支援水平 / 垂直顯示自動滾動的跑馬燈控制元件 --- SKAutoScrollLabel 的使用和實現
阿新 • • 發佈:2019-01-09
簡述
SKAutoScrollLabel是一個同時支援水平/垂直兩種型別的“跑馬燈”效果的自動滾動UILabel。在滾動的邊緣使用了梯度褪色來解決滾動邊緣生硬的效果問題,總體效果呈現出混然天成的感覺,並且使用簡單方便。如果你覺得還不錯,請star支援一下吧~
效果圖
如何開始
1.從GitHub上Clone-->SKAutoScrollLabel,然後檢視Demo
2.直接將目錄下的SKAutoScrollLabel拷貝到工程中,或在podfile資料夾中新增 pod
'SKAutoScrollLabel'
使用方法
初始化
SKAutoScrollLabel * leftLabel = [[SKAutoScrollLabel alloc] initWithFrame:CGRectMake(50, 50, [UIScreen mainScreen].bounds.size.width - 100, 50)];
[self.view addSubview:leftLabel];
基本設定
leftLabel.backgroundColor = [UIColor blackColor];// 背景色
leftLabel.textColor = [UIColor whiteColor];// 字型顏色
leftLabel.font = [UIFont systemFontOfSize:16];// 字型大小
leftLabel.direction = SK_AUTOSCROLL_DIRECTION_LEFT ;// 滾動方向,這是向左滾動
leftLabel.text = text;// 顯示內容
實現
※ 這裡僅列出關鍵步驟,具體方法請查閱原始碼
- 我們需要建立一個數組,來存放我們滾動時所需要展示的label,這裡我們只建立兩個label存放到陣列中即可(滾動只需要兩個即可達成持續跑馬燈的效果)
// 建立label陣列 NSMutableSet * labelSet = [[NSMutableSet alloc] init]; for (NSInteger i = 0; i < kLabelCount; i++) { UILabel * label = [UILabel new]; label.backgroundColor = [UIColor
2.區分水平和垂直的UILabel
static void each_object(NSArray *objects, void (^block)(UILabel * label)) {
for (UILabel * label in objects) {
block(label);
}
}
__block float offset = 0;
// 遍歷label陣列中的元素
each_object(self.labels, ^(UILabel *label) {
[label sizeToFit];
CGRect frame = label.frame;
// 垂直
if (self.direction != SK_AUTOSCROLL_DIRECTION_RIGHT && self.direction != SK_AUTOSCROLL_DIRECTION_LEFT) {
// 動態獲取長度和高度, 以此達到將label垂直的目的
NSDictionary * attribute = [NSDictionary dictionaryWithObjectsAndKeys:self.font,NSFontAttributeName, nil];
CGSize sizeWord = [@"一" boundingRectWithSize:self.bounds.size options:NSStringDrawingUsesFontLeading | NSStringDrawingUsesLineFragmentOrigin attributes:attribute context:nil].size;
CGFloat wordWidth = sizeWord.width;
CGSize sizeStr = [self.text boundingRectWithSize:CGSizeMake(wordWidth, CGFLOAT_MAX) options:NSStringDrawingUsesFontLeading | NSStringDrawingUsesLineFragmentOrigin attributes:attribute context:nil].size;
CGFloat wordHeight = sizeStr.height;
frame.origin = CGPointMake((CGRectGetWidth(self.frame) / 2) - (wordWidth / 2), offset);
frame.size = CGSizeMake(wordWidth, wordHeight);
label.frame = frame;
label.numberOfLines = 0;
offset += CGRectGetHeight(label.bounds) + self.labelSpacing;
} else {// 水平
frame.origin = CGPointMake(offset, 0);
frame.size.height = CGRectGetHeight(self.bounds);
label.frame = frame;
offset += CGRectGetWidth(label.bounds) + self.labelSpacing;
// 重新定位label在scrollview中的位置
label.center = CGPointMake(label.center.x, roundf(self.center.y - CGRectGetMinY(self.frame)));
}
});
3.判斷滾動條件,是否允許滾動
// (水平方向) 判斷當前scrollLabel是否大於self的寬度,如果是就開始滾動
if (CGRectGetWidth(self.scrollLabel.bounds) > CGRectGetWidth(self.bounds)) {
CGSize size = CGSizeMake(CGRectGetWidth(self.scrollLabel.bounds) + CGRectGetWidth(self.bounds) + self.labelSpacing, CGRectGetHeight(self.bounds));
self.scrollView.contentSize = size;
EACH_LABEL(hidden, NO);
[self applyGradientMaskForFadeLength:kDefaultFadeLength enableFade:self.scrolling];
[self scrollLabelIfNeeded];
} else if (CGRectGetHeight(self.scrollLabel.bounds) > CGRectGetHeight(self.bounds)) {// (垂直方向) 判斷當前scrollLabel是否大於self的高度,如果是就開始滾動
CGSize size = CGSizeMake(CGRectGetWidth(self.bounds), CGRectGetHeight(self.scrollLabel.bounds) + self.labelSpacing);
self.scrollView.contentSize = size;
EACH_LABEL(hidden, NO);
[self applyGradientMaskForFadeLength:kDefaultFadeLength enableFade:self.scrolling];
[self scrollLabelIfNeeded];
} else {
// 隱藏其他label
EACH_LABEL(hidden, self.scrollLabel != label);
// 調整scrollView和scrollLabel
self.scrollView.contentSize = self.bounds.size;
self.scrollLabel.frame = self.bounds;
self.scrollLabel.hidden = NO;
self.scrollLabel.textAlignment = NSTextAlignmentCenter;
[self.scrollView.layer removeAllAnimations];
[self applyGradientMaskForFadeLength:0 enableFade:NO];
}
4.自動滾動動畫
switch (self.direction) {// 滾動方向
case SK_AUTOSCROLL_DIRECTION_LEFT:
self.scrollView.contentOffset = CGPointZero;
break;
case SK_AUTOSCROLL_DIRECTION_RIGHT:
self.scrollView.contentOffset = CGPointMake(width + self.labelSpacing, 0);
break;
case SK_AUTOSCROLL_DIRECTION_TOP:
self.scrollView.contentOffset = CGPointZero;
break;
case SK_AUTOSCROLL_DIRECTION_BOTTOM:
self.scrollView.contentOffset = CGPointMake(0, height - 10 - CGRectGetHeight(self.bounds));
break;
}
// 滾動動畫, UIViewAnimationOptionRepeat一直重複動畫
[UIView animateWithDuration:duration delay:self.autoScrollInterval options:UIViewAnimationOptionRepeat animations:^{
switch (self.direction) {
case SK_AUTOSCROLL_DIRECTION_LEFT:
self.scrollView.contentOffset = CGPointMake(width + self.labelSpacing, 0);
break;
case SK_AUTOSCROLL_DIRECTION_RIGHT:
self.scrollView.contentOffset = CGPointZero;
break;
case SK_AUTOSCROLL_DIRECTION_TOP:
self.scrollView.contentOffset = CGPointMake(0, CGRectGetHeight(self.scrollLabel.bounds) + self.labelSpacing);
break;
case SK_AUTOSCROLL_DIRECTION_BOTTOM:
self.scrollView.contentOffset = CGPointZero;
break;
}
} completion:^(BOOL finished) {
_scrolling = NO;
// 移除陰影
[self applyGradientMaskForFadeLength:kDefaultFadeLength enableFade:NO];
// 完成後循呼叫
if (finished) {
[self performSelector:@selector(scrollLabelIfNeeded)];
}
}];
5.使用CAGradientLayer在滾動邊緣的製造梯度褪色效果
// 建立梯度mask和消失長度
CAGradientLayer * gradientMask = [CAGradientLayer layer];
gradientMask.bounds = self.layer.bounds;
gradientMask.position = CGPointMake(CGRectGetMidX(self.bounds), CGRectGetMidY(self.bounds));
gradientMask.shouldRasterize = YES;
gradientMask.rasterizationScale = [UIScreen mainScreen].scale;
CGFloat fadePoint = 0;
// 垂直方向的梯度褪色
if (self.direction != SK_AUTOSCROLL_DIRECTION_RIGHT && self.direction != SK_AUTOSCROLL_DIRECTION_LEFT) {
gradientMask.startPoint = CGPointMake(CGRectGetMidX(self.frame), 0);
gradientMask.endPoint = CGPointMake(CGRectGetMidX(self.frame), 1);
fadePoint = fadeLength / CGRectGetHeight(self.bounds);
// 水平方向的梯度褪色
} else {
gradientMask.startPoint = CGPointMake(0, CGRectGetMidY(self.frame));
gradientMask.endPoint = CGPointMake(1, CGRectGetMidY(self.frame));
fadePoint = fadeLength / CGRectGetWidth(self.bounds);
}
// 設定漸變mask顏色和位置
id transparent = (id)[UIColor clearColor].CGColor;
id opaque = (id)[UIColor blackColor].CGColor;
gradientMask.colors = @[transparent, opaque, opaque, transparent];
// 計算褪色
NSNumber * leftFadePoint = @(fadePoint);
NSNumber * rightFadePoint = @(1 - fadePoint);
if (!fade) {
switch (self.direction) {
case SK_AUTOSCROLL_DIRECTION_LEFT:
leftFadePoint = @0;
break;
case SK_AUTOSCROLL_DIRECTION_RIGHT:
leftFadePoint = @0;
rightFadePoint = @1;
break;
case SK_AUTOSCROLL_DIRECTION_TOP:
leftFadePoint = @0;
break;
case SK_AUTOSCROLL_DIRECTION_BOTTOM:
leftFadePoint = @0;
rightFadePoint = @1;
break;
}
}
// 將計算結果交給mask
gradientMask.locations = @[@0, leftFadePoint, rightFadePoint, @1];
[CATransaction begin];
[CATransaction setDisableActions:YES];
self.layer.mask = gradientMask;
[CATransaction commit];
感謝你花時間閱讀以上內容, 如果這個專案能夠幫助到你,記得告訴我
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