1		//创建字幕轨道
2		RMVPMediaVideoBlendItem *blendItem1 = [[RMVPMediaVideoBlendItem alloc] initWithBlendMode:RMVPMediaVideoBlendModeNormal];
3
4        subtitleTrack = [[RMVPMediaVisibleTrack alloc] initWithBlendItem:blendItem1];
5
6        subtitleTrack.trackId = kBDMVMediaVisibleSubtitleTrackId;
7
8        [self.videoTrack addVideoTrack:subtitleTrack];
9		//添加字幕片段
10        RMVPMediaTextSegment *subtitleSegment = [[RMVPMediaTextSegment alloc] init];
11
12        [subtitleTrack addSegment: subtitleSegment];
13
14
15		//配置字幕与预览实时显示
16		 CGFloat videoWidth = self.previewer.previewConfig.width;
17
18   		 CGFloat videoHeight = self.previewer.previewConfig.height;
19
20    	[self.videoTrack setupSubtitleStyleWithPreviewSize:CGSizeMake(videoWidth, videoHeight)];

1	//获取字幕轨道中字幕片段
2	RMVPMediaTextSegment *textSegment = [self.videoTrack subtitleSegment];
3	
4	//设置字幕内容，获取媒体轨道中心当前时间
5    CMTime currentTime = self.previewer.cursor.cursorTime;
6
7
8	//新增字幕
9	if (!currentItem) {
10
11        currentItem = [[RMVPMediaTextItem alloc] init];
12
13        currentItem.mainText = self.tmpMainTitle;
14
15        currentItem.subText = self.tmpSubTitle;
16
17        RMVPMediaTextItem *nextTextItem = nil;
18
19        NSArray *textAllItems = [textSegment textAllItem];
20
21        for (RMVPMediaTextItem *tmpItem in textAllItems) {
22
23            CMTimeRange timeRange = tmpItem.timeRange;
24            if (CMTimeCompare(timeRange.start, currentTime) > 0) {
25                nextTextItem = tmpItem;
26                break;
27            }
28        }
29
30        CGFloat newSubtitleDuration = [BDMVEditSubtitleSettings sharedInstance].addSubtitleDuration;
31
32        if (newSubtitleDuration <= 0) newSubtitleDuration = 2;
33
34        if (nextTextItem) {
35
36            CMTime eventualDuration;
37
38            CMTime nextItemStartTime = nextTextItem.timeRange.start;
39
40            CMTime gapTime = CMTimeSubtract(nextItemStartTime, currentTime);
41
42            if (CMTimeCompare(gapTime, CMTimeMake(newSubtitleDuration, 1)) >= 0) {
43                eventualDuration = CMTimeMake(newSubtitleDuration, 1);
44            } else {
45                eventualDuration = gapTime;
46            }
47
48            currentItem.timeRange = CMTimeRangeMake(currentTime, eventualDuration);
49
50            NSInteger index = [textSegment textIndexAtRefTime:nextItemStartTime];
51			//插入字幕到指定位置
52            [textSegment insertTextAtIndex:index item:currentItem];
53
54            [self.subtitleEditManager.seekBarAera insertSubtitleAtIndex:index];
55
56        } else {
57
58            CMTime eventualDuration;
59
60            CMTime mediaDuration = self.tracksCenter.userTrack.trackDuration;
61
62            CMTime remainingDuration = CMTimeSubtract(mediaDuration, currentTime);
63
64            if (CMTimeCompare(remainingDuration, CMTimeMake(newSubtitleDuration, 1)) >= 0) {
65
66                eventualDuration = CMTimeMake(newSubtitleDuration, 1);
67
68            } else {
69
70                eventualDuration = remainingDuration;
71
72            }
73
74            currentItem.timeRange = CMTimeRangeMake(currentTime, eventualDuration);
75			//追加字幕
76            [textSegment addTextWithItem:currentItem];
77
78            [self.subtitleEditManager.seekBarAera addSubtitle];
79
80        }
81  
82        NSInteger index = [textSegment textIndexAtRefTime:self.previewer.cursor.cursorTime];
83		//更新字幕显示位置，详见[3.3.4 设置字幕画面位置]
84        [self updateSubtitleDisplayAndRealSubtitlePositonWithTransition:SubtitleInitTranslation itemIndex:index];
85
86    } else { // 编辑字幕
87
88        currentItem.mainText = self.tmpMainTitle;
89
90        currentItem.subText = self.tmpSubTitle;
91
92        NSInteger index = [textSegment textIndexAtRefTime:currentTime];
93
94        [self.subtitleEditManager.seekBarAera editSubtitleAtIndex:index];
95    }

1    //设置字幕显示位置
2    currentFrame = self.displaySubtitleTextView.frame;//displayView的位置已经更新
3
4    CGSize scale = [self currentVideoScale];
5
6    BDMVPreviewTransform transform = self.subtitlePreviewTransform;
7
8    CGFloat left = (CGRectGetMinX(currentFrame) - CGRectGetMinX(availabelRect) + Subtitle_InputView_OffsetX) / transform.scale;
9
10    left += [self currentVideoInvisibleHorizontalPadding];
11
12    CGFloat bottom = (CGRectGetMaxY(availabelRect) - CGRectGetMaxY(currentFrame) + Subtitle_InputView_OffsetX) / transform.scale;
13
14    CGFloat right = (CGRectGetMaxX(availabelRect) - CGRectGetMaxX(currentFrame) + Subtitle_InputView_OffsetX) / transform.scale;
15
16    right += [self currentVideoInvisibleHorizontalPadding];
17
18    RMVPMediaTextSegment *currentSegment = [self.tracksCenter subtitleSegment];
19
20    NSDictionary *attributes = @{@"marginBottom":@(bottom * scale.height),
21
22                                 @"marginLeft":@(left * scale.width),
23
24                                 @"marginRight":@(right * scale.width)};
25
26    [currentSegment updateStyleAtIndex:index styleAttributes:attributes];