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  • iOS绘图

    iOS 绘图

    关于下面的绘制图形都是在drawRect方法中,所以我们需要建立一个类叫CustonView,继承于UIView,然后实现drawRect方法。

    绘制一个字符串

    UIFont *helveticacabold = [UIFont fontWithName:@"HelveticaNeue-Bold" size:40.f];
        NSString *string = @"some String";
        NSDictionary *attibute = @{NSForegroundColorAttributeName:[UIColor whiteColor],NSFontAttributeName:helveticacabold};
        [string drawAtPoint:CGPointMake(40, 200) withAttributes:attibute];
    

    将字符串画在一个矩形中

    //画在一个矩形
        UIFont *helveticacabold = [UIFont fontWithName:@"HelveticaNeue-Bold" size:40.f];
        NSString *string = @"some String";
        NSDictionary *attibute = @{NSForegroundColorAttributeName:[UIColor whiteColor],NSFontAttributeName:helveticacabold};
        [string drawInRect:CGRectMake(40, 200, 100, 100) withAttributes:attibute];
    

    获取color的分量信息

     UIColor *steelBlueColor = [UIColor colorWithRed:0.3f green:0.4f blue:0.6f alpha:1.0f];
    
        CGColorRef colorRef = steelBlueColor.CGColor;
        const CGFloat *components = CGColorGetComponents(colorRef);
        NSUInteger compentsCount = CGColorGetNumberOfComponents(colorRef);
    
        NSUInteger count = 0;
        for (count = 0; count < compentsCount; count++) {
            NSLog(@"compenent %lu = %.02f",count+1,components[count]);
        }
    

    绘制线段

    // 1. 为图形上下文选择一个颜色
        [[UIColor brownColor] set];
        // 2. 获取图形上下文的句柄
        CGContextRef currentContext = UIGraphicsGetCurrentContext();
        // 3. 设置线条的宽度 第一个参数是当前图形上下文 , 第二个是线条的宽度
        CGContextSetLineWidth(currentContext, 10.0f);
        // 4. 设置线条的起点
        CGContextMoveToPoint(currentContext, 50.0f, 10.0f);
        // 5. 设置终点
        // 线
        CGContextAddLineToPoint(currentContext, 100.0f, 200.0f);
        // 矩形
    //    CGContextAddRect(currentContext, CGRectMake(50, 50, 100, 100));
        // 6. 绘制上下文
        CGContextStrokePath(currentContext);
    

    绘制一个X

    // 1. 创建一个可变的句柄
        CGMutablePathRef path = CGPathCreateMutable();
        // 2. 充满屏幕
        CGRect screenBounds = [UIScreen mainScreen].bounds;
        // 3. 开始top-left
        CGPathMoveToPoint(path, NULL, screenBounds.origin.x, screenBounds.origin.y);
        CGPathAddLineToPoint(path, NULL, screenBounds.size.width, screenBounds.size.height);
        // 4. 开始另一条线,top-right
        CGPathMoveToPoint(path, NULL, screenBounds.size.width, screenBounds.origin.y);
        // 5. 画线,form top-right to bottom-left
        CGPathAddLineToPoint(path, NULL, screenBounds.origin.x, screenBounds.size.height);
        // 6. 获取图形上下文
        CGContextRef currentRef = UIGraphicsGetCurrentContext();
        CGContextAddPath(currentRef, path);
        [[UIColor blueColor] setStroke];
        CGContextDrawPath(currentRef, kCGPathStroke);
        CGPathRelease(path);
    

    绘制矩形

    CGMutablePathRef path = CGPathCreateMutable();
        CGRect rectangle = CGRectMake(10.0f, 10.0f, 200.0f, 300.0f);
        CGPathAddRect(path, NULL, rectangle);
        CGContextRef currentContext = UIGraphicsGetCurrentContext();
        CGContextAddPath(currentContext, path);
        //充满矩形的颜色
        [[UIColor yellowColor] setFill];
        //画线的颜色
        [[UIColor brownColor] setStroke];
        CGContextSetLineWidth(currentContext, 10.0f);
        CGContextDrawPath(currentContext, kCGPathFillStroke);
        CGPathRelease(path);
    

    为形状添加阴影

    // 1. 获取图形上下文
        CGContextRef currentContext = UIGraphicsGetCurrentContext();
    //     避免第二个矩形会被应用,需要保存上下文
        CGContextSaveGState(currentContext);
    //     2. 设置阴影 参数: 1.图形上下文 2. 偏移量-偏移量相对于将要应用阴影的形状的右边和底部。x偏移量越大,阴影更向形状的右边延伸,y偏移量越大,阴影更向形状的底部延伸。 3. 应用到阴影的模糊值,·
        CGContextSetShadowWithColor(currentContext, CGSizeMake(10.0f, 10.0f), 20.0f, [UIColor grayColor].CGColor);
        CGMutablePathRef path = CGPathCreateMutable();
        CGRect firstRect = CGRectMake(55.0f, 60.0f, 150.0f, 150.0f);
        CGPathAddRect(path, NULL, firstRect);
        CGContextAddPath(currentContext, path);
        [[UIColor colorWithRed:0.20f green:0.60f blue:0.80f alpha:1.0f] setFill];
        CGContextDrawPath(currentContext, kCGPathFill);
        CGPathRelease(path);
    //    回到之前上下文的状态   避免第二个矩形会被应用,
        CGContextRestoreGState(currentContext);
    

    创建和绘制渐变

    // 1. 创建色彩空间
        CGContextRef currentContext = UIGraphicsGetCurrentContext();
    //    CGContextSaveGState(currentContext);
        CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
        UIColor *startColor = [UIColor orangeColor];
        CGFloat *startColorComponents = (CGFloat *)CGColorGetComponents([startColor CGColor]);
        UIColor *endColor = [UIColor blueColor];
        CGFloat *endColorComponents = (CGFloat *)CGColorGetComponents([endColor CGColor]);
        // 2. 获取开始颜色和终点颜色的分量之后,我们将他们放入一个扁平数组传递到CGGradientCreateWithColorComonents函数
        CGFloat colorComponents[8] = {
            startColorComponents[0],
            startColorComponents[1],
            startColorComponents[2],
            startColorComponents[3],
            //终点颜色分量
            endColorComponents[0],
            endColorComponents[1],
            endColorComponents[2],
            endColorComponents[3],
        };
        // 3. 因为我们在数组中只有两个颜色,所以我们首先需要指定的是渐变最开始的位置0。0f,接着指定他结束的位置1.0f,
        CGFloat colorIndices[2] = {
            0.0f, /*
                   color 0
                   */
            1.0f, /*
                   color 1
                   */
        };
        // 4. 调用CGGradientCreateWithColorComonents函数
        CGGradientRef gradient = CGGradientCreateWithColorComponents(colorSpace, (CGFloat *)colorComponents, (CGFloat*)colorIndices, 2);
        // 5. 释放色彩空间
        CGColorSpaceRelease(colorSpace);
        // 6. 绘制线性渐变
        CGRect screenBounds = [UIScreen mainScreen].bounds;
        CGPoint startPoint, endPoint;
        startPoint = CGPointMake(120,260);
        endPoint = CGPointMake(200.0f,220);
        // kCGGradientDrawsAfterEndLocation 扩展整个渐变到渐变的终点之后的所有点 kCGGradientDrawsBeforeStartLocation 扩展整个渐变到渐变的起点之前的所有点
        //  0 不扩展
        CGContextDrawLinearGradient(currentContext, gradient, startPoint, endPoint, 0);
        CGGradientRelease(gradient);
    

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  • 原文地址:https://www.cnblogs.com/ldnh/p/7927956.html
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