Quartz2D知识点聚合案例

Quartz2D知识点聚合

基本

     //画图片
    UIImage *image = [UIImage imageNamed:@"阿狸头像"];
    [image drawInRect:rect];

    //字体
    NSString *title = @"标题";
    NSMutableDictionary *atr = [NSMutableDictionary dictionary];
    atr[NSFontAttributeName] = [UIFont systemFontOfSize:15];
    //    atr[NSForegroundœColorAttributeName] = [UIColor greenColor];
    [title drawInRect:CGRectMake(120, 20, 100, 20) withAttributes:atr];

    //椭圆
    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(10, 20, 70, 130)];
    [path stroke];

    //方形
    UIBezierPath *path1 = [UIBezierPath bezierPathWithRect:CGRectMake(10, 200, 10, 50)];

    [path1 stroke];

    //圆角方形
    UIBezierPath *path2 = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(100, 30, 100, 100) cornerRadius:10];
    [path2 stroke];

    //一个角圆角
    UIBezierPath *path3 = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(210, 90, 80, 70) byRoundingCorners:UIRectCornerTopRight cornerRadii:CGSizeMake(20, 30)];
    [path3 stroke];

    //圆弧
    UIBezierPath *path4 = [UIBezierPath bezierPathWithArcCenter:CGPointMake(130, 230) radius:70 startAngle:0 endAngle:M_PI clockwise:YES];
    [path4 stroke];

// 1.获得当前上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();

    // 2.拼接路径
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointMake(10, 20)];
    [path addQuadCurveToPoint:CGPointMake(200, 80) controlPoint:CGPointMake(100, 200)];

    // 3. 添加路径到上下文
    CGContextAddPath(ctx, path.CGPath);

    // 4.渲染上下文
    CGContextStrokePath(ctx);

变换

    //变换
    //平移
//    CGContextTranslateCTM(ctx, 10, 20);
    //旋转
    CGContextRotateCTM(ctx, M_PI_4);
    //缩放
    CGContextScaleCTM(ctx, 1.2, 1.2);

上下文栈

• 先保存或者还原上下文栈，再设置状态

// 1.获得当前上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();

    // 2.拼接路径
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointMake(10, 20)];
    [path addQuadCurveToPoint:CGPointMake(200, 80) controlPoint:CGPointMake(100, 200)];

    // 3. 添加路径到上下文
    CGContextAddPath(ctx, path.CGPath);

    //保存上下文
    CGContextSaveGState(ctx);

    //设置上下文状态
    CGContextSetLineWidth(ctx, 10);
    [[UIColor redColor] set];

    // 4.渲染上下文
    CGContextStrokePath(ctx);

    // 2.拼接路径
    path = [UIBezierPath bezierPath];
    [path moveToPoint:CGPointMake(100, 80)];
    [path addLineToPoint:CGPointMake(200, 200)];

    // 3. 添加路径到上下文
    CGContextAddPath(ctx, path.CGPath);
    //还原上下文
    CGContextRestoreGState(ctx);
    //设置上下文状态
    CGContextSetLineWidth(ctx, 5);
    [[UIColor blueColor] set];

    // 4.渲染上下文
    CGContextStrokePath(ctx);

生成图片

    UIImage *image = [UIImage imageNamed:@"小黄人"];
    UIGraphicsBeginImageContextWithOptions(image.size, YES, 0);

    [image drawAtPoint:CGPointZero];

    NSString *str = @"小黄人";

    [str drawAtPoint:CGPointZero withAttributes:nil];

    image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

截图

• 给定裁减区域再渲染

    //开启图片上下文
    UIGraphicsBeginImageContext(view.frame.size);
    //获得当前上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();

    //给定裁减区域-----
    //渲染图片
    [view.layer renderInContext:ctx];

    //从当前上下文得到一张图片
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    //关闭图片上下文
    UIGraphicsEndImageContext();

    return image;

擦除

• 先渲染到上下文，再擦除

 UITouch *touch = [touches anyObject];

    CGPoint point = [touch locationInView:self.imageView];

    //开启上下文
    UIGraphicsBeginImageContextWithOptions(self.imageView.frame.size, NO, 0);

    //获得当前上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    //渲染到上下文
    [self.imageView.layer renderInContext:ctx];

    //获取擦除区域
    CGRect rect = CGRectMake(point.x - 10, point.y - 10, 20, 20);
    // 擦除上下文的内容
    CGContextClearRect(ctx, rect);

    // 生成图片
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    _imageView.image = image;
    // 关闭上下文
    UIGraphicsEndImageContext();