Question

非常简单的问题......我有一个像素数组，如何在屏幕上显示它们？

#define WIDTH 10
#define HEIGHT 10
#define SIZE WIDTH*HEIGHT

unsigned short pixels[SIZE];

for (int i = 0; i < WIDTH; i++) {
    for (int j = 0; j < HEIGHT; j++) {
        pixels[j*HEIGHT + i] = 0xFFFF;
    }
}

就是这样......现在我怎样才能在屏幕上显示它们？

Answer 1

创建一个新的“Cocoa应用程序”（如果你不知道如何创建一个cocoa应用程序，请转到Cocoa Dev Center）
子类NSView（如果您不知道如何对视图进行子类化read section "Create the NSView Subclass"）
在接口构建器

在NSView中使用此代码

#import "MyView.h"

@implementation MyView

#define WIDTH 400
#define HEIGHT 400
#define SIZE (WIDTH*HEIGHT)
#define BYTES_PER_PIXEL 2
#define BITS_PER_COMPONENT 5
#define BITS_PER_PIXEL 16

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

- (void)drawRect:(NSRect)dirtyRect
{
    // Get current context
    CGContextRef context = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];

    // Colorspace RGB
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    // Pixel Matrix allocation
    unsigned short *pixels = calloc(SIZE, sizeof(unsigned short));

    // Random pixels will give you a non-organized RAINBOW 
    for (int i = 0; i < WIDTH; i++) {
        for (int j = 0; j < HEIGHT; j++) {
            pixels[i+ j*HEIGHT] = arc4random() % USHRT_MAX;
        }
    }

    // Provider
    CGDataProviderRef provider = CGDataProviderCreateWithData(nil, pixels, SIZE, nil);

    // CGImage
    CGImageRef image = CGImageCreate(WIDTH,
                                     HEIGHT,
                                     BITS_PER_COMPONENT,
                                     BITS_PER_PIXEL,
                                     BYTES_PER_PIXEL*WIDTH,
                                     colorSpace,
                                     kCGImageAlphaNoneSkipFirst,
                                     // xRRRRRGGGGGBBBBB - 16-bits, first bit is ignored!
                                     provider,
                                     nil, //No decode
                                     NO,  //No interpolation
                                     kCGRenderingIntentDefault); // Default rendering

// Draw
CGContextDrawImage(context, self.bounds, image);

// Once everything is written on screen we can release everything
CGImageRelease(image);
CGColorSpaceRelease(colorSpace);
CGDataProviderRelease(provider);

}
@end

Answer 2

有很多方法可以做到这一点。其中一个更简单的方法是使用CGContextDrawImage。在drawRect：

CGContextRef ctx = [[NSGraphicsContext currentContext] graphicsPort];
CGDataProviderRef provider = CGDataProviderCreateWithData(nil, bitmap, bitmap_bytes, nil);
CGImageRef img = CGImageCreate(..., provider, ...);
CGDataProviderRelease(provider);    
CGContextDrawImage(ctx, dstRect, img);
CGImageRelease(img);

CGImageCreate有一堆我在这里遗漏的参数，因为正确的值将取决于你的位图格式。 See the CGImage reference for details.

请注意，如果您的位图是静态的，那么保持CGImageRef而不是立即处理它可能是有意义的。您最了解应用程序的工作原理，因此您可以决定这是否合理。

Answer 3

我通过使用带有NSBitmapImageRep的NSImageView从像素值创建图像来解决了这个问题。如何创建像素值有很多选项。就我而言，我使用了32位像素（RGBA）。在此代码中，pixels是像素值的巨大数组。 display是NSImageView的出口。

    NSBitmapImageRep *myBitmap;
    NSImage *myImage;
    unsigned char *buff[4];
    unsigned char *pixels;
    int width, height, rectSize;
    NSRect myBounds;

    myBounds = [display bounds];
    width = myBounds.size.width;
    height = myBounds.size.height;

    rectSize = width * height;


    memset(buff, 0, sizeof(buff));
    pixels = malloc(rectSize * 4);

    (fill in pixels array)

    buff[0] = pixels;

    myBitmap = [[NSBitmapImageRep alloc] initWithBitmapDataPlanes:buff
            pixelsWide:width
            pixelsHigh:height 
            bitsPerSample:8
            samplesPerPixel:4 
            hasAlpha:YES
            isPlanar:NO
            colorSpaceName:NSCalibratedRGBColorSpace
            bitmapFormat:0
            bytesPerRow:(4 * width)
            bitsPerPixel:32];

    myImage = [[NSImage alloc] init];
    [myImage addRepresentation:myBitmap];
    [display setImage: myImage];
    [myImage release];
    [myBitmap release];

    free(pixels);

如何在NSWindow上显示像素数组？

3 个答案: