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//
// GTMNSBezierPath+Shading.m
//
// Category for radial and axial stroke and fill functions for NSBezierPaths
//
// Copyright 2006-2008 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
//
#import "GTMNSBezierPath+Shading.h"
#import "GTMNSBezierPath+CGPath.h"
#import "GTMShading.h"
#import "GTMGeometryUtils.h"
#import "GTMMethodCheck.h"
@interface NSBezierPath (GTMBezierPathShadingAdditionsPrivate)
// Fills a CGPathRef either axially or radially with the given shading.
//
// Args:
// path: path to fill
// axially: if YES fill axially, otherwise fill radially
// asStroke: if YES, clip to the stroke of the path, otherwise
// clip to the fill
// from: where to shade from
// fromRadius: in a radial fill, the radius of the from circle
// to: where to shade to
// toRadius: in a radial fill, the radius of the to circle
// extendingStart: if true, extend the fill with the first color of the shade
// beyond |from| away from |to|
// extendingEnd: if true, extend the fill with the last color of the shade
// beyond |to| away from |from|
// shading: the shading to use for the fill
//
- (void)gtm_fillCGPath:(CGPathRef)path
axially:(BOOL)axially
asStroke:(BOOL)asStroke
from:(NSPoint)fromPoint fromRadius:(CGFloat)fromRadius
to:(NSPoint)toPoint toRadius:(CGFloat)toRadius
extendingStart:(BOOL)extendingStart extendingEnd:(BOOL)extendingEnd
shading:(id<GTMShading>)shading;
// Returns the point which is the projection of a line from point |pointA|
// to |pointB| by length
//
// Args:
// pointA: first point
// pointB: second point
// length: distance to project beyond |pointB| which is in line with
// |pointA| and |pointB|
//
// Returns:
// the projected point
- (NSPoint)gtm_projectLineFrom:(NSPoint)pointA
to:(NSPoint)pointB
by:(CGFloat)length;
@end
@implementation NSBezierPath (GTMBezierPathAdditionsPrivate)
- (void)gtm_fillCGPath:(CGPathRef)path
axially:(BOOL)axially asStroke:(BOOL)asStroke
from:(NSPoint)fromPoint fromRadius:(CGFloat)fromRadius
to:(NSPoint)toPoint toRadius:(CGFloat)toRadius
extendingStart:(BOOL)extendingStart extendingEnd:(BOOL)extendingEnd
shading:(id<GTMShading>)shading {
CGFunctionRef shadingFunction = [shading shadeFunction];
if (nil != shadingFunction) {
CGContextRef currentContext = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
if (nil != currentContext) {
CGContextSaveGState(currentContext);
CGFloat lineWidth = [self lineWidth];
CGContextSetLineWidth(currentContext, lineWidth);
if (asStroke) {
// if we are using the stroke, we offset the from and to points
// by half the stroke width away from the center of the stroke.
// Otherwise we tend to end up with fills that only cover half of the
// because users set the start and end points based on the center
// of the stroke.
CGFloat halfWidth = lineWidth * 0.5;
fromPoint = [self gtm_projectLineFrom:toPoint to:fromPoint by:halfWidth];
toPoint = [self gtm_projectLineFrom:fromPoint to:toPoint by:-halfWidth];
}
CGColorSpaceRef colorspace = [shading colorSpace];
if (nil != colorspace) {
CGPoint toCGPoint = {.x = toPoint.x, .y = toPoint.y};
CGPoint fromCGPoint = {.x = fromPoint.x, .y = fromPoint.y};
CGShadingRef myCGShading;
if(axially) {
myCGShading = CGShadingCreateAxial(colorspace, fromCGPoint,
toCGPoint, shadingFunction,
extendingStart == YES,
extendingEnd == YES);
}
else {
myCGShading = CGShadingCreateRadial(colorspace, fromCGPoint, fromRadius,
toCGPoint, toRadius, shadingFunction,
extendingStart == YES,
extendingEnd == YES);
}
if (nil != myCGShading) {
CGContextAddPath(currentContext,path);
if(asStroke) {
CGContextReplacePathWithStrokedPath(currentContext);
}
CGContextClip(currentContext);
CGContextDrawShading(currentContext, myCGShading);
CGShadingRelease(myCGShading);
}
}
CGContextRestoreGState(currentContext);
}
}
}
- (NSPoint)gtm_projectLineFrom:(NSPoint)pointA
to:(NSPoint)pointB
by:(CGFloat)length {
NSPoint newPoint = NSMakePoint(pointB.x, pointB.y);
CGFloat x = (pointB.x - pointA.x);
CGFloat y = (pointB.y - pointA.y);
if (fpclassify(x) == FP_ZERO) {
newPoint.y += length;
} else if (fpclassify(y) == FP_ZERO) {
newPoint.x += length;
} else {
#if CGFLOAT_IS_DOUBLE
CGFloat angle = atan(y / x);
newPoint.x += sin(angle) * length;
newPoint.y += cos(angle) * length;
#else
CGFloat angle = atanf(y / x);
newPoint.x += sinf(angle) * length;
newPoint.y += cosf(angle) * length;
#endif
}
return newPoint;
}
@end
@implementation NSBezierPath (GTMBezierPathShadingAdditions)
GTM_METHOD_CHECK(NSBezierPath, gtm_CGPath);
- (void)gtm_strokeAxiallyFrom:(NSPoint)fromPoint to:(NSPoint)toPoint
extendingStart:(BOOL)extendingStart extendingEnd:(BOOL)extendingEnd
shading:(id<GTMShading>)shading {
CGPathRef thePath = [self gtm_CGPath];
if (nil != thePath) {
[self gtm_fillCGPath:thePath axially:YES asStroke:YES
from:fromPoint fromRadius:(CGFloat)0.0
to:toPoint toRadius:(CGFloat)0.0
extendingStart:extendingStart extendingEnd:extendingEnd
shading:shading];
}
}
- (void)gtm_strokeRadiallyFrom:(NSPoint)fromPoint fromRadius:(CGFloat)fromRadius
to:(NSPoint)toPoint toRadius:(CGFloat)toRadius
extendingStart:(BOOL)extendingStart extendingEnd:(BOOL)extendingEnd
shading:(id<GTMShading>)shading {
CGPathRef thePath = [self gtm_CGPath];
if (nil != thePath) {
[self gtm_fillCGPath:thePath axially:NO asStroke:YES
from:fromPoint fromRadius:fromRadius
to:toPoint toRadius:toRadius
extendingStart:extendingStart extendingEnd:extendingEnd
shading:shading];
}
}
- (void)gtm_fillAxiallyFrom:(NSPoint)fromPoint to:(NSPoint)toPoint
extendingStart:(BOOL)extendingStart extendingEnd:(BOOL)extendingEnd
shading:(id<GTMShading>)shading {
CGPathRef thePath = [self gtm_CGPath];
if (nil != thePath) {
[self gtm_fillCGPath:thePath axially:YES asStroke:NO
from:fromPoint fromRadius:(CGFloat)0.0
to:toPoint toRadius:(CGFloat)0.0
extendingStart:extendingStart extendingEnd:extendingEnd
shading:shading];
}
}
- (void)gtm_fillRadiallyFrom:(NSPoint)fromPoint fromRadius:(CGFloat)fromRadius
to:(NSPoint)toPoint toRadius:(CGFloat)toRadius
extendingStart:(BOOL)extendingStart extendingEnd:(BOOL)extendingEnd
shading:(id<GTMShading>)shading {
CGPathRef thePath = [self gtm_CGPath];
if (nil != thePath) {
[self gtm_fillCGPath:thePath axially:NO asStroke:NO
from:fromPoint fromRadius:fromRadius
to:toPoint toRadius:toRadius
extendingStart:extendingStart extendingEnd:extendingEnd
shading:shading];
}
}
@end
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