Class: Pango::Renderer

Inherits:

Object

• Object
• Pango::Renderer

Defined in:

(unknown)

Overview

Class structure for Pango::Renderer.

The following vfuncs take user space coordinates in Pango units and have default implementations:

• draw_glyphs

• draw_rectangle

• draw_error_underline

• draw_shape

• draw_glyph_item

The default draw_shape implementation draws nothing.

The following vfuncs take device space coordinates as doubles and must be implemented:

• draw_trapezoid

• draw_glyph

Instance Method Summary

• #activate ⇒ nil

  Does initial setup before rendering operations on renderer.

• #deactivate ⇒ nil

  Cleans up after rendering operations on renderer.

• #draw_error_underline(x, y, width, height) ⇒ nil

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

• #draw_glyph(font, glyph, x, y) ⇒ nil

  Draws a single glyph with coordinates in device space.

• #draw_glyph_item(text, glyph_item, x, y) ⇒ nil

  Draws the glyphs in glyph_item with the specified Pango::Renderer, embedding the text associated with the glyphs in the output if the output format supports it (PDF for example).

• #draw_glyphs(font, glyphs, x, y) ⇒ nil

  Draws the glyphs in glyphs with the specified Pango::Renderer.

• #draw_layout(layout, x, y) ⇒ nil

  Draws layout with the specified Pango::Renderer.

• #draw_layout_line(line, x, y) ⇒ nil

  Draws line with the specified Pango::Renderer.

• #draw_rectangle(part, x, y, width, height) ⇒ nil

  Draws an axis-aligned rectangle in user space coordinates with the specified Pango::Renderer.

• #draw_trapezoid(part, y1_, x11, x21, y2, x12, x22) ⇒ nil

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

• #get_alpha(part) ⇒ Integer

  Gets the current alpha for the specified part.

• #get_color(part) ⇒ Pango::Color

  Gets the current rendering color for the specified part.

• #layout ⇒ Pango::Layout

  Gets the layout currently being rendered using renderer.

• #layout_line ⇒ Pango::LayoutLine

  Gets the layout line currently being rendered using renderer.

• #matrix ⇒ Pango::Matrix

  Gets the transformation matrix that will be applied when rendering.

• #matrix=(matrix) ⇒ nil

  Sets the transformation matrix that will be applied when rendering.

• #part_changed(part) ⇒ nil

  Informs Pango that the way that the rendering is done for part has changed in a way that would prevent multiple pieces being joined together into one drawing call.

• #set_alpha(part, alpha) ⇒ nil

  Sets the alpha for part of the rendering.

• #set_color(part, color) ⇒ nil

  Sets the color for part of the rendering.

Instance Method Details

#activate ⇒ nil

Does initial setup before rendering operations on renderer. pango_renderer_deactivate() should be called when done drawing. Calls such as pango_renderer_draw_layout() automatically activate the layout before drawing on it. Calls to pango_renderer_activate() and pango_renderer_deactivate() can be nested and the renderer will only be initialized and deinitialized once.

Returns:

• (nil)

#deactivate ⇒ nil

Cleans up after rendering operations on renderer. See docs for pango_renderer_activate().

Returns:

• (nil)

#draw_error_underline(x, y, width, height) ⇒ nil

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 pango_renderer_activate() to activate a renderer.

Parameters:

• x (Integer) —

  X coordinate of underline, in Pango units in user coordinate system

• y (Integer) —

  Y coordinate of underline, in Pango units in user coordinate system

• width (Integer) —

  width of underline, in Pango units in user coordinate system

• height (Integer) —

  height of underline, in Pango units in user coordinate system

Returns:

• (nil)

#draw_glyph(font, glyph, x, y) ⇒ nil

Draws a single glyph with coordinates in device space.

Parameters:

• font (Pango::Font) —

  a Pango::Font

• glyph (Pango::Glyph) —

  the glyph index of a single glyph

• x (Float) —

  X coordinate of left edge of baseline of glyph

• y (Float) —

  Y coordinate of left edge of baseline of glyph

Returns:

• (nil)

#draw_glyph_item(text, glyph_item, x, y) ⇒ nil

Draws the glyphs in glyph_item with the specified Pango::Renderer, embedding the text associated with the glyphs in the output if the output format supports it (PDF for example).

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

If text is nil, this simply calls pango_renderer_draw_glyphs().

The default implementation of this method simply falls back to pango_renderer_draw_glyphs().

Parameters:

• text (String) —

  the UTF-8 text that glyph_item refers to, or nil

• glyph_item (Pango::GlyphItem) —

  a Pango::GlyphItem

• x (Integer) —

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

• y (Integer) —

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

Returns:

• (nil)

#draw_glyphs(font, glyphs, x, y) ⇒ nil

Draws the glyphs in glyphs with the specified Pango::Renderer.

Parameters:

• font (Pango::Font) —

  a Pango::Font

• glyphs (Pango::GlyphString) —

  a Pango::GlyphString

• x (Integer) —

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

• y (Integer) —

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

Returns:

• (nil)

#draw_layout(layout, x, y) ⇒ nil

Draws layout with the specified Pango::Renderer.

Parameters:

• layout (Pango::Layout) —

  a Pango::Layout

• x (Integer) —

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

• y (Integer) —

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

Returns:

• (nil)

#draw_layout_line(line, x, y) ⇒ nil

Draws line with the specified Pango::Renderer.

Parameters:

• line (Pango::LayoutLine) —

  a Pango::LayoutLine

• x (Integer) —

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

• y (Integer) —

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

Returns:

• (nil)

#draw_rectangle(part, x, y, width, height) ⇒ nil

Draws an axis-aligned rectangle in user space coordinates with the specified Pango::Renderer.

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

Parameters:

• part (Pango::RenderPart) —

  type of object this rectangle is part of

• x (Integer) —

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

• y (Integer) —

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

• width (Integer) —

  width of rectangle in Pango units in user space coordinates

• height (Integer) —

  height of rectangle in Pango units in user space coordinates

Returns:

• (nil)

#draw_trapezoid(part, y1_, x11, x21, y2, x12, x22) ⇒ nil

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

Parameters:

• part (Pango::RenderPart) —

  type of object this trapezoid is part of

• y1_ (Float) —

  Y coordinate of top of trapezoid

• x11 (Float) —

  X coordinate of left end of top of trapezoid

• x21 (Float) —

  X coordinate of right end of top of trapezoid

• y2 (Float) —

  Y coordinate of bottom of trapezoid

• x12 (Float) —

  X coordinate of left end of bottom of trapezoid

• x22 (Float) —

  X coordinate of right end of bottom of trapezoid

Returns:

• (nil)

#get_alpha(part) ⇒ Integer

Gets the current alpha for the specified part.

Parameters:

• part (Pango::RenderPart) —

  the part to get the alpha for

Returns:

• (Integer) —

  the alpha for the specified part, or 0 if it hasn’t been set and should be inherited from the environment.

#get_color(part) ⇒ Pango::Color

Gets the current rendering color for the specified part.

Parameters:

• part (Pango::RenderPart) —

  the part to get the color for

Returns:

• (Pango::Color) —

  the color for the specified part, or nil if it hasn’t been set and should be inherited from the environment.

#layout ⇒ Pango::Layout

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.

Returns:

• (Pango::Layout) —

  the layout, or nil if no layout is being rendered using renderer at this time.

#layout_line ⇒ Pango::LayoutLine

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.

Returns:

• (Pango::LayoutLine) —

  the layout line, or nil if no layout line is being rendered using renderer at this time.

#matrix ⇒ Pango::Matrix

Gets the transformation matrix that will be applied when rendering. See pango_renderer_set_matrix().

Returns:

• (Pango::Matrix) —

  the matrix, or nil if no matrix has been set (which is the same as the identity matrix). The returned matrix is owned by Pango and must not be modified or freed.

#matrix=(matrix) ⇒ nil

Sets the transformation matrix that will be applied when rendering.

Parameters:

• matrix (Pango::Matrix) —

  a Pango::Matrix, or nil to unset any existing matrix. (No matrix set is the same as setting the identity matrix.)

Returns:

• (nil)

#part_changed(part) ⇒ nil

Informs Pango that the way that the rendering is done for part has changed in a way that would prevent multiple pieces being joined together into one drawing call. For instance, if a subclass of Pango::Renderer was to add a stipple option for drawing underlines, it needs to call

<informalexample><programlisting> pango_renderer_part_changed (render, PANGO_RENDER_PART_UNDERLINE); </programlisting></informalexample>

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

Parameters:

• part (Pango::RenderPart) —

  the part for which rendering has changed.

Returns:

• (nil)

#set_alpha(part, alpha) ⇒ nil

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.

Parameters:

• part (Pango::RenderPart) —

  the part to set the alpha for

• alpha (Integer) —

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

Returns:

• (nil)

#set_color(part, color) ⇒ nil

Sets the color for part of the rendering. Also see pango_renderer_set_alpha().

Parameters:

• part (Pango::RenderPart) —

  the part to change the color of

• color (Pango::Color) —

  the new color or nil to unset the current color

Returns:

• (nil)