diff options
Diffstat (limited to 'examples/widgets/doc/src')
| -rw-r--r-- | examples/widgets/doc/src/collidingmice-example.qdoc | 54 |
1 files changed, 26 insertions, 28 deletions
diff --git a/examples/widgets/doc/src/collidingmice-example.qdoc b/examples/widgets/doc/src/collidingmice-example.qdoc index 09503b4b9a..563f76c1b7 100644 --- a/examples/widgets/doc/src/collidingmice-example.qdoc +++ b/examples/widgets/doc/src/collidingmice-example.qdoc @@ -48,7 +48,7 @@ application window. We will first review the \c Mouse class to see how to animate - items and detect item collision, and then we will review the \c + items and detect item collisions, and then we will review the \c main() function to see how to put the items into a scene and how to implement the corresponding view. @@ -90,7 +90,7 @@ calling the item's \l {QGraphicsItem::setRotation()}{setRotation()} function we alter the direction in which the mouse will start moving. - When the QGraphicsScene decides to advance the scene a frame it will + When the QGraphicsScene decides to advance the scene by a frame, it will call QGraphicsItem::advance() on each of the items. This enables us to animate our mouse using our reimplementation of the advance() function. @@ -98,10 +98,10 @@ \snippet graphicsview/collidingmice/mouse.cpp 5 \snippet graphicsview/collidingmice/mouse.cpp 6 - First, we don't bother doing any advance if the step is 0 since we want to our advance in - the actual advance (advance() is called twice, once with step == 0 indicating that items - are about to advance and with step == 1 for the actual advance). We also ensure that the - mice stays within a circle with a radius of 150 pixels. + First, we don't bother doing any advance if the step is \c 0. This is because + advance() is called twice: once with step == \c 0, indicating that items + are about to advance, and then with step == \c 1 for the actual advance. + We also ensure that the mouse stays within a circle with a radius of 150 pixels. Note the \l {QGraphicsItem::mapFromScene()}{mapFromScene()} function provided by QGraphicsItem. This function maps a position @@ -126,7 +126,7 @@ the parent's coordinate system. For items with no parent, the given position is interpreted as scene coordinates. QGraphicsItem also provides a \l {QGraphicsItem::}{mapToParent()} function to - map a position given in item coordinates, to the parent's + map a position given in item coordinates to the parent's coordinate system. If the item has no parent, the position will be mapped to the scene's coordinate system instead. @@ -140,7 +140,7 @@ defines the outer bounds of the item as a rectangle. Note that the Graphics View framework uses the bounding rectangle to determine whether the item requires redrawing, so all painting must be - restricted inside this rectangle. + done inside this rectangle. \snippet graphicsview/collidingmice/mouse.cpp 3 @@ -148,7 +148,7 @@ {QGraphicsItem::paint()}{paint()} function to paint the contents of the item; the function paints the item in local coordinates. - Note the painting of the ears: Whenever a mouse item collides with + Note the painting of the ears: whenever a mouse item collides with other mice items its ears are filled with red; otherwise they are filled with dark yellow. We use the QGraphicsScene::collidingItems() function to check if there are @@ -166,17 +166,15 @@ {QGraphicsItem::collidesWithItem()}{collidesWithItem()} function to provide your own custom item and shape collision algorithm. - This completes the \c Mouse class implementation, it is now ready + This completes the \c Mouse class implementation; it is now ready for use. Let's take a look at the \c main() function to see how to implement a scene for the mice and a view for displaying the contents of the scene. \section1 The Main() Function - In this example we have chosen to let the \c main() function - provide the main application window, creating the items and the - scene, putting the items into the scene and creating a - corresponding view. + The \c main() function provides the main application window, + as well as creating the items, their scene, and a corresponding view. \snippet graphicsview/collidingmice/main.cpp 0 @@ -192,18 +190,18 @@ The QGraphicsScene class serves as a container for QGraphicsItems. It also provides functionality that lets you efficiently determine the location of items as well as determining - which items that are visible within an arbitrary area on the + which items are visible within an arbitrary area on the scene. When creating a scene it is recommended to set the scene's - rectangle, i.e., the rectangle that defines the extent of the + rectangle; the rectangle that defines the extent of the scene. It is primarily used by QGraphicsView to determine the view's default scrollable area, and by QGraphicsScene to manage item indexing. If not explicitly set, the scene's default rectangle will be the largest bounding rectangle of all the items - on the scene since the scene was created (i.e., the rectangle will - grow when items are added or moved in the scene, but it will never - shrink). + on the scene since the scene was created. This means that the + rectangle will grow when items are added or moved in the scene, + but it will never shrink. \snippet graphicsview/collidingmice/main.cpp 2 @@ -213,8 +211,8 @@ searched. Adding, moving and removing items, however, is done in constant time. This approach is ideal for dynamic scenes, where many items are added, moved or removed continuously. The - alternative is \l {QGraphicsScene::BspTreeIndex}{BspTreeIndex} - which makes use of binary search resulting in item location + alternative is \l {QGraphicsScene::BspTreeIndex}{BspTreeIndex}, + which makes use of a binary search to achieve item location algorithms that are of an order closer to logarithmic complexity. \snippet graphicsview/collidingmice/main.cpp 3 @@ -223,9 +221,9 @@ \snippet graphicsview/collidingmice/main.cpp 4 - To be able to view the scene we must also create a QGraphicsView + To be able to view the scene, we must also create a QGraphicsView widget. The QGraphicsView class visualizes the contents of a scene - in a scrollable viewport. We also ensure that the contents is + in a scrollable viewport. We also ensure that the contents are rendered using antialiasing, and we create the cheese background by setting the view's background brush. @@ -240,14 +238,14 @@ Then we set the cache mode; QGraphicsView can cache pre-rendered content in a pixmap, which is then drawn onto the viewport. The purpose of such caching is to speed up the total rendering time - for areas that are slow to render, e.g., texture, gradient and + for areas that are slow to render, for example: texture, gradient, and alpha blended backgrounds. The \l {QGraphicsView::CacheMode}{CacheMode} property holds which parts - of the view that are cached, and the \l + of the view are cached, and the \l {QGraphicsView::CacheBackground}{CacheBackground} flag enables caching of the view's background. - By setting the \l {QGraphicsView::dragMode}{dragMode} property we + By setting the \l {QGraphicsView::dragMode}{dragMode} property, we define what should happen when the user clicks on the scene background and drags the mouse. The \l {QGraphicsView::ScrollHandDrag}{ScrollHandDrag} flag makes the @@ -264,9 +262,9 @@ advance() slot of the scene. Every time the timer fires, the scene will advance one frame. - We then tell the timer to fire every 1000/33 millisecond. This will + We then tell the timer to fire every 1000/33 milliseconds. This will give us a frame rate of 30 frames a second, which is fast enough for most - animations. Doing the animation with a single timer connect to advance the + animations. Doing the animation with a single timer connection to advance the scene ensures that all the mice are moved at one point and, more importantly, only one update is sent to the screen after all the mice have moved. |