I have a component extending a Spark List, and when I scroll using the mouse wheel it scrolls too much in one go. I have tried looking for the handler that deals with mouse wheel scrolling in the List class and VerticalLayout class to override but I cannot find it.
Is there another way I'm supposed to change this, or am I missing something?
The "delta" property of MouseEvent.MOUSE_WHEEL defines how many lines will be scrolled by one wheel-scrolling. You could try changing it in the MOUSE_WHEEL handler (during capture phase). For example the following code will scroll line-by-line:
protected function init(event:FlexEvent):void
{
list.addEventListener(MouseEvent.MOUSE_WHEEL, list_mouseWheelHandler, true);
}
protected function list_mouseWheelHandler(event:MouseEvent):void
{
event.delta = event.delta > 0 ? 1 : -1;
}
The "horizontalLineScrollSize" and "verticalLineScrollSize" properties determine how many pixels to scroll when the user selects the scroll bar arrows. The "verticalLineScrollSize" property also controls the amount of scrolling when using the "mouse wheel". The default value is 5 pixels.
The "horizontalPageScrollSize" and "verticalPageScrollSize" properties determine how many pixels to scroll when the user selects the "scroll bar track". The default value is 20 pixels.
More details: http://livedocs.adobe.com/flex/3/html/help.html?content=containers_intro_4.html
Related
I've creates a "touch-list" component for EmberJS, based on ember-collection, with ember-gestures mixed in:
import RecognizerMixin from 'ember-gestures/mixins/recognizers';
export default Ember.Component.extend(RecognizerMixin, {
recognizers: 'tap press swipe',
...
swipeLeft(event) {
...
event.preventDefault();
event.stopPropagation();
},
...
My test app has two panels, one for the list and the other for item details. (Slighly out-of-date source code is on GitHub.) On a screen 640px or wider, the container for the panels is set to the viewport width, and all is well - horizontal swipes are recognized, and don't trigger scrolling.
On a screen 639px or narrower, I set the container to twice the viewport width, and each panel to the viewport width. Horizontal swipes on the list header or detail panel scroll, as expected.
The problem is horizontal swipes on list items on touchscreen devices. They are recognized as gestures, and handled by list items, but they also cause horizontal scrolling! As seen above, I call event.preventDefault(); and event.stopPropagation(); but that doesn't help.
How can I prevent swipes from causing horizontal scrolling?
My solution was to change the layout so horizontal scrolling never happens. Now, the horizontal movement of the panels is implemented using transform: translateX(-100%);
I have thusly advanced to a new level of confusion:
How do I set a class on a parent element when a route is the first one loaded?
I have a QTextEdit widget with a vertical scroll bar.
report_text = new QTextEdit();
report_text->setAcceptRichText(true);
report_text->setReadOnly(true);
report_text->setTextInteractionFlags(Qt::NoTextInteraction);
report_text->setAlignment(Qt::AlignTop);
report_text->setWordWrapMode(QTextOption::NoWrap);
report_text->setFrameStyle(QFrame::NoFrame);
report_text->setMinimumSize(600, 380);
report_text->setSizePolicy(QSizePolicy::MinimumExpanding, QSizePolicy::Preferred);
This is Qt 4.8 embedded.
Now I need a method or an event I can send to the widget to make it it scroll up or down just as if the up or down buttons on the scroll bar had been pressed.
I tried the scroll() method, but I scrolls the whole widget, including the scroll bar.
I also tried sending a QWheelEvent, but nothing happens.
QWheelEvent ev(QPoint(), 10, 0, 0);
report_text->setFocus();
QApplication::sendEvent(report_text, &ev);
What am I missing?
It is probable that the delta you provided is just way too small.
From the documentation of QWheelEvent::delta():
Returns the distance that the wheel is rotated, in eighths of a
degree. A positive value indicates that the wheel was rotated forwards
away from the user; a negative value indicates that the wheel was
rotated backwards toward the user.
Most mouse types work in steps of 15 degrees, in which case the delta
value is a multiple of 120; i.e., 120 units * 1/8 = 15 degrees.
The text scrolling in Qt unit is the number of whole line. So if the widget computes that you want to scroll 0.9 lines, he might do nothing.
So try again with
QWheelEvent ev(QPoint(), 120, 0, 0);
Note: Nothing here apply to an event with control or shift modifier.
Here is what I found as a suitable solution:
The vertical scrollbar may be accessed using the QTextEdit::verticalScrollBar() method.
Scrollbars have a triggerAction() method to conveniently simulate user interaction with the buttons and the slider. The available actions are defined in QAbstractSlider.
So the resulting code is only a single line:
report_text->verticalScrollBar()->triggerAction(QAbstractSlider::SliderSingleStepAdd);
Interestingly, this works even when the scrollbar is hidden with
report_text->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
I got a multiple selection CListBox with horizontal scroll bar enabled and showed correctly. Problem is, that when I use function
lst.ResetContent() and fill it back, I can't find way to scroll text in the rows back to the same position. I tried to use
lst.SetScrollPos(SB_HORZ, horizScroll, TRUE); , where horizScroll = lst.GetScrollPos(SB_HORZ); This works correctly on scroll bar itself, but
text in the row stays not scrolled (manual scrolling functions OK).
Structure of my program is:
CListBox lst;
int horizScroll;
/*Periodically doing code bellow*/
//Get current scroll position
horizScroll = lst.GetScrollPos(SB_HORZ);
//Reset current content
lst.ResetContent();
//Add item into CListBox (UNICODE in my application)
lst.AddString(L"Some longer text then width of CListBox");
//Calculate horizontal extent and set it through
lst.SetHorizontalExtent(calculatedWidth);
//Try to scroll text (scrolls only scroll bar, not text itself)
lst.SetScrollPos(SB_HORZ, horizScroll, TRUE);
UpdateData(FALSE);
Thanks in advance!
EDIT:
As "rrirower" answered correctly,
lst.PostMessage(WM_HSCROLL, MAKEWPARAM(SB_THUMBPOSITION, 250), 0);
message does the job. Scroll position from horizScroll works perfectly. I suggest posting this message twice, because if you do it only once, text is re-scrolled visually from beginning to the wanted position. When you post it twice, text visually stays at the correct position and scroll bar just quickly comes to the right place.
If I understand you correctly, you're trying to scroll the text in the list box horizontally using the program code. If you use Spy++, you'll see that when you manually scroll, using the mouse, a series of WM_HSCROLL messages is posted to the list box control. You can accomplish the same thing by doing this...
lst.PostMessage(WM_HSCROLL, MAKEWPARAM(SB_THUMBPOSITION, 250), 0);
You need to calculate the position (I used 250 above), but, the above code should move the text and the scroll bar horizontally.
After some reading it seems that Invalidate should do the trick. Since as I understand you have one text line this should be fine, however if the painting itself is complex and requires resources you can use ScrollWindowEx and then InvalidateRect on the rectangle returned by the latter to repaint only the changed area.
I have a window inherited from CScrollView that handles WM_PAINT and displays a graph. This graph has elements of different types and type of element is marked by the shape of element.
I want to display some legend so that user knows what each shape means. Since user will not look at this legend often the idea is that in the upper right corner of the view control there will be a small icon. When user moves the mouse over this icon it will expand into small rectangle displaying the legend of shapes used in graph. When mouse is moved outside this rectangle it will collapse back to small icon.
This is what I have tried so far:
Draw the hotspot icon and legend rectangle using GDI in handler of WM_PAINT of view class.
Implement hotspot as a separate window that is created as a child of a scroll view.
Implement hotspot as a separate window but create it as a popup window with no parent.
Version 1 and 2 behave strangely if user scrolls the graph view.
In version 1 I can see artifacts (button is smeared across the view) while performing scroll I guess that during the scroll existing image is not invalidated but only moved.
In version 2 there is no smearing but I need to move the child window whenever I get VM_HSCROLL and WM_VSCROLL messages and these messages are not precise enough to be used this way. During scroll I can see my button moving couple of pixels and then jumping to correct position.
Version 3 is the most disturbing and because legend is not child of a graph view I get some strange behaviour where legend button is displayed even when graph view is not shown and I think that there are too many problems with this one to be viable development path to invest time in.
I think that the version 2 is the most promising but I need to find a way to make a child window stay at one place during scroll.
Did anyone have success in implementing something like this? Is there some other implementation I can investigate?
CScrollView has OnScrollBy virtual method that scrolls the entire client area of view control. You can override this method and implement your own scroll functionality.
::ScrollWindowEx has a parameter prcScroll that can specify only a portion of client area that will be scrolled.
New OnScrollBy splits client area into 4 stripes and calls ::ScrollWindowEx for each one of them.
These stripes are:
client area above icon (rectangle width across entire client area)
client area on the left of icon (rectangle height same as icon)
client area on the right of icon (rectangle height same as icon)
client area underneath icon (rectangle width across entire client area)
1 1 1 1 1
2 2 2 * 3
4 4 4 4 4
4 4 4 4 4
After scrolling all individual client rectangles, just invalidate client area where icon is located.
You may just simply use
CPoint GetScrollPosition( ) const;
method to obtain current scroll position of scroll view and recalculate your 'static' label offset accordingly.
BTW: Instead of WM_PAINT use CScrollView's method
virtual void OnDraw( CDC* pDC );
it's important
I have a member of CWnd class name mywindow
and i want to add to it a scroll-bar.
how i can do it?
i try already to do:
mywindow.EnableScrollBarCtrl(SB_BOTH,TRUE);
it display both Horizontal and Vertical scroll-bars,
but i cannot push the buttons or move the scroll-bars.
i try also after the first command:
mywindow.EnableScrollBar(SB_BOTH,ESB_ENABLE_BOTH);
and it change nothing.
can someone could show me a simple example how to add scroll-bar to this member?
thanks a lot,
Tal
Enabling the scroll bars isn't enough. You have to react to the window messages WM_HSCROLLand WM_VSCROLL. Using the GetScrollInfo method you get the position (value) of the scroll bars and then you draw your window content according to this position.
Look up some scroll bar tutorials such as http://www.codeproject.com/KB/dialog/scrolling_support.aspx . In essence, dwo's comment above is what you need to do - handle those messages and set the virtual client area size.
There must be some 'overflow' before scroll bars became active.
Write some 'sufficiently long' data in your view and the scrollbars will become active (at least, that was my experience time ago).
Usually scroll bars get handled 'automatically' from MFC components like (for instance) text editor or form view. I.e. will became visible when needed also without explicit call EnableScrollBarCtrl ...