我有一个大小为4096 x 4096的CATiledLayer,我想渲染成一个尺寸为1024 x 1024的PNG
这不是这样做的......
-(NSData *)createPNGFormat
{
UIGraphicsBeginImageContext(CGSizeMake(1024, 1024));
tiledLayer.transform = CATransform3DMakeScale(0.25, 0.25, 1.0);
[tiledLayer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return UIImagePNGRepresentation(image);
}
关于如何做到这一点的任何想法?
答案 0 :(得分:2)
[First Hack]蛮力,按平铺渲染。这有效(慢慢地)
-(UIImage *)renderTileX:(NSInteger)xpos tileY:(NSInteger)ypos scale:(CGFloat)ascale
{
CGSize tiledsize = tiledLayer.tileSize;
CGRect tiledframe = tiledLayer.bounds;
CALayer *container = [CALayer layer];
container.frame = CGRectMake(0, 0, tiledsize.width,tiledsize.height);
UIGraphicsBeginImageContext(tiledsize);
[container addSublayer:tiledLayer];
tiledLayer.frame = CGRectMake(-tiledsize.width*xpos,-tiledsize.height*ypos, tiledframe.size.width, tiledframe.size.height);
[container renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[tiledLayer removeFromSuperlayer];
CGFloat fsize = tiledsize.width*ascale;
CGRect apicrect = CGRectMake(0,0,fsize,fsize);
UIGraphicsBeginImageContext(apicrect.size);
[image drawInRect:apicrect];
UIImage *thumb = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return thumb;
}
-(UIImage *)renderTiledLayer
{
UIGraphicsBeginImageContext(CGSizeMake(1024, 1024));
for (NSInteger x = 0 ; x<4; x++) {
for (NSInteger y = 0; y < 4; y++) {
NSLog(@"render %d:%d",x,y);
UIImage *tile = [self renderTileX:x tileY:y scale:0.25];
[tile drawAtPoint:CGPointMake(x*256, y*256)];
}
}
UIImage *fimage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return fimage;
}
[使用Google ...]更好的方法
-(UIImage *)createThumb
{
UIGraphicsBeginImageContext(CGSizeMake(1024, 1024));
CGContextScaleCTM(UIGraphicsGetCurrentContext(), 0.25, 0.25);
[tiledLayer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *fimage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return fimage;
}