iOS中实现动态区域裁剪图片功能实例

裁剪区域本身就是在 UIImageView 上放上一层 UIView，再在 UIView 上绘制出一个白边框的方格 Layer。

首先自定义一个 CAShapeLayer

#import <QuartzCore/QuartzCore.h>

@interface YasicClipAreaLayer : CAShapeLayer

@property(assign, nonatomic) NSInteger cropAreaLeft;
@property(assign, nonatomic) NSInteger cropAreaTop;
@property(assign, nonatomic) NSInteger cropAreaRight;
@property(assign, nonatomic) NSInteger cropAreaBottom;

- (void)setCropAreaLeft:(NSInteger)cropAreaLeft CropAreaTop:(NSInteger)cropAreaTop CropAreaRight:(NSInteger)cropAreaRight CropAreaBottom:(NSInteger)cropAreaBottom;


@end

@implementation YasicClipAreaLayer

- (instancetype)init
{
 self = [super init];
 if (self) {
 _cropAreaLeft = 50;
 _cropAreaTop = 50;
 _cropAreaRight = SCREEN_WIDTH - self.cropAreaLeft;
 _cropAreaBottom = 400;
 }
 return self;
}

- (void)drawInContext:(CGContextRef)ctx
{
 UIGraphicsPushContext(ctx);
 
 CGContextSetStrokeColorWithColor(ctx, [UIColor whiteColor].CGColor);
 CGContextSetLineWidth(ctx, lineWidth);
 CGContextMoveToPoint(ctx, self.cropAreaLeft, self.cropAreaTop);
 CGContextAddLineToPoint(ctx, self.cropAreaLeft, self.cropAreaBottom);
 CGContextSetShadow(ctx, CGSizeMake(2, 0), 2.0);
 CGContextStrokePath(ctx);
 
 CGContextSetStrokeColorWithColor(ctx, [UIColor whiteColor].CGColor);
 CGContextSetLineWidth(ctx, lineWidth);
 CGContextMoveToPoint(ctx, self.cropAreaLeft, self.cropAreaTop);
 CGContextAddLineToPoint(ctx, self.cropAreaRight, self.cropAreaTop);
 CGContextSetShadow(ctx, CGSizeMake(0, 2), 2.0);
 CGContextStrokePath(ctx);
 
 CGContextSetStrokeColorWithColor(ctx, [UIColor whiteColor].CGColor);
 CGContextSetLineWidth(ctx, lineWidth);
 CGContextMoveToPoint(ctx, self.cropAreaRight, self.cropAreaTop);
 CGContextAddLineToPoint(ctx, self.cropAreaRight, self.cropAreaBottom);
 CGContextSetShadow(ctx, CGSizeMake(-2, 0), 2.0);
 CGContextStrokePath(ctx);
 
 CGContextSetStrokeColorWithColor(ctx, [UIColor whiteColor].CGColor);
 CGContextSetLineWidth(ctx, lineWidth);
 CGContextMoveToPoint(ctx, self.cropAreaLeft, self.cropAreaBottom);
 CGContextAddLineToPoint(ctx, self.cropAreaRight, self.cropAreaBottom);
 CGContextSetShadow(ctx, CGSizeMake(0, -2), 2.0);
 CGContextStrokePath(ctx);
 
 UIGraphicsPopContext();
}

- (void)setCropAreaLeft:(NSInteger)cropAreaLeft
{
 _cropAreaLeft = cropAreaLeft;
 [self setNeedsDisplay];
}

- (void)setCropAreaTop:(NSInteger)cropAreaTop
{
 _cropAreaTop = cropAreaTop;
 [self setNeedsDisplay];
}

- (void)setCropAreaRight:(NSInteger)cropAreaRight
{
 _cropAreaRight = cropAreaRight;
 [self setNeedsDisplay];
}

- (void)setCropAreaBottom:(NSInteger)cropAreaBottom
{
 _cropAreaBottom = cropAreaBottom;
 [self setNeedsDisplay];
}

- (void)setCropAreaLeft:(NSInteger)cropAreaLeft CropAreaTop:(NSInteger)cropAreaTop CropAreaRight:(NSInteger)cropAreaRight CropAreaBottom:(NSInteger)cropAreaBottom
{
 _cropAreaLeft = cropAreaLeft;
 _cropAreaRight = cropAreaRight;
 _cropAreaTop = cropAreaTop;
 _cropAreaBottom = cropAreaBottom;
 
 [self setNeedsDisplay];
}

@end								 
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