Re:how to define scroll bar's page size value?
A page size value is whatever you want it to be. In your WM_HSCROLL or WM_VSCROLL
handlers you increment or decrement the value by whatever you feel like. For example, for
a "page" you might increment or decrement by the GetClientRect() values Width() or
Height() values appropriately. Or half of them. Or 3/4 of them. Or whatever.
The thumb size, which is the thumb size, has nothing to do with the amount of space you
will scroll on a page-up/down or page-left/right operation. Instead, it is the amount of
the range that is visible.
So if you have a window 200 pixels high, and you have an image 800 pixels high, you might
set the scroll range to be 0..600 (that's 0..(picture size - client height)). You would
set the nPage value to 200. This would give a wide thumb position. It would *not* change
the amount you scroll in a WM_HSCROLL/WM_VSCROLL handler when a page request comes in. It
just shows the amount of the image being shown.
joe
On 10 Jan 2007 00:33:43 -0800, "Purusothaman A" <
Purusothaman.A@gmail.com>wrote:
Quote
Hi all,
I have a confusion about calculating scroll bar's page size.
In my application, I am drawing an image according to scroll bar
position.
m_iGeneratedImgWidth - Width size of the image (this value is always
bigger)
rect.right - Width of the drawing area.
how to define scroll bar's page size value?
SCROLLINFO info;
info.cbSize = sizeof(SCROLLINFO);
info.fMask = SIF_RANGE|SIF_PAGE|SIF_POS;
info.nPos = 0;
info.nMin = 0;
info.nMax = m_iGeneratedImgWidth - rect.right;
info.nPage = ?
In my OnHScrollBar() function, for SB_PAGELEFT / SB_PAGERIGHT codes, I
subtract/add 10 for displaying image.
I want to set correct value, because this is the only way to change
size of the tracking thumb of scroll bar control.
:)
Purusothaman A
Joseph M. Newcomer [MVP]
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