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[Gtk2hs-commit] (main branch): Tutorial_Port: The Layout Container (Chapter 6.3)
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From: Duncan C. <dun...@wo...> - 2007-11-10 18:17:58
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Fri Nov 9 07:29:40 PST 2007 hth...@zo...
* Tutorial_Port: The Layout Container (Chapter 6.3)
addfile ./docs/tutorial/Tutorial_Port/Example_Code/GtkChap6-3.hs
hunk ./docs/tutorial/Tutorial_Port/Example_Code/GtkChap6-3.hs 1
+import Graphics.UI.Gtk
+
+main :: IO ()
+main = do
+ initGUI
+ window <- windowNew
+ set window [windowTitle := "Alphabet" , windowDefaultWidth := 350,
+ windowDefaultHeight := 350 , containerBorderWidth := 10]
+ sw <- scrolledWindowNew Nothing Nothing
+ set sw [scrolledWindowPlacement := CornerBottomRight, [_$_]
+ scrolledWindowShadowType := ShadowEtchedIn,
+ scrolledWindowHscrollbarPolicy := PolicyAutomatic,
+ scrolledWindowVscrollbarPolicy := PolicyAutomatic ]
+ containerAdd window sw
+
+ layt <- layoutNew Nothing Nothing
+ layoutSetSize layt myLayoutWidth myLayoutHeight
+ widgetModifyBg layt StateNormal (Color 65535 65535 65535)
+ containerAdd sw layt [_$_]
+ [_$_]
+ upleft <- labelNew (Just "[_\e2_][_\80_][_\a1_](0,0)")
+ layoutPut layt upleft 0 0
+ upright <- labelNew (Just ("[_\e2_][_\80_][_\a1_](" ++ (show (myLayoutWidth - 50)) ++",0)"))
+ layoutPut layt upright (myLayoutWidth -50) 0
+ dwnright <- labelNew (Just ("[_\e2_][_\80_][_\a1_](0," ++ (show (myLayoutHeight -20)) ++ ")"))
+ layoutPut layt dwnright 0 (myLayoutHeight -20)
+ dwnleft <- labelNew (Just ("[_\e2_][_\80_][_\a1_](" ++ (show(myLayoutWidth -70)) ++ "," ++
+ (show (myLayoutHeight -20)) ++ ")"))
+ layoutPut layt dwnleft (myLayoutWidth -70) (myLayoutHeight - 20)
+ [_$_]
+ labels <- sequence $ map (labelNew . Just) txtls
+ sequence_ $ map (\x -> widgetModifyFg x StateNormal (Color 0 0 45000)) labels
+ [_$_]
+ let wnums = zip labels [0..]
+ sequence_ $ map (myLayoutPut layt) wnums [_$_]
+
+ widgetShowAll window
+ onDestroy window mainQuit
+ mainGUI
+
+-- parameters
+myLayoutWidth :: Int
+myLayoutWidth = 800
+
+myLayoutHeight :: Int
+myLayoutHeight = 800
+
+txtls :: [String]
+txtls = map (\x -> x:[]) ['A'..'Z']
+-- end parameters
+
+step :: Double
+step = (2 * pi)/(fromIntegral (length txtls))
+
+ox :: Int
+ox = myLayoutWidth `div` 2
+
+oy :: Int
+oy = myLayoutHeight `div` 2
+
+radius :: Double
+radius = 0.25 * (fromIntegral ox)
+
+angle :: Int -> Double
+angle num = 1.5 * pi + (fromIntegral num) * step
+
+num2x :: Int -> Int
+num2x n = ox + relx where [_$_]
+ relx = round $ radius * (cos (angle n))
+
+num2y :: Int -> Int
+num2y n = oy + rely where
+ rely = round $ radius * (sin (angle n))
+
+myLayoutPut :: Layout -> (Label, Int) -> IO ()
+myLayoutPut lt (lb, n) = do [_$_]
+ layoutPut lt lb (num2x n) (num2y n) [_$_]
+ labelSetAngle lb (letterAngle n)
+
+letterAngle :: Int -> Double
+letterAngle n = (270 - degree) where
+ degree = (angle n) * (180.0 /pi)
addfile ./docs/tutorial/Tutorial_Port/Images/GtkChap6-3.png
binary ./docs/tutorial/Tutorial_Port/Images/GtkChap6-3.png
hunk ./docs/tutorial/Tutorial_Port/chap6-2.xhtml 21
- <a href="chap6-2.xhtml">Next</a>
+ <a href="chap6-3.xhtml">Next</a>
hunk ./docs/tutorial/Tutorial_Port/chap6-2.xhtml 258
- <br />6.3</span>
+ <br />The Layout Container</span>
addfile ./docs/tutorial/Tutorial_Port/chap6-3.xhtml
hunk ./docs/tutorial/Tutorial_Port/chap6-3.xhtml 1
+<?xml version="1.0" encoding="utf-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
+ "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+ <head>
+ <meta http-equiv="Content-Type"
+ content="text/html; charset=utf-8" />
+ <title>Gtk2Hs Tutorial: The Layout Container</title>
+ <link href="default.css" type="text/css" rel="stylesheet" />
+ </head>
+ <body>
+ <div id="header">
+ <h1>Gtk2Hs Tutorial</h1>
+ <span class="nav-previous">
+ <a href="chap6-2.xhtml">Previous</a>
+ </span>
+ <span class="nav-home">
+ <a href="index.xhtml">Home</a>
+ </span>
+ <span class="nav-next">
+ <a href="chap6-4.xhtml">Next</a>
+ </span>
+ </div>
+ <h2>6.3 The Layout Container</h2>
+ <p>Until now packing of widgets has been done either through
+ sequencing in horizontal or vertical boxes, or in a table. You
+ can, however, also place widgets in any position you like,
+ using a [_$_]
+ <code>Fixed</code> or a [_$_]
+ <code>Layout</code> widget. Use of the [_$_]
+ <code>Fixed</code> container is not recommended, because it does
+ not resize well.</p>
+ <p>The Layout container is similar to the Fixed container
+ except that it implements an infinite (where infinity is less
+ than 2^32) scrolling area. The X window system has a limitation
+ where windows can be at most 32767 pixels wide or tall. The
+ Layout container gets around this by doing some
+ exotic stuff using window and bit gravities, so that you can
+ have smooth scrolling even when you have many child widgets in
+ your scrolling area. Since it is used in a scrolled window, the
+ disadvantages of the [_$_]
+ <code>Fixed</code> widget do not apply.</p>
+ <p>A Layout container is created using:</p>
+ <pre class="codebox">layoutNew :: Maybe Adjustment -> Maybe Adjustment -> IO Layout
+</pre>
+ <p>As you can see, you can optionally specify the Adjustment
+ objects that the Layout widget will use for its scrolling.</p>
+ <p>You can add and move widgets in the Layout container using
+ the following two functions:</p>
+ <pre class="codebox">layoutPut :: (LayoutClass self, WidgetClass childWidget)
+=> self -> childWidget -> Int -> Int -> IO ()
+layoutMove :: (LayoutClass self, WidgetClass childWidget)
+=> self -> childWidget -> Int -> Int -> IO () [_$_]
+</pre>
+ <p>The first argument is the x position, the second the y
+ position. The top left is (0,0), x grows from left to right,
+ and y from top to bottom.</p>
+ <p>The size of the [_$_]
+ <code>Layout</code> container can be set using the next
+ function:</p>
+ <pre class="codebox">layoutSetSize :: LayoutClass self => self -> Int -> Int -> IO ()
+</pre>
+ <p>The first argument is the width of the entire scrollable
+ area, the second the height.</p>
+ <p>In the example we place a list of labels, each with an upper
+ case letter of the alphabet, in a circle around a chosen
+ centre. The labels are positioned perpendicular to the radius
+ using the Gtk2Hs function:</p>
+ <pre class="codebox">labelSetAngle :: labelClass self => self -> Double -> IO ()
+</pre>
+ <p>The angle is in degrees, measured counterclockwise.</p>
+ <img src="Images/GtkChap6-3.png" alt="Alphabet"
+ id="imgGtkChap6-3" />
+ <p>The layout widget is placed into a scrolled window with [_$_]
+ <code>containerAdd</code> because it is scrollable, and so does
+ not need a view port, as in Chapter 6.1. The labels are
+ positioned using angular coordinates, which are then
+ transformed into Cartesian coordinates with the Prelude [_$_]
+ <code>sin</code> and [_$_]
+ <code>cos</code> functions. These take radians as their
+ arguments (between 0 and (2 * pi)). Width and Height in the
+ example are parametrized, as is the list to be displayed.
+ Furthermore, in [_$_]
+ <code>main</code> the corners of the [_$_]
+ <code>Layout</code> are marked, so you can easily experiment with its
+ size, if you want. Note that the actual marker has been replaced with '+' here, because
+ the validator complained.</p>
+ <pre class="codebox">import Graphics.UI.Gtk
+
+main :: IO ()
+main = do
+ initGUI
+ window <- windowNew
+ set window [windowTitle := "Alphabet" , windowDefaultWidth := 350,
+ windowDefaultHeight := 350 , containerBorderWidth := 10]
+ sw <- scrolledWindowNew Nothing Nothing
+ set sw [scrolledWindowPlacement := CornerBottomRight, [_$_]
+ scrolledWindowShadowType := ShadowEtchedIn,
+ scrolledWindowHscrollbarPolicy := PolicyAutomatic,
+ scrolledWindowVscrollbarPolicy := PolicyAutomatic ]
+ containerAdd window sw
+
+ layt <- layoutNew Nothing Nothing
+ layoutSetSize layt myLayoutWidth myLayoutHeight
+ widgetModifyBg layt StateNormal (Color 65535 65535 65535)
+ containerAdd sw layt [_$_]
+ [_$_]
+ upleft <- labelNew (Just "+(0,0)")
+ layoutPut layt upleft 0 0
+ upright <- labelNew (Just ("+(" ++ (show (myLayoutWidth - 50)) ++",0)"))
+ layoutPut layt upright (myLayoutWidth -50) 0
+ dwnright <- labelNew (Just ("+(0," ++ (show (myLayoutHeight -20)) ++ ")"))
+ layoutPut layt dwnright 0 (myLayoutHeight -20)
+ dwnleft <- labelNew (Just ("+(" ++ (show(myLayoutWidth -70)) ++ "," ++
+ (show (myLayoutHeight -20)) ++ ")"))
+ layoutPut layt dwnleft (myLayoutWidth -70) (myLayoutHeight - 20)
+ [_$_]
+ labels <- sequence $ map (labelNew . Just) txtls
+ sequence_ $ map (\x -> widgetModifyFg x StateNormal (Color 0 0 45000)) labels
+ [_$_]
+ let wnums = zip labels [0..]
+ sequence_ $ map (myLayoutPut layt) wnums [_$_]
+
+ widgetShowAll window
+ onDestroy window mainQuit
+ mainGUI
+
+-- parameters
+myLayoutWidth :: Int
+myLayoutWidth = 800
+
+myLayoutHeight :: Int
+myLayoutHeight = 800
+
+txtls :: [String]
+txtls = map (\x -> x:[]) ['A'..'Z']
+-- end parameters
+
+step :: Double
+step = (2 * pi)/(fromIntegral (length txtls))
+
+ox :: Int
+ox = myLayoutWidth `div` 2
+
+oy :: Int
+oy = myLayoutHeight `div` 2
+
+radius :: Double
+radius = 0.25 * (fromIntegral ox)
+
+angle :: Int -> Double
+angle num = 1.5 * pi + (fromIntegral num) * step
+
+num2x :: Int -> Int
+num2x n = ox + relx where [_$_]
+ relx = round $ radius * (cos (angle n))
+
+num2y :: Int -> Int
+num2y n = oy + rely where
+ rely = round $ radius * (sin (angle n))
+
+myLayoutPut :: Layout -> (Label, Int) -> IO ()
+myLayoutPut lt (lb, n) = do [_$_]
+ layoutPut lt lb (num2x n) (num2y n) [_$_]
+ labelSetAngle lb (letterAngle n)
+
+letterAngle :: Int -> Double
+letterAngle n = (270 - degree) where
+ degree = (angle n) * (180.0 /pi)
+</pre>
+ <div id="footer">
+ <span class="nav-previous">
+ <a href="chap6-1.xhtml">Previous</a>
+ <br />6.2 Event Boxes and Button Boxes</span>
+ <span class="nav-home">
+ <a href="index.xhtml">Home</a>
+ </span>
+ <span class="nav-next">
+ <a href="chap6-4.xhtml">Next</a>
+ <br />6.4</span>
+ </div>
+ </body>
+</html>
hunk ./docs/tutorial/Tutorial_Port/index.xhtml 98
+ <li>
+ <a href="chap6-3.xhtml">6.3 The Layout Container</a>
+ </li> [_$_]
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