.. _patterns: ******** Patterns ******** .. currentmodule:: cairo Patterns are the paint with which cairo draws. The primary use of patterns is as the source for all cairo drawing operations, although they can also be used as masks, that is, as the brush too. A cairo *Pattern* is created by using one of the *PatternType* constructors listed below, or implicitly through *Context.set_source_()* methods. class Pattern() =============== *Pattern* is the abstract base class from which all the other pattern classes derive. It cannot be instantiated directly. .. class:: Pattern() .. method:: get_extend() :returns: the current extend strategy used for drawing the *Pattern*. :rtype: int Gets the current extend mode for the *Pattern*. See :ref:`EXTEND attributes ` for details on the semantics of each extend strategy. .. method:: get_matrix() :returns: a new :class:`Matrix` which stores a copy of the *Pattern's* transformation matrix .. method:: set_extend(extend) :param extend: an :ref:`EXTEND ` describing how the area outside of the *Pattern* will be drawn Sets the mode to be used for drawing outside the area of a *Pattern*. The default extend mode is :data:`cairo.EXTEND_NONE` for :class:`SurfacePattern` and :data:`cairo.EXTEND_PAD` for :class:`Gradient` Patterns. .. method:: set_matrix(matrix) :param matrix: a :class:`Matrix` Sets the *Pattern's* transformation matrix to *matrix*. This matrix is a transformation from user space to pattern space. When a *Pattern* is first created it always has the identity matrix for its transformation matrix, which means that pattern space is initially identical to user space. Important: Please note that the direction of this transformation matrix is from user space to pattern space. This means that if you imagine the flow from a *Pattern* to user space (and on to device space), then coordinates in that flow will be transformed by the inverse of the *Pattern* matrix. For example, if you want to make a *Pattern* appear twice as large as it does by default the correct code to use is:: matrix = cairo.Matrix(xx=0.5,yy=0.5) pattern.set_matrix(matrix) Meanwhile, using values of 2.0 rather than 0.5 in the code above would cause the *Pattern* to appear at half of its default size. Also, please note the discussion of the user-space locking semantics of :class:`Context.set_source`. class SolidPattern(:class:`Pattern`) ==================================== .. class:: SolidPattern(red, green, blue, alpha=1.0) :param red: red component of the color :type red: float :param green: green component of the color :type green: float :param blue: blue component of the color :type blue: float :param alpha: alpha component of the color :type alpha: float :returns: a new *SolidPattern* :raises: *MemoryError* in case of no memory Creates a new *SolidPattern* corresponding to a translucent color. The color components are floating point numbers in the range 0 to 1. If the values passed in are outside that range, they will be clamped. .. method:: get_rgba() :returns: (red, green, blue, alpha) a tuple of float Gets the solid color for a *SolidPattern*. .. versionadded:: 1.4 class SurfacePattern(:class:`Pattern`) ====================================== .. class:: SurfacePattern(surface) :param surface: a cairo :class:`Surface` :returns: a newly created *SurfacePattern* for the given surface. :raises: *MemoryError* in case of no memory. .. method:: get_filter() :returns: the current :ref:`FILTER ` used for resizing the *SurfacePattern*. .. method:: get_surface() :returns: the :class:`Surface` of the *SurfacePattern*. .. versionadded:: 1.4 .. method:: set_filter(filter) :param filter: a :ref:`FILTER ` describing the filter to use for resizing the *Pattern* Note that you might want to control filtering even when you do not have an explicit *Pattern* object, (for example when using :meth:`Context.set_source_surface`). In these cases, it is convenient to use :meth:`Context.get_source` to get access to the pattern that cairo creates implicitly. For example:: context.set_source_surface(image, x, y) surfacepattern.set_filter(context.get_source(), cairo.FILTER_NEAREST) class Gradient(:class:`Pattern`) ================================ *Gradient* is an abstract base class from which other *Pattern* classes derive. It cannot be instantiated directly. .. class:: Gradient() .. method:: add_color_stop_rgb(offset, red, green, blue) :param offset: an offset in the range [0.0 .. 1.0] :type offset: float :param red: red component of color :type red: float :param green: green component of color :type green: float :param blue: blue component of color :type blue: float Adds an opaque color stop to a *Gradient* pattern. The offset specifies the location along the gradient's control vector. For example, a *LinearGradient's* control vector is from (x0,y0) to (x1,y1) while a *RadialGradient's* control vector is from any point on the start circle to the corresponding point on the end circle. The color is specified in the same way as in :meth:`Context.set_source_rgb`. If two (or more) stops are specified with identical offset values, they will be sorted according to the order in which the stops are added, (stops added earlier will compare less than stops added later). This can be useful for reliably making sharp color transitions instead of the typical blend. .. method:: add_color_stop_rgba(offset, red, green, blue, alpha) :param offset: an offset in the range [0.0 .. 1.0] :type offset: float :param red: red component of color :type red: float :param green: green component of color :type green: float :param blue: blue component of color :type blue: float :param alpha: alpha component of color :type alpha: float Adds an opaque color stop to a *Gradient* pattern. The offset specifies the location along the gradient's control vector. For example, a *LinearGradient's* control vector is from (x0,y0) to (x1,y1) while a *RadialGradient's* control vector is from any point on the start circle to the corresponding point on the end circle. The color is specified in the same way as in :meth:`Context.set_source_rgb`. If two (or more) stops are specified with identical offset values, they will be sorted according to the order in which the stops are added, (stops added earlier will compare less than stops added later). This can be useful for reliably making sharp color transitions instead of the typical blend. class LinearGradient(:class:`Gradient`) ======================================= .. class:: LinearGradient(x0, y0, x1, y1) :param x0: x coordinate of the start point :type x0: float :param y0: y coordinate of the start point :type y0: float :param x1: x coordinate of the end point :type x1: float :param y1: y coordinate of the end point :type y1: float :returns: a new *LinearGradient* :raises: *MemoryError* in case of no memory Create a new *LinearGradient* along the line defined by (x0, y0) and (x1, y1). Before using the *Gradient* pattern, a number of color stops should be defined using :meth:`Gradient.add_color_stop_rgb` or :meth:`Gradient.add_color_stop_rgba` Note: The coordinates here are in pattern space. For a new *Pattern*, pattern space is identical to user space, but the relationship between the spaces can be changed with :meth:`Pattern.set_matrix` .. method:: get_linear_points() :returns: (x0, y0, x1, y1) - a tuple of float * x0: return value for the x coordinate of the first point * y0: return value for the y coordinate of the first point * x1: return value for the x coordinate of the second point * y1: return value for the y coordinate of the second point Gets the gradient endpoints for a *LinearGradient*. .. versionadded:: 1.4 class RadialGradient(:class:`Gradient`) ======================================= .. class:: RadialGradient(cx0, cy0, radius0, cx1, cy1, radius1) :param cx0: x coordinate for the center of the start circle :type cx0: float :param cy0: y coordinate for the center of the start circle :type cy0: float :param radius0: radius of the start circle :type radius0: float :param cx1: x coordinate for the center of the end circle :type cx1: float :param cy1: y coordinate for the center of the end circle :type cy1: float :param radius1: radius of the end circle :type radius1: float :returns: the newly created *RadialGradient* :raises: *MemoryError* in case of no memory Creates a new *RadialGradient* pattern between the two circles defined by (cx0, cy0, radius0) and (cx1, cy1, radius1). Before using the gradient pattern, a number of color stops should be defined using :meth:`Gradient.add_color_stop_rgb` or :meth:`Gradient.add_color_stop_rgba`. Note: The coordinates here are in pattern space. For a new pattern, pattern space is identical to user space, but the relationship between the spaces can be changed with :meth:`Pattern.set_matrix`. .. method:: get_radial_circles() :returns: (x0, y0, r0, x1, y1, r1) - a tuple of float * x0: return value for the x coordinate of the center of the first circle * y0: return value for the y coordinate of the center of the first circle * r0: return value for the radius of the first circle * x1: return value for the x coordinate of the center of the second circle * y1: return value for the y coordinate of the center of the second circle * r1: return value for the radius of the second circle Gets the *Gradient* endpoint circles for a *RadialGradient*, each specified as a center coordinate and a radius. .. versionadded:: 1.4