关于这个问题,我已经在另一篇blog中有所提及:
不过原有的转换代码使用Obj-C写的,在这里我们尝试将其转换为Swift语言,然后利用它实现一个测试小程序.
首先贴出原来Objc的代码:
- (void) setupTextLayer
{
if (self.pathLayer != nil) {
[self.penLayer removeFromSuperlayer];
[self.pathLayer removeFromSuperlayer];
self.pathLayer = nil;
self.penLayer = nil;
}
// Create path from text
// See: http://www.codeproject.com/KB/iPhone/Glyph.aspx
// License: The Code Project Open License (CPOL) 1.02 http://www.codeproject.com/info/cpol10.aspx
CGMutablePathRef letters = CGPathCreateMutable();
CTFontRef font = CTFontCreateWithName(CFSTR("Helvetica-Bold"), 72.0f, NULL);
NSDictionary *attrs = [NSDictionary dictionaryWithObjectsAndKeys:
(id)font, kCTFontAttributeName,
nil];
NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:@"你好,大熊猫侯佩!"
//NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:@"hello world!"
attributes:attrs];
CTLineRef line = CTLineCreateWithAttributedString((CFAttributedStringRef)attrString);
CFArrayRef runArray = CTLineGetGlyphRuns(line);
// for each RUN
for (CFIndex runIndex = 0; runIndex < CFArrayGetCount(runArray); runIndex++)
{
// Get FONT for this run
CTRunRef run = (CTRunRef)CFArrayGetValueAtIndex(runArray, runIndex);
CTFontRef runFont = CFDictionaryGetValue(CTRunGetAttributes(run), kCTFontAttributeName);
// for each GLYPH in run
for (CFIndex runGlyphIndex = 0; runGlyphIndex < CTRunGetGlyphCount(run); runGlyphIndex++)
{
// get Glyph & Glyph-data
CFRange thisGlyphRange = CFRangeMake(runGlyphIndex, 1);
CGGlyph glyph;
CGPoint position;
CTRunGetGlyphs(run, thisGlyphRange, &glyph);
CTRunGetPositions(run, thisGlyphRange, &position);
// Get PATH of outline
{
CGPathRef letter = CTFontCreatePathForGlyph(runFont, glyph, NULL);
CGAffineTransform t = CGAffineTransformMakeTranslation(position.x, position.y);
CGPathAddPath(letters, &t, letter);
CGPathRelease(letter);
}
}
}
CFRelease(line);
UIBezierPath *path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointZero];
[path appendPath:[UIBezierPath bezierPathWithCGPath:letters]];
CGPathRelease(letters);
CFRelease(font);
CAShapeLayer *pathLayer = [CAShapeLayer layer];
pathLayer.frame = self.animationLayer.bounds;
pathLayer.bounds = CGPathGetBoundingBox(path.CGPath);
//pathLayer.backgroundColor = [[UIColor yellowColor] CGColor];
pathLayer.geometryFlipped = YES;
pathLayer.path = path.CGPath;
pathLayer.strokeColor = [[UIColor blackColor] CGColor];
pathLayer.fillColor = nil;
pathLayer.lineWidth = 5.0f;
//pathLayer.lineJoin = kCALineJoinBevel;
pathLayer.lineJoin = kCALineJoinMiter;
[self.animationLayer addSublayer:pathLayer];
self.pathLayer = pathLayer;
//happy commit
NSLog(@"hello world!!!");
//UIImage *penImage = [UIImage imageNamed:@"noun_project_347_2.png"];
UIImage *penImage = [UIImage imageNamed:@"bee.png"];
CALayer *penLayer = [CALayer layer];
penLayer.contents = (id)penImage.CGImage;
penLayer.anchorPoint = CGPointZero;
penLayer.frame = CGRectMake(0.0f, 0.0f, penImage.size.width/5, penImage.size.height/5);
[pathLayer addSublayer:penLayer];
self.penLayer = penLayer;
}
看起来颇长啊!不过不要太在意,因为我们要用Swift重写的代码只提取其中中间的一部分,这样可以更好的重用.
新建一个项目,基于Swift语言.
在项目中新建一个Swift源代码文件,该文件扩展了String类,我们在其扩展中先写一个帮助方法的存根:
extension String{
func toPath(font:CTFont)->CGPath{
}
}toPath方法用来实现任意String实例到CGPath路径的转换,在其中添加如下内容:
let letters:CGMutablePathRef = CGPathCreateMutable()
let attrs = [kCTFontAttributeName as String:font]
let attrString:NSAttributedString = NSAttributedString(string: self, attributes: attrs)
let line:CTLine = CTLineCreateWithAttributedString(attrString)
let runArray = CTLineGetGlyphRuns(line)
for runIndex in 0..<CFArrayGetCount(runArray){
let run = CFArrayGetValueAtIndex(runArray, runIndex)
let runb = unsafeBitCast(run, CTRun.self)
//let runFont:CTFont = CFDictionaryGetValue(CTRunGetAttributes(runb), kCTFontAttributeName as String) as! CTFont
let CTFontName = unsafeBitCast(kCTFontAttributeName, UnsafePointer<Void>.self)
let runFontC = CFDictionaryGetValue(CTRunGetAttributes(runb), CTFontName)
let runFont = unsafeBitCast(runFontC, CTFont.self)
//for each GLYPH in run
for runGlyphIndex in 0..<CTRunGetGlyphCount(runb){
//get Glyph & Glyph-data
let glyphRange = CFRange(location: runGlyphIndex, length: 1)
//let glyph:UnsafeMutablePointer<CGGlyph> = UnsafeMutablePointer<CGGlyph>.alloc(1)
//glyph.initialize(0)
var glyph:CGGlyph = 0
let position:UnsafeMutablePointer<CGPoint> = UnsafeMutablePointer<CGPoint>.alloc(1)
position.initialize(CGPoint.zero)
CTRunGetGlyphs(runb, glyphRange, &glyph)
CTRunGetPositions(runb, glyphRange, position)
//Get PATH of outline
//let letter = CTFontCreatePathForGlyph(runFont, glyph.memory, nil)
let letter = CTFontCreatePathForGlyph(runFont, glyph, nil)
var t = CGAffineTransformMakeTranslation(position.memory.x, position.memory.y)
//let tx:UnsafeMutablePointer<CGAffineTransform> = UnsafeMutablePointer<CGAffineTransform>.alloc(1)
//tx.initialize(t)
CGPathAddPath(letters, &t, letter)
//CGPathRelease(letter)
position.destroy()
position.dealloc(1)
}
}
let path = UIBezierPath()
path.moveToPoint(CGPoint.zero)
path.appendPath(UIBezierPath(CGPath: letters))
return path.CGPath大家可以对照原来的Obj-c版本看一下,大致都是一一对应的,只有少数几个涉及操作C语言数据的地方有修改,大家可以参考我写的另一篇blog:
核心功能有了,下面就好办了!我们想要的是点击屏幕开始显示动画,于是重载如下方法:
override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
if isAnimating { return }
isAnimating = true
flyerLayer.opacity = 0.8
pathLayer.removeAllAnimations()
flyerLayer.removeAllAnimations()
let strokeAnimation = CABasicAnimation(keyPath: "strokeEnd")
strokeAnimation.duration = 20.0
strokeAnimation.fromValue = 0.0
strokeAnimation.toValue = 1.0
strokeAnimation.delegate = self
pathLayer.addAnimation(strokeAnimation, forKey: nil)
let flyAnimation = CAKeyframeAnimation(keyPath: "position")
flyAnimation.duration = 20.0
flyAnimation.path = pathLayer.path
flyAnimation.calculationMode = kCAAnimationPaced
flyerLayer.addAnimation(flyAnimation, forKey: nil)
}
下面是App实际运行的效果:
