VTT subtitle rendering implementation class. More...

#include "AliVttSubtitleView.h"

Inheritance diagram for AliVttRenderImpl:

Instance Methods
(void)	- actualShow:withContext:
	Actually display subtitle.

(void)	- applyBackgroundColorStyle:contentAttribute:
	Apply background color style.

(void)	- applyColorStyle:contentAttribute:
	Apply text color style.

(void)	- applyDecorationStyle:contentAttribute:
	Apply text decoration styles (underline, strikethrough, etc.)

(void)	- applyFontStyle:contentAttribute:context:
	Apply font style.

(void)	- applyLayerSetting:styleStr:
	Apply layer settings.

(void)	- applyStrokeAndShadow:contentAttribute:context:
	Apply stroke and shadow effects.

(CGFloat)	- calculateMaxTextWidth
	Calculate maximum text width.

(void)	- clear
	Clear all subtitle display content.

(BOOL)	- containsFullWidthCharacters:
	Detect if string contains full-width characters.

(BOOL)	- containsUpperGlyphCharacters:
	Detect if string contains superscript characters.

(NSAttributedString *)	- createStyledText:dialogueObj:withContext:
	Create styled attributed text.

(NSAttributedString *)	- createStyledTextSegment:context:
	Create styled string for single text segment.

(void)	- customizeAttribuets:locationAttribute:
	Customize content attributes and location information (for subclass override)

(UIFont *)	- customizeFont:contentAttribute:contentText:
	Customize font (for subclass override)

(void)	- customizeParagraphStyle:withFont:contentText:
	Customize paragraph style (for subclass override)

(AliVttDialogueObj *)	- findDialogueObjByIdx:
	Find subtitle dialogue object by index.

(AliVttDialogueObj *)	- findIdleDialogueObj
	Find idle subtitle dialogue object.

(UIFont *)	- generateFontWithName:fontSize:isBold:isItalic:
	Generate font with specified style.

(void)	- getActualTextPositions:withContext:
	Calculate subtitle display position.

(void)	- getActualTextSize:dialogue:withContext:
	Calculate actual text size.

(UIColor *)	- getColorFromValue:
	Create UIColor object from integer value.

(void)	- getParentViewSize:h:
	Get parent view size.

(CGSize)	- getSizeFromStr:withMaxtextWidth:
	Calculate display size of attributed text.

(nullable AliWebVttHeader *)	- getVttHeader
	Get VTT header information.

(void)	- hideDialogue:atIndex:
	Hide subtitle at specified index.

(void)	- initialDialogueObj:index:
	Initialize subtitle dialogue object.

(CGPoint)	- maybeApplyDefaultPosition:withContext:
	Apply default position rules.

(CGFloat)	- maybeForcebeCenter:withContext:
	Force center alignment (when position is out of range)

(CGFloat)	- maybeUpperThanBase:withContext:
	Ensure position is above baseline.

(RenderContext *)	- prepareRenderContext
	Prepare rendering context.

(CGPoint)	- processAttributePosition:withContext:
	Process location attributes and calculate base coordinates.

(CGFloat)	- processXPositon:withContext:
	Process X direction position.

(CGFloat)	- processYPosition:withContext:
	Process Y direction position.

(void)	- renderSubtitleContent:contentAttributes:locationAttribute:
	Main method for rendering subtitle content.

(void)	- safelyRemoveObserverIfNeeded
	Safely remove observer.

(void)	- setup:
	Initialize renderer and set parent layer.

(void)	- setVttHeader:
	Set VTT header information.

(void)	- showDialogue:atIndex:
	Show subtitle at specified index.

(RenderContext *)	- updateRenderContext:withSubStr:
	Update rendering context.

(void)	- updateVideoDisPlay:height:scaleMode:
	Update video display information.

Properties
Class	constClass
	全局常量类，所有实例共享 Global constant class shared by all instances

NSMutableArray *	dialogueArr
	管理的字幕对话框对象数组 Array of managed subtitle dialogue objects

float	mContentsScale
	内容缩放比例 (pixels / contentsScale = points) Content scale ratio (pixels / contentsScale = points)

CALayer *	mLayer
	字幕渲染的父图层 Parent layer for subtitle rendering

float	mVideoDisPlayHeightPoint
	视频显示区域高度，单位为点(point) Video display area height in points

float	mVideoDisPlayWidthPoint
	视频显示区域宽度，单位为点(point) Video display area width in points

Detailed Description

VTT subtitle rendering implementation class.

Core rendering engine responsible for subtitle parsing, style application, layout calculation, and display. Supports various features of the WebVTT standard, including styles, positions, regions, etc.

Note: This class can be inherited to implement custom rendering logic

Method Documentation

◆ actualShow:withContext:

- (void) actualShow:		(AliVttDialogueObj *)	dialogueObj
withContext:		(RenderContext *)	context

Actually display subtitle.

Parameters

dialogueObj	Subtitle dialogue object
context	Rendering context

Note: Sets final frame and displays layer

◆ applyBackgroundColorStyle:contentAttribute:

- (void) applyBackgroundColorStyle:		(AliVttDialogueObj *)	dialogueObj
contentAttribute:		(VttContentAttribute *)	contentAttribute

Apply background color style.

Parameters

dialogueObj	Subtitle dialogue object
contentAttribute	Content attribute

◆ applyColorStyle:contentAttribute:

- (void) applyColorStyle:		(NSMutableDictionary *)	attrs
contentAttribute:		(VttContentAttribute *)	contentAttribute

Apply text color style.

Parameters

attrs	Attributes dictionary
contentAttribute	Content attribute

◆ applyDecorationStyle:contentAttribute:

- (void) applyDecorationStyle:		(NSMutableDictionary *)	attrs
contentAttribute:		(VttContentAttribute *)	contentAttribute

Apply text decoration styles (underline, strikethrough, etc.)

Parameters

attrs	Attributes dictionary
contentAttribute	Content attribute

◆ applyFontStyle:contentAttribute:context:

- (void) applyFontStyle:	(NSMutableDictionary *)	attrs
contentAttribute:	(VttContentAttribute *)	contentAttribute
context:	(RenderContext *)	context

Apply font style.

Parameters

attrs	Attributes dictionary
contentAttribute	Content attribute
context	Rendering context

◆ applyLayerSetting:styleStr:

- (void) applyLayerSetting:		(AliVttDialogueObj *)	dialogueObj
styleStr:		(NSAttributedString *)	styleStr

Apply layer settings.

Parameters

dialogueObj	Subtitle dialogue object
styleStr	Styled text

Note: Sets alignment, wrapping and other CATextLayer properties

◆ applyStrokeAndShadow:contentAttribute:context:

- (void) applyStrokeAndShadow:	(NSMutableDictionary *)	attrs
contentAttribute:	(VttContentAttribute *)	contentAttribute
context:	(RenderContext *)	context

Apply stroke and shadow effects.

Parameters

attrs	Attributes dictionary
contentAttribute	Content attribute
context	Rendering context

◆ calculateMaxTextWidth

- (CGFloat) calculateMaxTextWidth

Calculate maximum text width.

Returns: Maximum text width value

◆ clear

- (void) clear

Clear all subtitle display content.

Note: Remove all layers and clear dialogue array

◆ containsFullWidthCharacters:

- (BOOL) containsFullWidthCharacters: (NSString *) string

Detect if string contains full-width characters.

Parameters

string String to be detected

Returns: Returns YES if contains full-width characters, otherwise NO

Note: Full-width characters include Chinese, Japanese, Korean, etc.

◆ containsUpperGlyphCharacters:

- (BOOL) containsUpperGlyphCharacters: (NSString *) string

Detect if string contains superscript characters.

Parameters

string String to be detected

Returns: Returns YES if contains superscript characters, otherwise NO

Note: Mainly detects complex characters with superscripts and subscripts like Thai

◆ createStyledText:dialogueObj:withContext:

- (NSAttributedString *) createStyledText:	(NSArray< VttContentAttribute * > *)	contentAttributes
dialogueObj:	(AliVttDialogueObj *)	dialogueObj
withContext:	(RenderContext **)	context

Create styled attributed text.

Parameters

contentAttributes	Content attributes array
dialogueObj	Subtitle dialogue object
context	Double pointer to rendering context

Returns: Created NSAttributedString object

Note: Also sets background color and calculates text size

◆ createStyledTextSegment:context:

- (NSAttributedString *) createStyledTextSegment:		(VttContentAttribute *)	contentAttribute
context:		(RenderContext **)	context

Create styled string for single text segment.

Parameters

contentAttribute	Content attribute
context	Double pointer to rendering context

Returns: Styled text segment

◆ customizeAttribuets:locationAttribute:

- (void) customizeAttribuets:		(NSMutableArray< VttContentAttribute * > *)	contentAttributes
locationAttribute:		(VttLocationAttribute *)	locationAttribute

Customize content attributes and location information (for subclass override)

Parameters

contentAttributes	Array of content attribute objects
locationAttribute	Location attribute object

Note: Default implementation is empty, subclasses can override to implement special attribute processing logic, such as batch setting text styles or handling rich text behaviors

◆ customizeFont:contentAttribute:contentText:

- (UIFont *) customizeFont:	(UIFont *)	originalFont
contentAttribute:	(VttContentAttribute *)	contentAttribute
contentText:	(NSString *)	text

Customize font (for subclass override)

Parameters

originalFont	Original font
contentAttribute	Content attribute
text	Text content

Returns: Customized font, default returns original font

Note: Subclasses can override to apply special font processing logic

◆ customizeParagraphStyle:withFont:contentText:

- (void) customizeParagraphStyle:	(NSMutableParagraphStyle *)	paragraphStyle
withFont:	(UIFont *)	font
contentText:	(NSString *)	text

Customize paragraph style (for subclass override)

Parameters

paragraphStyle	Paragraph style object
font	Font object
text	Text content

Note: Default implementation is empty, subclasses can override to customize line spacing and other properties

◆ findDialogueObjByIdx:

- (AliVttDialogueObj *) findDialogueObjByIdx: (NSInteger) index

Find subtitle dialogue object by index.

Parameters

index Subtitle index

Returns: Found dialogue object, returns nil if not found

◆ findIdleDialogueObj

- (AliVttDialogueObj *) findIdleDialogueObj

Find idle subtitle dialogue object.

Returns: Idle dialogue object, returns nil if not found

Note: Idle means the object whose layer is in hidden state

◆ generateFontWithName:fontSize:isBold:isItalic:

- (UIFont *) generateFontWithName:	(NSString *)	fontName
fontSize:	(CGFloat)	fontSize
isBold:	(BOOL)	isBold
isItalic:	(BOOL)	isItalic

Generate font with specified style.

Parameters

fontName	Font name
fontSize	Font size
isBold	Whether bold
isItalic	Whether italic

Returns: Generated UIFont object

◆ getActualTextPositions:withContext:

- (void) getActualTextPositions:		(VttLocationAttribute *)	locationAttribute
withContext:		(RenderContext *)	context

Calculate subtitle display position.

Parameters

locationAttribute	Location attribute
context	Rendering context

Note: Calculates final x,y coordinates based on location attributes and default rules

◆ getActualTextSize:dialogue:withContext:

- (void) getActualTextSize:	(NSAttributedString *)	styleStr
dialogue:	(AliVttDialogueObj *)	dialogueObj
withContext:	(RenderContext *)	context

Calculate actual text size.

Parameters

styleStr	Styled text string
dialogueObj	Subtitle dialogue object
context	Rendering context

◆ getColorFromValue:

- (UIColor *) getColorFromValue: (NSInteger) value

Create UIColor object from integer value.

Parameters

value Color value in ARGB format

Returns: Corresponding UIColor object

◆ getParentViewSize:h:

- (void) getParentViewSize:		(CGFloat *)	w
h:		(CGFloat *)	h

Get parent view size.

Parameters

w	Width pointer for returning width value
h	Height pointer for returning height value

◆ getSizeFromStr:withMaxtextWidth:

- (CGSize) getSizeFromStr:		(NSMutableAttributedString *)	attrStr
withMaxtextWidth:		(CGFloat)	maxTextWidth

Calculate display size of attributed text.

Parameters

attrStr	Attributed text string
maxTextWidth	Maximum text width

Returns: Calculated text size

◆ getVttHeader

- (nullable AliWebVttHeader *) getVttHeader

Get VTT header information.

Returns: AliWebVttHeader object, returns nil if not set

◆ hideDialogue:atIndex:

- (void) hideDialogue:		(NSString *)	data
atIndex:		(int)	index

Hide subtitle at specified index.

Parameters

data	Subtitle data string
index	Subtitle index

◆ initialDialogueObj:index:

- (void) initialDialogueObj:		(AliVttDialogueObj **)	obj
index:		(NSUInteger)	index

Initialize subtitle dialogue object.

Parameters

obj	Double pointer to dialogue object for returning created or reused object
index	Subtitle index

Note: Creates new object if passed object is nil; otherwise reuses existing object

◆ maybeApplyDefaultPosition:withContext:

- (CGPoint) maybeApplyDefaultPosition:		(CGPoint)	locationPoint
withContext:		(RenderContext *)	context

Apply default position rules.

Parameters

locationPoint	Coordinate point calculated from location attributes
context	Rendering context

Returns: Final coordinate point after applying default rules

◆ maybeForcebeCenter:withContext:

- (CGFloat) maybeForcebeCenter:		(CGFloat)	x
withContext:		(RenderContext *)	context

Force center alignment (when position is out of range)

Parameters

x	X coordinate
context	Rendering context

Returns: Adjusted X coordinate

◆ maybeUpperThanBase:withContext:

- (CGFloat) maybeUpperThanBase:		(CGFloat)	y
withContext:		(RenderContext *)	context

Ensure position is above baseline.

Parameters

y	Y coordinate
context	Rendering context

Returns: Adjusted Y coordinate

◆ prepareRenderContext

- (RenderContext *) prepareRenderContext

Prepare rendering context.

Returns: Initialized rendering context object

Note: Calculates basic information like parent view, video display area, etc.

◆ processAttributePosition:withContext:

- (CGPoint) processAttributePosition:		(VttLocationAttribute *)	locationAttribute
withContext:		(RenderContext *)	context

Process location attributes and calculate base coordinates.

Parameters

locationAttribute	Location attribute
context	Rendering context

Returns: Calculated coordinate point

◆ processXPositon:withContext:

- (CGFloat) processXPositon:		(VttLocationAttribute *)	locationAttribute
withContext:		(RenderContext *)	context

Process X direction position.

Parameters

locationAttribute	Location attribute
context	Rendering context

Returns: X coordinate value

◆ processYPosition:withContext:

- (CGFloat) processYPosition:		(VttLocationAttribute *)	locationAttribute
withContext:		(RenderContext *)	context

Process Y direction position.

Parameters

locationAttribute	Location attribute
context	Rendering context

Returns: Y coordinate value

◆ renderSubtitleContent:contentAttributes:locationAttribute:

- (void) renderSubtitleContent:	(AliVttDialogueObj *)	dialogueObj
contentAttributes:	(NSArray< VttContentAttribute * > *)	contentAttributes
locationAttribute:	(VttLocationAttribute *)	locationAttribute

Main method for rendering subtitle content.

Parameters

dialogueObj	Subtitle dialogue object
contentAttributes	Content attributes array
locationAttribute	Location attribute

Note: This is the entry method of rendering pipeline, coordinating various rendering steps

◆ safelyRemoveObserverIfNeeded

- (void) safelyRemoveObserverIfNeeded

Safely remove observer.

Note: Called during dealloc to avoid observer-related crashes

◆ setup:

- (void) setup: (CALayer *) view

Initialize renderer and set parent layer.

Parameters

view	CALayer object for displaying subtitles

Note: This method automatically switches to main thread for UI operation thread safety

◆ setVttHeader:

- (void) setVttHeader: (NSString *) header

Set VTT header information.

Parameters

header VTT header string containing style and region definitions

◆ showDialogue:atIndex:

- (void) showDialogue:		(NSString *)	data
atIndex:		(int)	index

Show subtitle at specified index.

Parameters

data	Subtitle data string
index	Subtitle index

◆ updateRenderContext:withSubStr:

- (RenderContext *) updateRenderContext:		(RenderContext *)	context
withSubStr:		(NSAttributedString *)	subAttributedString

Update rendering context.

Parameters

context	Rendering context
subAttributedString	Sub attributed string

Returns: Updated rendering context

◆ updateVideoDisPlay:height:scaleMode:

- (void) updateVideoDisPlay:	(int)	videoWidth
height:	(int)	videoHeight
scaleMode:	(AVPScalingMode)	mode

Update video display information.

Parameters

videoWidth	Video width in pixels
videoHeight	Video height in pixels
mode	Video scaling mode

Property Documentation

◆ constClass

- (Class) constClass

readwritenonatomicassign

全局常量类，所有实例共享 Global constant class shared by all instances

◆ dialogueArr

- (NSMutableArray*) dialogueArr

readwritenonatomicstrong

管理的字幕对话框对象数组 Array of managed subtitle dialogue objects

◆ mContentsScale

- (float) mContentsScale

readwritenonatomicassign

内容缩放比例 (pixels / contentsScale = points) Content scale ratio (pixels / contentsScale = points)

◆ mLayer

- (CALayer*) mLayer

readwritenonatomicstrong

字幕渲染的父图层 Parent layer for subtitle rendering

◆ mVideoDisPlayHeightPoint

- (float) mVideoDisPlayHeightPoint

readwritenonatomicassign

视频显示区域高度，单位为点(point) Video display area height in points

◆ mVideoDisPlayWidthPoint

- (float) mVideoDisPlayWidthPoint

readwritenonatomicassign

视频显示区域宽度，单位为点(point) Video display area width in points

The documentation for this class was generated from the following file:

AliVttSubtitleView.h

Instance Methods

Properties

Detailed Description

Method Documentation

◆ actualShow:withContext:

◆ applyBackgroundColorStyle:contentAttribute:

◆ applyColorStyle:contentAttribute:

◆ applyDecorationStyle:contentAttribute:

◆ applyFontStyle:contentAttribute:context:

◆ applyLayerSetting:styleStr:

◆ applyStrokeAndShadow:contentAttribute:context:

◆ calculateMaxTextWidth

◆ clear

◆ containsFullWidthCharacters:

◆ containsUpperGlyphCharacters:

◆ createStyledText:dialogueObj:withContext:

◆ createStyledTextSegment:context:

◆ customizeAttribuets:locationAttribute:

◆ customizeFont:contentAttribute:contentText:

◆ customizeParagraphStyle:withFont:contentText:

◆ findDialogueObjByIdx:

◆ findIdleDialogueObj

◆ generateFontWithName:fontSize:isBold:isItalic:

◆ getActualTextPositions:withContext:

◆ getActualTextSize:dialogue:withContext:

◆ getColorFromValue:

◆ getParentViewSize:h:

◆ getSizeFromStr:withMaxtextWidth:

◆ getVttHeader

◆ hideDialogue:atIndex:

◆ initialDialogueObj:index:

◆ maybeApplyDefaultPosition:withContext:

◆ maybeForcebeCenter:withContext:

◆ maybeUpperThanBase:withContext:

◆ prepareRenderContext

◆ processAttributePosition:withContext:

◆ processXPositon:withContext:

◆ processYPosition:withContext:

◆ renderSubtitleContent:contentAttributes:locationAttribute:

◆ safelyRemoveObserverIfNeeded

◆ setup:

◆ setVttHeader:

◆ showDialogue:atIndex:

◆ updateRenderContext:withSubStr:

◆ updateVideoDisPlay:height:scaleMode:

Property Documentation

◆ constClass

◆ dialogueArr

◆ mContentsScale

◆ mLayer

◆ mVideoDisPlayHeightPoint

◆ mVideoDisPlayWidthPoint