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MetalShaderShowcase/AAPLTexture.mm

/*

 Copyright (C) 2014 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

*/

#import "AAPLTexture.h"

@implementation AAPLTexture

@private

    id <MTLTexture>  _texture;

    MTLTextureType   _target;

    uint32_t         _width;

    uint32_t         _height;

    uint32_t         _depth;

    uint32_t         _format;

    BOOL             _hasAlpha;

    BOOL             _flip;

    NSString        *_path;

- (instancetype) initWithResourceName:(NSString *)name

                            extension:(NSString *)ext

    NSString *path = [[NSBundle mainBundle] pathForResource:name

                                                     ofType:ext];

    if(!path)

        return nil;

    } // if

    self = [super init];

    if(self)

        _path     = path;

        _width    = 0;

        _height   = 0;

        _depth    = 1;

        _format   = MTLPixelFormatRGBA8Unorm;

        _target   = MTLTextureType2D;

        _texture  = nil;

        _hasAlpha = NO;

        _flip     = YES;

    } // if

    return self;

} // initWithResourceName

- (void) dealloc

    _path    = nil;

    _texture = nil;

} // dealloc

- (void) setFlip:(BOOL)flip

    _flip = flip;

} // setFlip

// assumes png file

- (BOOL) finalize:(id <MTLDevice>)device

    UIImage *pImage = [UIImage imageWithContentsOfFile:_path];

    if(!pImage)

        pImage = nil;

        return NO;

    } // if

    CGColorSpaceRef pColorSpace = CGColorSpaceCreateDeviceRGB();

    if(!pColorSpace)

        pImage = nil;

        return NO;

    } // if

    _width  = uint32_t(CGImageGetWidth(pImage.CGImage));

    _height = uint32_t(CGImageGetHeight(pImage.CGImage));

    uint32_t width    = _width;

    uint32_t height   = _height;

    uint32_t rowBytes = width * 4;

    CGContextRef pContext = CGBitmapContextCreate(NULL,

                                                  width,

                                                  height,

8,

                                                  rowBytes,

                                                  pColorSpace,

                                                  CGBitmapInfo(kCGImageAlphaPremultipliedLast));

    CGColorSpaceRelease(pColorSpace);

    if(!pContext)

        return NO;

    } // if

    CGRect bounds = CGRectMake(0.0f, 0.0f, width, height);

    CGContextClearRect(pContext, bounds);

    // Vertical Reflect

    if(_flip)

        CGContextTranslateCTM(pContext, width, height);

        CGContextScaleCTM(pContext, -1.0, -1.0);

    } // if

    CGContextDrawImage(pContext, bounds, pImage.CGImage);

    pImage = nil;

    MTLTextureDescriptor *pTexDesc = [MTLTextureDescriptor texture2DDescriptorWithPixelFormat:MTLPixelFormatRGBA8Unorm

                                                                                        width:width

                                                                                       height:height

                                                                                    mipmapped:NO];

    _target  = pTexDesc.textureType;

    _texture = [device newTextureWithDescriptor:pTexDesc];

    pTexDesc = nil;

    if(!_texture)

        CGContextRelease(pContext);

        return NO;

    } // if

    const void *pPixels = CGBitmapContextGetData(pContext);

    if(pPixels != NULL)

        MTLRegion region = MTLRegionMake2D(0, 0, width, height);

        [_texture replaceRegion:region

                    mipmapLevel:0

                      withBytes:pPixels

                    bytesPerRow:rowBytes];

    } // if

    CGContextRelease(pContext);

    return YES;

} // finalize

@end

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