0

我在 SKTexture 上写了一个梯度生成函数作为类别。它在 1x 屏幕上运行良好，但视网膜渲染纹理太大，双倍宽度和双倍高度，即错误的比例。我一直试图通过在像素和点之间进行更改来使其正确，但无法正确。有人能帮助我吗？

+(SKTexture*)gradientWithSize:(const CGSize)SIZE colors:(NSArray*)colors {
    // Hopefully this function would be platform independent one day.

    // Correct way to find scale?
    DLog(@"backingScaleFactor: %f", [[NSScreen mainScreen] backingScaleFactor]);
    const CGFloat SCALE = [[NSScreen mainScreen] backingScaleFactor];
    //const size_t WIDTH_PIXELS = SIZE.width * SCALE;
    //const size_t HEIGHT_PIXELS = SIZE.height * SCALE;
    CGContextRef cgcontextref = MyCreateBitmapContext(SIZE.width, SIZE.height, SCALE);
    NSAssert(cgcontextref != NULL, @"Failed creating context!");
    //  CGBitmapContextCreate(
    //                                                    NULL, // let the OS handle the memory
    //                                                    WIDTH_PIXELS,
    //                                                    HEIGHT_PIXELS,

    CAGradientLayer* gradient = CAGradientLayer.layer;
    //gradient.contentsScale = SCALE;
    gradient.frame = CGRectMake(0, 0, SIZE.width, SIZE.height);

    NSMutableArray* convertedcolors = [NSMutableArray array];
    for (SKColor* skcolor in colors) {
        [convertedcolors addObject:(id)skcolor.CGColor];
    }
    gradient.colors = convertedcolors;
    [gradient renderInContext:cgcontextref];

    CGImageRef imageref = CGBitmapContextCreateImage(cgcontextref);
    DLog(@"imageref pixel size: %zu %zu", CGImageGetWidth(imageref), CGImageGetHeight(imageref));

    SKTexture* texture1 = [SKTexture textureWithCGImage:imageref];
    DLog(@"size of gradient texture: %@", NSStringFromSize(texture1.size));

    CGImageRelease(imageref);

    CGContextRelease(cgcontextref);

    return texture1;
}
CGContextRef MyCreateBitmapContext(const size_t POINTS_W, const size_t POINTS_H, const CGFloat SCALE) {
    CGContextRef    context = NULL;
    CGColorSpaceRef colorSpace;
    void *          bitmapData;
    //int             bitmapByteCount;
    size_t             bitmapBytesPerRow;

    const size_t PIXELS_W = POINTS_W * SCALE;
    const size_t PIXELS_H = POINTS_H * SCALE;

    bitmapBytesPerRow   = (PIXELS_W * 4);// 1
    //bitmapByteCount     = (bitmapBytesPerRow * pixelsHigh);

    colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);// 2
    bitmapData = NULL;

#define kBitmapInfo     kCGImageAlphaPremultipliedLast
    //#define kBitmapInfo       kCGImageAlphaPremultipliedFirst
    //#define kBitmapInfo       kCGImageAlphaNoneSkipFirst
    // According to http://stackoverflow.com/a/18921840/129202 it should be safe to just cast
    CGBitmapInfo bitmapinfo = (CGBitmapInfo)kBitmapInfo; //kCGImageAlphaNoneSkipFirst; //0; //kCGBitmapAlphaInfoMask; //kCGImageAlphaNone; //kCGImageAlphaNoneSkipFirst;
    context = CGBitmapContextCreate (bitmapData,// 4
                                     PIXELS_W,
                                     PIXELS_H,
                                     8,      // bits per component
                                     bitmapBytesPerRow,
                                     colorSpace,
                                     bitmapinfo
                                     );
    if (context == NULL) {
        free (bitmapData);// 5
        fprintf (stderr, "Context not created!");
        return NULL;
    }
    CGColorSpaceRelease( colorSpace );// 6

    // TEST!!
//  CGContextClipToRect(context, CGRectMake(0, 0, POINTS_W, POINTS_H));
    CGContextClipToRect(context, CGRectMake(0, 0, PIXELS_W, PIXELS_H));
    CGContextScaleCTM(context, SCALE, SCALE);

    return context;// 7
}

因此，总而言之，我希望+(SKTexture*)gradientWithSize:(const CGSize)SIZE colors:(NSArray*)colors使用 SIZE 的点数来调用。

4

1 回答 1

0

根据 LearnCocos2D 的建议更新了如下代码。何时缩放而不是令人困惑（因为在文档中，CGBitmapContextCreate明确采用PIXELS中的宽度和高度）但这似乎在视网膜屏幕上也具有正确的大小。我仍然不知道渲染的分辨率是否真的是视网膜 - 但这很难用眼睛来确认，因为毕竟这是一个渐变......我仍然使用相同的上下文创建功能来创建纹理中继器（启用将colorWithPatternImage 与 Sprite Kit一起使用）。也许我以后有时间尝试使用这个新版本重复使用详细的纹理......而且gradient.contentsScale = SCALE;打开或关闭也不会产生明显的差异。

+(SKTexture*)gradientWithSize:(const CGSize)SIZE colors:(NSArray*)colors {
    // Hopefully this function would be platform independent one day.

    CGContextRef cgcontextref = MyCreateBitmapContext(SIZE.width, SIZE.height);
    NSAssert(cgcontextref != NULL, @"Failed creating context!");

    CAGradientLayer* gradient = CAGradientLayer.layer;
    DLog(@"gradient.contentScale: %f", gradient.contentsScale);
    //gradient.contentsScale = SCALE;
    DLog(@"gradient.contentScale: %f", gradient.contentsScale);
    gradient.frame = CGRectMake(0, 0, SIZE.width, SIZE.height);

    NSMutableArray* convertedcolors = [NSMutableArray array];
    for (SKColor* skcolor in colors) {
        [convertedcolors addObject:(id)skcolor.CGColor];
    }
    gradient.colors = convertedcolors;
    [gradient renderInContext:cgcontextref];

    CGImageRef imageref = CGBitmapContextCreateImage(cgcontextref);
    DLog(@"imageref pixel size: %zu %zu", CGImageGetWidth(imageref), CGImageGetHeight(imageref));

    SKTexture* texture1 = [SKTexture textureWithCGImage:imageref];
    DLog(@"size of gradient texture: %@", NSStringFromSize(texture1.size));

    CGImageRelease(imageref);

    CGContextRelease(cgcontextref);

    return texture1;
}
CGContextRef MyCreateBitmapContext(const size_t POINTS_W, const size_t POINTS_H/*, const CGFloat SCALE*/) {
    CGContextRef    context = NULL;
    CGColorSpaceRef colorSpace;
    void *          bitmapData;
    size_t             bitmapBytesPerRow;

    bitmapBytesPerRow   = (POINTS_W * 4);

    colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
    bitmapData = NULL;

#define kBitmapInfo     kCGImageAlphaPremultipliedLast
    // According to https://stackoverflow.com/a/18921840/129202 it should be safe to just cast
    CGBitmapInfo bitmapinfo = (CGBitmapInfo)kBitmapInfo;
    context = CGBitmapContextCreate (bitmapData,
                                     POINTS_W,
                                     POINTS_H,
                                     8,
                                     bitmapBytesPerRow,
                                     colorSpace,
                                     bitmapinfo
                                     );
    if (context == NULL) {
        free (bitmapData);
        fprintf (stderr, "Context not created!");
        return NULL;
    }
    CGColorSpaceRelease(colorSpace);

    return context;
}

结果如下。左边只是一个使用 SKSpriteNode 创建的黄色矩形。右边是使用上述函数生成的纹理创建的矩形。这两个矩形在相同的位置并且具有相同的点大小，只是锚点不同。

SKColor* color1 = SKColor.blueColor;
SKColor* color2 = [SKColor colorWithCalibratedRed:1 green:0 blue:0 alpha:0.5];
SKTexture* textureGradient = [SKTexture gradientWithSize:SIZE colors:@[color1, color2]];
SKSpriteNode* spriteGradient = [SKSpriteNode spriteNodeWithTexture:textureGradient];

1x 分辨率 渐变 1x 分辨率

2 倍分辨率（视网膜） 渐变 2x 分辨率

于 2013-10-24T01:43:27.183 回答