Graphics.BeginContainer(const RectF, const RectF, Unit) method

Artikel
03/07/2012

Applies to: desktop apps only

The Graphics::BeginContainer method begins a new graphics container.

Syntax

GraphicsContainer BeginContainer(
  [in, ref]  const RectF &dstrect,
  [in, ref]  const RectF &srcrect,
  [in]       Unit unit
);

Parameters

dstrect [in, ref]
Type: const RectF

Reference to a rectangle that, together with srcrect, specifies a transformation for the container.
srcrect [in, ref]
Type: const RectF

Reference to a rectangle that, together with dstrect, specifies a transformation for the container.
unit [in]
Type: Unit

Unit of measure for the container.

Return value

Type:

Type: GraphicsContainer

This method returns a value that identifies the container.

Remarks

Use this method to create nested graphics containers. Graphics containers are used to retain graphics state, such as transformations, clipping regions, and various rendering properties.

The Graphics::BeginContainer method returns a value of type GraphicsContainer. When you have finished using a container, pass that value to the Graphics::EndContainer method. The GraphicsContainer data type is defined in Gdiplusenums.h.

The dstrect and srcrect parameters specify a transformation. It is the transformation that, when applied to srcrect, results in dstrect.

When you call the Graphics::BeginContainer method of a Graphics object, an information block that holds the state of the Graphics object is put on a stack. The Graphics::BeginContainer method returns a value that identifies that information block. When you pass the identifying value to the Graphics::EndContainer method, the information block is removed from the stack and is used to restore the Graphics object to the state it was in at the time of the Graphics::BeginContainer call.

Containers can be nested; that is, you can call the Graphics::BeginContainer method several times before you call the Graphics::EndContainer method. Each time you call the Graphics::BeginContainer method, an information block is put on the stack, and you receive an identifier for the information block. When you pass one of those identifiers to the Graphics::EndContainer method, the Graphics object is returned to the state it was in at the time of the BeginContainer call that returned that particular identifier. The information block placed on the stack by that Graphics::BeginContainer call is removed from the stack, and all information blocks placed on that stack after that Graphics::BeginContainer call are also removed.

Calls to the Graphics::Save method place information blocks on the same stack as calls to the Graphics::BeginContainer method. Just as an Graphics::EndContainer call is paired with a Graphics::BeginContainer call, a Graphics::Restore call is paired with a Graphics::Save call.

Caution When you call Graphics::EndContainer, all information blocks placed on the stack (by Graphics::Save or by Graphics::BeginContainer) after the corresponding call to Graphics::BeginContainer are removed from the stack. Likewise, when you call Graphics::Restore, all information blocks placed on the stack (by Graphics::Save or by Graphics::BeginContainer) after the corresponding call to Graphics::Save are removed from the stack.

For more information about graphics containers, see Nested Graphics Containers.

Examples

The following example calls the BeginContainer method to create a graphics container. The code specifies a transformation for the container by passing two rectangles to the BeginContainer method. The code calls Graphics::FillEllipse twice: once inside the container and once outside the container (after the call to Graphics::EndContainer).

VOID Example_BeginContainer3(HDC hdc)
{
   Graphics graphics(hdc);

   // Define a translation and scale transform for the container.
   RectF srcRect(0, 0, 200, 100);
   RectF destRect(100, 100, 200, 200);

   // Create a graphics container with a (100, 100) translation 
   // and (1, 2) scale.
   GraphicsContainer container;
   container = graphics.BeginContainer(destRect, srcRect, UnitPixel);

   // Fill a rectangle in the container.
   SolidBrush redBrush(Color(255, 255, 0, 0));
   graphics.FillEllipse(&redBrush, 0, 0, 100, 60);

   // End the container.
   graphics.EndContainer(container);

   // Fill a rectangle outside the container.
   SolidBrush blueBrush(Color(255, 0, 0, 255));
   graphics.FillEllipse(&blueBrush, 0, 0, 100, 60);
}

Requirements

Minimum supported client	Windows XP, Windows 2000 Professional
Minimum supported server	Windows 2000 Server
Product	GDI+ 1.0
Header	Gdiplusgraphics.h (include Gdiplus.h)
Library	Gdiplus.lib
DLL	Gdiplus.dll

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