gdkPangoRendererNew(screen)
gdkPangoRendererGetDefault(screen)
gdkPangoRendererSetDrawable(object, drawable = NULL)
gdkPangoRendererSetGc(object, gc = NULL)
gdkPangoRendererSetStipple(object, part, stipple)
gdkPangoRendererSetOverrideColor(object, part, color = NULL)
gdkPangoContextGet()
gdkPangoContextGetForScreen(screen)
gdkPangoContextSetColormap(context, colormap)
gdkPangoAttrEmbossedNew(embossed)
gdkPangoAttrStippleNew(stipple)
gdkPangoLayoutGetClipRegion(layout, x.origin, index.ranges)
gdkPangoLayoutLineGetClipRegion(line, x.origin, index.ranges)
gdkPangoRenderer(screen)PangoLayout object is the first step in rendering text,
and requires getting a handle to a PangoContext. For GTK+ programs,
you'll usually want to use gtkWidgetGetPangoContext, or
gtkWidgetCreatePangoLayout, rather than using the lowlevel
gdkPangoContextGetForScreen. Once you have a PangoLayout, you
can set the text and attributes of it with Pango functions like
pangoLayoutSetText and get its size with pangoLayoutGetSize.
(Note that Pango uses a fixed point system internally, so converting
between Pango units and pixels using PANGO_SCALE or the pangoPixels() function.)
Rendering a Pango layout is done most simply with gdkDrawLayout;
you can also draw pieces of the layout with gdkDrawLayout or
gdkDrawGlyphs. GdkPangoRenderer is a subclass of PangoRenderer
that is used internally to implement these functions. Using it
directly or subclassing it can be useful in some cases. See the
GdkPangoRenderer documentation for details.
window <- NULLRADIUS <- 150 N.WORDS <- 10 FONT <- "Sans Bold 27"
rotated.text.expose.event <- function(widget, event, data) {
# matrix describing font transformation, initialize to identity matrix <- pangoMatrixInit()
width <- widget[["allocation"]][["width"]] height <- widget[["allocation"]][["height"]]
# Get the default renderer for the screen, and set it up for drawing renderer <- gdkPangoRendererGetDefault(widget$getScreen()) renderer$setDrawable(widget[["window"]]) renderer$setGc(widget[["style"]][["blackGc"]])
# Set up a transformation matrix so that the user space coordinates for # the centered square where we draw are [-RADIUS, RADIUS], [-RADIUS, RADIUS] # We first center, then change the scale device.radius <- min(width, height) / 2. matrix$translate(device.radius + (width - 2 * device.radius) / 2, device.radius + (height - 2 * device.radius) / 2) matrix$scale(device.radius / RADIUS, device.radius / RADIUS)
# Create a PangoLayout, set the font and text context <- widget$createPangoContext() layout <- pangoLayoutNew(context) layout$setText("Text") desc <- pangoFontDescriptionFromString(FONT) layout$setFontDescription(desc)
# Draw the layout N.WORDS times in a circle for (i in 1:N.WORDS) { rotated.matrix <- matrix$copy() angle <- (360 * i) / N.WORDS
color <- list() # Gradient from red at angle 60 to blue at angle 300 color$red <- 65535 * (1 + cos((angle - 60) * pi / 180)) / 2 color$green <- 0 color$blue <- 65535 - color$red
renderer$setOverrideColor("foreground", color)
rotated.matrix$rotate(angle)
context$setMatrix(rotated.matrix)
# Inform Pango to re-layout the text with the new transformation matrix layout$contextChanged()
size <- layout$getSize() renderer$drawLayout(layout, - size$width / 2, - RADIUS * 1024) }
# Clean up default renderer, since it is shared renderer$setOverrideColor("foreground", NULL) renderer$setDrawable(NULL) renderer$setGc(NULL)
return(FALSE) }
white <- c( 0, "0xffff", "0xffff", "0xffff" )
window <- gtkWindowNew("toplevel") window$setTitle("Rotated Text") drawing.area <- gtkDrawingAreaNew() window$add(drawing.area)
# This overrides the background color from the theme drawing.area$modifyBg("normal", white)
gSignalConnect(drawing.area, "expose-event", rotated.text.expose.event)
window$setDefaultSize(2 * RADIUS, 2 * RADIUS)
window$showAll() Output of
gdkPangoRenderer is the equivalent of gdkPangoRendererNew.