| GET_DRAW_VIEW question [message #16132] |
Fri, 02 July 1999 00:00  |
Daniel Peduzzi
Messages: 29
Registered: June 1999
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Junior Member |
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I'm interested in retrieving the viewport position for a scrolling
draw widget via the GET_DRAW_VIEW keyword to WIDGET_CONTROL.
This seems to work well for the case when the viewport size equals
the size of the draw widget (in which case, I don't need the widget
to be scrollable.) But for all other cases when the viewport size
is smaller than the actual widget size, I get the same non-zero offset
of 19 (on an Ultrabook.)
The code below illustrates what I'm seeing. Since GET_DRAW_VIEW
returns the "X and Y position relative to the lower left corner of
the graphics area", I'm converting the Y value so that it is relative
to the top of the draw widget. (I also enabled button events so I had a
way to invoke the "scroll event" procedure for the window with no scroll bars.)
pro scroll_event, event
widget_control, event.id, get_draw_view=view
g = widget_info(event.id,/geometry)
view[1] = g.draw_ysize - view[1] - g.ysize
print,view
end
device, true_color=24, decomposed=0
x = 300
scroll_x = 300
y = 200
scroll_y = 200
; Create a draw widget where the viewport size equals the actual size
drawbase1 = widget_base(title='Viewport = Size')
drawwin1 = widget_draw(drawbase1, /viewport_events, xsize=x, ysize=y, $
x_scroll_size=scroll_x, y_scroll_size=scroll_y, $
event_pro='scroll_event', /button_events)
; Now create a draw widget where the viewport size is LESS than the actual size
scroll_y = 100
drawbase2 = widget_base(title='Viewport < Size')
drawwin2 = widget_draw(drawbase2, /viewport_events, xsize=x, ysize=y, $
x_scroll_size=scroll_x, y_scroll_size=scroll_y, $
event_pro='scroll_event', /button_events)
widget_control, drawbase1, /realize
widget_control, drawbase2, /realize
xmanager, 'window_1', drawbase1, /no_block
xmanager, 'window_2', drawbase2, /no_block
end
Clicking in the first window yields a viewport position of (0,0) as expected.
However, moving the scroll bar of the second window to its topmost position
consistently yields a (0, 19).
Does anyone know why this is the case? Should I simply compensate for this
offset by subtracting 19 from the y position? I'm concerned that this value
may be different on other systems.
Any help is appreciated!
Dan Peduzzi
peduzzi@mediaone.net
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