Diff of Flash/SWF/spec/The_Display_List

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TITLE:Chapter 4: The_Display_List
#contents

* The Display List [#The_Display_List]
- Displaying a frame of a SWF file is a three-stage process:
- 1. Objects are defined with definition tags such as DefineShape, DefineSprite, and so on. Each object is given a unique ID called a character, and is stored in a repository called the dictionary.
- 2. Selected characters are copied from the dictionary and placed on the display list, which is the list of the characters that will be displayed in the next frame.
- 3. Once complete, the contents of the display list are rendered to the screen with ShowFrame.

...

** Clipping layers [#Clipping_layers]
** Using the display list [#Using_the_display_list]

** Display list tags [#Display_list_tags]

*** PlaceObject [#PlaceObject]

- The PlaceObject tag adds a character to the display list.
- The CharacterId identifies the character to be added.
-The Depth field specifies the stacking order of the character. 
- The Matrix field species the position, scale, and rotation of the character.
- If the size of the PlaceObject tag exceeds the end of the transformation matrix, it is assumed that a ColorTransform field is appended to the record.
- The ColorTransform field specifies a color effect (such as transparency) that is applied to the character. The same character can be added more than once to the display list with a different depth and transformation matrix.

- %% NOTE %% (これ、何処からコピーした？)
- %% If a character does not change from frame to frame, you do not need to replace the unchanged character after each frame.%%
* NOTE [#pb251f20]
-- %% If a character does not change from frame to frame, you do not need to replace the unchanged character after each frame.%%
- NOTE
-- PlaceObject is rarely used in SWF 3 and later versions; it is superseded by PlaceObject2 and PlaceObject3.
- The minimum file format version is SWF 1.

- PlaceObject
| Field | Type | Comment |h
| Header |RECORDHEADER | Tag type = 4 |
| CharacterId | UI16 | ID of character to place |
| Depth | UI16 | Depth of character |
| Matrix | MATRIX | Transform matrix data |
| ColorTransform (optional) | CXFORM | Color transform data |

*** PlaceObject2 [#PlaceObject2]

- The PlaceObject2 tag extends the functionality of the PlaceObject tag.
- The PlaceObject2 tag can both add a character to the display list, and modify the attributes of a character that is already on the display list.
- The PlaceObject2 tag changed slightly from SWF 4 to SWF 5.
- In SWF 5, clip actions were added.

- The tag begins with a group of flags that indicate which fields are present in the tag.
- The optional fields are CharacterId, Matrix, ColorTransform, Ratio, ClipDepth, Name, and ClipActions.
- The Depth field is the only field that is always required.
- The depth value determines the stacking order of the character.
- Characters with lower depth values are displayed underneath characters with higher depth values.
- A depth value of 1 means the character is displayed at the bottom of the stack.
- Any given depth can have only one character.
- This means a character that is already on the display list can be identified by its depth alone (that is, a CharacterId is not required).
- The PlaceFlagMove and PlaceFlagHasCharacter tags indicate whether a new character is being added to the display list, or a character already on the display list is being modified.
- The meaning of the flags is as follows:
 ■ PlaceFlagMove = 0 and PlaceFlagHasCharacter = 1
- A new character (with ID of CharacterId) is placed on the display list at the specified depth.
- Other fields set the attributes of this new character.
 ■ PlaceFlagMove = 1 and PlaceFlagHasCharacter = 0
- The character at the specified depth is modified.
- Other fields modify the attributes of this character.
- Because any given depth can have only one character, no CharacterId is
required.
 ■ PlaceFlagMove = 1 and PlaceFlagHasCharacter = 1
- The character at the specified Depth is removed, and a new character (with ID of CharacterId) is placed at that depth.
- Other fields set the attributes of this new character.
- For example, a character that is moved over a series of frames has PlaceFlagHasCharacter set in the first frame, and PlaceFlagMove set in subsequent frames.
- The first frame places the new character at the desired depth, and sets the initial transformation matrix.
- Subsequent frames replace the transformation matrix of the character at the desired depth.
- The optional fields in PlaceObject2 have the following meaning:
- ■ The CharacterId field specifies the character to be added to the display list.
-- CharacterId is used only when a new character is being added.
--  If a character that is already on the display list is being modified, the CharacterId field is absent.
- ■ The Matrix field specifies the position, scale and rotation of the character being added or modified.
- ■ The ColorTransform field specifies the color effect applied to the character being added or modified.
- ■ The Ratio field specifies a morph ratio for the character being added or modified.
--  This field applies only to characters defined with DefineMorphShape, and controls how far the morph has progressed.
--  A ratio of zero displays the character at the start of the morph.
--  A ratio of 65535 displays the character at the end of the morph.
--  For values between zero and 65535 Flash Player interpolates between the start and end shapes, and displays an inbetween shape.
- ■ The ClipDepth field specifies the top-most depth that will be masked by the character being added.
--  A ClipDepth of zero indicates that this is not a clipping character.
- ■ The Name field specifies a name for the character being added or modified.
--  This field is typically used with sprite characters, and is used to identify the sprite for SetTarget actions.
--  It allows the main file (or other sprites) to perform actions inside the sprite (see “Sprites and Movie Clips” on page 231).
■ The ClipActions field, which is valid only for placing sprite characters, defines one or more event handlers to be invoked when certain events occur.

- The minimum file format version is SWF 3.
 (以下、フィールド詳細)

*** PlaceObject3 [#PlaceObject3]
*** ClipEventFlags [#ClipEventFlags]
*** RemoveObject [#RemoveObject]
*** RemoveObject2 [#RemoveObject2]
*** ShowFrame [#ShowFrame]