8.1.3 KineticFusion Text Handling Features

Each text symbol is associated with a single Font symbol. A font defines the look and feel of a text symbol defining the shapes for each character, called glyphs, and additional font information including style, codepage and font metrics. Font metrics details additional information for specifying the gaps between characters, the default gap between consecutive lines of text and the location of the base line of each character shape, so that all character line up naturally. There are two kinds of Font symbols supported:

• Embedded font symbols: the outline of each character of the font used in the SWF is exported with the SWF. Embedded font symbols can be used for any text including rotated text.
• Device fonts: only the general font description is included with the SWF and the Flash Player is responsible for finding a system font that matches this information to render the text. Device fonts are only applicable for dynamic/input text symbols and text displayed using a device font cannot be rotated.

When an SWF movie containing font symbols is decompiled, all the font symbols are stored externally in SWF files in a repository. The fonts are stored in native SWF format so that they can be quickly loaded when referenced. These fonts are stored in a repository specific to the decompiled SWF as the font definitions are often incomplete storing only the font information need for that specific SWF. A reference to the font file is added to the output RVML document. An example of such a font in RVML is:

<Repository repositoryType='File' 
            repositoryBase='C:\repository' 
            repositoryName='TestResources'>
    <Font id='Arial.Italic.Bold' fontName='Arial' fontStyle='(bold, italic)' 
          resourceLocation='Arial_001.swf' 
          knownCodes='32, [48-49], 101, 116, 120' 
          fontRange='defined' />
</Repository> 

This is extracted from the output of an SWF that has been decompiled by KineticFusion. The font file is stored in the TestResources repository under c:\repository and the font file is stored in the file 'fonts/bolditalic/Arial_001.swf'. KineticFusion automatically lists the known characters defined in the font, for reference only.

KineticFusion can also use TrueType fonts. These are the native fonts for many operating systems and contain a great deal of compressed font information that needs to be converted to SWF format before they can be used in SWFs. For this reason, TrueType fonts should be used sparingly from RVML as it is often more advantageous to convert a TrueType font to SWF format just once and store it as a system font. An example of such a font in RVML is:

<Repository repositoryType='AbsoluteFile'>
       <Font id='Arial.Italic.Bold' fontName='Arial Bold Italic'  
              resourceType="external" resourceLocation='c:/Windows/Fonts/Arialbi.ttf' 
              fontRange='defined' />
</Repository>

KineticFusion uses two different RVML elements to represent text within an SWF. Each element type is associated with a Font symbol and a font size and color.

A static text element is used for the following kinds of text:

• Text that needs to be rotated/skewed
• Text that needs to look the same on all platforms
• Text that cannot be altered or selected
• Text that can be used as masking symbol
• Text that need to take advantage of kerning information for better presentation

Each font resource created by KineticFusion is stored inside an SWF movie that contains a single font definition and a testcard so that users can browse the font. The test card displays the standard characters of the font, however each test card is also editable. Clicking on a single line of text allows the user to see exactly how specified text will look in the font.

It is not uncommon for users to wish to change the contents of one or more text symbols in an an SWF movie. This is easy to do using KineticFusion but thee are several things that users should be aware of. Pay attention as this may save you some time later!

SWFs are often created using the bare minimum of font characters required to render the text they are displaying. This means that the external font file that was decompiled from the SWF will not be a complete font file: it may be missing glyphs, advances, and even character codes.

When character codes are missing, this will be represented by a segment having a binaryCodes attribute instead of a text attribute. This is generally not the case for SWFs created within the last couple of years, however some older SWFs did not specify character codes for the glyphs and so only the location of the glyph inside the font definition can be used. In this case, it is extremely difficult to retrieve the desired text by inspecting either the segment element or the font itself. Instead, you need to manually identify the text from the Flash player, and replace the 'binaryCodes' and the 'fontID' attribute with a new Font reference.

Equally it's possible that the advances are not specified for the glyphs defined in a font - this is common if the font is used only for the rendering of static text, since static text already has the advance information embedded in each segment. There is no way for KineticFusion to know for sure what the actual advance a glyph was defined to have from only the segment advances information. This information, as mentioned previously, is a combination of the advance and kerning information so that the advance for the character 'A' followed by the character 'V' is less than the advance for the character 'A' followed by a 'X'. KineticFusion will attempt to guess the general advance using the maximum specified advance for each included character however when the sample set is small this can still generate errors. If, when modifying segment text using known characters, it appears that the spacing between the the characters is distorted, there are two possible reasons:

• The 'advances' attribute value was not set to 'auto' after modifying the text. This is a common cause of error - the new text will not have the same characters in the same order unless you're using a non-proportional font, ensure that known advances are used by getting KineticFusion to recalculate advances
• The advances calculated by KineticFusion are wrong. This is possible where there was not enough information to remove any kerning adjustment from a glyph advance and so an advance may be less than it should be given the character that's following it. Here are two possible solutions to this:
  • decompile the SWF again and make manual adjustments to the advance list for those characters that need adjusting
  • decompile the SWF font file as a FontDefinition and make adjustments inside the font file instead.

Of course, in cases like this, it may be better to scrap the decompiled font altogether and replace it with a similar system font reference.