Re: [Foxgui-users]Scrolling wave view

[Davy D. <dd...@ne...>]

ohOHoh... It all makes sense now... I was looking at FXScrollBox's implementations of
getContentWidth/Height methods and trying to figure out HOW-IN-THE-WORLD just returning 1
did any good.... I was like... is this thing just not useful yet?
It didn't even cross my mind to override these....

Thanks...  This is my initial reaction to reading your mail... I may have more questions...
but this helps a lot....



jeroen wrote:

> You're on the right track using FXScrollArea for this; it supports auto-scrolling,
> i.e. when you get near the edge it starts to scroll (the speed is proportional
> to the closeness to the edge).
>
> FXScrollArea is meant as a base class.  At the very least, you should implement:
>
>   virtual FXint getContentWidth();
>   virtual FXint getContentHeight();
>
> These two will measure the content size (in your case this may depend on the zoom
> factor) and return that. Note, sometimes the content size must be obtained via
> painful amount of computation (e.g. iterating over all wave samples and measuring
> the peaks so as to determine vertical size).  In that case it is customary to
> keep member variables representing the computed size and return that, and only
> recompute them when there is reason to believe content may have changed.
>
>   long onPaint(FXObject*,FXSelector,void*);
>
> Of course, this should paint the waveform. Note that the content is offset by
> pos_x and pos_y.  These numbers are negative!
>
>   long onLeftBtnPress(FXObject*,FXSelector,void*);
>
> Initiate selection operation.
>
>   long onLeftBtnRelease(FXObject*,FXSelector,void*);
>
> End selection operation.
>
>   long onRightBtnPress(FXObject*,FXSelector,void*);
>
> Start right-mouse scroll.
>
>   long onRightBtnRelease(FXObject*,FXSelector,void*);
>
> End right mouse scroll; if we didn't move the mouse, then this may also popup
> a context menu.
>
>   long onMotion(FXObject*,FXSelector,void*);
>
> If we were right-mouse scrolling, call setPosition() to adjust the scroll position
> accordingly.
>
> If we were selecting, call startAutoScroll().  This tests if we're close to the
> edge.  If startAutoScroll() returns TRUE then simply return.  Otherwise, we're
> not close to the edge and you should process the mouse coords to select the
> appropriate audio samples.
>
>   long onAutoScroll(FXObject*,FXSelector,void*);
>
> This handler is a kind-of mouse moved message issued while the mouse is more-or-less
> standing still near an edge. The implementation should call FXScrollArea::onAutoScroll()
> then perform similar code as in onMotion() to select audio samples.
>
> If you're not scrolling ALL of the content, you may have to implement
>
>   virtual void moveContents(FXint x,FXint y);
>
> To BLIT the fragment that *is* scrolled. For example some tick marks on the
> left or right will probably not be scrolled (see FXTable for an extreme case).
>
> In some cases, a widget needs to update some info when its resized; in this case
> you will re-implement:
>
>   virtual void layout();
>
> The implementation should call FXScrollArea::layout() to place the scrollbars.
> You can perform some extra stuff before or after.
>
> This may look a bit complex, but I think if you look at FXList and FXImageView,
> you'll see that your code will be very similar to that.  FXScrollArea does a
> lot already (placing scrollbars, based on the viewport and content size, and
> the autoscrolling timer management.
>
> ===
>
> If you want to go all-out, you can extend this with clipboard, drag-and-drop,
> selection support.  This will allow cut-and-paste between FXWaveView and other
> WAV aware applications (provided the mime-types match).
>
> Good luck.
>
>                 Jeroen
>
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