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ASTextKitShadower.mm
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executable file
·148 lines (122 loc) · 4.12 KB
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/*
* Copyright (c) 2014-present, 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 "ASTextKitShadower.h"
static inline CGSize _insetSize(CGSize size, UIEdgeInsets insets)
{
return UIEdgeInsetsInsetRect({.size = size}, insets).size;
}
static inline UIEdgeInsets _invertInsets(UIEdgeInsets insets)
{
return {
.top = -insets.top,
.left = -insets.left,
.bottom = -insets.bottom,
.right = -insets.right
};
}
@implementation ASTextKitShadower {
UIEdgeInsets _calculatedShadowPadding;
}
- (instancetype)initWithShadowOffset:(CGSize)shadowOffset
shadowColor:(UIColor *)shadowColor
shadowOpacity:(CGFloat)shadowOpacity
shadowRadius:(CGFloat)shadowRadius
{
if (self = [super init]) {
_shadowOffset = shadowOffset;
_shadowColor = shadowColor;
_shadowOpacity = shadowOpacity;
_shadowRadius = shadowRadius;
_calculatedShadowPadding = UIEdgeInsetsMake(-INFINITY, -INFINITY, INFINITY, INFINITY);
}
return self;
}
/*
* This method is duplicated here because it gets called frequently, and we were
* wasting valuable time constructing a state object to ask it.
*/
- (BOOL)_shouldDrawShadow
{
return _shadowOpacity != 0.0 && _shadowColor != nil && (_shadowRadius != 0 || !CGSizeEqualToSize(_shadowOffset, CGSizeZero));
}
- (void)setShadowInContext:(CGContextRef)context
{
if ([self _shouldDrawShadow]) {
CGColorRef textShadowColor = CGColorRetain(_shadowColor.CGColor);
CGSize textShadowOffset = _shadowOffset;
CGFloat textShadowOpacity = _shadowOpacity;
CGFloat textShadowRadius = _shadowRadius;
if (textShadowOpacity != 1.0) {
CGFloat inherentAlpha = CGColorGetAlpha(textShadowColor);
CGColorRef oldTextShadowColor = textShadowColor;
textShadowColor = CGColorCreateCopyWithAlpha(textShadowColor, inherentAlpha * textShadowOpacity);
CGColorRelease(oldTextShadowColor);
}
CGContextSetShadowWithColor(context, textShadowOffset, textShadowRadius, textShadowColor);
CGColorRelease(textShadowColor);
}
}
- (UIEdgeInsets)shadowPadding
{
if (_calculatedShadowPadding.top == -INFINITY) {
if (![self _shouldDrawShadow]) {
return UIEdgeInsetsZero;
}
UIEdgeInsets shadowPadding = UIEdgeInsetsZero;
// min values are expected to be negative for most typical shadowOffset and
// blurRadius settings:
shadowPadding.top = fminf(0.0f, _shadowOffset.height - _shadowRadius);
shadowPadding.left = fminf(0.0f, _shadowOffset.width - _shadowRadius);
shadowPadding.bottom = fminf(0.0f, -_shadowOffset.height - _shadowRadius);
shadowPadding.right = fminf(0.0f, -_shadowOffset.width - _shadowRadius);
_calculatedShadowPadding = shadowPadding;
}
return _calculatedShadowPadding;
}
- (CGSize)insetSizeWithConstrainedSize:(CGSize)constrainedSize
{
return _insetSize(constrainedSize, _invertInsets([self shadowPadding]));
}
- (CGRect)insetRectWithConstrainedRect:(CGRect)constrainedRect
{
return UIEdgeInsetsInsetRect(constrainedRect, _invertInsets([self shadowPadding]));
}
- (CGSize)outsetSizeWithInsetSize:(CGSize)insetSize
{
return _insetSize(insetSize, [self shadowPadding]);
}
- (CGRect)outsetRectWithInsetRect:(CGRect)insetRect
{
return UIEdgeInsetsInsetRect(insetRect, [self shadowPadding]);
}
- (CGRect)offsetRectWithInternalRect:(CGRect)internalRect
{
return (CGRect){
.origin = [self offsetPointWithInternalPoint:internalRect.origin],
.size = internalRect.size
};
}
- (CGPoint)offsetPointWithInternalPoint:(CGPoint)internalPoint
{
UIEdgeInsets shadowPadding = [self shadowPadding];
return (CGPoint){
internalPoint.x + shadowPadding.left,
internalPoint.y + shadowPadding.top
};
}
- (CGPoint)offsetPointWithExternalPoint:(CGPoint)externalPoint
{
UIEdgeInsets shadowPadding = [self shadowPadding];
return (CGPoint){
externalPoint.x - shadowPadding.left,
externalPoint.y - shadowPadding.top
};
}
@end