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TRSGPCanvasRegion Class

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The TRSGPRegion class describes an area of the display surface. The area can be any shape. In other words, the boundary of the area can be a combination of curved and straight lines. Regions can also be created from the interiors of rectangles, paths, or a combination of these. Regions are used in clipping and hit-testing operations.

Notes to Implementers
Wraps the Canvas' region. Needed because GDI+ API doesn't expose handle for Graphic's Region

Namespace: RSGdiPlusGraphics

	Name	Description
	Create(TRSGPCanvas)	Overloaded. Creates a region that is infinite (Overrides RSGdiPlusGraphics.TRSGPGraphicsObject.Create(TRSGPCanvas).)
	Create(TRSGPCanvas,GpRegion)	Overloaded. Creates a region that is defined by data obtained from another region. (Inherited from RSGdiPlusGraphics.TRSGPRegion.)
	Create(TRSGPCanvas,HRGN)	Overloaded. Creates a region that is identical to the region that is specified by a handle to a GDI region. (Inherited from RSGdiPlusGraphics.TRSGPRegion.)
	Create(TRSGPCanvas,TBytes)	Overloaded. Creates a region that is defined by data obtained from another region. The Data parameter is an array of bytes that specifies a region. The data contained in the bytes is obtained from another region by using the GetData method. (Inherited from RSGdiPlusGraphics.TRSGPRegion.)
	Create(TRSGPCanvas,TRect)	Overloaded. Creates a region that is defined by a rectangle. (Inherited from RSGdiPlusGraphics.TRSGPRegion.)
	Create(TRSGPCanvas,TRectF)	Overloaded. Creates a region that is defined by a rectangle. (Inherited from RSGdiPlusGraphics.TRSGPRegion.)
	Create(TRSGPCanvas,TRSGPPath)	Overloaded. Creates a region that is defined by a path. (Inherited from RSGdiPlusGraphics.TRSGPRegion.)

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Name

Description

Bounds

Specifies the rectangle that encloses this region.

If you set the bounds, the region is replaced with a rectangle of that size.

Handle

Handle of the graphics object, used by the MS GDI+ flat API routines (Inherited from RSGdiPlusGraphics.TRSGPGraphicsObject.)

OnChange

Occurs when the graphics object changes.

Note
There are two events that are exactly the same, OnChanged and OnChange. The extra event name is to allow easier transition from other Delphi libraries, either the VCL (OnChanged) or FMX (OnChange) libraries. Use either one as needed. Only one event is triggered.

OnChanged

Occurs when the graphics object changes.

Note
There are two events that are exactly the same, OnChanged and OnChange. The extra event name is to allow easier transition from other Delphi libraries, either the VCL (OnChanged) or FMX (OnChange) libraries. Use either one as needed. Only one event is triggered.

Owner

Canvas that owns the object. The Canvas will free this graphics object if it is destroyed. However, to keep memory use under control, it is recommended that you free graphics objects when you are finished with them. (Inherited from RSGdiPlusGraphics.TRSGPGraphicsObject.)

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Name

Description

ApplyMatrix(TRSGPMatrix)

Transforms this region by multiplying each of its data points by a specified matrix. (Overrides RSGdiPlusGraphics.TRSGPRegion.ApplyMatrix(TRSGPMatrix).)

Assign(GpRegion)

Copies the GDI+ region to the TRSGPRegion (Overrides RSGdiPlusGraphics.TRSGPRegion.Assign(GpRegion).)

Assign(HRGN)

Represents method Assign(HRGN). (Overrides RSGdiPlusGraphics.TRSGPRegion.Assign(HRGN).)

Assign(TPersistent)

Represents method Assign(TPersistent). (Overrides RSGdiPlusGraphics.TRSGPRegion.Assign(TPersistent).)

Changed

Call this method when the graphics object changes. It triggers an OnChange event. (Inherited from RSGdiPlusGraphics.TRSGPGraphicsObject.)

Clear

Updates this region to an empty region. In other words, the region occupies no space on the display device. (Overrides RSGdiPlusGraphics.TRSGPRegion.Clear.)

Clone

Creates a copy of the current region.

Note
It is the responsibility of the calling code to free the region.

Combine(TRect,TRSGPRegionCombineMode)

Overloaded. Combines the current region with the rectangle region

The mode parameter controls how the combining takes place:

cmReplace

New region replaces existing region

cmComplement

Specifies that the existing region is replaced by the portion of the new region that is outside of the existing region.

cmExclude

Specifies that the existing region is replaced by the portion of itself that is outside of the new region.

cmIntersect

Updates this region to the portion of itself that intersects the specified object's interior.

cmUnion

Updates this region to all portions (intersecting and nonintersecting) of itself and all portions of another object

cmXOR

Updates this region to the nonintersecting portions of itself and the specified object's interior

By default, the region is replaced with the input.

Combine(TRectF,TRSGPRegionCombineMode)

Overloaded. Combines the current region with the rectangle region

The mode parameter controls how the combining takes place:

cmReplace

New region replaces existing region

cmComplement

Specifies that the existing region is replaced by the portion of the new region that is outside of the existing region.

cmExclude

Specifies that the existing region is replaced by the portion of itself that is outside of the new region.

cmIntersect

Updates this region to the portion of itself that intersects the specified object's interior.

cmUnion

Updates this region to all portions (intersecting and nonintersecting) of itself and all portions of another object

cmXOR

Updates this region to the nonintersecting portions of itself and the specified object's interior

By default, the region is replaced with the input.

Combine(TRSGPPath,TRSGPRegionCombineMode)

Overloaded. Combines the current region with the path.

The mode parameter controls how the combining takes place:

cmReplace

New region replaces existing region

cmComplement

Specifies that the existing region is replaced by the portion of the new region that is outside of the existing region.

cmExclude

Specifies that the existing region is replaced by the portion of itself that is outside of the new region.

cmIntersect

Updates this region to the portion of itself that intersects the specified object's interior.

cmUnion

Updates this region to all portions (intersecting and nonintersecting) of itself and all portions of another object

cmXOR

Updates this region to the nonintersecting portions of itself and the specified object's interior

By default, the region is replaced with the input.

Combine(TRSGPRegion,TRSGPRegionCombineMode)

Overloaded. Combines the current region with the data from the input region

The mode parameter controls how the combining takes place:

cmReplace

New region replaces existing region

cmComplement

Specifies that the existing region is replaced by the portion of the new region that is outside of the existing region.

cmExclude

Specifies that the existing region is replaced by the portion of itself that is outside of the new region.

cmIntersect

Updates this region to the portion of itself that intersects the specified object's interior.

cmUnion

Updates this region to all portions (intersecting and nonintersecting) of itself and all portions of another object

cmXOR

Updates this region to the nonintersecting portions of itself and the specified object's interior

By default, the region is replaced with the input.

Equals(TObject)

Overloaded. Determines whether this region is equal to an object. If the Obj is a region, the method compares the shape of the region to see if they are equal. (Overrides RSGdiPlusGraphics.TRSGPRegion.Equals(TObject).)

GetBounds

Returns a rectangle that encloses this region. (Overrides RSGdiPlusGraphics.TRSGPRegion.GetBounds.)

GetData

Returns the data that describes this region. (Overrides RSGdiPlusGraphics.TRSGPRegion.GetData.)

GetHandle

Call this method to acquire a handle from the GDI+ flat API library (Overrides RSGdiPlusGraphics.TRSGPRegion.GetHandle.)

GetHRGN

Creates a Windows Graphics Device Interface (GDI) region from this region. (Overrides RSGdiPlusGraphics.TRSGPRegion.GetHRGN.)

GetRegionScans

Overloaded. Gets an array of rectangles that approximate this region. The region is transformed by the owner canvas' matrix before the rectangles are calculated. (Overrides RSGdiPlusGraphics.TRSGPRegion.GetRegionScans.)

IsEmpty

Determines whether this region is empty. (Overrides RSGdiPlusGraphics.TRSGPRegion.IsEmpty.)

IsInfinite

Determines whether this region is infinite. (Overrides RSGdiPlusGraphics.TRSGPRegion.IsInfinite.)

IsVisible(TPoint)

Overloaded. Returns true if the point is inside this region. (Overrides RSGdiPlusGraphics.TRSGPRegion.IsVisible(TPoint).)

IsVisible(TPointF)

Overloaded. Returns true if the point is inside this region.
(Overrides RSGdiPlusGraphics.TRSGPRegion.IsVisible(TPointF).)

IsVisible(TRect)

Overloaded. Returns true if a rectangle intersects this region. (Overrides RSGdiPlusGraphics.TRSGPRegion.IsVisible(TRect).)

IsVisible(TRectF)

Overloaded. Returns true if a rectangle intersects this region. (Overrides RSGdiPlusGraphics.TRSGPRegion.IsVisible(TRectF).)

MakeInfinite

Updates this region to an infinite region. (Overrides RSGdiPlusGraphics.TRSGPRegion.MakeInfinite.)

Notification(TRSGPCanvas)

Called when the Canvas is releasing control of the graphics object. The canvas will no longer be responsible for freeing the graphics object. (Inherited from RSGdiPlusGraphics.TRSGPGraphicsObject.)

Prepare(TRectF,Single)

Prepare the graphics object for drawing. Graphics objects respond in this method to upcoming calls. For example, gradient brushes can make sure the gradient will cover the entire rectangle. (Inherited from RSGdiPlusGraphics.TRSGPGraphicsObject.)

QueryInterface(TGUID,Void)

Represents method QueryInterface(TGUID,Void). (Inherited from RSGdiPlusGraphics.TRSGPGraphicsObject.)

ReleaseHandle

Releases the underlying GDI+ object back to the GDI+ library. (Overrides RSGdiPlusGraphics.TRSGPRegion.ReleaseHandle.)

Translate(Integer,Integer)

Overloaded. Offsets this region by specified amounts in the horizontal and vertical directions. (Overrides RSGdiPlusGraphics.TRSGPRegion.Translate(Integer,Integer).)

Translate(Single,Single)

Overloaded. Offsets this region by specified amounts in the horizontal and vertical directions. (Overrides RSGdiPlusGraphics.TRSGPRegion.Translate(Single,Single).)

Update

Update native graphics object (Inherited from RSGdiPlusGraphics.TRSGPGraphicsObject.)

_AddRef

Represents method _AddRef. (Inherited from RSGdiPlusGraphics.TRSGPGraphicsObject.)

_Release

Represents method _Release. (Inherited from RSGdiPlusGraphics.TRSGPGraphicsObject.)

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TRSGPCanvasRegion Class

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