Drawing text on GTK's DrawingArea in Haskell
I have a DrawingArea
onto which I can draw using primitives such as drawRectangle
and drawLine
. How do I draw text onto that area? I'm most interested in something that quickly outputs a single line of text.
Graphics.UI.Gtk.Gdk.Drawable.layoutLine
seems to be what I want, but it wants a Graphics.Rendering.Pango.Layout.LayoutLine
as input. How do I construct that LayoutLine
?
Are there better alternatives th开发者_开发问答an doing it this way?
Thanks!
I don't know if you would consider using Cairo. If so, I think the function showText
may be what you are looking for. Use the cairo function moveTo
to move to a specific location before writing the text. This is one of the simplest working examples I can produce:
import Graphics.UI.Gtk
import Graphics.Rendering.Cairo
main :: IO ()
main = do
initGUI
window <- windowNew
drawingArea <- drawingAreaNew
containerAdd window drawingArea
drawingArea `onExpose` (\_ -> renderScene drawingArea)
window `onDestroy` mainQuit
windowSetDefaultSize window 640 480
widgetShowAll window
mainGUI
renderScene :: DrawingArea -> IO Bool
renderScene da = do
dw <- widgetGetDrawWindow da
renderWithDrawable dw $ do setSourceRGBA 0.5 0.5 0.5 1.0
moveTo 100.0 100.0
showText "HelloWorld"
return True
I found the following to be an excellent guide, even though it was not for Haskell: http://zetcode.com/tutorials/cairographicstutorial/cairotext/
I've found the way to do this with Pango.
layout <- widgetCreateLayout drawAreaWidget stringToDraw
Then you can use this newly-created layout with functions such as drawLayout
and drawLayoutWithColors
.
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