我正在将两个 UIImage 合并到一个上下文中。它可以工作,但执行起来很慢,我需要一个更快的解决方案。因为我的解决方案是在 iPad 1G 上调用 mergeImage: withImage:
大约需要 400 毫秒。
这是我的做法:
-(CGContextRef)mergeImage:(UIImage*)img1 withImage:(UIImage*)img2
{
CGSize size = [ImageToolbox getScreenSize];
CGContextRef context = [ImageToolbox createARGBBitmapContextFromImageSize:CGSizeMake(size.width, size.height)];
CGContextSetRenderingIntent(context, kCGRenderingIntentSaturation);
CGContextDrawImage(context, CGRectMake(0, 0, size.width, size.height), img1.CGImage);
CGContextDrawImage(context, CGRectMake(0, 0, size.width, size.height), img2.CGImage);
return context;
}
下面是 ImageToolbox 类的静态方法:
static CGRect screenRect;
+ (CGContextRef)createARGBBitmapContextFromImageSize:(CGSize)imageSize
{
CGContextRef context = NULL;
CGColorSpaceRef colorSpace;
void * bitmapData;
int bitmapByteCount;
int bitmapBytesPerRow;
size_t pixelsWide = imageSize.width;
size_t pixelsHigh = imageSize.height;
bitmapBytesPerRow = (pixelsWide * 4);
bitmapByteCount = (bitmapBytesPerRow * pixelsHigh);
colorSpace = CGColorSpaceCreateDeviceRGB();
if (colorSpace == NULL)
{
fprintf(stderr, "Error allocating color space\n");
return NULL;
}
bitmapData = malloc( bitmapByteCount );
if (bitmapData == NULL)
{
fprintf (stderr, "Memory not allocated!");
CGColorSpaceRelease( colorSpace );
return NULL;
}
context = CGBitmapContextCreate (bitmapData,
pixelsWide,
pixelsHigh,
8, // bits per component
bitmapBytesPerRow,
colorSpace,
kCGImageAlphaPremultipliedFirst);
if (context == NULL)
{
free (bitmapData);
fprintf (stderr, "Context not created!");
}
CGColorSpaceRelease( colorSpace );
return context;
}
+(CGSize)getScreenSize
{
if (screenRect.size.width == 0 && screenRect.size.height == 0)
{
screenRect = [[UIScreen mainScreen] bounds];
}
return CGSizeMake(screenRect.size.height, screenRect.size.width-20);
}
有什么提高性能的建议吗?
最佳答案
我肯定会推荐使用 Instruments 来分析哪些消息花费的时间最多,这样您就可以真正地分解它。此外,我已经编写了一些方法,我认为它们应该用更少的代码来做同样的事情,但是你必须按照你所做的方式写出所有内容才能真正保持可定制性。不管怎样,它们在这里:
-(CGContextRef)mergeImage:(UIImage *)img1 withImage:(UIImage *)img2
{
CGSize size = [ImageToolbox getScreenSize];
CGRect rect = CGRectMake(0, 0, size.width, size.height);
UIGraphicsBeginImageContextWithOptions(size, YES, 1.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRenderingIntent(context, kCGRenderingIntentSaturation);
[img1 drawInRect:rect];
[img2 drawInRect:rect];
UIGraphicsEndImageContext();
return context;
}
或者如果您想要立即合成图像:
- (UIImage *)mergeImage:(UIImage *)img1 withImage:(UIImage *)img2
{
CGSize size = [ImageToolbox getScreenSize];
CGRect rect = CGRectMake(0, 0, size.width, size.height);
UIGraphicsBeginImageContextWithOptions(size, YES, 1.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRenderingIntent(context, kCGRenderingIntentSaturation);
[img1 drawInRect:rect];
[img2 drawInRect:rect];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
我不知道它们是否会更快,但我真的不知道如何轻松地加快您所拥有的速度,除非您将仪器配置文件分解。
无论如何,我希望这对您有所帮助。
关于iphone - 合并两个 UIImages 比 CGContextDrawImage 更快,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10802189/