Q3ScrollView Class Reference
[Qt3Support module]

Details Relevant for All Views

Normally you will use the first or third method if you want any child widgets in the view.

Note that the widget you see in the scrolled area is the viewport() widget, not the Q3ScrollView itself. So to turn mouse tracking on, for example, use viewport()->setMouseTracking(true).

To enable drag-and-drop, you would setAcceptDrops(true) on the Q3ScrollView (because drag-and-drop events propagate to the parent). But to work out the logical position in the view, you would need to map the drop co-ordinate from being relative to the Q3ScrollView to being relative to the contents; use the function viewportToContents() for this.

To handle mouse events on the scrolling area, subclass scrollview as you would subclass other widgets, but rather than reimplementing mousePressEvent(), reimplement contentsMousePressEvent() instead. The contents specific event handlers provide translated events in the coordinate system of the scrollview. If you reimplement mousePressEvent(), you'll get called only when part of the Q3ScrollView is clicked: and the only such part is the "corner" (if you don't set a cornerWidget()) and the frame; everything else is covered up by the viewport, clipper or scroll bars.

When you construct a Q3ScrollView, some of the window flags apply to the viewport() instead of being sent to the QWidget constructor for the Q3ScrollView.

• An image-manipulation widget would use WNoAutoErase|WStaticContents because the widget draws all pixels itself, and when its size increases, it only needs a paint event for the new part because the old part remains unchanged.
• A scrolling game widget in which the background scrolls as the characters move might use WNoAutoErase (in addition to WStaticContents) so that the window system background does not flash in and out during scrolling.
• A word processing widget might use WNoAutoErase and repaint itself line by line to get a less-flickery resizing. If the widget is in a mode in which no text justification can take place, it might use WStaticContents too, so that it would only get a repaint for the newly visible parts.

Child widgets may be moved using addChild() or moveChild(). Use childX() and childY() to get the position of a child widget.

A widget may be placed in the corner between the vertical and horizontal scroll bars with setCornerWidget(). You can get access to the scroll bars using horizontalScrollBar() and verticalScrollBar(), and to the viewport with viewport(). The scroll view can be scrolled using scrollBy(), ensureVisible(), setContentsPos() or center().

The visible area is given by visibleWidth() and visibleHeight(), and the contents area by contentsWidth() and contentsHeight(). The contents may be repainted using one of the repaintContents() or updateContents() functions.

Coordinate conversion is provided by contentsToViewport() and viewportToContents().

The contentsMoving() signal is emitted just before the contents are moved to a new position.

Warning: Q3ScrollView currently does not erase the background when resized, i.e. you must always clear the background manually in scrollview subclasses. This will change in a future version of Qt and we recommend specifying the WNoAutoErase flag explicitly.

Member Type Documentation

 {
     // Fill a 40000 by 50000 rectangle at (100000,150000)

     // Calculate the coordinates...
     int x1 = 100000, y1 = 150000;
     int x2 = x1+40000-1, y2 = y1+50000-1;

     // Clip the coordinates so X/Windows will not have problems...
     if (x1 < clipx) x1=clipx;
     if (y1 < clipy) y1=clipy;
     if (x2 > clipx+clipw-1) x2=clipx+clipw-1;
     if (y2 > clipy+cliph-1) y2=clipy+cliph-1;

     // Paint using the small coordinates...
     if (x2 >= x1 && y2 >= y1)
         p->fillRect(x1, y1, x2-x1+1, y2-y1+1, red);
 }