllable boundaries.
The descriptions which follow will help font developers understand the rationale for the Telugu feature encoding model and help application developers better understand how layout clients can divide responsibilities with operating system functions.
Character properties are used in parsing syllables and identifying its parts, in determining proper character or glyph reordering and in OpenType feature application. Properties for each character are divided into two types: static properties and dynamic properties.
Static properties define basic characteristics that do not change from font to font: character type (consonant, matra, vedic sign, etc.) or type of matra reordering. They differ from script to script, but can't be controlled by font developer.
*Note: in old shaping-engine implementations, all consonant properties were static: consonants were assumed to have particular conjoining forms. In the new implementation model, consonant conjoining behavior is a dynamic property.
Each of the features above is applied together with 'locl' feature to input sequences consisting of two characters: for 'rphf' and 'half', features are applied to Consonant + Halant combinations; for 'pref', 'blwf' and 'pstf', features are applied to Halant + Consonant combinations. This is done for each consonant. If these two glyphs form a ligature, with no additional glyphs in context, this means the consonant has the corresponding form. For instance, if a substitution occurs when the 'half' and 'locl' features are applied to a sequence Da + Halant, then Da is classified as having a half form.
Note that a font may be implemented to re-order a Ra to pre-base position only in certain syllables and display it as a below-base or post-base form otherwise. This means that the Pre-base-form classification is not mutually exclusive with either Below-base-form or Post-base-form classifications. However, all classifications are determined as described above using context-free substitutions.
The consonant parts include all associated halants and nuktas. (For example, an instance of BelowBaseConsonant consists of a sequence of Halant + Below-base-forming Consonant.) All parts are optional, except the main consonant.
All parts are shown in the order they would occur within a syllable, with one qualification: depending on a font implementation, PreBaseReorderingRa may occur before all BelowBaseConsonants, after BelowBaseConsonants and before PostBaseConsonants, or after PostBaseConsonants. Also, a font may be implemented to re-order a Ra to pre-base position only in certain syllables and display it as a below-base or post-base form otherwise. Thus, final determination of whether an occurrence of Ra in a specific syllable can be treated as a pre-base reordering Ra can be made only after the 'pref' feature has been applied to that syllable.
There could be several main consonants in the case where more than one consonant doesn't have a half-, below-base, post-base or pre-base form. In a case of a cluster where the first consonant does not have a half form, the shaping engine will recognize it as the 1st 'full form' and go on to identify the 2nd full form consonant, if there is one. This information will then be used to determine the reordering behavior of the reph or any matras, vowel modifiers or stress marks.
Once the Indic shaping engine has analyzed the cluster as described above, it creates and manages a buffer of appropriately reordered elements (glyphs) representing the cluster, according to several rules (described below).
The OpenType lookups in an Indic font must be written to match glyph sequences after re-ordering has occurred. OpenType fonts should not have substitutions that attempt to perform the re-ordering. If a font developer attempted to encode such reordering information in an OpenType font, they would need to add a huge number of many-to-many glyph mappings to cover the general algorithms that a shaping engine will use.
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