org.havi.ui

Interface HLook

All Superinterfaces:

Cloneable

All Known Subinterfaces:

HAdjustableLook, HExtendedLook

All Known Implementing Classes:

HAnimateLook, HGraphicLook, HListGroupLook, HMultilineEntryLook, HRangeLook, HSinglelineEntryLook, HTextLook

public interface HLook
extends Cloneable

The HLook interface defines the "look" of a component and may be regarded as a mechanism to allow a "pluggable" paint method to be attached to the component. Instead of having to subclass the entire component to change its look, it is possible to simply implement an HLook that will render the component "look" and then associate this HLook implementation with the component.

Borders

An implementation of HLook will also include code to draw implementation-specific borders. The application or component can query the reserved space for an HLook with the getInsets method.

Since the border area is included in the overall size of the component, the border effectively constrains the area available for rendering content to the rectangle which has an upper-left corner location of (insets.left, insets.top), and has a size of width - (insets.left + insets.right) by height - (insets.top + insets.bottom).

Invocation Mechanism

The showLook method of the HLook interface will be called by the havi.ui framework in response to the paint method of the HVisible being called by the AWT lightweight component framework. Applications should simply invoke the component repaint method as in normal AWT, rather than calling the showLook method directly.

Content Rendering

Some looks make use of content stored on an associated HVisible. These looks are:

• HAnimateLook - for animated graphical content
• HGraphicLook - for static graphical content
• HTextLook - for static textual content
• HSinglelineEntryLook - for single line text entry content
• HMultilineEntryLook - for multiline text entry content
• HListGroupLook - for list element content

Some of these looks may support the scaling and alignment of their content as an implementation option. The scaling and alignment modes supported are specified in the class description of HVisible. The table below details which features the content-based platform looks should support:

HLook	Scaling	Alignment
HAnimateLook	Optional	Mandatory
HGraphicLook	Optional	Mandatory
HListGroupLook	Optional	Mandatory
HTextLook	Not used	Mandatory
HSinglelineEntryLook	Not used	Not used
HMultilineEntryLook	Not used	Not used

Where scaling support is optional all implementations must as a minimum support the RESIZE_NONE scaling mode. Platforms are not required to support scaling of textual content by default.

Looks should use the getHorizontalAlignment and getVerticalAlignment methods to retrieve the current alignment modes, and the getResizeMode method to determine the active scaling mode, where supported. However, note that HAVi platform looks which render text content using the HDefaultTextLayoutManager class shall delegate the alignment of text content to the layout manager.

Rendering Hints

HLook provides a method, widgetChanged which can be called by an HVisible with one or more hints to inform the look that something has changed. This method provides information to the look about what has changed, which allows smarter repainting than having the HVisible simply call its repaint method. The hint constants are defined on HVisible. See the class definition for HVisible for more information.

Private Data

Implementations of HLook may store private data on each instance of an HVisible to optimize the drawing of that component. However, this is an implementation option. Furthermore such data may be invalidated by another part of the system, for example if setLook is called on HVisible. Therefore if this mechanism is used by implementations of HLook those implementations must be capable of regenerating such data on the fly, according to the current state of the HVisible.

Platform Looks

The HAVi UI provides a number of classes implementing the HLook interface. Applications wishing to provide their own HLooks may directly implement this interface or may subclass those provided by the platform.

Default Behavior

Unless already specified in a particular HLook, implementations of HLook should use:

• the foreground color of each associated HVisible (using the java.awt.Component method getForeground) to determine the Color to render both the content and border (as necessary)
• the background color of each associated HVisible (using the java.awt.Component method getBackground) to determine the Color used to render a rectangular area to fill the component and erase any previous content, as specified by the current background drawing mode for that component - see setBackgroundMode on HVisible.
• the current alignment mode of each associated HVisible (using getHorizontalAlignment and getVerticalAlignment) to determine how to align content.
• the current scaling mode of each associated HVisible (using to getResizeMode) to determine how to scale content.

See Also:

HVisible.setLook(org.havi.ui.HLook), HVisible.setLookData(java.lang.Object, java.lang.Object), HVisible.paint(java.awt.Graphics), HVisible.setBackgroundMode(int), HVisible.setHorizontalAlignment(int), HVisible.setVerticalAlignment(int), HVisible.setResizeMode(int), HTextLook, HGraphicLook, HAnimateLook, HRangeLook, HSinglelineEntryLook, HMultilineEntryLook

Method Summary

Methods

Modifier and Type	Method and Description
Insets	getInsets(HVisible hvisible) Determines the insets of this HLook, which indicate the size of the border.
Dimension	getMaximumSize(HVisible hvisible) Gets the maximum size of the HVisible component when drawn with this HLook.
Dimension	getMinimumSize(HVisible hvisible) Gets the minimum size of the HVisible component when drawn with this HLook.
Dimension	getPreferredSize(HVisible hvisible) Gets the preferred size of the HVisible component when drawn with this HLook.
boolean	isOpaque(HVisible hvisible) Returns true if the entire painted area of the HVisible when using this look is fully opaque, i.e.
void	showLook(Graphics g, HVisible visible, int state) The showLook method is responsible for repainting the entire HVisible component, (including any content set on the component, and the component background), subject to the clipping rectangle of the Graphics object passed to it.
void	widgetChanged(HVisible visible, HChangeData[] changes) Called by the HVisible whenever its content, state, or any other data changes.

Method Detail

showLook

void showLook(Graphics g,
            HVisible visible,
            int state)

The showLook method is responsible for repainting the entire HVisible component, (including any content set on the component, and the component background), subject to the clipping rectangle of the Graphics object passed to it.

The showLook method should not modify the clipRect (clipping rectangle) of the Graphics object that is passed to it in a way which includes any area not part of that original clipRect. If any modifications are made, the original clipRect shall be restored.

For looks which draw content (e.g. HTextLook, HGraphicLook and HAnimateLook), if no content is associated with the component, the showLook method paints the component with its current background Color according to the setBackgroundMode method of HVisible and draws any (implementation-specific) borders. Note that by default the background mode is set so as to not paint a background. Furthermore on platforms which support transparent colors the background Color may be partially or completely transparent.

Any resources explicitly associated with an HLook should be loaded by the HLook during its creation, etc. Note that the "standard" looks don't load content by default.

This method is called from the paint method of HVisible and must never be called from elsewhere. Components wishing to redraw themselves should call their repaint method in the usual way.

Parameters:

g - the graphics context.

visible - the visible.

state - the state parameter indicates the state of the visible, allowing the look to render the appropriate content for that state. Note that some components (e.g. HStaticRange, HRange, HRangeValue) do not use state-based content.

widgetChanged

void widgetChanged(HVisible visible,
                 HChangeData[] changes)

Called by the HVisible whenever its content, state, or any other data changes. See the class description of HVisible for more information about the changes parameter.

The implementation of this method should work out which graphical areas of the HVisible have changed and make any relevant calls to trigger the repainting of those areas.

A minimum implementation of this method could simply call

 visible.repaint()
 

Parameters:

visible - the HVisible which has changed

changes - an array containing hint data and associated hint objects. If this argument is null a full repaint will be triggered.

getMinimumSize

Dimension getMinimumSize(HVisible hvisible)

Gets the minimum size of the HVisible component when drawn with this HLook.

This size may be determined in several ways depending on the information available to the look. These steps are performed in order and the first available result is returned. For the purposes of this algorithm HLook classes that do not use content (e.g. HRangeLook) are treated as if no content was present.

The extra space required for border decoration can be determined from the getInsets method.

1. If this look is an HTextLook and if HVisible.getTextLayoutManager() returns an HDefaultTextLayoutManager, then this method should delegate the call to its getMinimumSize() method plus any additional dimensions that the HLook requires for border decoration etc. If the HDefaultTextLayoutManager returns a zero size, then proceed with the following steps.
2. If the HLook supports the scaling of its content (e.g. an HGraphicLook) and scaling is requested and content is set, then the return value is a size containing the width of the narrowest content and the height of the shortest content plus any additional dimensions that the HLook requires for border decoration etc.
3. If the HLook does not support scaling of content or no scaling is requested, and content is set then the return value is a size sufficiently large to hold each piece of content plus any additional dimensions that the HLook requires for border decoration etc.
4. If no content is available but a default preferred size has been set using setDefaultSize has been called to set then the return value is this value (as obtained with getDefaultSize) plus any additional dimensions that the HLook requires for border decoration etc.
5. If there is no content or default size set then the return value is an implementation-specific minimum size plus any additional dimensions that the HLook requires for border decoration etc.

Parameters:

hvisible - HVisible to which this HLook is attached.

Returns:

A dimension object indicating this HLook's minimum size.

See Also:

HVisible.getMinimumSize()

getPreferredSize

Dimension getPreferredSize(HVisible hvisible)

Gets the preferred size of the HVisible component when drawn with this HLook.

This size may be determined in several ways depending on the information available to the look. These steps are performed in order and the first available result is returned. For the purposes of this algorithm HLook classes that do not use content (e.g. HRangeLook) are treated as if no content was present.

The extra space required for border decoration can be determined from the getInsets method.

1. If a default preferred size has been set for this HVisible (using setDefaultSize) then the return value is this size (obtained with getDefaultSize) plus any additional dimensions that the HLook requires for border decoration etc.
2. If this look is an HTextLook and if a default preferred size has not been set and HVisible.getTextLayoutManager() returns an HDefaultTextLayoutManager, then this method should delegate the call to its getPreferredSize() method plus any additional dimensions that the HLook requires for border decoration etc. If the HDefaultTextLayoutManager returns a zero size, then proceed with the following steps.
3. If this HLook does not support scaling of content or no scaling is requested, and content is present then the return value is a size that is sufficiently large to hold each piece of content plus any additional dimensions that the HLook requires for border decoration etc.
4. If this HLook supports the scaling of its content (e.g. an HGraphicLook) and content is set then the return value is the current size of the HVisible as returned by getSize).
5. If there is no content and no default size set then the return value is the current size of the HVisible as returned by getSize).

If a default preferred size has been set for this HVisible (using setDefaultSize()) and the default preferred size has a NO_DEFAULT_WIDTH then the return value is a Dimension with this height (obtained with getDefaultSize()) and the preferred width for the content plus any additional dimensions that the HLook requires for border decoration etc.

If a default preferred size has been set for this HVisible (using setDefaultSize()) and the default preferred size has a NO_DEFAULT_HEIGHT then the return value is a Dimension with this width (obtained with getDefaultSize()) and the preferred height for the content plus any additional dimensions that the HLook requires for border decoration etc.

Parameters:

hvisible - HVisible to which this HLook is attached.

Returns:

A dimension object indicating the preferred size of the HVisible when drawn with this HLook.

See Also:

HVisible.getPreferredSize(), HVisible.setDefaultSize(java.awt.Dimension)

getMaximumSize

Dimension getMaximumSize(HVisible hvisible)

Gets the maximum size of the HVisible component when drawn with this HLook.

This size may be determined in several ways depending on the information available to the look. These steps are performed in order and the first available result is returned. For the purposes of this algorithm HLook classes that do not use content (e.g. HRangeLook) are treated as if no content was present.

The extra space required for border decoration can be determined from the getInsets method.

1. If this look is an HTextLook and if HVisible.getTextLayoutManager() returns an HDefaultTextLayoutManager, then this method should delegate the call to its getMaximumSize() method plus any additional dimensions that the HLook requires for border decoration etc. If the HDefaultTextLayoutManager returns a zero size, then proceed with the following steps.
2. If the HLook supports the scaling of its content (e.g. an HGraphicLook) then the return value is the current size of the HVisible (as returned by HVisible#getSize).
3. If the HLook does not support scaling of content or no scaling is requested, and content is set then the return value is a size sufficiently large to hold each piece of content plus any additional dimensions that the HLook requires for border decoration etc.
4. If there is no content set then a maximum size of [Short.MAX_VALUE, Short.MAX_VALUE] is returned as a Dimension.

Parameters:

hvisible - HVisible to which this HLook is attached.

Returns:

A dimension object indicating this HLook's maximum size.

See Also:

HVisible.getMaximumSize()

isOpaque

boolean isOpaque(HVisible hvisible)

Returns true if the entire painted area of the HVisible when using this look is fully opaque, i.e. the showLook method guarantees that all pixels are painted in an opaque Color.

The default value is implementation specific and depends on the background painting mode of the given HVisible. The consequences of an invalid overridden value are implementation specific.

Parameters:

hvisible - the visible to test

Returns:

true if all the pixels with the java.awt.Component#getBounds method of an HVisible using this look are fully opaque, i.e. the showLook method guarantees that all pixels are painted in an opaque Color, otherwise false.

getInsets

Insets getInsets(HVisible hvisible)

Determines the insets of this HLook, which indicate the size of the border. This area is reserved for the HLook to use for drawing borders around the associated HVisible.

Parameters:

hvisible - HVisible to which this HLook is attached.

Returns:

the insets of this HLook.