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require 'Qt'
class Hello < Qt::Widget
signals 'clicked()'
slots 'animate()'
# Constructs a Hello widget. Starts a 40 ms animation timer
def initialize (text)
super()
@b = 0
@text = text
@sin_tbl = [0, 38, 71, 92, 100, 92, 71, 38, 0, -38, -71, -92, -100, -92, -71, -38]
timer = Qt::Timer.new(self);
connect(timer, SIGNAL('timeout()'), SLOT('animate()'))
timer.start(40);
resize(260, 130)
end
# This slot is called each time the timer fires.
def animate
@b = (@b + 1) & 15
repaint(false)
end
# Handles mouse button release events for the Hello widget.
#
# We emit the clicked() signal when the mouse is released inside
# the widget.
def mouseReleaseEvent(e)
if (rect.contains(e.pos))
emit clicked
end
end
# Handles paint events for the Hello widget.
#
# Flicker-free update. The text is first drawn in the pixmap and the
# pixmap is then blt'ed to the screen.
def paintEvent(e)
if @text.empty?
return
end
# 1: Compute some sizes, positions etc.
fm = fontMetrics
w = fm.width(@text) + 20
h = fm.height * 2
pmx = width/2 - w/2
pmy = height/2 - h/2
# 2: Create the pixmap and fill it with the widget's background
pm = Qt::Pixmap.new(w, h)
pm.fill(self, pmx, pmy)
# 3: Paint the pixmap. Cool wave effect
p = Qt::Painter.new;
x = 10
y = h/2 + fm.descent
i = 0
p.begin(pm)
p.setFont(font)
for i in 0..@text.size-1
j = (@b+i) & 15
p.setPen(Qt::Color.new((15-j)*16,255,255,Qt::Color.Hsv) )
p.drawText( x, y-@sin_tbl[j]*h/800, @text[i,1], 1 )
x += fm.width(@text[i,1])
end
p.end
#4: Copy the pixmap to the Hello widget
bitBlt(self, pmx, pmy, pm)
end
end
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