ScrollWindow function (winuser.h)

The ScrollWindow function scrolls the contents of the specified window’s client area.

Syntax

Parameters

Handle to the window where the client area is to be scrolled.

Specifies the amount, in device units, of horizontal scrolling. If the window being scrolled has the CS_OWNDC or CS_CLASSDC style, then this parameter uses logical units rather than device units. This parameter must be a negative value to scroll the content of the window to the left.

Specifies the amount, in device units, of vertical scrolling. If the window being scrolled has the CS_OWNDC or CS_CLASSDC style, then this parameter uses logical units rather than device units. This parameter must be a negative value to scroll the content of the window up.

Pointer to the RECT structure specifying the portion of the client area to be scrolled. If this parameter is NULL, the entire client area is scrolled.

Pointer to the RECT structure containing the coordinates of the clipping rectangle. Only device bits within the clipping rectangle are affected. Bits scrolled from the outside of the rectangle to the inside are painted; bits scrolled from the inside of the rectangle to the outside are not painted.

Return value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

If the caret is in the window being scrolled, ScrollWindow automatically hides the caret to prevent it from being erased and then restores the caret after the scrolling is finished. The caret position is adjusted accordingly.

The area uncovered by ScrollWindow is not repainted, but it is combined into the window’s update region. The application eventually receives a WM_PAINT message notifying it that the region must be repainted. To repaint the uncovered area at the same time the scrolling is in action, call the UpdateWindow function immediately after calling ScrollWindow.

If the lpRect parameter is NULL, the positions of any child windows in the window are offset by the amount specified by the XAmount and YAmount parameters; invalid (unpainted) areas in the window are also offset. ScrollWindow is faster when lpRect is NULL.

If lpRect is not NULL, the positions of child windows are not changed and invalid areas in the window are not offset. To prevent updating problems when lpRect is not NULL, call UpdateWindow to repaint the window before calling ScrollWindow.

ScrollWindowEx function (winuser.h)

The ScrollWindowEx function scrolls the contents of the specified window’s client area.

Syntax

Parameters

Handle to the window where the client area is to be scrolled.

Specifies the amount, in device units, of horizontal scrolling. This parameter must be a negative value to scroll to the left.

Specifies the amount, in device units, of vertical scrolling. This parameter must be a negative value to scroll up.

Pointer to a RECT structure that specifies the portion of the client area to be scrolled. If this parameter is NULL, the entire client area is scrolled.

Pointer to a RECT structure that contains the coordinates of the clipping rectangle. Only device bits within the clipping rectangle are affected. Bits scrolled from the outside of the rectangle to the inside are painted; bits scrolled from the inside of the rectangle to the outside are not painted. This parameter may be NULL.

Handle to the region that is modified to hold the region invalidated by scrolling. This parameter may be NULL.

Pointer to a RECT structure that receives the boundaries of the rectangle invalidated by scrolling. This parameter may be NULL.

Specifies flags that control scrolling. This parameter can be a combination of the following values.

Value	Meaning
SW_ERASE	Erases the newly invalidated region by sending a WM_ERASEBKGND message to the window when specified with the SW_INVALIDATE flag.
SW_INVALIDATE	Invalidates the region identified by the hrgnUpdate parameter after scrolling.
SW_SCROLLCHILDREN	Scrolls all child windows that intersect the rectangle pointed to by the prcScroll parameter. The child windows are scrolled by the number of pixels specified by the dx and dy parameters. The system sends a WM_MOVE message to all child windows that intersect the prcScroll rectangle, even if they do not move.
SW_SMOOTHSCROLL	Scrolls using smooth scrolling. Use the HIWORD portion of the flags parameter to indicate how much time, in milliseconds, the smooth-scrolling operation should take.

Return value

If the function succeeds, the return value is SIMPLEREGION (rectangular invalidated region), COMPLEXREGION (nonrectangular invalidated region; overlapping rectangles), or NULLREGION (no invalidated region).

If the function fails, the return value is ERROR. To get extended error information, call GetLastError.

Remarks

If the SW_INVALIDATE and SW_ERASE flags are not specified, ScrollWindowEx does not invalidate the area that is scrolled from. If either of these flags is set, ScrollWindowEx invalidates this area. The area is not updated until the application calls the UpdateWindow function, calls the RedrawWindow function (specifying the RDW_UPDATENOW or RDW_ERASENOW flag), or retrieves the WM_PAINT message from the application queue.

If the window has the WS_CLIPCHILDREN style, the returned areas specified by hrgnUpdate and prcUpdate represent the total area of the scrolled window that must be updated, including any areas in child windows that need updating.

If the SW_SCROLLCHILDREN flag is specified, the system does not properly update the screen if part of a child window is scrolled. The part of the scrolled child window that lies outside the source rectangle is not erased and is not properly redrawn in its new destination. To move child windows that do not lie completely within the rectangle specified by prcScroll, use the DeferWindowPos function. The cursor is repositioned if the SW_SCROLLCHILDREN flag is set and the caret rectangle intersects the scroll rectangle.

All input and output coordinates (for prcScroll, prcClip, prcUpdate, and hrgnUpdate) are determined as client coordinates, regardless of whether the window has the CS_OWNDC or CS_CLASSDC class style. Use the LPtoDP and DPtoLP functions to convert to and from logical coordinates, if necessary.

Win32 API: How to scroll down automatically a text inside EDIT control?

I have an EDIT control created like this:

As you can see it is a read-only EDIT area where multi lines text can be displayed. It is supposed to be a console where I can display some information for users when they use the program. I would like the text area to automatically scroll to the bottom-most entry (the newest one) whenever a new line (or message for an user) is added. I’ve implemented this:

That code is scrolling vertical scrollbar to the end of an EDIT control after adding new msg and it works great, the scrollbar gets scrolled but the text still remains visible from the beginning — it rewinds to the beginning after addition while scrollbar rewinds to the bottom. How to make it properly?

Last but not least — this is might be important — in order to display a message firstly I capture the text that is already displayed by using: GetDlgItemText ( h2, ID_EDIT_CONSOLE, buf, len + 1 ); then I convert buf into string and add to that string a new message that I want to display. Then I convert it back to char array and set it up with SetDlgItemText. I seperate lines by using \r\n. I’ve coded it that way because I didn’t know how to add a line to an EDIT control in different way than using SetDlgItemText. And it adds only one entry AFAIK — if used twice I will not come up with two entries added to an EDIT control, but the first one will get replaced by second function call.