[英]NSImage to NSBitmapImageRep
如何將NSImage轉換為NSBitmapImageRep? 我有代碼:
- (NSBitmapImageRep *)bitmapImageRepresentation
{
NSBitmapImageRep *ret = (NSBitmapImageRep *)[self representations];
if(![ret isKindOfClass:[NSBitmapImageRep class]])
{
ret = nil;
for(NSBitmapImageRep *rep in [self representations])
if([rep isKindOfClass:[NSBitmapImageRep class]])
{
ret = rep;
break;
}
}
if(ret == nil)
{
NSSize size = [self size];
size_t width = size.width;
size_t height = size.height;
size_t bitsPerComp = 32;
size_t bytesPerPixel = (bitsPerComp / CHAR_BIT) * 4;
size_t bytesPerRow = bytesPerPixel * width;
size_t totalBytes = height * bytesPerRow;
NSMutableData *data = [NSMutableData dataWithBytesNoCopy:calloc(totalBytes, 1) length:totalBytes freeWhenDone:YES];
CGColorSpaceRef space = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
CGContextRef ctx = CGBitmapContextCreate([data mutableBytes], width, height, bitsPerComp, bytesPerRow, CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB), kCGBitmapFloatComponents | kCGImageAlphaPremultipliedLast);
if(ctx != NULL)
{
[NSGraphicsContext saveGraphicsState];
[NSGraphicsContext setCurrentContext:[NSGraphicsContext graphicsContextWithGraphicsPort:ctx flipped:[self isFlipped]]];
[self drawAtPoint:NSZeroPoint fromRect:NSZeroRect operation:NSCompositeCopy fraction:1.0];
[NSGraphicsContext restoreGraphicsState];
CGImageRef img = CGBitmapContextCreateImage(ctx);
ret = [[NSBitmapImageRep alloc] initWithCGImage:img];
[self addRepresentation:ret];
CFRelease(img);
CFRelease(space);
CGContextRelease(ctx);
}
}
return ret;
}
它可以工作,但它會導致內存泄漏。 至少當我在ARC使用它時。 使用initWithData:[nsimagename TIFFRepresentation]
它無法正常工作。 一些圖像的表示並不好。 我認為這取決於圖像的格式和色彩空間。 還有其他方法可以實現嗎?
結果與mrwalker建議的解決方案:
原始圖片:
轉換為bitmapimagerep並返回圖像1次:
轉換為bitmapimagerep並返回圖像3次:
如您所見,每次轉換為NSBitmapImageRep后圖像都會變暗
@Julius:你的代碼太復雜了,包含了幾個bug。 我將僅對第一行進行修正:
- (NSBitmapImageRep *)bitmapImageRepresentation
{
for( NSImageRep *rep in [self representations] )
if( [rep isKindOfClass:[NSBitmapImageRep class]] ) return rep;
return nil;
}
如果它是表示中的成員,則將提取第一個NSBitmapImageRep
,如果沒有NSBitmapImageRep
,則返回nil。 我會給你另一個解決方案,無論NSImageReps
在表示中是什么,它都會起作用: NSBitmapImageRep
, NSPDFImageRep
或NSCGImageSnapshotRep
或......
- (NSBitmapImageRep *)bitmapImageRepresentation
{
CGImageRef CGImage = [self CGImageForProposedRect:nil context:nil hints:nil];
return [[[NSBitmapImageRep alloc] initWithCGImage:CGImage] autorelease];
}
或者為了避免NSImage的子類化,您可以寫:
NSImage *img = [[[NSImage alloc] initWithContentsOfFile:filename] autorelease];
CGImageRef CGImage = [img CGImageForProposedRect:nil context:nil hints:nil];
NSBitmapImageRep *rep = [[[NSBitmapImageRep alloc] initWithCGImage:CGImage] autorelease];
這只會返回一個NSBitmapImageRep
這可能不夠好,如果圖像中包含一個以上的表示(例如很多NSBitmapImageRep
從TIFF文件S)。 但添加一些代碼很簡單。
您可以嘗試使用Mike Ash的“獲取和解釋圖像數據”博客文章改編的方法:
- (NSBitmapImageRep *)bitmapImageRepresentation {
int width = [self size].width;
int height = [self size].height;
if(width < 1 || height < 1)
return nil;
NSBitmapImageRep *rep = [[NSBitmapImageRep alloc]
initWithBitmapDataPlanes: NULL
pixelsWide: width
pixelsHigh: height
bitsPerSample: 8
samplesPerPixel: 4
hasAlpha: YES
isPlanar: NO
colorSpaceName: NSDeviceRGBColorSpace
bytesPerRow: width * 4
bitsPerPixel: 32];
NSGraphicsContext *ctx = [NSGraphicsContext graphicsContextWithBitmapImageRep: rep];
[NSGraphicsContext saveGraphicsState];
[NSGraphicsContext setCurrentContext: ctx];
[self drawAtPoint: NSZeroPoint fromRect: NSZeroRect operation: NSCompositeCopy fraction: 1.0];
[ctx flushGraphics];
[NSGraphicsContext restoreGraphicsState];
return [rep autorelease];
}
也許遲到了派對,但這是來自@mrwalker響應的Swift 3版本:
extension NSImage {
func bitmapImageRepresentation(colorSpaceName: String) -> NSBitmapImageRep? {
let width = self.size.width
let height = self.size.height
if width < 1 || height < 1 {
return nil
}
if let rep = NSBitmapImageRep(bitmapDataPlanes: nil, pixelsWide: Int(width), pixelsHigh: Int(height), bitsPerSample: 8, samplesPerPixel: 4, hasAlpha: true, isPlanar: false, colorSpaceName: colorSpaceName, bytesPerRow: Int(width) * 4, bitsPerPixel: 32)
{
let ctx = NSGraphicsContext.init(bitmapImageRep: rep)
NSGraphicsContext.saveGraphicsState()
NSGraphicsContext.setCurrent(ctx)
self.draw(at: NSZeroPoint, from: NSZeroRect, operation: NSCompositingOperation.copy, fraction: 1.0)
ctx?.flushGraphics()
NSGraphicsContext.restoreGraphicsState()
return rep
}
return nil
}
}
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