即使将视图的.alpha属性设置为非1值,我也会做一些要求我获取视图快照的完全不透明版本的内容。
我通过iOS 7中的快照创建快照:
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0f);
[self drawViewHierarchyInRect:CGRectMake(0, 0, size.width, size.height) afterScreenUpdates:NO];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
我正在考虑将其转换为位图数据并将所有alpha值修改为1 - view.alpha。我认为这样可行,但我需要获得非预乘的位图数据。
CGContextRef context = NULL;
CGColorSpaceRef colorSpace;
uint32_t *bitmapData;
size_t bitsPerPixel = 32;
size_t bitsPerComponent = 8;
size_t bytesPerPixel = bitsPerPixel / bitsPerComponent;
size_t width = CGImageGetWidth(image);
size_t height = CGImageGetHeight(image);
size_t bytesPerRow = width * bytesPerPixel;
size_t bufferLength = bytesPerRow * height;
colorSpace = CGColorSpaceCreateDeviceRGB();
if(!colorSpace) {
NSLog(@"Error allocating color space RGB\n");
return NULL;
}
// Allocate memory for image data
bitmapData = (uint32_t *)malloc(bufferLength);
if(!bitmapData) {
NSLog(@"Error allocating memory for bitmap\n");
CGColorSpaceRelease(colorSpace);
return NULL;
}
//Create bitmap context
context = CGBitmapContextCreate(bitmapData,
width,
height,
bitsPerComponent,
bytesPerRow,
colorSpace,
(kCGBitmapAlphaInfoMask & kCGImageAlphaLast)); //RGBA
除非有更简单的方法,为什么我不能让kCGImageAlphaLast工作? kCGImageAlphaPremultipliedLast似乎有效,但这不起作用。
<Error>: CGBitmapContextCreate: unsupported parameter combination: 8 integer bits/component; 32 bits/pixel; 3-component color space; kCGImageAlphaLast; 8192 bytes/row.
答案 0 :(得分:1)
为什么不把这个视图放在containerView中?改变容器的alpha,然后保留这个“图像生成视图”,其alpha值为1.0 ....你的UI保持不变,你得到了你的图像......