Renderer

Added in version 1.8.

class Renderer(**properties: Any)

Superclasses: Object

PangoRenderer is a base class for objects that can render text provided as PangoGlyphString or PangoLayout.

By subclassing PangoRenderer and overriding operations such as draw_glyphs and draw_rectangle, renderers for particular font backends and destinations can be created.

Methods

class Renderer
activate() → None

Does initial setup before rendering operations on renderer.

deactivate should be called when done drawing. Calls such as draw_layout automatically activate the layout before drawing on it.

Calls to activate and deactivate can be nested and the renderer will only be initialized and deinitialized once.

Added in version 1.8.

deactivate() → None

Cleans up after rendering operations on renderer.

See docs for activate.

Added in version 1.8.

draw_error_underline(x: int, y: int, width: int, height: int) → None

Draw a squiggly line that approximately covers the given rectangle in the style of an underline used to indicate a spelling error.

The width of the underline is rounded to an integer number of up/down segments and the resulting rectangle is centered in the original rectangle.

This should be called while renderer is already active. Use activate to activate a renderer.

Added in version 1.8.

Parameters:

  • x – X coordinate of underline, in Pango units in user coordinate system

  • y – Y coordinate of underline, in Pango units in user coordinate system

  • width – width of underline, in Pango units in user coordinate system

  • height – height of underline, in Pango units in user coordinate system

draw_glyph(font: Font, glyph: int, x: float, y: float) → None

Draws a single glyph with coordinates in device space.

Added in version 1.8.

Parameters:

  • font – a PangoFont

  • glyph – the glyph index of a single glyph

  • x – X coordinate of left edge of baseline of glyph

  • y – Y coordinate of left edge of baseline of glyph

draw_glyph_item(text: str | None, glyph_item: GlyphItem, x: int, y: int) → None

Draws the glyphs in glyph_item with the specified PangoRenderer, embedding the text associated with the glyphs in the output if the output format supports it.

This is useful for rendering text in PDF.

Note that this method does not handle attributes in glyph_item. If you want colors, shapes and lines handled automatically according to those attributes, you need to use draw_layout_line() or draw_layout().

Note that text is the start of the text for layout, which is then indexed by glyph_item->item->offset.

If text is None, this simply calls draw_glyphs.

The default implementation of this method simply falls back to draw_glyphs.

Added in version 1.22.

Parameters:

  • text – the UTF-8 text that glyph_item refers to

  • glyph_item – a PangoGlyphItem

  • x – X position of left edge of baseline, in user space coordinates in Pango units

  • y – Y position of left edge of baseline, in user space coordinates in Pango units

draw_glyphs(font: Font, glyphs: GlyphString, x: int, y: int) → None

Draws the glyphs in glyphs with the specified PangoRenderer.

Added in version 1.8.

Parameters:

  • font – a PangoFont

  • glyphs – a PangoGlyphString

  • x – X position of left edge of baseline, in user space coordinates in Pango units.

  • y – Y position of left edge of baseline, in user space coordinates in Pango units.

draw_layout(layout: Layout, x: int, y: int) → None

Draws layout with the specified PangoRenderer.

This is equivalent to drawing the lines of the layout, at their respective positions relative to x, y.

Added in version 1.8.

Parameters:

  • layout – a PangoLayout

  • x – X position of left edge of baseline, in user space coordinates in Pango units.

  • y – Y position of left edge of baseline, in user space coordinates in Pango units.

draw_layout_line(line: LayoutLine, x: int, y: int) → None

Draws line with the specified PangoRenderer.

This draws the glyph items that make up the line, as well as shapes, backgrounds and lines that are specified by the attributes of those items.

Added in version 1.8.

Parameters:

  • line – a PangoLayoutLine

  • x – X position of left edge of baseline, in user space coordinates in Pango units.

  • y – Y position of left edge of baseline, in user space coordinates in Pango units.

draw_rectangle(part: RenderPart, x: int, y: int, width: int, height: int) → None

Draws an axis-aligned rectangle in user space coordinates with the specified PangoRenderer.

This should be called while renderer is already active. Use activate to activate a renderer.

Added in version 1.8.

Parameters:

  • part – type of object this rectangle is part of

  • x – X position at which to draw rectangle, in user space coordinates in Pango units

  • y – Y position at which to draw rectangle, in user space coordinates in Pango units

  • width – width of rectangle in Pango units

  • height – height of rectangle in Pango units

draw_trapezoid(part: RenderPart, y1_: float, x11: float, x21: float, y2: float, x12: float, x22: float) → None

Draws a trapezoid with the parallel sides aligned with the X axis using the given PangoRenderer; coordinates are in device space.

Added in version 1.8.

Parameters:

  • part – type of object this trapezoid is part of

  • y1 – Y coordinate of top of trapezoid

  • x11 – X coordinate of left end of top of trapezoid

  • x21 – X coordinate of right end of top of trapezoid

  • y2 – Y coordinate of bottom of trapezoid

  • x12 – X coordinate of left end of bottom of trapezoid

  • x22 – X coordinate of right end of bottom of trapezoid

get_alpha(part: RenderPart) → int

Gets the current alpha for the specified part.

Added in version 1.38.

Parameters:

part – the part to get the alpha for

get_color(part: RenderPart) → Color | None

Gets the current rendering color for the specified part.

Added in version 1.8.

Parameters:

part – the part to get the color for

get_layout() → Layout | None

Gets the layout currently being rendered using renderer.

Calling this function only makes sense from inside a subclass’s methods, like in its draw_shape vfunc, for example.

The returned layout should not be modified while still being rendered.

Added in version 1.20.

get_layout_line() → LayoutLine | None

Gets the layout line currently being rendered using renderer.

Calling this function only makes sense from inside a subclass’s methods, like in its draw_shape vfunc, for example.

The returned layout line should not be modified while still being rendered.

Added in version 1.20.

get_matrix() → Matrix | None

Gets the transformation matrix that will be applied when rendering.

See set_matrix.

Added in version 1.8.

part_changed(part: RenderPart) → None

Informs Pango that the way that the rendering is done for part has changed.

This should be called if the rendering changes in a way that would prevent multiple pieces being joined together into one drawing call. For instance, if a subclass of PangoRenderer was to add a stipple option for drawing underlines, it needs to call

pango_renderer_part_changed (render, PANGO_RENDER_PART_UNDERLINE);

When the stipple changes or underlines with different stipples might be joined together. Pango automatically calls this for changes to colors. (See set_color)

Added in version 1.8.

Parameters:

part – the part for which rendering has changed.

set_alpha(part: RenderPart, alpha: int) → None

Sets the alpha for part of the rendering.

Note that the alpha may only be used if a color is specified for part as well.

Added in version 1.38.

Parameters:

  • part – the part to set the alpha for

  • alpha – an alpha value between 1 and 65536, or 0 to unset the alpha

set_color(part: RenderPart, color: Color | None = None) → None

Sets the color for part of the rendering.

Also see set_alpha.

Added in version 1.8.

Parameters:

  • part – the part to change the color of

  • color – the new color or None to unset the current color

set_matrix(matrix: Matrix | None = None) → None

Sets the transformation matrix that will be applied when rendering.

Added in version 1.8.

Parameters:

matrix – a PangoMatrix, or None to unset any existing matrix (No matrix set is the same as setting the identity matrix.)

Virtual Methods

class Renderer
do_begin() → None

Do renderer-specific initialization before drawing

do_draw_error_underline(x: int, y: int, width: int, height: int) → None

Draw a squiggly line that approximately covers the given rectangle in the style of an underline used to indicate a spelling error.

The width of the underline is rounded to an integer number of up/down segments and the resulting rectangle is centered in the original rectangle.

This should be called while renderer is already active. Use activate to activate a renderer.

Added in version 1.8.

Parameters:

  • x – X coordinate of underline, in Pango units in user coordinate system

  • y – Y coordinate of underline, in Pango units in user coordinate system

  • width – width of underline, in Pango units in user coordinate system

  • height – height of underline, in Pango units in user coordinate system

do_draw_glyph(font: Font, glyph: int, x: float, y: float) → None

Draws a single glyph with coordinates in device space.

Added in version 1.8.

Parameters:

  • font – a PangoFont

  • glyph – the glyph index of a single glyph

  • x – X coordinate of left edge of baseline of glyph

  • y – Y coordinate of left edge of baseline of glyph

do_draw_glyph_item(text: str | None, glyph_item: GlyphItem, x: int, y: int) → None

Draws the glyphs in glyph_item with the specified PangoRenderer, embedding the text associated with the glyphs in the output if the output format supports it.

This is useful for rendering text in PDF.

Note that this method does not handle attributes in glyph_item. If you want colors, shapes and lines handled automatically according to those attributes, you need to use draw_layout_line() or draw_layout().

Note that text is the start of the text for layout, which is then indexed by glyph_item->item->offset.

If text is None, this simply calls draw_glyphs.

The default implementation of this method simply falls back to draw_glyphs.

Added in version 1.22.

Parameters:

  • text – the UTF-8 text that glyph_item refers to

  • glyph_item – a PangoGlyphItem

  • x – X position of left edge of baseline, in user space coordinates in Pango units

  • y – Y position of left edge of baseline, in user space coordinates in Pango units

do_draw_glyphs(font: Font, glyphs: GlyphString, x: int, y: int) → None

Draws the glyphs in glyphs with the specified PangoRenderer.

Added in version 1.8.

Parameters:

  • font – a PangoFont

  • glyphs – a PangoGlyphString

  • x – X position of left edge of baseline, in user space coordinates in Pango units.

  • y – Y position of left edge of baseline, in user space coordinates in Pango units.

do_draw_rectangle(part: RenderPart, x: int, y: int, width: int, height: int) → None

Draws an axis-aligned rectangle in user space coordinates with the specified PangoRenderer.

This should be called while renderer is already active. Use activate to activate a renderer.

Added in version 1.8.

Parameters:

  • part – type of object this rectangle is part of

  • x – X position at which to draw rectangle, in user space coordinates in Pango units

  • y – Y position at which to draw rectangle, in user space coordinates in Pango units

  • width – width of rectangle in Pango units

  • height – height of rectangle in Pango units

do_draw_shape(attr: AttrShape, x: int, y: int) → None

draw content for a glyph shaped with PangoAttrShape x, y are the coordinates of the left edge of the baseline, in user coordinates.

Parameters:

  • attr

  • x

  • y

do_draw_trapezoid(part: RenderPart, y1_: float, x11: float, x21: float, y2: float, x12: float, x22: float) → None

Draws a trapezoid with the parallel sides aligned with the X axis using the given PangoRenderer; coordinates are in device space.

Added in version 1.8.

Parameters:

  • part – type of object this trapezoid is part of

  • y1 – Y coordinate of top of trapezoid

  • x11 – X coordinate of left end of top of trapezoid

  • x21 – X coordinate of right end of top of trapezoid

  • y2 – Y coordinate of bottom of trapezoid

  • x12 – X coordinate of left end of bottom of trapezoid

  • x22 – X coordinate of right end of bottom of trapezoid

do_end() → None

Do renderer-specific cleanup after drawing

do_part_changed(part: RenderPart) → None

Informs Pango that the way that the rendering is done for part has changed.

This should be called if the rendering changes in a way that would prevent multiple pieces being joined together into one drawing call. For instance, if a subclass of PangoRenderer was to add a stipple option for drawing underlines, it needs to call

pango_renderer_part_changed (render, PANGO_RENDER_PART_UNDERLINE);

When the stipple changes or underlines with different stipples might be joined together. Pango automatically calls this for changes to colors. (See set_color)

Added in version 1.8.

Parameters:

part – the part for which rendering has changed.

do_prepare_run(run: GlyphItem) → None

updates the renderer for a new run

Parameters:

run

Fields

class Renderer
active_count
matrix

The current transformation matrix for the Renderer; may be None, which should be treated the same as the identity matrix.

parent_instance
priv
strikethrough
underline