pyhanko.pdf_utils.layout module
Layout utilities (to be expanded)
- exception pyhanko.pdf_utils.layout.LayoutError(msg: str, *args)
Bases:
ValueError
Indicates an error in a layout computation.
- exception pyhanko.pdf_utils.layout.BoxSpecificationError(msg: Optional[str] = None)
Bases:
LayoutError
Raised when a box constraint is over/underspecified.
- class pyhanko.pdf_utils.layout.BoxConstraints(width=None, height=None, aspect_ratio: Optional[Fraction] = None)
Bases:
object
Represents a box of potentially variable width and height. Among other uses, this can be leveraged to produce a variably sized box with a fixed aspect ratio.
If width/height are not defined yet, they can be set by assigning to the
width
andheight
attributes.- property width: int
- Returns
The width of the box.
- Raises
BoxSpecificationError – if the box’s width could not be determined.
- property width_defined: bool
- Returns
True
if the box currently has a well-defined width,False
otherwise.
- property height: int
- Returns
The height of the box.
- Raises
BoxSpecificationError – if the box’s height could not be determined.
- property height_defined: bool
- Returns
True
if the box currently has a well-defined height,False
otherwise.
- property aspect_ratio: Fraction
- Returns
The aspect ratio of the box.
- Raises
BoxSpecificationError – if the box’s aspect ratio could not be determined.
- property aspect_ratio_defined: bool
- Returns
True
if the box currently has a well-defined aspect ratio,False
otherwise.
- class pyhanko.pdf_utils.layout.AxisAlignment(value)
Bases:
Enum
Class representing one-dimensional alignment along an axis.
- ALIGN_MIN = 1
Align maximally towards the negative end of the axis.
- ALIGN_MID = 2
Center content along the axis.
- ALIGN_MAX = 3
Align maximally towards the positive end of the axis.
- classmethod from_x_align(align_str: str) AxisAlignment
Convert from a horizontal alignment config string.
- Parameters
align_str – A string: ‘left’, ‘mid’ or ‘right’.
- Returns
An
AxisAlignment
value.- Raises
ConfigurationError – on unexpected string inputs.
- classmethod from_y_align(align_str: str) AxisAlignment
Convert from a vertical alignment config string.
- Parameters
align_str – A string: ‘bottom’, ‘mid’ or ‘top’.
- Returns
An
AxisAlignment
value.- Raises
ConfigurationError – on unexpected string inputs.
- property flipped
- align(container_len: int, inner_len: int, pre_margin, post_margin) int
- class pyhanko.pdf_utils.layout.Margins(left: int = 0, right: int = 0, top: int = 0, bottom: int = 0)
Bases:
ConfigurableMixin
Class describing a set of margins.
- left: int = 0
- right: int = 0
- top: int = 0
- bottom: int = 0
- classmethod uniform(num)
Return a set of uniform margins.
- Parameters
num – The uniform margin to apply to all four sides.
- Returns
Margins(num, num, num, num)
- static effective(dim_name, container_len, pre, post)
Internal helper method to compute effective margins.
- effective_width(width)
Compute width without margins.
- Parameters
width – The container width.
- Returns
The width after subtracting the left and right margins.
- Raises
LayoutError – if the container width is too short to accommodate the margins.
- effective_height(height)
Compute height without margins.
- Parameters
height – The container height.
- Returns
The height after subtracting the top and bottom margins.
- Raises
LayoutError – if the container height is too short to accommodate the margins.
- classmethod from_config(config_dict)
Attempt to instantiate an object of the class on which it is called, by means of the configuration settings passed in.
First, we check that the keys supplied in the dictionary correspond to data fields on the current class. Then, the dictionary is processed using the
process_entries()
method. The resulting dictionary is passed to the initialiser of the current class as a kwargs dict.- Parameters
config_dict – A dictionary containing configuration values.
- Returns
An instance of the class on which it is called.
- Raises
ConfigurationError – when an unexpected configuration key is encountered or left unfilled, or when there is a problem processing one of the config values.
- class pyhanko.pdf_utils.layout.InnerScaling(value)
Bases:
Enum
Class representing a scaling convention.
- NO_SCALING = 1
Never scale content.
- STRETCH_FILL = 2
Scale content to fill the entire container.
- STRETCH_TO_FIT = 3
Scale content while preserving aspect ratio until either the maximal width or maximal height is reached.
- SHRINK_TO_FIT = 4
Scale content down to fit in the container, while preserving the original aspect ratio.
- classmethod from_config(config_str: str) InnerScaling
Convert from a configuration string.
- Parameters
config_str – A string: ‘none’, ‘stretch-fill’, ‘stretch-to-fit’, ‘shrink-to-fit’
- Returns
An
InnerScaling
value.- Raises
ConfigurationError – on unexpected string inputs.
- class pyhanko.pdf_utils.layout.SimpleBoxLayoutRule(x_align: AxisAlignment, y_align: AxisAlignment, margins: Margins = Margins(left=0, right=0, top=0, bottom=0), inner_content_scaling: InnerScaling = InnerScaling.SHRINK_TO_FIT)
Bases:
ConfigurableMixin
Class describing alignment, scaling and margin rules for a box positioned inside another box.
- x_align: AxisAlignment
Horizontal alignment settings.
- y_align: AxisAlignment
Vertical alignment settings.
- margins: Margins = Margins(left=0, right=0, top=0, bottom=0)
Container (inner) margins. Defaults to all zeroes.
- inner_content_scaling: InnerScaling = 4
Inner content scaling rule.
- classmethod process_entries(config_dict)
Hook method that can modify the configuration dictionary to overwrite or tweak some of their values (e.g. to convert string parameters into more complex Python objects)
Subclasses that override this method should call
super().process_entries()
, and leave keys that they do not recognise untouched.- Parameters
config_dict – A dictionary containing configuration values.
- Raises
ConfigurationError – when there is a problem processing a relevant entry.
- substitute_margins(new_margins: Margins) SimpleBoxLayoutRule
- fit(container_box: BoxConstraints, inner_nat_width: int, inner_nat_height: int) Positioning
Position and possibly scale a box within a container, according to this layout rule.
- Parameters
container_box –
BoxConstraints
describing the container.inner_nat_width – The inner box’s natural width.
inner_nat_height – The inner box’s natural height.
- Returns
A
Positioning
describing the scaling & position of the lower left corner of the inner box.
- class pyhanko.pdf_utils.layout.Positioning(x_pos: int, y_pos: int, x_scale: float, y_scale: float)
Bases:
ConfigurableMixin
Class describing the position and scaling of an object in a container.
- x_pos: int
Horizontal coordinate
- y_pos: int
Vertical coordinate
- x_scale: float
Horizontal scaling
- y_scale: float
Vertical scaling
- as_cm()
Convenience method to convert this
Positioning
into a PDFcm
operator.- Returns
A byte string representing the
cm
operator corresponding to thisPositioning
.