Hero Size Report - Functional and Design Specification

Summary and Background

The Flex 3.x/4.0 compiler provides a -link-report option which generates an XML based report detailing all of the ActionScript class definitions included within the SWF, along with the approximate size in bytes of each. The legacy link report also provides detailed dependency information for each class.

While very useful, the link report feature is somewhat limiting at times. For example, when analyzing a SWF during development it is sometimes useful to understand what beyond ActionScript bytecode contributes to the size of the file.

Although it's possible to introspect a SWF using the SDK's swfdump utility, the swfdump report does not currently provide a high level summary suitable for quickly narrowing down problem areas related to SWF size.

Flash Authoring has historically provided a publish-time 'size report' that presents an at-a-glance costing of all the ActionScript bytecode, fonts, images, sounds, videos, and other symbols within the resulting SWF. This report is useful when trying to reduce the size of your SWF, as you can identify specific bitmap or media assets which could be compressed further, or identify fonts which contain too many unnecessary glyphs.

Flex 4.5 will introduce a new -size-report option useful for summarizing the 'cost' of each type data within the SWF (script, media, fonts, etc.).

Usage Scenarios

A developer notices that after embedding a series of image assets into his application, his SWF has grown to an unacceptable size. By utilizing the size report feature, he is able to quickly determine that a few of his images had a much larger size (in bytes) than the others. After adjusting the compression options for the specific embeds, and replacing others with vector assets, the developer was able to optimize his SWF size.

A designer notices that after embedding (3) fonts, one of the fonts was accounting for many more bytes than the others. By limiting the range of embedded characters for the given font, the SWF size was greatly improved.

Detailed Description

Usage: -size-report <filename>. When used with either mxmlc or compc, an XML size report will be generated containing the following data (if applicable):

(All sizes are reported in bytes.)

Summary

The root report tag will contain a single swf tag, containing both the compressed and uncompressed size of the SWF (in bytes).

<?xml version="1.0" encoding="UTF-8"?>
<report>
  <swf size="584654" compressedSize="268252">
    ...
  </swf>
</report>

[HeaderData]

The size of the actual SWF file format header, product info, and various other marker data.

<!-- Header data (SWF attributes, metadata, product info, SWF markers, etc.) -->
<headerData totalSize="533">
  <data type="metaData" size="465"/>
  <data type="productInfo" size="28"/>
  <data type="swfHeader" size="21"/>
  <data type="fileAttributes" size="6"/>
  <data type="scriptLimits" size="6"/>
  <data type="backgroundColor" size="5"/>
  <data type="endMarker" size="2"/>
</headerData>

Frame Summary

A frame by frame summary of all script and tag data for each frame. Flex applications usually consist of 2 or more frames, with the first frame containing all preloader logic as well as the top level SystemManager definition.

<!-- Cumulative frame size summary. -->
<frames totalSize="584121">
  <frame name="_stest_mx_managers_SystemManager" size="50815" frame="1"/>
  <frame name="stest" size="533306" frame="2"/>
</frames>

Actionscript

The ActionScript data associated with this SWF is detailed further in the actionScript portion of the report. For release mode swfs all ActionScript bytecode and constant pool data is consolidated into a single block within the frame that it is associated with. For debug mode swfs or debug swcs, the abc blocks are generally broken down by symbol. All entries are sorted largest to smallest.

<!-- Actionscript code and constant data. -->
<actionScript totalSize="570124">
  <abc name="frame2" size="519385" frame="2"/>
  <abc name="frame1" size="50739" frame="1"/>
</actionScript>

Frame Data

Additional SWF tags related to frame definitions (frame labels, symbol definitions, export definitions, showFrame tags, etc.).

<!-- Additional frame tags (symbolClass, exportAssets, showFrame, etc). -->
<frameData totalSize="1211">
  <tag type="symbolClass" size="586" frame="2"/>
  <tag type="exportAssets" size="539" frame="2"/>
  <tag type="symbolClass" size="39" frame="1"/>
  <tag type="frameLabel" size="35" frame="1"/>
  <tag type="frameLabel" size="8" frame="2"/>
  <tag type="showFrame" size="2" frame="1"/>
  <tag type="showFrame" size="2" frame="2"/>
</frameData>

Bitmap Data

All embedded bitmap data (corresponding internally to defineBits, definebitsJPEG2/3/4 or defineBitsLossless/2 tags) is detailed in the bitmaps section of the report. All entries are sorted largest to smallest. If appropriate, the symbol name of each bitmap is provided.

Note: The original file name is not provided currently, as the information is not available at the time the tags are encoded. Possible future enhancement.

<!-- defineBits, definebitsJPEG2/3/4, or defineBitsLossless/2 -->
<bitmaps totalSize="19688">
  <bitmap name="myApp_icon" size="19688" frame="2"/>
</bitmaps>

Fonts

All embedded font data (corresponding internally to defineFont/2/3/4 tags) is detailed in the fonts section of the report. All entries are sorted largest to smallest. If appropriate, the symbol name of each font is provided.

_Note: The original font face name or path is not provided currently, nor any enumeration of the embedded glyphs, as the information is not available at the time the tags are encoded. DefineFont4 format also does not allow easy enumeration of the embedded glyphs. Possible future enhancement._

<!-- defineFont/2/3/4. -->
<fonts totalSize="61600">
  <font name="myApp__embed__font_MyriadProItalic_medium_italic_1543977508"
      fontName="MyriadProItalic" size="31265" frame="2"/>
  <font name="myApp__embed__font_MyriadProBold_bold_normal_290064645"
      fontName="MyriadProBold" size="30335" frame="2"/>
</fonts>

Sprite Data

All sprite data (corresponding internally to the defineSprite tag) is detailed in the sprites section of the report. All entries are sorted largest to smallest. If appropriate, the symbol name of each sprite definition is provided.

<!-- defineSprite. -->
<sprites totalSize="19">
  <sprite name="_stest_Styles__embed_css_Assets_swf_mx_skins_cursor_BusyCursor_1687245514" size="19" frame="2"/>
</sprites>

<!-- defineShape/2/3/4. -->
<shapes totalSize="261">
  <shape size="261" frame="2"/>
</shapes>

<!-- SWF, Pixel Bender, or other miscellaneous embed data. -->
<binaryData totalSize="2298">
  <data name="mx.graphics.shaderClasses.SaturationShader_ShaderClass" size="2298" frame="2"/>
</binaryData>

<!-- defineSound -->
<sounds totalSize="2983">
  <sound name="myApp_ding" size="2983" frame="2"/>
</sounds>

<!-- defineVideoStream -->
<videos totalSize="28900">
  <video name="myApp_loop" size="28900" frame="2"/>
</videos>

<?xml version="1.0" encoding="UTF-8"?>
<report>
  <swf size="74624" compressedSize="38485">

    <!-- Header data (SWF attributes, product info, markers, etc.) -->
    <headerData totalSize="533">
      <data type="metaData" size="465"/>
      <data type="productInfo" size="28"/>
      <data type="swfHeader" size="21"/>
      <data type="fileAttributes" size="6"/>
      <data type="scriptLimits" size="6"/>
      <data type="backgroundColor" size="5"/>
      <data type="endMarker" size="2"/>
    </headerData>

    <!-- Cumulative frame size summary. -->
    <frames totalSize="74091">
      <frame name="_RTest_mx_managers_SystemManager" size="56409" frame="1"/>
      <frame name="RTest" size="17682" frame="2"/>
    </frames>

    <!-- Actionscript code and constant data. -->
    <actionScript totalSize="73608">
      <abc name="frame1" size="56333" frame="1"/>
      <abc name="frame2" size="17275" frame="2"/>
    </actionScript>

    <!-- defineSprite. -->
    <sprites totalSize="19">
      <sprite name="_RTest_Styles__embed_css_Assets_swf_mx_skins_cursor_BusyCursor_1134830057" size="19" frame="2"/>
    </sprites>

    <!-- defineShape/2/3/4. -->
    <shapes totalSize="261">
      <shape size="261" frame="2"/>
    </shapes>

    <!-- Additional frame tags (symbolClass, exportAssets, showFrame, etc). -->
    <frameData totalSize="203">
      <tag type="symbolClass" size="84" frame="2"/>
      <tag type="symbolClass" size="39" frame="1"/>
      <tag type="frameLabel" size="35" frame="1"/>
      <tag type="exportAssets" size="33" frame="2"/>
      <tag type="frameLabel" size="8" frame="2"/>
      <tag type="showFrame" size="2" frame="1"/>
      <tag type="showFrame" size="2" frame="2"/>
    </frameData>
  </swf>
</report>

Additional Implementation Details

Not applicable.

Prototype Work

A prototype exists and has been checked into the Flex 4.5 feature branch. The implementation will be modified as necessary to account for specification changes or related feedback.

Compiler Work

A new *[TagEncoder]* derivative (*TagEncoderReporter*) was created which tallies all the relevant size data while the SWF tags are being emitted. A *SizeReport* instance is used to collect the statistics, and when requested, SizeReport::generate() is used internally to generate the requested XML report.

Web Tier Compiler Impact

A new compiler flag is provided to enable generation of the size report (-size-report).

Flex Feature Dependencies

Not applicable.

Backwards Compatibility

Not applicable.

Accessibility

Not applicable.

Performance

Not applicable.

Globalization

Not applicable.

Localization

Compiler Features

Not applicable.

Framework Features

Not applicable.

Issues and Recommendations

Not applicable at this time.

Documentation

Not applicable.

QA

Suggested focus areas and test cases to consider (not exhaustive):

• Test that you receive valid size-report data for both mxmlc (SWF) and compc (SWC) usage.
• Ensure that the size report captures each of the embed types accurately.
• Ensure cumulative totals appear accurate.