react-native/Libraries/Image/RCTImageUtils.h

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/*
* Copyright (c) 2013, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
*/
#import <UIKit/UIKit.h>
#import <React/RCTDefines.h>
#import <React/RCTResizeMode.h>
NS_ASSUME_NONNULL_BEGIN
/**
* This function takes an source size (typically from an image), a target size
* and scale that it will be drawn at (typically in a CGContext) and then
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* calculates the rectangle to draw the image into so that it will be sized and
* positioned correctly according to the specified resizeMode.
*/
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RCT_EXTERN CGRect RCTTargetRect(CGSize sourceSize, CGSize destSize,
CGFloat destScale, RCTResizeMode resizeMode);
/**
* This function takes a source size (typically from an image), a target rect
* that it will be drawn into (typically relative to a CGContext), and works out
* the transform needed to draw the image at the correct scale and position.
*/
RCT_EXTERN CGAffineTransform RCTTransformFromTargetRect(CGSize sourceSize,
CGRect targetRect);
/**
* This function takes an input content size & scale (typically from an image),
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* a target size & scale at which it will be displayed (typically in a
* UIImageView) and then calculates the optimal size at which to redraw the
* image so that it will be displayed correctly with the specified resizeMode.
*/
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RCT_EXTERN CGSize RCTTargetSize(CGSize sourceSize, CGFloat sourceScale,
CGSize destSize, CGFloat destScale,
RCTResizeMode resizeMode, BOOL allowUpscaling);
/**
* This function takes an input content size & scale (typically from an image),
* a target size & scale that it will be displayed at, and determines if the
* source will need to be upscaled to fit (which may result in pixelization).
*/
RCT_EXTERN BOOL RCTUpscalingRequired(CGSize sourceSize, CGFloat sourceScale,
CGSize destSize, CGFloat destScale,
RCTResizeMode resizeMode);
/**
* This function takes the source data for an image and decodes it at the
* specified size. If the original image is smaller than the destination size,
* the resultant image's scale will be decreased to compensate, so the
* width/height of the returned image is guaranteed to be >= destSize.
* Pass a destSize of CGSizeZero to decode the image at its original size.
*/
RCT_EXTERN UIImage *__nullable RCTDecodeImageWithData(NSData *data,
CGSize destSize,
CGFloat destScale,
RCTResizeMode resizeMode);
/**
* This function takes the source data for an image and decodes just the
* metadata, without decompressing the image itself.
*/
RCT_EXTERN NSDictionary<NSString *, id> *__nullable RCTGetImageMetadata(NSData *data);
/**
* Convert an image back into data. Images with an alpha channel will be
* converted to lossless PNG data. Images without alpha will be converted to
* JPEG. The `quality` argument controls the compression ratio of the JPEG
* conversion, with 1.0 being maximum quality. It has no effect for images
* using PNG compression.
*/
RCT_EXTERN NSData *__nullable RCTGetImageData(CGImageRef image, float quality);
/**
* This function transforms an image. `destSize` is the size of the final image,
* and `destScale` is its scale. The `transform` argument controls how the
* source image will be mapped to the destination image.
*/
RCT_EXTERN UIImage *__nullable RCTTransformImage(UIImage *image,
CGSize destSize,
CGFloat destScale,
CGAffineTransform transform);
/*
* Return YES if image has an alpha component
*/
RCT_EXTERN BOOL RCTImageHasAlpha(CGImageRef image);
NS_ASSUME_NONNULL_END