def doRotatedEllipses(context):
totreps = 144
tint = 1.0
tintIncrement = 1.0 / totreps
# Create a new transform consisting of a 45 degrees rotation.
theTransform = Quartz.CGAffineTransformMakeRotation(math.pi / 4)
# Apply a scale to the transform just created.
theTransform = Quartz.CGAffineTransformScale(theTransform, 1, 2)
# Place the first ellipse at a good location.
Quartz.CGContextTranslateCTM(context, 100.0, 100.0)
for _ in range(totreps):
# Make a snapshot the coordinate system.
Quartz.CGContextSaveGState(context)
# Set up the coordinate system for the rotated ellipse.
Quartz.CGContextConcatCTM(context, theTransform)
Quartz.CGContextBeginPath(context)
Quartz.CGContextAddArc(context, 0.0, 0.0, 45.0, 0.0, 2 * math.pi, 0)
# Set the fill color for this instance of the ellipse.
Quartz.CGContextSetRGBFillColor(context, tint, 0.0, 0.0, 1.0)
Quartz.CGContextDrawPath(context, Quartz.kCGPathFill)
# Restore the coordinate system to that of the snapshot.
Quartz.CGContextRestoreGState(context)
# Compute the next tint color.
tint -= tintIncrement
# Move over by 1 unit in x for the next ellipse.
Quartz.CGContextTranslateCTM(context, 1.0, 0.0)
def doRotatedEllipsesWithCGPath(context):
totreps = 144
tint = 1.0
tintIncrement = 1.0 / totreps
# Create a new transform consisting of a 45 degree rotation.
theTransform = Quartz.CGAffineTransformMakeRotation(math.pi / 4)
# Apply a scaling transformation to the transform just created.
theTransform = Quartz.CGAffineTransformScale(theTransform, 1, 2)
# Create a mutable CGPath object.
path = Quartz.CGPathCreateMutable()
if path is None:
print("Couldn't create path!")
return
# Add a circular arc to the CGPath object, transformed
# by an affine transform.
Quartz.CGPathAddArc(path, theTransform, 0.0, 0.0, 45.0, 0.0, 2 * math.pi,
False)
# Close the CGPath object.
Quartz.CGPathCloseSubpath(path)
# Place the first ellipse at a good location.
Quartz.CGContextTranslateCTM(context, 100, 100)
for _ in range(totreps):
Quartz.CGContextBeginPath(context)
# Add the CGPath object to the current path in the context.
Quartz.CGContextAddPath(context, path)
# Set the fill color for this instance of the ellipse.
Quartz.CGContextSetRGBFillColor(context, tint, 0.0, 0.0, 1.0)
# Filling the path implicitly closes it.
Quartz.CGContextFillPath(context)
# Compute the next tint color.
tint -= tintIncrement
# Move over for the next ellipse.
Quartz.CGContextTranslateCTM(context, 1, 0.0)
def testFunctions(self):
tf = Quartz.CGAffineTransformMake(1.5, 2.5, 3.5, 4.5, 5.5, 6.5)
self.assertIsInstance(tf, Quartz.CGAffineTransform)
self.assertEqual(tf.a, 1.5)
self.assertEqual(tf.b, 2.5)
self.assertEqual(tf.c, 3.5)
self.assertEqual(tf.d, 4.5)
self.assertEqual(tf.tx, 5.5)
self.assertEqual(tf.ty, 6.5)
tf = Quartz.CGAffineTransformMakeTranslation(2.5, 3.5)
self.assertIsInstance(tf, Quartz.CGAffineTransform)
self.assertEqual(tf.a, 1.0)
self.assertEqual(tf.b, 0.0)
self.assertEqual(tf.c, 0.0)
self.assertEqual(tf.d, 1.0)
self.assertEqual(tf.tx, 2.5)
self.assertEqual(tf.ty, 3.5)
tf = Quartz.CGAffineTransformMakeScale(2.5, 3.5)
self.assertIsInstance(tf, Quartz.CGAffineTransform)
self.assertEqual(tf.a, 2.5)
self.assertEqual(tf.b, 0.0)
self.assertEqual(tf.c, 0.0)
self.assertEqual(tf.d, 3.5)
self.assertEqual(tf.tx, 0.0)
self.assertEqual(tf.ty, 0.0)
tf = Quartz.CGAffineTransformMakeRotation(3.4)
self.assertIsInstance(tf, Quartz.CGAffineTransform)
self.assertResultHasType(Quartz.CGAffineTransformIsIdentity, objc._C_BOOL)
self.assertTrue(Quartz.CGAffineTransformIsIdentity(tf) is False)
self.assertTrue(
Quartz.CGAffineTransformIsIdentity(Quartz.CGAffineTransformIdentity) is True
)
tf = Quartz.CGAffineTransformTranslate(tf, 2.5, 3.5)
self.assertIsInstance(tf, Quartz.CGAffineTransform)
tf = Quartz.CGAffineTransformScale(tf, 5.5, 9.5)
self.assertIsInstance(tf, Quartz.CGAffineTransform)
tf = Quartz.CGAffineTransformRotate(tf, 0.8)
self.assertIsInstance(tf, Quartz.CGAffineTransform)
tf = Quartz.CGAffineTransformInvert(tf)
self.assertIsInstance(tf, Quartz.CGAffineTransform)
tf2 = Quartz.CGAffineTransformConcat(
tf, Quartz.CGAffineTransformMake(1.0, 1.0, 1.0, 1.0, 1.0, 1.0)
)
self.assertIsInstance(tf2, Quartz.CGAffineTransform)
self.assertResultHasType(Quartz.CGAffineTransformEqualToTransform, objc._C_BOOL)
self.assertTrue(Quartz.CGAffineTransformEqualToTransform(tf, tf2) is False)
self.assertTrue(Quartz.CGAffineTransformEqualToTransform(tf2, tf2) is True)
pt = Quartz.CGPointApplyAffineTransform((2.5, 3.5), tf)
self.assertIsInstance(pt, Quartz.CGPoint)
sz = Quartz.CGSizeApplyAffineTransform((2.5, 3.5), tf)
self.assertIsInstance(sz, Quartz.CGSize)
rct = Quartz.CGRectApplyAffineTransform(((2.5, 3.5), (4.5, 5.5)), tf)
self.assertIsInstance(rct, Quartz.CGRect)
def doEllipseShading(context):
black = [0, 0, 0]
red = [1, 0, 0]
# This function describes a color ramp where the starting color
# is red, the ending color is black.
redBlackFunction = createFunctionWithStartEndColorRamp(red, black)
if redBlackFunction is None:
print("Couldn't create the red-black function!")
return
Quartz.CGContextTranslateCTM(context, 100, 300)
# Shading 1.
# To obtain an elliptical shading requires that user space
# at the time the shading is painted is transformed so that
# the circles which define the radial shading geometry are
# rotated and elliptical. User space will be rotated
# by 45 degrees, then scaled by 1 in x and 2 in y to produce
# the ellipses.
# Compute the transform needed to create the rotated ellipses.
t = Quartz.CGAffineTransformMakeRotation(Utilities.DEGREES_TO_RADIANS(45))
t = Quartz.CGAffineTransformScale(t, 1, 2)
circleACenter = Quartz.CGPoint(x=0, y=0)
circleBCenter = Quartz.CGPoint(x=circleACenter.x + 144, y=circleACenter.y)
circleARadius = 45
circleBRadius = 45
# Don't extend this shading.
extendStart = extendEnd = False
shading = Quartz.CGShadingCreateRadial(
Utilities.getTheCalibratedRGBColorSpace(), circleACenter,
circleARadius, circleBCenter, circleBRadius, redBlackFunction,
extendStart, extendEnd)
if shading is None:
# Couldn't create the shading so release
# the function before returning.
print("Couldn't create the shading!")
return
Quartz.CGContextSaveGState(context)
if 1:
# Transform coordinates for the drawing of the shading.
# This transform produces the rotated elliptical shading.
# This produces the left shading in the figure, the
# one where both the ellipses and the shading are
# rotated relative to default user space.
Quartz.CGContextConcatCTM(context, t)
Quartz.CGContextDrawShading(context, shading)
del shading
Quartz.CGContextRestoreGState(context)
Quartz.CGContextTranslateCTM(context, 300, 10)
# Shading 2.
# Now draw the shading where the shading ellipses are
# rotated but the axis between the origins of
# the ellipses lies parallel to the x axis in default
# user space. This is similar to the shading drawn
# manually in Chapter 5.
#
# To compute the correct origins for the shading,
# the code needs to compute the points that,
# transformed by the matrix t used to paint the shading,
# produce the desired coordinates. We want coordinates
# that are transformed as follows:
#
# P' = P x t
#
# where P' is the point in untransformed user space that
# we want as the origin, P is the point in transformed
# user space that will be transformed by t, the matrix
# which transforms the circles into rotated ellipses.
#
# So we want to calculate P such that P' = P x t .
#
# Notice that if P = P' x Inverse(t) then:
#
# P' = P' x Inverse(t) x t = P' x Identity = P'.
#
# This means that we can calculate the point P
# by computing P' x Inverse(t).
inverseT = Quartz.CGAffineTransformInvert(t)
# Now the code can transform the coordinates through the
# inverse transform to compute the new coordinates. These
# coordinates, when transformed with the transform t,
# produce the original coordinate.
circleACenter = Quartz.CGPointApplyAffineTransform(circleACenter, inverseT)
circleBCenter = Quartz.CGPointApplyAffineTransform(circleBCenter, inverseT)
shading = Quartz.CGShadingCreateRadial(
Utilities.getTheCalibratedRGBColorSpace(), circleACenter,
circleARadius, circleBCenter, circleBRadius, redBlackFunction,
extendStart, extendEnd)
# The code is finished with the function so release it.
del redBlackFunction
if shading is None:
print("Couldn't create the shading!")
return
# Transform coordinates for the drawing of the shading.
# This transform produces the rotated elliptical shading.
Quartz.CGContextConcatCTM(context, t)
Quartz.CGContextDrawShading(context, shading)
