ios 基本图形的绘制 基于bitmap 位图

#import "UIImage+MJ.h"

@implementation UIImage (MJ)
+ (instancetype)waterImageWithBg:(NSString *)bg logo:(NSString *)logo
{
UIImage *bgImage = [UIImage imageNamed:bg];

// 1.创建一个基于位图的上下文(开启一个基于位图的上下文)
UIGraphicsBeginImageContextWithOptions(bgImage.size, NO, 0.0);

// 2.画背景
[bgImage drawInRect:CGRectMake(0, 0, bgImage.size.width, bgImage.size.height)];

// 3.画右下角的水印
UIImage *waterImage = [UIImage imageNamed:logo];
CGFloat scale = 0.2;
CGFloat margin = 5;
CGFloat waterW = waterImage.size.width * scale;
CGFloat waterH = waterImage.size.height * scale;
CGFloat waterX = bgImage.size.width - waterW - margin;
CGFloat waterY = bgImage.size.height - waterH - margin;
[waterImage drawInRect:CGRectMake(waterX, waterY, waterW, waterH)];

// 4.从上下文中取得制作完毕的UIImage对象
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

// 5.结束上下文
UIGraphicsEndImageContext();

return newImage;
}
@end

// 1.返回水印图片
UIImage *newImage = [UIImage waterImageWithBg:@"scene" logo:@"logo"];

// 2.显示图片
self.iconView.image = newImage;

#import "UIImage+MJ.h"

@implementation UIImage (MJ)
+ (instancetype)circleImageWithName:(NSString *)name borderWidth:(CGFloat)borderWidth borderColor:(UIColor *)borderColor
{
// 1.加载原图
UIImage *oldImage = [UIImage imageNamed:name];

// 2.开启上下文
CGFloat imageW = oldImage.size.width + 2 * borderWidth;
CGFloat imageH = oldImage.size.height + 2 * borderWidth;
CGSize imageSize = CGSizeMake(imageW, imageH);
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);

// 3.取得当前的上下文
CGContextRef ctx = UIGraphicsGetCurrentContext();

// 4.画边框(大圆)
[borderColor set];
CGFloat bigRadius = imageW * 0.5; // 大圆半径
CGFloat centerX = bigRadius; // 圆心
CGFloat centerY = bigRadius;
CGContextAddArc(ctx, centerX, centerY, bigRadius, 0, M_PI * 2, 0);
CGContextFillPath(ctx); // 画圆

// 5.小圆
CGFloat smallRadius = bigRadius - borderWidth;
CGContextAddArc(ctx, centerX, centerY, smallRadius, 0, M_PI * 2, 0);
// 裁剪(后面画的东西才会受裁剪的影响)
CGContextClip(ctx);

// 6.画图
[oldImage drawInRect:CGRectMake(borderWidth, borderWidth, oldImage.size.width, oldImage.size.height)];

// 7.取图
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

// 8.结束上下文
UIGraphicsEndImageContext();

return newImage;
}<strong>
@end</strong>

- (void)viewDidLoad
{
[super viewDidLoad];

UIImage *newImage = [UIImage circleImageWithName:@"me" borderWidth:3 borderColor:[UIColor whiteColor]];
self.iconView.image = newImage;

NSData *data = UIImagePNGRepresentation(newImage);
NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"new.png"];
[data writeToFile:path atomically:YES];
}

#import "UIImage+MJ.h"

@implementation UIImage (MJ)
+ (instancetype)captureWithView:(UIView *)view
{
// 1.开启上下文
UIGraphicsBeginImageContextWithOptions(view.frame.size, NO, 0.0);

// 2.将控制器view的layer渲染到上下文
[view.layer renderInContext:UIGraphicsGetCurrentContext()];

// 3.取出图片
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

// 4.结束上下文
UIGraphicsEndImageContext();

return newImage;
}
@end

- (IBAction)clip {
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
// 1.捕捉
UIImage *newImage = [UIImage captureWithView:self.view];

// 2.写文件
NSData *data = UIImagePNGRepresentation(newImage);
NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"new.png"];
[data writeToFile:path atomically:YES];
});
}

- (void)imageBg
{
UIImage *oldImage = [UIImage imageNamed:@"me"];

UIGraphicsBeginImageContextWithOptions(self.view.frame.size, NO, 0.0);
[oldImage drawInRect:self.view.bounds];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

self.view.backgroundColor = [UIColor colorWithPatternImage:newImage];
}

- (void)viewDidLoad
{
[super viewDidLoad];

//    self.view.backgroundColor = [UIColor redColor];

// 1.创建一行背景图片
CGFloat rowW = self.view.frame.size.width;
//    CGFloat rowH = 40;
CGFloat rowH = 30;
UIGraphicsBeginImageContextWithOptions(CGSizeMake(rowW, rowH), NO, 0.0);

CGContextRef ctx = UIGraphicsGetCurrentContext();
// 画矩形框
[[UIColor redColor] set];
CGContextAddRect(ctx, CGRectMake(0, 0, rowW, rowH));
CGContextFillPath(ctx);

// 2.画线
[[UIColor greenColor] set];
CGFloat lineWidth = 2;
CGContextSetLineWidth(ctx, lineWidth);
CGFloat dividerX = 0;
CGFloat dividerY = rowH - lineWidth;
CGContextMoveToPoint(ctx, dividerX, dividerY);
CGContextAddLineToPoint(ctx, rowW - dividerX, dividerY);
CGContextStrokePath(ctx);

// 3.取图
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

// 4.结束上下文
UIGraphicsEndImageContext();

// 5.设置为背景
self.textView.backgroundColor = [UIColor colorWithPatternImage:newImage];
}