ShadowOverlayHelper

public final class ShadowOverlayHelper

ShadowOverlayHelper is a helper class for shadow, overlay color and rounded corner. There are many choices to implement Shadow, overlay color. Initialize it with ShadowOverlayHelper.Builder and it decides the best strategy based on options user choose and current platform version.

  • For shadow: it may use 9-patch with opticalBounds or Z-value based shadow for API >= 21. When 9-patch is used, it requires a ShadowOverlayContainer to include 9-patch views.
  • For overlay: it may use ShadowOverlayContainer which overrides draw() or it may use setForeground(new ColorDrawable()) for API>=23. The foreground support might be disabled if rounded corner is applied due to performance reason.
  • For rounded-corner: it uses a ViewOutlineProvider for API>=21.
There are two different strategies: use Wrapper with a ShadowOverlayContainer; or apply rounded corner, overlay and rounded-corner to the view itself. Below is an example of how helper is used. ShadowOverlayHelper mHelper = new ShadowOverlayHelper.Builder(). .needsOverlay(true).needsRoundedCorner(true).needsShadow(true) .build(); mHelper.prepareParentForShadow(parentView); // apply optical-bounds for 9-patch shadow. mHelper.setOverlayColor(view, Color.argb(0x80, 0x80, 0x80, 0x80)); mHelper.setShadowFocusLevel(view, 1.0f); ... View initializeView(View view) { if (mHelper.needsWrapper()) { ShadowOverlayContainer wrapper = mHelper.createShadowOverlayContainer(context); wrapper.wrap(view); return wrapper; } else { mHelper.onViewCreated(view); return view; } } ...

Summary

Nested types
public final class ShadowOverlayHelper.Builder

Builder for creating ShadowOverlayHelper.
public final class ShadowOverlayHelper.Options

Option values for ShadowOverlayContainer.

Constants
static final int

Shadows depend on the size, shape, and position of the view.
static final int

No shadow.
static final int

Shadows are fixed.

Public methods
ShadowOverlayContainer

Create ShadowOverlayContainer for this helper.
int
boolean
boolean
boolean

Returns true if a "wrapper" ShadowOverlayContainer is needed.
void

Must be called when view is created for cases needsWrapper is false.
void

prepareParentForShadow must be called on parent of container before using shadow.
static void
setNoneWrapperOverlayColor(View view, int color)

Set overlay color for view other than ShadowOverlayContainer.
static void
setNoneWrapperShadowFocusLevel(View view, float level)

Set shadow focus level (0 to 1).
void
setOverlayColor(View view, int color)

Set overlay color for view, it can be a ShadowOverlayContainer if needsWrapper() is true, or other view type.
void
setShadowFocusLevel(View view, float level)

Set shadow focus level (0 to 1).
static boolean

Returns true if the platform sdk supports dynamic shadows.
static boolean

Returns true if view.setForeground() is supported.
static boolean

Returns true if the platform sdk supports rounded corner through outline.
static boolean

Return true if the platform sdk supports shadow.

Constants

SHADOW_DYNAMIC

Added in 1.1.0
public static final int SHADOW_DYNAMIC = 3

Shadows depend on the size, shape, and position of the view.

SHADOW_NONE

Added in 1.1.0
public static final int SHADOW_NONE = 1

No shadow.

SHADOW_STATIC

Added in 1.1.0
public static final int SHADOW_STATIC = 2

Shadows are fixed.

Public methods

createShadowOverlayContainer

Added in 1.1.0
public ShadowOverlayContainer createShadowOverlayContainer(Context context)

Create ShadowOverlayContainer for this helper.

Parameters
Context context

Context to create view.
Returns
ShadowOverlayContainer

ShadowOverlayContainer.

getShadowType

Added in 1.1.0
public int getShadowType()

needsOverlay

Added in 1.1.0
public boolean needsOverlay()

needsRoundedCorner

Added in 1.1.0
public boolean needsRoundedCorner()

needsWrapper

Added in 1.1.0
public boolean needsWrapper()

Returns true if a "wrapper" ShadowOverlayContainer is needed. When needsWrapper() is true, call createShadowOverlayContainer to create the wrapper.

onViewCreated

Added in 1.1.0
public void onViewCreated(View view)

Must be called when view is created for cases needsWrapper is false.

Parameters
View view

prepareParentForShadow

Added in 1.1.0
public void prepareParentForShadow(ViewGroup parent)

prepareParentForShadow must be called on parent of container before using shadow. Depending on Shadow type, optical bounds might be applied.

setNoneWrapperOverlayColor

Added in 1.1.0
public static void setNoneWrapperOverlayColor(View view, int color)

Set overlay color for view other than ShadowOverlayContainer. See also setOverlayColor.

setNoneWrapperShadowFocusLevel

Added in 1.1.0
public static void setNoneWrapperShadowFocusLevel(View view, float level)

Set shadow focus level (0 to 1). 0 for unfocused, 1 for fully focused. This is for view other than ShadowOverlayContainer. See also setShadowFocusLevel.

setOverlayColor

Added in 1.1.0
public void setOverlayColor(View view, int color)

Set overlay color for view, it can be a ShadowOverlayContainer if needsWrapper() is true, or other view type.

setShadowFocusLevel

Added in 1.1.0
public void setShadowFocusLevel(View view, float level)

Set shadow focus level (0 to 1). 0 for unfocused, 1 for fully focused.

supportsDynamicShadow

Added in 1.1.0
public static boolean supportsDynamicShadow()

Returns true if the platform sdk supports dynamic shadows.

supportsForeground

Added in 1.1.0
public static boolean supportsForeground()

Returns true if view.setForeground() is supported.

supportsRoundedCorner

Added in 1.1.0
public static boolean supportsRoundedCorner()

Returns true if the platform sdk supports rounded corner through outline.

supportsShadow

Added in 1.1.0
public static boolean supportsShadow()

Return true if the platform sdk supports shadow.