UIImageView显示图片和图层显示_篱下悠然_新浪博客
0、autoresizing使用前的解释：
UIViewAutoresizing是一个枚举类型，默认是UIViewAutoresizingNone，也就是不做任何处理。
_bgView.contentMode = UIViewContentModeScaleToFill;
typedef NS_OPTIONS(NSUInteger, UIViewAutoresizing) {
UIViewAutoresizingNone = 0,
UIViewAutoresizingFlexibleLeftMargin = 1 << 0,
UIViewAutoresizingFlexibleWidth = 1 << 1,
UIViewAutoresizingFlexibleRightMargin = 1 << 2,
UIViewAutoresizingFlexibleTopMargin = 1 << 3,
UIViewAutoresizingFlexibleHeight = 1 << 4,
UIViewAutoresizingFlexibleBottomMargin = 1 << 5
};
各属性解释：
| UIViewAutoresizingNone |
不会随父视图的改变而改变 |
| UIViewAutoresizingFlexibleLeftMargin |
自动调整view与父视图左边距，以保证右边距不变 |
| UIViewAutoresizingFlexibleWidth |
自动调整view的宽度，保证左边距和右边距不变 |
| UIViewAutoresizingFlexibleRightMargin |
自动调整view与父视图右边距，以保证左边距不变 |
| UIViewAutoresizingFlexibleTopMargin |
自动调整view与父视图上边距，以保证下边距不变 |
| UIViewAutoresizingFlexibleHeight |
自动调整view的高度，以保证上边距和下边距不变 |
| UIViewAutoresizingFlexibleBottomMargin |
自动调整view与父视图的下边距，以保证上边距不变 |
UIViewContentMode 各类型效果
UIViewContentMode
_bgView.autoresizingMask = UIViewAutoresizingFlexibleHeight;
typedef NS_ENUM(NSInteger, UIViewContentMode) {
但凡在设置图片模式的枚举中包含Scale这个单词的值, 都会对原有的图片进行缩放
UIViewContentModeScaleToFill,
按照"UIImageView"的宽高比缩放图片至图片填充整个UIImageView;
UIViewContentModeScaleAspectFit,
按照"图片的宽高"比例缩放图片至图片的宽度或者高度和UIImageView一样, 并且让整个图片都在UIImageView中. 然后居中显示
UIViewContentModeScaleAspectFill,
按照"图片的宽高"比例缩放图片至图片的宽度和高度填充整个UIImageView. 然后居中显示
UIViewContentModeRedraw,
UIViewContentModeCenter,
UIViewContentModeTop,
UIViewContentModeBottom,
UIViewContentModeLeft,
UIViewContentModeRight,
UIViewContentModeTopLeft,
UIViewContentModeTopRight,
UIViewContentModeBottomLeft,
UIViewContentModeBottomRight,
};
二 imageView图层显示
switch ([imageViewFrames count]) {
case 5:
if (index == 2 ) {
imageView.layer.zPosition = 1;
}else{
imageView.layer.zPosition = 0;
}
break;
case 4:
if (index == 0) {
imageView.layer.zPosition = 2;
}else if( index == 1){
imageView.layer.zPosition = 1;
}else{
imageView.layer.zPosition = 0;
}
break;
default:
break;
}
三 图片剪裁
- (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage {
CGImageRef maskRef = maskImage.CGImage;
CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),
CGImageGetHeight(maskRef),
CGImageGetBitsPerComponent(maskRef),
CGImageGetBitsPerPixel(maskRef),
CGImageGetBytesPerRow(maskRef),
CGImageGetDataProvider(maskRef), NULL, false);
CGImageRef masked = CGImageCreateWithMask([image CGImage], mask);
return [UIImage imageWithCGImage:masked];
}
iOS加载网络图片
sd加载网络图片，在得到图片的回调中，进行图片的裁剪。但是需要注意得到裁剪的图片后，要注意释放，否则内存会爆掉（特别是需要处理过多裁剪的图片时）
[imageView sd_setImageWithURL:[NSURL URLWithString:[ymData.showImageArray objectAtIndex:i]] placeholderImage:[UIImage imageNamed:@"default_img.png"] completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) { if (image != nil) { if (image.size.height>image.size.width) {//图片的高要大于与宽 CGRect rect = CGRectMake(0, image.size.height/2-image.size.width/2, image.size.width, image.size.width);//创建矩形框 CGImageRef cgimg = CGImageCreateWithImageInRect([image CGImage], rect); imageView.image=[UIImage imageWithCGImage:cgimg]; CGImageRelease(cgimg); }else{ CGRect rect = CGRectMake(image.size.width/2-image.size.height/2, 0, image.size.height, image.size.height);//创建矩形框 CGImageRef cgimg = CGImageCreateWithImageInRect([image CGImage], rect); imageView.image=[UIImage imageWithCGImage:cgimg]; CGImageRelease(cgimg); } }
}];
UIImageView显示图片
通常我们得到的图片要显示在UIImageView里。但是图片的尺寸比例跟UIImageView的比例尺寸还不一样，这时。惯性思维就是要对图片就行处理裁剪啊什么的，得到跟UIImageView比例一样的图片，这样才不会失真。其实，不用对图片做任何处理，UIImageView的属性早已搞定了一切。
imageView.contentMode = UIViewContentModeScaleAspectFill imageView.clipsToBounds = YES
UIViewContentModeScaleAspectFill会保证图片比例不变，但是是填充整个ImageView的，只有部分图片显示出来（而且需要设置clipsToBounds为YES，把多余的部分裁掉）。ImageView显示图片保证图片不失真，看起来不像压缩过的图片的方法只需设置这两个属性即可，就其他的属性自己查看SDK慢慢了解运用吧。
我们在做iOS开发的时候，往往需要实现不规则形状的头像，如：
那如何去实现？
通常图片都是矩形的，如果想在客户端去实现不规则的头像，需要自己去实现。
1.使用layer去实现, 见https://blog.csdn.net/johnzhjfly/article/details/39993345<喎�"/kf/ware/vc/" target="_blank" class="keylink">vcD4KPHA+PC9wPgo8cD4yLsq508NDQVNoYXBlTGF5ZXIsIENBTGF5ZXLI57rOyKXKtc/WPC9wPgo8cD7O0sPHwLS/tL+0yOe6zsq508NDQVNoYXBlTGF5ZXLIpcq1z9YsPC9wPgo8cD62qNLl0ru49lNoYXBlZEltYWdlVmlld6OsvMyz0NPaVUlWaWV3o6wgtPrC68jnz8KjujwvcD4KPHA+PC9wPgo8cHJlIGNsYXNzPQ=="brush:java;">#import "ShapedImageView.h" @interface ShapedImageView() { CALayer *_contentLayer; CAShapeLayer *_maskLayer; } @end @implementation ShapedImageView - (instancetype)initWithFrame:(CGRect)frame { self = [super initWithFrame:frame]; if (self) { [self setup]; } return self; } - (void)setup { _maskLayer = [CAShapeLayer layer]; _maskLayer.path = [UIBezierPath bezierPathWithOvalInRect:self.bounds].CGPath; _maskLayer.fillColor = [UIColor blackColor].CGColor; _maskLayer.strokeColor = [UIColor redColor].CGColor; _maskLayer.frame = self.bounds; _maskLayer.contentsCenter = CGRectMake(0.5, 0.5, 0.1, 0.1); _maskLayer.contentsScale = [UIScreen mainScreen].scale; _contentLayer = [CALayer layer]; _contentLayer.mask = _maskLayer; _contentLayer.frame = self.bounds; [self.layer addSublayer:_contentLayer]; } - (void)setImage:(UIImage *)image { _contentLayer.contents = (id)image.CGImage; } @end 声明了用于maskLayer个CAShapedLayer， CAShapedLayer有个path的属性，将内容Layer的mask设置为maskLayer, 就可以获取到我们想要的形状。
path我们可以使用CAMutablePath任意的构造，上述的代码运行想过如下：
如果将代码改成
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_maskLayer = [CAShapeLayer layer];
_maskLayer.path = [UIBezierPath bezierPathWithRoundedRect:self.bounds cornerRadius: 20 ].CGPath;
_maskLayer.fillColor = [UIColor blackColor].CGColor;
_maskLayer.strokeColor = [UIColor redColor].CGColor;
_maskLayer.frame = self.bounds;
_maskLayer.contentsCenter = CGRectMake( 0.5 , 0.5 , 0.1 , 0.1 );
_maskLayer.contentsScale = [UIScreen mainScreen].scale; //非常关键设置自动拉伸的效果且不变形
_contentLayer = [CALayer layer];
_contentLayer.mask = _maskLayer;
_contentLayer.frame = self.bounds;
[self.layer addSublayer:_contentLayer];
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如果将代码改成:
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CGMutablePathRef path = CGPathCreateMutable();
CGPoint origin = self.bounds.origin;
CGFloat radius = CGRectGetWidth(self.bounds) / 2 ;
CGPathMoveToPoint(path, NULL, origin.x, origin.y + 2 *radius);
CGPathMoveToPoint(path, NULL, origin.x, origin.y + radius);
CGPathAddArcToPoint(path, NULL, origin.x, origin.y, origin.x + radius, origin.y, radius);
CGPathAddArcToPoint(path, NULL, origin.x + 2 * radius, origin.y, origin.x + 2 * radius, origin.y + radius, radius);
CGPathAddArcToPoint(path, NULL, origin.x + 2 * radius, origin.y + 2 * radius, origin.x + radius, origin.y + 2 * radius, radius);
CGPathAddLineToPoint(path, NULL, origin.x, origin.y + 2 * radius);
_maskLayer = [CAShapeLayer layer];
_maskLayer.path = path;
_maskLayer.fillColor = [UIColor blackColor].CGColor;
_maskLayer.strokeColor = [UIColor clearColor].CGColor;
_maskLayer.frame = self.bounds;
_maskLayer.contentsCenter = CGRectMake( 0.5 , 0.5 , 0.1 , 0.1 );
_maskLayer.contentsScale = [UIScreen mainScreen].scale; //非常关键设置自动拉伸的效果且不变形
_contentLayer = [CALayer layer];
_contentLayer.mask = _maskLayer;
_contentLayer.frame = self.bounds;
[self.layer addSublayer:_contentLayer];
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理论上我们可以构造出任意想要的形状，但是有些形状如果你不熟悉几何知识的话是构造不出正确的
path的，从代码上我们可以看到我们可以通过设置CALayer的contents属性来设置显示的内容，那我啤"/kf/web/php/" target="_blank" class="keylink">PHPC9wPgo8cD7Kx7K7yse/ydLUzai5/cno1sNDQVNoYXBlZExheWVytcRjb250ZW50c8C0yejWw21hc2tMYXllcsTYo7+08LC4yse/z7aotcSjrLT6wuvI58/Co7o8L3A+CjxwPjwvcD4KPHByZSBjbGFzcz0="brush:java;"> _maskLayer = [CAShapeLayer layer]; _maskLayer.fillColor = [UIColor blackColor].CGColor; _maskLayer.strokeColor = [UIColor clearColor].CGColor; _maskLayer.frame = self.bounds; _maskLayer.contentsCenter = CGRectMake(0.5, 0.5, 0.1, 0.1); _maskLayer.contentsScale = [UIScreen mainScreen].scale; //非常关键设置自动拉伸的效果且不变形 _maskLayer.contents = (id)[UIImage imageNamed:@"[email protected]"].CGImage; _contentLayer = [CALayer layer]; _contentLayer.mask = _maskLayer; _contentLayer.frame = self.bounds; [self.layer addSublayer:_contentLayer];
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gray_bubble_right就是你想要的形状，运行效果如下:
源代码:https://github.com/heavensword/ShapedImageView