def getSizeFromRatio(boundingBox: BoundingBox,
aspectRatio: float) -> Tuple[float, float, bool]:
"""Given a bounding box and desired aspect ratio, this function calculates the closest pixel size (width and height) that
that is larger than the bounding box and at the correct aspect ratio.
Returns the width, height, and a boolean value indicating wheter the new aspect ratio is wider or not
Args:
BoundingBox (BoundingBox): bounding box representing the smallest size
aspectRatio (float): desired aspect ratio
Returns:
Tuple[float,float,bool]: width, height, isWider
"""
if boundingBox.aspectRatio(
) > aspectRatio: # The box is wider than we need
height = boundingBox.width() / aspectRatio
return boundingBox.width(), height, False
elif boundingBox.aspectRatio(
) < aspectRatio: # The box is taller than we need
width = boundingBox.height() * aspectRatio
return width, boundingBox.height(), True
def findBestCrop(boundingBox: BoundingBox, imageDimensions: Tuple[int, int],
aspectRatio: float) -> BoundingBox:
"""Cwaculates a crop that has the desired aspect ratio and contains the bounding box provided.
Args:
boundingBox (BoundingBox): the bounding box that needs to be adjusted to the desired aspect ratio
imageDimensions (Tuple[int,int]): the dimensions (height, width) of the full image that the bounding box is from
aspectRatio (float): The aspect ratio of the crop that will be calculated and returned (width/height)
Returns:
BoundingBox: The smallest bounding box that is as close to the specified aspect ratio as possible
and contains the specified bounding box (function parameter). The specified bounding box is as
centered as possible in the output bounding box.
"""
if (boxRatioIsEqual(boundingBox, aspectRatio)):
return boundingBox
newWidth, newHeight, isWider = getSizeFromRatio(boundingBox, aspectRatio)
if isWider: #Then center horizontaly
if newWidth <= imageDimensions[
1]: # If true, then the new bounding box can be contained within the image
widthDiff = newWidth - boundingBox.width()
adjustment = math.floor(widthDiff / 2)
x1 = boundingBox.left() - adjustment
x2 = x1 + newWidth - 1
y1 = boundingBox.top()
y2 = boundingBox.bottom()
#Check that the new box is within bounds of the image
if x1 < 0: #if left of the box extends past the left of the image
x1 = 0
x2 = x1 + newWidth - 1
elif x2 >= imageDimensions[1]: #if true
x2 = imageDimensions[0] - 1
x1 = x2 - newWidth + 1
return BoundingBox(x1, y1, x2, y2)
else: #The smallest bounding box with the right aspect ratio would exceed the bounds of the image
#Make the image as wide as possible but still fit in the image
x1 = imageDimensions[0]
x2 = imageDimensions[1]
y1 = boundingBox.top()
y2 = boundingBox.bottom()
return BoundingBox(x1, y1, x2, y2)
else: #The new bounding box is taller than the given bounding box
if newHeight <= imageDimensions[
0]: # The new bounding box can be contained within the image
heightDiff = newHeight - boundingBox.height()
adjustment = math.floor(heightDiff / 2)
y1 = boundingBox.top() - adjustment
y2 = y1 + newHeight - 1
x1 = boundingBox.left()
x2 = boundingBox.right()
#Check that the new box is within the bounds of the image
if y1 < 0: #if true the top of the box extends past the top of the image
y1 = 0
y2 = y1 + newHeight - 1
elif y2 > imageDimensions[
1]: #if true the bottom of the box extends past the bottom of the image
y2 = imageDimensions[0] - 1
y1 = y2 - newHeight + 1
return BoundingBox(x1, y1, x2, y2)
else: #The smallest bounding box with the correct aspect ratio cannot be conatined within the image
y1 = 0
y2 = imageDimensions[1]
x1 = boundingBox.left()
x2 = boundingBox.right()
return BoundingBox(x1, y1, x2, y2)
