如何将多个NSImages组合成一个大图像？

Question

我有一个对象的集合，描述一个图像名称，它的大小和它的X/Y位置。集合是按“层”排序的，所以我可以将图像组合成一种画家的算法。

由此，我可以确定容纳所有图像所需的矩形，所以现在我要做的是：

• 创建某种缓冲区来保存结果(相当于iPhoneOS所称的UIGraphicsContext)。
• 将所有图像绘制到缓冲区中。
• 从缓冲区的复合结果中获取一个新的NSImage。

在iPhoneOS中，这是我想要的代码：

UIGraphicsBeginImageContext (woSize);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    [[UIColor clearColor] set];
    CGContextFillRect(ctx, NSMakeRect(0, 0, woSize.width, woSize.height));
    // draw my various images, here.
    // i.e. Various repetitions of [myImage drawAtPoint:somePoint];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

我要找的是如何在桌面可可/NS中做到这一点。

谢谢!

Answer 1

NSImage* resultImage = [[[NSImage alloc] initWithSize:imageSize] autorelease];
[resultImage lockFocus];

[anotherImage drawAtPoint:aPoint fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:1.0];
// Or any of the other about 6 options; see Apple's guide to pick.

[resultImage unlockFocus];

查看苹果绘图指南以获得更长、更详细的答案。

Answer 2

#import <Cocoa/Cocoa.h>

@interface CompositeView : NSView {
    NSImage *bottom;
    NSImage *top;
}
- (IBAction)takeBottomFrom: (id)aView;
- (IBAction)takeTopFrom: (id)aView;
@end

#import "CompositeView.h"

@implementation CompositeView
- (IBAction)takeBottomFrom: (id)aView
{
    id img = [[aView image] retain];
    [bottom release];
    bottom = img;
    [self setNeedsDisplay: YES];
}

- (IBAction)takeTopFrom: (id)aView
{
    id img = [[aView image] retain];
    [top release];
    top = img;
    [self setNeedsDisplay: YES];
}

- (void)drawRect:(NSRect)rect
{
    NSCompositingOperation op = 0;
    NSRect bounds = [self bounds];
    NSSize imageSize = bounds.size;
    imageSize.width /= 7;
    imageSize.height /= 2;

    NSRect bottomRect = { {0,0}, [bottom size] };
    NSRect topRect = { {0,0}, [top size] };

    for (unsigned y=0 ; y<2 ; y++)
    {
        for (unsigned x=0 ; x<7 ; x++)
        {
            NSRect drawRect;

            drawRect.origin.y = y * imageSize.height;
            drawRect.origin.x = x * imageSize.width;
            drawRect.size = imageSize;

            [bottom drawInRect: drawRect
                      fromRect: bottomRect
                     operation: NSCompositeCopy
                      fraction: 1];

            [top drawInRect: drawRect
                   fromRect: topRect
                  operation: op++
                   fraction: 1];
        }
    }
}

- (id)initWithFrame:(NSRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code here.
    }
    return self;
}

@end