如何将 UIView 添加到 CALayer

Posted 2023-03-13

【中文标题】如何将 UIView 添加到 CALayer

【英文标题】：How to add a UIView to a CALayer

【发布时间】：2016-07-17 08:17:41

【问题描述】：

我正在尝试将自定义 UIView 添加到 CALayer 但它没有被渲染。

我没有将自定义视图添加到另一个视图。相反，我试图将其直接添加到CALayer。

如果我确实将自定义视图添加到另一个视图（即[self.view addSubview:customView]），它可以工作，但由于某种原因，在触摸屏幕的那一刻开始导致崩溃。

基本上是这样

[self.view addSubview:customView];
[layer addSublayer:customView.layer]; //Causes crashes the minute the screen is touched

下面是代码：

CustomView *customView = [[CustomView alloc] initWithFrame:frame];

//I'm not adding the custom view to another view
//Instead I'm trying to add it to a CALayer

CALayer *layer = [CALayer layer];
[Layer setFrame:frame2];
[layer addSublayer: customView.layer];

附：我目前的解决方法是将 UIView 转换为 UIImage 并将其添加到 CALayer。

Belo 是自定义 UIView 代码：

- (id)initWithFrame:(CGRect)frame 
self = [super initWithFrame:frame];
if (self) 
    self.font = [UIFont fontWithName:ARCVIEW_DEFAULT_FONT_NAME size:ARCVIEW_DEFAULT_FONT_SIZE];
    self.text = @"Curva Style Label";

    NSLog(@"FONT = %@, TEXT = %@", self.font, self.text);

    self.radius = ARCVIEW_DEFAULT_RADIUS;
    self.showsGlyphBounds = NO;
    self.showsLineMetrics = NO;
    self.dimsSubstitutedGlyphs = NO;
    self.color = [UIColor whiteColor];
    self.arcSize = ARCVIEW_DEFAULT_ARC_SIZE;
    self.shiftH = self.shiftV = 0.0f;

return self;

- (id)initWithFrame:(CGRect)frame font:(UIFont *)font text:(NSString *)text radius:(float)radius arcSize:(float)arcSize color:(UIColor *)color

self = [super initWithFrame:frame];
if (self) 
    self.font = font;
    self.text = text;
    self.radius = radius;
    self.showsGlyphBounds = NO;// Border add for each Text
    self.showsLineMetrics = NO;
    self.dimsSubstitutedGlyphs = NO;
    self.color = color;
    self.arcSize = arcSize;
    self.shiftH = self.shiftV = 0.0f;

return self;

typedef struct GlyphArcInfo 
CGFloat         width;
CGFloat         angle;  // in radians

字形弧信息；

static void PrepareGlyphArcInfo(CTLineRef line, CFIndex glyphCount, GlyphArcInfo *glyphArcInfo, CGFloat arcSizeRad)

NSArray *runArray = (NSArray *)CTLineGetGlyphRuns(line);

    // Examine each run in the line, updating glyphOffset to track how far along the run is in terms of glyphCount.
CFIndex glyphOffset = 0;
for (id run in runArray) 
    CFIndex runGlyphCount = CTRunGetGlyphCount((CTRunRef)run);

        // Ask for the width of each glyph in turn.
    CFIndex runGlyphIndex = 0;
    for (; runGlyphIndex < runGlyphCount; runGlyphIndex++) 
        glyphArcInfo[runGlyphIndex + glyphOffset].width = CTRunGetTypographicBounds((CTRunRef)run, CFRangeMake(runGlyphIndex, 1), NULL, NULL, NULL);
    

    glyphOffset += runGlyphCount;


double lineLength = CTLineGetTypographicBounds(line, NULL, NULL, NULL);

CGFloat prevHalfWidth = glyphArcInfo[0].width / 2.0;
glyphArcInfo[0].angle = (prevHalfWidth / lineLength) * arcSizeRad;

    // Divide the arc into slices such that each one covers the distance from one glyph's center to the next.
CFIndex lineGlyphIndex = 1;
for (; lineGlyphIndex < glyphCount; lineGlyphIndex++) 
    CGFloat halfWidth = glyphArcInfo[lineGlyphIndex].width / 2.0;
    CGFloat prevCenterToCenter = prevHalfWidth + halfWidth;

    glyphArcInfo[lineGlyphIndex].angle = (prevCenterToCenter / lineLength) * arcSizeRad;

    prevHalfWidth = halfWidth;

-(void)setText:(NSString *)text
//[_string release];
_string = text;

[self setNeedsDisplay];

-(void)setArcSize:(CGFloat)degrees

_arcSize = degrees * M_PI/180.0;

-(CGFloat)arcSize
NSLog(@"arcSize %f",_arcSize * 180.0/M_PI);

return _arcSize * 180.0/M_PI;

- (void)drawRect:(CGRect)rect 
    // Don't draw if we don't have a font or string

NSLog(@"FONT = %@, TEXT = %@", self.font, self.text);

if (self.font == NULL || self.text == NULL) 
    return;

    // Initialize the text matrix to a known value
CGContextRef context = UIGraphicsGetCurrentContext();
    //Reset the transformation
    //Doing this means you have to reset the contentScaleFactor to 1.0
CGAffineTransform t0 = CGContextGetCTM(context);
CGContextSetShadowWithColor(context, CGSizeMake(self.xOffsetShadow, self.yOffsetShadow), self.blurShadow, self.shadowColor.CGColor);

CGFloat xScaleFactor = t0.a > 0 ? t0.a : -t0.a;
CGFloat yScaleFactor = t0.d > 0 ? t0.d : -t0.d;
t0 = CGAffineTransformInvert(t0);
if (xScaleFactor != 1.0 || yScaleFactor != 1.0)
    t0 = CGAffineTransformScale(t0, xScaleFactor, yScaleFactor);

CGContextConcatCTM(context, t0);

CGContextSetTextMatrix(context, CGAffineTransformIdentity);

if(ARCVIEW_DEBUG_MODE)
        // Draw a black background (debug)
    CGContextSetFillColorWithColor(context, [UIColor blackColor].CGColor);
    CGContextFillRect(context, self.layer.bounds);


NSAttributedString *attStr = self.attributedString;
CFAttributedStringRef asr = (__bridge CFAttributedStringRef)attStr;
CTLineRef line = CTLineCreateWithAttributedString(asr);
assert(line != NULL);

CFIndex glyphCount = CTLineGetGlyphCount(line);
if (glyphCount == 0) 
    CFRelease(line);
    return;


GlyphArcInfo *  glyphArcInfo = (GlyphArcInfo*)calloc(glyphCount, sizeof(GlyphArcInfo));
PrepareGlyphArcInfo(line, glyphCount, glyphArcInfo, _arcSize);

    // Move the origin from the lower left of the view nearer to its center.
CGContextSaveGState(context);

CGContextTranslateCTM(context, CGRectGetMidX(rect)+_shiftH, CGRectGetMidY(rect)+_shiftV);

if(ARCVIEW_DEBUG_MODE)
        // Stroke the arc in red for verification.
    CGContextBeginPath(context);
    CGContextAddArc(context, 0.0, 0.0, self.radius, M_PI_2+_arcSize/2.0, M_PI_2-_arcSize/2.0, 1);
    CGContextSetRGBStrokeColor(context, 1.0, 0.0, 0.0, 1.0);
    CGContextStrokePath(context);


    // Rotate the context 90 degrees counterclockwise (per 180 degrees)
CGContextRotateCTM(context, _arcSize/2.0);

    // Now for the actual drawing. The angle offset for each glyph relative to the previous glyph has already been calculated; with that information in hand, draw those glyphs overstruck and centered over one another, making sure to rotate the context after each glyph so the glyphs are spread along a semicircular path.

CGPoint textPosition = CGPointMake(0.0, self.radius);
CGContextSetTextPosition(context, textPosition.x, textPosition.y);

CFArrayRef runArray = CTLineGetGlyphRuns(line);
CFIndex runCount = CFArrayGetCount(runArray);

CFIndex glyphOffset = 0;
CFIndex runIndex = 0;
for (; runIndex < runCount; runIndex++) 
    CTRunRef run = (CTRunRef)CFArrayGetValueAtIndex(runArray, runIndex);
    CFIndex runGlyphCount = CTRunGetGlyphCount(run);
    Boolean drawSubstitutedGlyphsManually = false;
    CTFontRef runFont = CFDictionaryGetValue(CTRunGetAttributes(run), kCTFontAttributeName);

        // Determine if we need to draw substituted glyphs manually. Do so if the runFont is not the same as the overall font.
    if (self.dimsSubstitutedGlyphs && ![self.font isEqual:(__bridge UIFont *)runFont]) 
        drawSubstitutedGlyphsManually = true;
    

    CFIndex runGlyphIndex = 0;
    for (; runGlyphIndex < runGlyphCount; runGlyphIndex++) 
        CFRange glyphRange = CFRangeMake(runGlyphIndex, 1);
        CGContextRotateCTM(context, -(glyphArcInfo[runGlyphIndex + glyphOffset].angle));

            // Center this glyph by moving left by half its width.
        CGFloat glyphWidth = glyphArcInfo[runGlyphIndex + glyphOffset].width;
        CGFloat halfGlyphWidth = glyphWidth / 2.0;
        CGPoint positionForThisGlyph = CGPointMake(textPosition.x - halfGlyphWidth, textPosition.y);

            // Glyphs are positioned relative to the text position for the line, so offset text position leftwards by this glyph's width in preparation for the next glyph.
        textPosition.x -= glyphWidth;

        CGAffineTransform textMatrix = CTRunGetTextMatrix(run);
        textMatrix.tx = positionForThisGlyph.x;
        textMatrix.ty = positionForThisGlyph.y;
        CGContextSetTextMatrix(context, textMatrix);

        if (!drawSubstitutedGlyphsManually) 
            CTRunDraw(run, context, glyphRange);
         
        else 
                // We need to draw the glyphs manually in this case because we are effectively applying a graphics operation by setting the context fill color. Normally we would use kCTForegroundColorAttributeName, but this does not apply as we don't know the ranges for the colors in advance, and we wanted demonstrate how to manually draw.
            CGFontRef cgFont = CTFontCopyGraphicsFont(runFont, NULL);
            CGGlyph glyph;
            CGPoint position;

            CTRunGetGlyphs(run, glyphRange, &glyph);
            CTRunGetPositions(run, glyphRange, &position);

            CGContextSetFont(context, cgFont);
            CGContextSetFontSize(context, CTFontGetSize(runFont));
            CGContextSetRGBFillColor(context, 0.25, 0.25, 0.25, 0.5);
            CGContextShowGlyphsAtPositions(context, &glyph, &position, 1);

            CFRelease(cgFont);
        

            // Draw the glyph bounds 
        if ((self.showsGlyphBounds) != 0) 
            CGRect glyphBounds = CTRunGetImageBounds(run, context, glyphRange);

            CGContextSetRGBStrokeColor(context, 0.0, 0.0, 1.0, 1.0);
            CGContextStrokeRect(context, glyphBounds);
        
            // Draw the bounding boxes defined by the line metrics
        if ((self.showsLineMetrics) != 0) 
            CGRect lineMetrics;
            CGFloat ascent, descent;

            CTRunGetTypographicBounds(run, glyphRange, &ascent, &descent, NULL);

                // The glyph is centered around the y-axis
            lineMetrics.origin.x = -halfGlyphWidth;
            lineMetrics.origin.y = positionForThisGlyph.y - descent;
            lineMetrics.size.width = glyphWidth; 
            lineMetrics.size.height = ascent + descent;

            CGContextSetRGBStrokeColor(context, 0.0, 1.0, 0.0, 1.0);
            CGContextStrokeRect(context, lineMetrics);
        
    

    glyphOffset += runGlyphCount;


CGContextSetFillColorWithColor(context, [UIColor clearColor].CGColor);
CGContextSetAlpha(context,0.0);
CGContextFillRect(context, rect);

CGContextRestoreGState(context);

free(glyphArcInfo);
CFRelease(line);

@synthesize font = _font;
@synthesize text = _string;
@synthesize radius = _radius;
@synthesize color = _color;
@synthesize arcSize = _arcSize;
@synthesize shiftH = _shiftH;
@synthesize shiftV = _shiftV;
@synthesize shadowColor = _shadowColor;
@synthesize xOffsetShadow = _xOffsetShadow;
@synthesize blurShadow = _blurShadow;
@synthesize yOffsetShadow = _yOffsetShadow;

@dynamic attributedString;

- (NSAttributedString *)attributedString 
    // Create an attributed string with the current font and string.
assert(self.font != nil);
assert(self.text != nil);

    // Create our attributes...

    // font
CTFontRef fontRef = CTFontCreateWithName((CFStringRef)self.font.fontName, self.font.pointSize, NULL);

    // color
CGColorRef colorRef = self.color.CGColor;

    // pack it into attributes dictionary

NSDictionary *attributesDict = [NSDictionary dictionaryWithObjectsAndKeys:
                                (__bridge id)fontRef, (id)kCTFontAttributeName,
                                colorRef, (id)kCTForegroundColorAttributeName,
                                nil];
assert(attributesDict != nil);


    // Create the attributed string
NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:self.text attributes:attributesDict];

return attrString;

@end

【问题讨论】：

显示崩溃日志。如果您这样做了，您不应该将 customView 添加为子视图 和 和图层...

【参考方案1】：

你真的应该问问题，而不是你试图解决问题的尝试：

[self.view addSubview:customView];
[layer addSublayer:customView.layer];
//Causes crashes the minute the screen is touched

不需要添加子视图和图层，添加子视图即可。你正在做的是断开某些东西，或者过度纠正某些东西并产生不想要的行为。

如果您想将图层添加到图层，请使用图层而不是视图。视图拥有它们的图层，您不应尝试断开它们的连接或在视图将被释放时保留图层。

因此，理想情况下，创建一个CALayer 子类并将您当前拥有的所有代码移动到它的drawInContext: 方法中。看起来您基本上可以复制并粘贴它，因为您当前的所有代码无论如何都会绘制到 CGContext 中。

【讨论】：

你的回答很有道理。谢谢！但我不知道如何将我的自定义 UIview 转换为 CAlayer。我在上面发布了我的自定义视图代码。任何帮助将不胜感激。

为什么需要图层？

因为我正在使用 videoComposition.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:compositionParentLayer];

我目前的解决方法是将 UIView 转换为 UIImage 并将其添加到 CALayer。

Wain，再次感谢您的帮助。按照您的建议，我可以开始工作了。