diff options
Diffstat (limited to 'doc/man/man3/qcanvas.3qt')
| -rw-r--r-- | doc/man/man3/qcanvas.3qt | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/doc/man/man3/qcanvas.3qt b/doc/man/man3/qcanvas.3qt index eade4e78e..4067e90b4 100644 --- a/doc/man/man3/qcanvas.3qt +++ b/doc/man/man3/qcanvas.3qt @@ -240,7 +240,7 @@ Destroys the canvas and all the canvas's canvas items. .SH "void QCanvas::advance ()\fC [virtual slot]\fR" Moves all QCanvasItem::animated() canvas items on the canvas and refreshes all changes to all views of the canvas. (An `animated' item is an item that is in motion; see setVelocity().) .PP -The advance takes place in two phases. In phase 0, the QCanvasItem::advance() function of each QCanvasItem::animated() canvas item is called with paramater 0. Then all these canvas items are called again, with parameter 1. In phase 0, the canvas items should not change position, merely examine other items on the canvas for which special processing is retquired, such as collisions between items. In phase 1, all canvas items should change positions, ignoring any other items on the canvas. This two-phase approach allows for considerations of "fairness", although no QCanvasItem subclasses supplied with Qt do anything interesting in phase 0. +The advance takes place in two phases. In phase 0, the QCanvasItem::advance() function of each QCanvasItem::animated() canvas item is called with paramater 0. Then all these canvas items are called again, with parameter 1. In phase 0, the canvas items should not change position, merely examine other items on the canvas for which special processing is required, such as collisions between items. In phase 1, all canvas items should change positions, ignoring any other items on the canvas. This two-phase approach allows for considerations of "fairness", although no QCanvasItem subclasses supplied with Qt do anything interesting in phase 0. .PP The canvas can be configured to call this function periodically with setAdvancePeriod(). .PP @@ -331,7 +331,7 @@ This signal is emitted whenever the canvas is resized. Each QCanvasView connects .SH "void QCanvas::retune ( int chunksze, int mxclusters = 100 )\fC [virtual]\fR" Change the efficiency tuning parameters to \fImxclusters\fR clusters, each of size \fIchunksze\fR. This is a slow operation if there are many objects on the canvas. .PP -The canvas is divided into chunks which are rectangular areas \fIchunksze\fR wide by \fIchunksze\fR 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 retquired when drawing since each change will affect many chunks. If you choose a chunk size which is too large the amount of drawing retquired will increase because for each change, a lot of drawing will be retquired since there will be many (unchanged) canvas items which are in the same chunk as the changed canvas items. +The canvas is divided into chunks which are rectangular areas \fIchunksze\fR wide by \fIchunksze\fR 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. .PP 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. .PP |