Question

我有一个相机应用程序将照片加载到带有遮罩的设备中。一切都好。当我尝试使用renderInContext将视图保存到图像时，我只看到没有任何蒙版的图像。

UIGraphicsBeginImageContext(contentView.bounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[contentView.layer renderInContext:context];
UIImage *outImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(outImage, self, @selector(image: didFinishSavingWithError: contextInfo:), context);

我从Apple那里读过一些文章，说renderInContext不支持掩码和组合。我在互联网上进行了一些搜索，以获取UIView首先需要绘制的信息作为上下文，然后使用renderInContext来保存图像。

现在我的问题是做什么工作的方法？那么drawRect，drawInRect，drawLayer，drawInContent或其他方法呢。任何人都可以给我一个提示。非常感谢。

Answer 1

我从这里开始：http://chinkisingh.com/2013/03/03/draw-on-iphoneipad-screen-using-bezier-paths-core-graphics-ios-app-development/

我有一个UIBezierPath，我想对它应用渐变并应用于现有图像，看看以下代码是否有帮助

    CGRect r = CGRectMake(0, 0, HEART_SIZE, HEART_SIZE);
    UIBezierPath *heart = [Bezier heartShape:r]; //this is only in my case

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    UIColor *darkPink = [UIColor colorWithHue:0.915 saturation:1.000 brightness:0.941 alpha:1.000];
    UIColor *lightPink = [UIColor colorWithHue:0.917 saturation:0.647 brightness:1.000 alpha:1.000];

    NSArray *gradientColors = [NSArray arrayWithObjects:
                               (id)darkPink.CGColor,
                               (id)lightPink.CGColor,
                               (id)darkPink.CGColor, nil];
    CGFloat gradientLocations[] = {0, 0.5, 1};
    CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef)gradientColors, gradientLocations);

    CGColorSpaceRelease(colorSpace);


    UIGraphicsBeginImageContext(r.size);
    heart.lineCapStyle = kCGLineCapRound;
    heart.lineWidth = 10.0f;
    [[UIColor blackColor] setStroke];
    [[UIColor redColor] setFill];
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSaveGState(context);

    [heart stroke]; //removed the black stroke around
    [heart fill];
    CGContextAddPath(context, heart.CGPath);
    CGContextClip(context);
    CGContextDrawLinearGradient(context, gradient, CGPointMake(10, 10), CGPointMake(210, 210), kCGGradientDrawsAfterEndLocation); //check that gradient is drawn in the right place

    CGGradientRelease(gradient);
    UIImage *theRightImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

renderInContext不支持掩码？

1 个答案: