q3canvas.cpp

奇趣公司比较新的qt/emd版本

    \i Canvas items are usually much faster to manipulate and redraw than
    child widgets, with the speed advantage becoming especially great when
    there are \e many canvas items and non-rectangular items. In most
    situations canvas items are also a lot more memory efficient than child
    widgets.

    \i It's easy to detect overlapping items (collision detection).

    \i The canvas can be larger than a widget. A million-by-million canvas
    is perfectly possible. At such a size a widget might be very
    inefficient, and some window systems might not support it at all,
    whereas Q3Canvas scales well. Even with a billion pixels and a million
    items, finding a particular canvas item, detecting collisions, etc.,
    is still fast (though the memory consumption may be prohibitive
    at such extremes).

    \i Two or more Q3CanvasView objects can view the same canvas.

    \i An arbitrary transformation matrix can be set on each Q3CanvasView
    which makes it easy to zoom, rotate or shear the viewed canvas.

    \i Widgets provide a lot more functionality, such as input (QKeyEvent,
    QMouseEvent etc.) and layout management (QGridLayout etc.).

    \endlist

    A canvas consists of a background, a number of canvas items organized by
    x, y and z coordinates, and a foreground. A canvas item's z coordinate
    can be treated as a layer number -- canvas items with a higher z
    coordinate appear in front of canvas items with a lower z coordinate.

    The background is white by default, but can be set to a different color
    using setBackgroundColor(), or to a repeated pixmap using
    setBackgroundPixmap() or to a mosaic of smaller pixmaps using
    setTiles(). Individual tiles can be set with setTile(). There
    are corresponding get functions, e.g. backgroundColor() and
    backgroundPixmap().

    Note that Q3Canvas does not inherit from QWidget, even though it has some
    functions which provide the same functionality as those in QWidget. One
    of these is setBackgroundPixmap(); some others are resize(), size(),
    width() and height(). \l Q3CanvasView is the widget used to display a
    canvas on the screen.

    Canvas items are added to a canvas by constructing them and passing the
    canvas to the canvas item's constructor. An item can be moved to a
    different canvas using Q3CanvasItem::setCanvas().

    Canvas items are movable (and in the case of Q3CanvasSprites, animated)
    objects that inherit Q3CanvasItem. Each canvas item has a position on the
    canvas (x, y coordinates) and a height (z coordinate), all of which are
    held as floating-point numbers. Moving canvas items also have x and y
    velocities. It's possible for a canvas item to be outside the canvas
    (for example Q3CanvasItem::x() is greater than width()). When a canvas
    item is off the canvas, onCanvas() returns false and the canvas
    disregards the item. (Canvas items off the canvas do not slow down any
    of the common operations on the canvas.)

    Canvas items can be moved with Q3CanvasItem::move(). The advance()
    function moves all Q3CanvasItem::animated() canvas items and
    setAdvancePeriod() makes Q3Canvas move them automatically on a periodic
    basis. In the context of the Q3Canvas classes, to `animate' a canvas item
    is to set it in motion, i.e. using Q3CanvasItem::setVelocity(). Animation
    of a canvas item itself, i.e. items which change over time, is enabled
    by calling Q3CanvasSprite::setFrameAnimation(), or more generally by
    subclassing and reimplementing Q3CanvasItem::advance(). To detect collisions
    use one of the Q3CanvasItem::collisions() functions.

    The changed parts of the canvas are redrawn (if they are visible in a
    canvas view) whenever update() is called. You can either call update()
    manually after having changed the contents of the canvas, or force
    periodic updates using setUpdatePeriod(). If you have moving objects on
    the canvas, you must call advance() every time the objects should
    move one step further. Periodic calls to advance() can be forced using
    setAdvancePeriod(). The advance() function will call
    Q3CanvasItem::advance() on every item that is \link
    Q3CanvasItem::animated() animated\endlink and trigger an update of the
    affected areas afterwards. (A canvas item that is `animated' is simply
    a canvas item that is in motion.)

    Q3Canvas organizes its canvas items into \e chunks; these are areas on
    the canvas that are used to speed up most operations. Many operations
    start by eliminating most chunks (i.e. those which haven't changed)
    and then process only the canvas items that are in the few interesting
    (i.e. changed) chunks. A valid chunk, validChunk(), is one which is on
    the canvas.

    The chunk size is a key factor to Q3Canvas's speed: if there are too many
    chunks, the speed benefit of grouping canvas items into chunks is
    reduced. If the chunks are too large, it takes too long to process each
    one. The Q3Canvas constructor tries to pick a suitable size, but you
    can call retune() to change it at any time. The chunkSize() function
    returns the current chunk size. The canvas items always make sure
    they're in the right chunks; all you need to make sure of is that
    the canvas uses the right chunk size. A good rule of thumb is that
    the size should be a bit smaller than the average canvas item
    size. If you have moving objects, the chunk size should be a bit
    smaller than the average size of the moving items.

    The foreground is normally nothing, but if you reimplement
    drawForeground(), you can draw things in front of all the canvas
    items.

    Areas can be set as changed with setChanged() and set unchanged with
    setUnchanged(). The entire canvas can be set as changed with
    setAllChanged(). A list of all the items on the canvas is returned by
    allItems().

    An area can be copied (painted) to a QPainter with drawArea().

    If the canvas is resized it emits the resized() signal.

    The examples/canvas application and the 2D graphics page of the
    examples/demo application demonstrate many of Q3Canvas's facilities.

    \sa Q3CanvasView Q3CanvasItem, QtCanvas, {Porting to Graphics View}
*/
void Q3Canvas::init(int w, int h, int chunksze, int mxclusters)
{
    d = new Q3CanvasData;
    awidth=w;
    aheight=h;
    chunksize=chunksze;
    maxclusters=mxclusters;
    chwidth=(w+chunksize-1)/chunksize;
    chheight=(h+chunksize-1)/chunksize;
    chunks=new Q3CanvasChunk[chwidth*chheight];
    update_timer = 0;
    bgcolor = white;
    grid = 0;
    htiles = 0;
    vtiles = 0;
    dblbuf = false;
    debug_redraw_areas = false;
}

/*!
    Create a Q3Canvas with no size. \a parent and \a name are passed to
    the QObject superclass.

    \warning You \e must call resize() at some time after creation to
    be able to use the canvas.
*/
Q3Canvas::Q3Canvas(QObject* parent, const char* name)
    : QObject(parent, name)
{
    init(0,0);
}

/*!
    Constructs a Q3Canvas that is \a w pixels wide and \a h pixels high.
*/
Q3Canvas::Q3Canvas(int w, int h)
{
    init(w,h);
}

/*!
    Constructs a Q3Canvas which will be composed of \a h tiles
    horizontally and \a v tiles vertically. Each tile will be an image
    \a tilewidth by \a tileheight pixels taken from pixmap \a p.

    The pixmap \a p is a list of tiles, arranged left to right, (and
    in the case of pixmaps that have multiple rows of tiles, top to
    bottom), with tile 0 in the top-left corner, tile 1 next to the
    right, and so on, e.g.

    \table
    \row \i 0 \i 1 \i 2 \i 3
    \row \i 4 \i 5 \i 6 \i 7
    \endtable

    The Q3Canvas is initially sized to show exactly the given number of
    tiles horizontally and vertically. If it is resized to be larger,
    the entire matrix of tiles will be repeated as often as necessary
    to cover the area. If it is smaller, tiles to the right and bottom
    will not be visible.

    \sa setTiles()
*/
Q3Canvas::Q3Canvas(QPixmap p,
	int h, int v, int tilewidth, int tileheight)
{
    init(h*tilewidth, v*tileheight, scm(tilewidth,tileheight));
    setTiles(p, h, v, tilewidth, tileheight);
}

void qt_unview(Q3Canvas* c)
{
    for (Q3CanvasView* view=c->d->viewList.first(); view != 0; view=c->d->viewList.next()) {
	view->viewing = 0;
    }
}

/*!
    Destroys the canvas and all the canvas's canvas items.
*/
Q3Canvas::~Q3Canvas()
{
    qt_unview(this);
    Q3CanvasItemList all = allItems();
    for (Q3CanvasItemList::Iterator it=all.begin(); it!=all.end(); ++it)
	delete *it;
    delete [] chunks;
    delete [] grid;
    delete d;
}

/*!
\internal
Returns the chunk at a chunk position \a i, \a j.
*/
Q3CanvasChunk& Q3Canvas::chunk(int i, int j) const
{
    return chunks[i+chwidth*j];
}

/*!
\internal
Returns the chunk at a pixel position \a x, \a y.
*/
Q3CanvasChunk& Q3Canvas::chunkContaining(int x, int y) const
{
    return chunk(x/chunksize,y/chunksize);
}

/*!
    Returns a list of all the items in the canvas.
*/
Q3CanvasItemList Q3Canvas::allItems()
{
    Q3CanvasItemList list;
    for (Q3PtrDictIterator<void> it=d->itemDict; it.currentKey(); ++it) {
	list.prepend((Q3CanvasItem*)it.currentKey());
    }
    return list;
}


/*!
    Changes the size of the canvas to have a width of \a w and a
    height of \a h. This is a slow operation.
*/
void Q3Canvas::resize(int w, int h)
{
    if (awidth==w && aheight==h)
	return;

    Q3CanvasItem* item;
    Q3PtrList<Q3CanvasItem> hidden;
    for (Q3PtrDictIterator<void> it=d->itemDict; it.currentKey(); ++it) {
	if (((Q3CanvasItem*)it.currentKey())->isVisible()) {
	    ((Q3CanvasItem*)it.currentKey())->hide();
	    hidden.append(((Q3CanvasItem*)it.currentKey()));
	}
    }

    int nchwidth=(w+chunksize-1)/chunksize;
    int nchheight=(h+chunksize-1)/chunksize;

    Q3CanvasChunk* newchunks = new Q3CanvasChunk[nchwidth*nchheight];

    // Commit the new values.
    //
    awidth=w;
    aheight=h;
    chwidth=nchwidth;
    chheight=nchheight;
    delete [] chunks;
    chunks=newchunks;

    for (item=hidden.first(); item != 0; item=hidden.next()) {
	item->show();
    }

    setAllChanged();

    emit resized();
}

/*!
    \fn void Q3Canvas::resized()

    This signal is emitted whenever the canvas is resized. Each
    Q3CanvasView connects to this signal to keep the scrollview's size
    correct.
*/

/*!
    Change the efficiency tuning parameters to \a mxclusters clusters,
    each of size \a chunksze. This is a slow operation if there are
    many objects on the canvas.

    The canvas is divided into chunks which are rectangular areas \a
    chunksze wide by \a chunksze high. Use a chunk size which is about
    the average size of the canvas items. If you choose a chunk size
    which is too small it will increase the amount of calculation
    required when drawing since each change will affect many chunks.
    If you choose a chunk size which is too large the amount of
    drawing required will increase because for each change, a lot of
    drawing will be required since there will be many (unchanged)
    canvas items which are in the same chunk as the changed canvas
    items.

    Internally, a canvas uses a low-resolution "chunk matrix" to keep
    track of all the items in the canvas. A 64x64 chunk matrix is the
    default for a 1024x1024 pixel canvas, where each chunk collects
    canvas items in a 16x16 pixel square. This default is also
    affected by setTiles(). You can tune this default using this
    function. For example if you have a very large canvas and want to
    trade off speed for memory then you might set the chunk size to 32
    or 64.

    The \a mxclusters argument is the number of rectangular groups of
    chunks that will be separately drawn. If the canvas has a large
    number of small, dispersed items, this should be about that
    number. Our testing suggests that a large number of clusters is
    almost always best.

*/
void Q3Canvas::retune(int chunksze, int mxclusters)
{
    maxclusters=mxclusters;

    if (chunksize!=chunksze) {
	Q3PtrList<Q3CanvasItem> hidden;
	for (Q3PtrDictIterator<void> it=d->itemDict; it.currentKey(); ++it) {
	    if (((Q3CanvasItem*)it.currentKey())->isVisible()) {
		((Q3CanvasItem*)it.currentKey())->hide();
		hidden.append(((Q3CanvasItem*)it.currentKey()));
	    }
	}

	chunksize=chunksze;

	int nchwidth=(awidth+chunksize-1)/chunksize;
	int nchheight=(aheight+chunksize-1)/chunksize;

	Q3CanvasChunk* newchunks = new Q3CanvasChunk[nchwidth*nchheight];

	// Commit the new values.
	//
	chwidth=nchwidth;
	chheight=nchheight;
	delete [] chunks;
	chunks=newchunks;

	for (Q3CanvasItem* item=hidden.first(); item != 0; item=hidden.next()) {
	    item->show();
	}
    }
}

/*!
    \fn int Q3Canvas::width() const

    Returns the width of the canvas, in pixels.
*/

/*!
    \fn int Q3Canvas::height() const

    Returns the height of the canvas, in pixels.
*/

/*!
    \fn QSize Q3Canvas::size() const

    Returns the size of the canvas, in pixels.
*/

/*!
    \fn QRect Q3Canvas::rect() const

    Returns a rectangle the size of the canvas.
*/


/*!
    \fn bool Q3Canvas::onCanvas(int x, int y) const

    Returns true if the pixel position (\a x, \a y) is on the canvas;
    otherwise returns false.

    \sa validChunk()
*/

/*!
    \fn bool Q3Canvas::onCanvas(const QPoint& p) const
    \overload

    Returns true if the pixel position \a p is on the canvas;
    otherwise returns false.

    \sa validChunk()
*/

/*!
    \fn bool Q3Canvas::validChunk(int x, int y) const

    Returns true if the chunk position (\a x, \a y) is on the canvas;
    otherwise returns false.

    \sa onCanvas()
*/

/*!
  \fn bool Q3Canvas::validChunk(const QPoint& p) const
  \overload

  Returns true if the chunk position \a p is on the canvas; otherwise
  returns false.

  \sa onCanvas()
*/

/*!
    \fn int Q3Canvas::chunkSize() const

    Returns the chunk size of the canvas.

    \sa retune()
*/

/*!
\fn bool Q3Canvas::sameChunk(int x1, int y1, int x2, int y2) const
\internal
Tells if the points (\a x1, \a y1) and (\a x2, \a y2) are within the same chunk.
*/

/*!
\internal
This method adds an the item \a item to the list of Q3CanvasItem objects
in the Q3Canvas. The Q3CanvasItem class calls this.
*/
void Q3Canvas::addItem(Q3CanvasItem* item)
{
    d->itemDict.insert((void*)item,(void*)1);
}

/*!
\internal
This method adds the item \a item to the list of Q3CanvasItem objects
to be moved. The Q3CanvasItem class calls this.
*/
void Q3Canvas::addAnimation(Q3CanvasItem* item)
{
    d->animDict.insert((void*)item,(void*)1);
}

/*!
\internal
This method adds the item \a item  to the list of Q3CanvasItem objects
which are no longer to be moved. The Q3CanvasItem class calls this.
*/
void Q3Canvas::removeAnimation(Q3CanvasItem* item)
{
    d->animDict.remove((void*)item);
}

/*!
\internal
This method removes the item \a item from the list of Q3CanvasItem objects
in this Q3Canvas. The Q3CanvasItem class calls this.
*/
void Q3Canvas::removeItem(Q3CanvasItem* item)
{
    d->itemDict.remove((void*)item);
}

/*!
\internal
This method adds the view \a view to the list of Q3CanvasView objects
viewing this Q3Canvas. The Q3CanvasView class calls this.
*/
void Q3Canvas::addView(Q3CanvasView* view)
{
    d->viewList.append(view);
    if (htiles>1 || vtiles>1 || pm.isNull())
	view->viewport()->setBackgroundColor(backgroundColor());
}

/*!