Class AsyncBoxView.ChildLocator
- java.lang.Object
-
- javax.swing.text.AsyncBoxView.ChildLocator
- Enclosing class:
- AsyncBoxView
public class AsyncBoxView.ChildLocator extends Object
A class to manage the effective position of the child views in a localized area while changes are being made around the localized area. The AsyncBoxView may be continuously changing, but the visible area needs to remain fairly stable until the layout thread decides to publish an update to the parent.
- Since:
- 1.3
Field Summary
Modifier and Type | Field | Description |
---|---|---|
protected Rectangle | childAlloc | A shape to use for the child allocation to avoid creating a lot of garbage. |
protected Rectangle | lastAlloc | The last seen allocation (for repainting when changes are flushed upward). |
protected AsyncBoxView.ChildState | lastValidOffset | The location of the last offset calculation that is valid. |
Constructor Summary
Constructor | Description |
---|---|
ChildLocator() | construct a child locator. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | childChanged(AsyncBoxView.ChildState cs) | Notification that a child changed. |
protected Shape | getChildAllocation(int index) | Fetch the allocation to use for a child view. |
Shape | getChildAllocation(int index,
Shape a) | Fetch the allocation to use for a child view. |
int | getViewIndexAtPoint(float x,
float y,
Shape a) | Fetches the child view index at the given point. |
protected int | getViewIndexAtVisualOffset(float targetOffset) | Locate the view responsible for an offset into the box along the major axis. |
void | paintChildren(Graphics g) | Paint the children that intersect the clip area. |
protected void | setAllocation(Shape a) | Copy the currently allocated shape into the Rectangle used to store the current allocation. |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Field Detail
lastValidOffset
protected AsyncBoxView.ChildState lastValidOffset
The location of the last offset calculation that is valid.
lastAlloc
protected Rectangle lastAlloc
The last seen allocation (for repainting when changes are flushed upward).
childAlloc
protected Rectangle childAlloc
A shape to use for the child allocation to avoid creating a lot of garbage.
Constructor Detail
ChildLocator
public ChildLocator()
construct a child locator.
Method Detail
childChanged
public void childChanged(AsyncBoxView.ChildState cs)
Notification that a child changed. This can effect whether or not new offset calculations are needed. This is called by a ChildState object that has changed it's major span. This can therefore be called by multiple threads.
- Parameters:
-
cs
- the child state
paintChildren
public void paintChildren(Graphics g)
Paint the children that intersect the clip area.
- Parameters:
-
g
- the rendering surface to use
getChildAllocation
public Shape getChildAllocation(int index, Shape a)
Fetch the allocation to use for a child view. This will update the offsets for all children not yet updated before the given index.
- Parameters:
-
index
- the child index -
a
- the allocation - Returns:
- the allocation to use for a child view
getViewIndexAtPoint
public int getViewIndexAtPoint(float x, float y, Shape a)
Fetches the child view index at the given point. This is called by the various View methods that need to calculate which child to forward a message to. This should be called by a block synchronized on this object, and would typically be followed with one or more calls to getChildAllocation that should also be in the synchronized block.
- Parameters:
-
x
- the X coordinate >= 0 -
y
- the Y coordinate >= 0 -
a
- the allocation to the View - Returns:
- the nearest child index
getChildAllocation
protected Shape getChildAllocation(int index)
Fetch the allocation to use for a child view. This does not update the offsets in the ChildState records.
- Parameters:
-
index
- the index - Returns:
- the allocation to use for a child view
setAllocation
protected void setAllocation(Shape a)
Copy the currently allocated shape into the Rectangle used to store the current allocation. This would be a floating point rectangle in a Java2D-specific implementation.
- Parameters:
-
a
- the allocation
getViewIndexAtVisualOffset
protected int getViewIndexAtVisualOffset(float targetOffset)
Locate the view responsible for an offset into the box along the major axis. Make sure that offsets are set on the ChildState objects up to the given target span past the desired offset.
- Parameters:
-
targetOffset
- the target offset - Returns:
- index of the view representing the given visual location (targetOffset), or -1 if no view represents that location