Quartz:无法创建具有渐变填充的圆角矩形
Quartz:无法创建具有渐变填充的圆角矩形
提问于 2011-09-05 00:16:31
我都快把头发扯下来了。我正在尝试创建一个渐变填充覆盖区域的矩形圆角。这是我的drawRect:中的代码
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextClearRect(ctx, rect);
CGFloat c = BUBBLE_INSET + BUBBLE_CORNER_RADIUS;
CGContextMoveToPoint(ctx, BUBBLE_INSET, c);
CGContextAddArcToPoint(ctx, BUBBLE_INSET, BUBBLE_INSET, c, BUBBLE_INSET, BUBBLE_CORNER_RADIUS);
CGContextAddLineToPoint(ctx, rect.size.width - c, BUBBLE_INSET);
CGContextAddArcToPoint(ctx, rect.size.width - BUBBLE_INSET, BUBBLE_INSET, rect.size.width - BUBBLE_INSET, c, BUBBLE_CORNER_RADIUS);
CGContextAddLineToPoint(ctx, rect.size.width - BUBBLE_INSET, rect.size.height - c);
CGContextAddArcToPoint(ctx, rect.size.width - BUBBLE_INSET, rect.size.height - BUBBLE_INSET, rect.size.width - c, rect.size.height - BUBBLE_INSET, BUBBLE_CORNER_RADIUS);
CGContextAddLineToPoint(ctx, c, rect.size.height - BUBBLE_INSET);
CGContextAddArcToPoint(ctx, BUBBLE_INSET, rect.size.height - BUBBLE_INSET, BUBBLE_INSET, rect.size.height - c, BUBBLE_CORNER_RADIUS);
CGContextClosePath(ctx);
CGContextClip(ctx);
CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
NSArray *colors = [NSArray arrayWithObjects:color1, color2, nil];
CGGradientRef gradient = CGGradientCreateWithColors(space, (CFArrayRef)colors, NULL);
CGColorSpaceRelease(space);
CGPoint p1 = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint p2 = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
CGContextDrawLinearGradient(ctx, gradient, p1, p2, 0);
CGGradientRelease(gradient);这段代码绘制一个空白的白色矩形。Path构建正确(我尝试调用CGContextFillPath()，结果用纯色很好地填充)，color1和color2值是正确的(在调试器中可以看到)。这段代码有什么问题？
回答 2
Stack Overflow用户
回答已采纳
发布于 2011-09-06 07:30:46
事实证明，color1和color2属于UIColor类型，这是完全错误的。更改了行
NSArray *colors = [NSArray arrayWithObjects:color1, color2, nil];至
NSArray *colors = [NSArray arrayWithObjects:[color1 CGColor], [color2 CGColor], nil];并且得到了我所期望的结果。
Stack Overflow用户
发布于 2011-09-05 02:12:31
我不确定您的颜色是如何包装在颜色数组中的。
尝试使用
CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);而不是。
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextClearRect(ctx, rect);
CGFloat c = BUBBLE_INSET + BUBBLE_CORNER_RADIUS;
CGContextMoveToPoint(ctx, BUBBLE_INSET, c);
CGContextAddArcToPoint(ctx, BUBBLE_INSET, BUBBLE_INSET, c, BUBBLE_INSET, BUBBLE_CORNER_RADIUS);
CGContextAddLineToPoint(ctx, rect.size.width - c, BUBBLE_INSET);
CGContextAddArcToPoint(ctx, rect.size.width - BUBBLE_INSET, BUBBLE_INSET, rect.size.width - BUBBLE_INSET, c, BUBBLE_CORNER_RADIUS);
CGContextAddLineToPoint(ctx, rect.size.width - BUBBLE_INSET, rect.size.height - c);
CGContextAddArcToPoint(ctx, rect.size.width - BUBBLE_INSET, rect.size.height - BUBBLE_INSET, rect.size.width - c, rect.size.height - BUBBLE_INSET, BUBBLE_CORNER_RADIUS);
CGContextAddLineToPoint(ctx, c, rect.size.height - BUBBLE_INSET);
CGContextAddArcToPoint(ctx, BUBBLE_INSET, rect.size.height - BUBBLE_INSET, BUBBLE_INSET, rect.size.height - c, BUBBLE_CORNER_RADIUS);
CGContextClosePath(ctx);
CGContextClip(ctx);
CGGradientRef gradient;
CGColorSpaceRef rgbColorspace;
size_t num_locations = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGFloat components[8] = { 1.0, 0.0, 0.0, 1.0, // Start color
1.0, 1.0, 1.0, 0.65 }; // End color
rgbColorspace = CGColorSpaceCreateDeviceRGB();
gradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);
CGPoint p1 = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint p2 = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
CGContextDrawLinearGradient(ctx, gradient, p1, p2, 0);
CGGradientRelease(gradient);你会得到这样的结果：
偏移量为5.0半径为10.0
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/7300514
复制相关文章
相似问题
腾讯云开发者
Copyright © 2013 - 2026 Tencent Cloud. All Rights Reserved. 腾讯云 版权所有
深圳市腾讯计算机系统有限公司 ICP备案/许可证号：粤B2-20090059 
粤公网安备44030502008569号
腾讯云计算（北京）有限责任公司 京ICP证150476号 | 京ICP备11018762号