CDC Class

Article
01/08/2013

Defines a class of device-context objects.

class CDC : public CObject

Members

Public Constructors

Name	Description
CDC::CDC	Constructs a CDC object.

Public Methods

Name	Description
CDC::AbortDoc	Terminates the current print job, erasing everything the application has written to the device since the last call of the StartDoc member function.
CDC::AbortPath	Closes and discards any paths in the device context.
CDC::AddMetaFileComment	Copies the comment from a buffer into a specified enhanced-format metafile.
CDC::AlphaBlend	Displays bitmaps that have transparent or semitransparent pixels.
CDC::AngleArc	Draws a line segment and an arc, and moves the current position to the ending point of the arc.
CDC::Arc	Draws an elliptical arc.
CDC::ArcTo	Draws an elliptical arc. This function is similar to Arc, except that the current position is updated.
CDC::Attach	Attaches a Windows device context to this CDC object.
CDC::BeginPath	Opens a path bracket in the device context.
CDC::BitBlt	Copies a bitmap from a specified device context.
CDC::Chord	Draws a chord (a closed figure bounded by the intersection of an ellipse and a line segment).
CDC::CloseFigure	Closes an open figure in a path.
CDC::CreateCompatibleDC	Creates a memory-device context that is compatible with another device context. You can use it to prepare images in memory.
CDC::CreateDC	Creates a device context for a specific device.
CDC::CreateIC	Creates an information context for a specific device. This provides a fast way to get information about the device without creating a device context.
CDC::DeleteDC	Deletes the Windows device context associated with this CDC object.
CDC::DeleteTempMap	Called by the CWinApp idle-time handler to delete any temporary CDC object created by FromHandle. Also detaches the device context.
CDC::Detach	Detaches the Windows device context from this CDC object.
CDC::DPtoHIMETRIC	Converts device units into HIMETRIC units.
CDC::DPtoLP	Converts device units into logical units.
CDC::Draw3dRect	Draws a three-dimensional rectangle.
CDC::DrawDragRect	Erases and redraws a rectangle as it is dragged.
CDC::DrawEdge	Draws the edges of a rectangle.
CDC::DrawEscape	Accesses drawing capabilities of a video display that are not directly available through the graphics device interface (GDI).
CDC::DrawFocusRect	Draws a rectangle in the style used to indicate focus.
CDC::DrawFrameControl	Draw a frame control.
CDC::DrawIcon	Draws an icon.
CDC::DrawState	Displays an image and applies a visual effect to indicate a state.
CDC::DrawText	Draws formatted text in the specified rectangle.
CDC::DrawTextEx	Draws formatted text in the specified rectangle using additional formats.
CDC::Ellipse	Draws an ellipse.
CDC::EndDoc	Ends a print job started by the StartDoc member function.
CDC::EndPage	Informs the device driver that a page is ending.
CDC::EndPath	Closes a path bracket and selects the path defined by the bracket into the device context.
CDC::EnumObjects	Enumerates the pens and brushes available in a device context.
CDC::Escape	Allows applications to access facilities that are not directly available from a particular device through GDI. Also allows access to Windows escape functions. Escape calls made by an application are translated and sent to the device driver.
CDC::ExcludeClipRect	Creates a new clipping region that consists of the existing clipping region minus the specified rectangle.
CDC::ExcludeUpdateRgn	Prevents drawing within invalid areas of a window by excluding an updated region in the window from a clipping region.
CDC::ExtFloodFill	Fills an area with the current brush. Provides more flexibility than the CDC::FloodFill member function.
CDC::ExtTextOut	Writes a character string within a rectangular region using the currently selected font.
CDC::FillPath	Closes any open figures in the current path and fills the path's interior by using the current brush and polygon-filling mode.
CDC::FillRect	Fills a given rectangle by using a specific brush.
CDC::FillRgn	Fills a specific region with the specified brush.
CDC::FillSolidRect	Fills a rectangle with a solid color.
CDC::FlattenPath	Transforms any curves in the path selected into the current device context, and turns each curve into a sequence of lines.
CDC::FloodFill	Fills an area with the current brush.
CDC::FrameRect	Draws a border around a rectangle.
CDC::FrameRgn	Draws a border around a specific region using a brush.
CDC::FromHandle	Returns a pointer to a CDC object when given a handle to a device context. If a CDC object is not attached to the handle, a temporary CDC object is created and attached.
CDC::GetArcDirection	Returns the current arc direction for the device context.
CDC::GetAspectRatioFilter	Retrieves the setting for the current aspect-ratio filter.
CDC::GetBkColor	Retrieves the current background color.
CDC::GetBkMode	Retrieves the background mode.
CDC::GetBoundsRect	Returns the current accumulated bounding rectangle for the specified device context.
CDC::GetBrushOrg	Retrieves the origin of the current brush.
CDC::GetCharABCWidths	Retrieves the widths, in logical units, of consecutive characters in a given range from the current font.
CDC::GetCharABCWidthsI	Retrieves the widths, in logical units, of consecutive glyph indices in a specified range from the current TrueType font.
CDC::GetCharacterPlacement	Retrieves various types of information on a character string.
CDC::GetCharWidth	Retrieves the fractional widths of consecutive characters in a given range from the current font.
CDC::GetCharWidthI	Retrieves the widths, in logical coordinates, of consecutive glyph indices in a specified range from the current font.
CDC::GetClipBox	Retrieves the dimensions of the tightest bounding rectangle around the current clipping boundary.
CDC::GetColorAdjustment	Retrieves the color adjustment values for the device context.
CDC::GetCurrentBitmap	Returns a pointer to the currently selected CBitmap object.
CDC::GetCurrentBrush	Returns a pointer to the currently selected CBrush object.
CDC::GetCurrentFont	Returns a pointer to the currently selected CFont object.
CDC::GetCurrentPalette	Returns a pointer to the currently selected CPalette object.
CDC::GetCurrentPen	Returns a pointer to the currently selected CPen object.
CDC::GetCurrentPosition	Retrieves the current position of the pen (in logical coordinates).
CDC::GetDCBrushColor	Retrieves the current brush color.
CDC::GetDCPenColor	Retrieves the current pen color.
CDC::GetDeviceCaps	Retrieves a specified kind of device-specific information about a given display device's capabilities.
CDC::GetFontData	Retrieves font metric information from a scalable font file. The information to retrieve is identified by specifying an offset into the font file and the length of the information to return.
CDC::GetFontLanguageInfo	Returns information about the currently selected font for the specified display context.
CDC::GetGlyphOutline	Retrieves the outline curve or bitmap for an outline character in the current font.
CDC::GetGraphicsMode	Retrieves the current graphics mode for the specified device context.
CDC::GetHalftoneBrush	Retrieves a halftone brush.
CDC::GetKerningPairs	Retrieves the character kerning pairs for the font that is currently selected in the specified device context.
CDC::GetLayout	Retrieves the layout of a device context (DC). The layout can be either left to right (default) or right to left (mirrored).
CDC::GetMapMode	Retrieves the current mapping mode.
CDC::GetMiterLimit	Returns the miter limit for the device context.
CDC::GetNearestColor	Retrieves the closest logical color to a specified logical color that the given device can represent.
CDC::GetOutlineTextMetrics	Retrieves font metric information for TrueType fonts.
CDC::GetOutputCharWidth	Retrieves the widths of individual characters in a consecutive group of characters from the current font using the output device context.
CDC::GetOutputTabbedTextExtent	Computes the width and height of a character string on the output device context.
CDC::GetOutputTextExtent	Computes the width and height of a line of text on the output device context using the current font to determine the dimensions.
CDC::GetOutputTextMetrics	Retrieves the metrics for the current font from the output device context.
CDC::GetPath	Retrieves the coordinates defining the endpoints of lines and the control points of curves found in the path that is selected into the device context.
CDC::GetPixel	Retrieves the RGB color value of the pixel at the specified point.
CDC::GetPolyFillMode	Retrieves the current polygon-filling mode.
CDC::GetROP2	Retrieves the current drawing mode.
CDC::GetSafeHdc	Returns CDC::m_hDC, the output device context.
CDC::GetStretchBltMode	Retrieves the current bitmap-stretching mode.
CDC::GetTabbedTextExtent	Computes the width and height of a character string on the attribute device context.
CDC::GetTextAlign	Retrieves the text-alignment flags.
CDC::GetTextCharacterExtra	Retrieves the current setting for the amount of intercharacter spacing.
CDC::GetTextColor	Retrieves the current text color.
CDC::GetTextExtent	Computes the width and height of a line of text on the attribute device context using the current font to determine the dimensions.
CDC::GetTextExtentExPointI	Retrieves the number of characters in a specified string that will fit within a specified space and fills an array with the text extent for each of those characters.
CDC::GetTextExtentPointI	Retrieves the width and height of the specified array of glyph indices.
CDC::GetTextFace	Copies the typeface name of the current font into a buffer as a null-terminated string.
CDC::GetTextMetrics	Retrieves the metrics for the current font from the attribute device context.
CDC::GetViewportExt	Retrieves the x- and y-extents of the viewport.
CDC::GetViewportOrg	Retrieves the x- and y-coordinates of the viewport origin.
CDC::GetWindow	Returns the window associated with the display device context.
CDC::GetWindowExt	Retrieves the x- and y-extents of the associated window.
CDC::GetWindowOrg	Retrieves the x- and y-coordinates of the origin of the associated window.
CDC::GetWorldTransform	Retrieves the current world-space to page-space transformation.
CDC::GradientFill	Fills rectangle and triangle structures with a gradating color.
CDC::GrayString	Draws dimmed (grayed) text at the given location.
CDC::HIMETRICtoDP	Converts HIMETRIC units into device units.
CDC::HIMETRICtoLP	Converts HIMETRIC units into logical units.
CDC::IntersectClipRect	Creates a new clipping region by forming the intersection of the current region and a rectangle.
CDC::InvertRect	Inverts the contents of a rectangle.
CDC::InvertRgn	Inverts the colors in a region.
CDC::IsPrinting	Determines whether the device context is being used for printing.
CDC::LineTo	Draws a line from the current position up to, but not including, a point.
CDC::LPtoDP	Converts logical units into device units.
CDC::LPtoHIMETRIC	Converts logical units into HIMETRIC units.
CDC::MaskBlt	Combines the color data for the source and destination bitmaps using the given mask and raster operation.
CDC::ModifyWorldTransform	Changes the world transformation for a device context using the specified mode.
CDC::MoveTo	Moves the current position.
CDC::OffsetClipRgn	Moves the clipping region of the given device.
CDC::OffsetViewportOrg	Modifies the viewport origin relative to the coordinates of the current viewport origin.
CDC::OffsetWindowOrg	Modifies the window origin relative to the coordinates of the current window origin.
CDC::PaintRgn	Fills a region with the selected brush.
CDC::PatBlt	Creates a bit pattern.
CDC::Pie	Draws a pie-shaped wedge.
CDC::PlayMetaFile	Plays the contents of the specified metafile on the given device. The enhanced version of PlayMetaFile displays the picture stored in the given enhanced-format metafile. The metafile can be played any number of times.
CDC::PlgBlt	Performs a bit-block transfer of the bits of color data from the specified rectangle in the source device context to the specified parallelogram in the given device context.
CDC::PolyBezier	Draws one or more Bzier splines. The current position is neither used nor updated.
CDC::PolyBezierTo	Draws one or more Bzier splines, and moves the current position to the ending point of the last Bzier spline.
CDC::PolyDraw	Draws a set of line segments and Bzier splines. This function updates the current position.
CDC::Polygon	Draws a polygon consisting of two or more points (vertices) connected by lines.
CDC::Polyline	Draws a set of line segments connecting the specified points.
CDC::PolylineTo	Draws one or more straight lines and moves the current position to the ending point of the last line.
CDC::PolyPolygon	Creates two or more polygons that are filled using the current polygon-filling mode. The polygons may be disjoint or they may overlap.
CDC::PolyPolyline	Draws multiple series of connected line segments. The current position is neither used nor updated by this function.
CDC::PtVisible	Specifies whether the given point is within the clipping region.
CDC::RealizePalette	Maps palette entries in the current logical palette to the system palette.
CDC::Rectangle	Draws a rectangle using the current pen and fills it using the current brush.
CDC::RectVisible	Determines whether any part of the given rectangle lies within the clipping region.
CDC::ReleaseAttribDC	Releases m_hAttribDC, the attribute device context.
CDC::ReleaseOutputDC	Releases m_hDC, the output device context.
CDC::ResetDC	Updates the m_hAttribDC device context.
CDC::RestoreDC	Restores the device context to a previous state saved with SaveDC.
CDC::RoundRect	Draws a rectangle with rounded corners using the current pen and filled using the current brush.
CDC::SaveDC	Saves the current state of the device context.
CDC::ScaleViewportExt	Modifies the viewport extent relative to the current values.
CDC::ScaleWindowExt	Modifies the window extents relative to the current values.
CDC::ScrollDC	Scrolls a rectangle of bits horizontally and vertically.
CDC::SelectClipPath	Selects the current path as a clipping region for the device context, combining the new region with any existing clipping region by using the specified mode.
CDC::SelectClipRgn	Combines the given region with the current clipping region by using the specified mode.
CDC::SelectObject	Selects a GDI drawing object such as a pen.
CDC::SelectPalette	Selects the logical palette.
CDC::SelectStockObject	Selects one of the predefined stock pens, brushes, or fonts provided by Windows.
CDC::SetAbortProc	Sets a programmer-supplied callback function that Windows calls if a print job must be aborted.
CDC::SetArcDirection	Sets the drawing direction to be used for arc and rectangle functions.
CDC::SetAttribDC	Sets m_hAttribDC, the attribute device context.
CDC::SetBkColor	Sets the current background color.
CDC::SetBkMode	Sets the background mode.
CDC::SetBoundsRect	Controls the accumulation of bounding-rectangle information for the specified device context.
CDC::SetBrushOrg	Specifies the origin for the next brush selected into a device context.
CDC::SetColorAdjustment	Sets the color adjustment values for the device context using the specified values.
CDC::SetDCBrushColor	Sets the current brush color.
CDC::SetDCPenColor	Sets the current pen color.
CDC::SetGraphicsMode	Sets the current graphics mode for the specified device context.
CDC::SetLayout	Changes the layout of a device context (DC).
CDC::SetMapMode	Sets the current mapping mode.
CDC::SetMapperFlags	Alters the algorithm that the font mapper uses when it maps logical fonts to physical fonts.
CDC::SetMiterLimit	Sets the limit for the length of miter joins for the device context.
CDC::SetOutputDC	Sets m_hDC, the output device context.
CDC::SetPixel	Sets the pixel at the specified point to the closest approximation of the specified color.
CDC::SetPixelV	Sets the pixel at the specified coordinates to the closest approximation of the specified color. SetPixelV is faster than SetPixel because it does not need to return the color value of the point actually painted.
CDC::SetPolyFillMode	Sets the polygon-filling mode.
CDC::SetROP2	Sets the current drawing mode.
CDC::SetStretchBltMode	Sets the bitmap-stretching mode.
CDC::SetTextAlign	Sets the text-alignment flags.
CDC::SetTextCharacterExtra	Sets the amount of intercharacter spacing.
CDC::SetTextColor	Sets the text color.
CDC::SetTextJustification	Adds space to the break characters in a string.
CDC::SetViewportExt	Sets the x- and y-extents of the viewport.
CDC::SetViewportOrg	Sets the viewport origin.
CDC::SetWindowExt	Sets the x- and y-extents of the associated window.
CDC::SetWindowOrg	Sets the window origin of the device context.
CDC::SetWorldTransform	Sets the current world-space to page-space transformation.
CDC::StartDoc	Informs the device driver that a new print job is starting.
CDC::StartPage	Informs the device driver that a new page is starting.
CDC::StretchBlt	Moves a bitmap from a source rectangle and device into a destination rectangle, stretching or compressing the bitmap if necessary to fit the dimensions of the destination rectangle.
CDC::StrokeAndFillPath	Closes any open figures in a path, strikes the outline of the path by using the current pen, and fills its interior by using the current brush.
CDC::StrokePath	Renders the specified path by using the current pen.
CDC::TabbedTextOut	Writes a character string at a specified location, expanding tabs to the values specified in an array of tab-stop positions.
CDC::TextOut	Writes a character string at a specified location using the currently selected font.
CDC::TransparentBlt	Transfers a bit-block of color data from the specified source device context into a destination device context, rendering a specified color transparent in the transfer.
CDC::UpdateColors	Updates the client area of the device context by matching the current colors in the client area to the system palette on a pixel-by-pixel basis.
CDC::WidenPath	Redefines the current path as the area that would be painted if the path were stroked using the pen currently selected into the device context.

Public Operators

Name	Description
CDC::operator HDC	Retrieves the handle of the device context.

Public Data Members

Name	Description
CDC::m_hAttribDC	The attribute-device context used by this CDC object.
CDC::m_hDC	The output-device context used by this CDC object.

Remarks

The CDC object provides member functions for working with a device context, such as a display or printer, as well as members for working with a display context associated with the client area of a window.

Do all drawing through the member functions of a CDC object. The class provides member functions for device-context operations, working with drawing tools, type-safe graphics device interface (GDI) object selection, and working with colors and palettes. It also provides member functions for getting and setting drawing attributes, mapping, working with the viewport, working with the window extent, converting coordinates, working with regions, clipping, drawing lines, and drawing simple shapes, ellipses, and polygons. Member functions are also provided for drawing text, working with fonts, using printer escapes, scrolling, and playing metafiles.

To use a CDC object, construct it, and then call its member functions that parallel Windows functions that use device contexts.

Note

Under Windows 95/98, all screen coordinates are limited to 16 bits. Therefore, an int passed to a CDC member function must lie in the range –32768 to 32767.

For specific uses, the Microsoft Foundation Class Library provides several classes derived from CDC . CPaintDC encapsulates calls to BeginPaint and EndPaint. CClientDC manages a display context associated with a window's client area. CWindowDC manages a display context associated with an entire window, including its frame and controls. CMetaFileDC associates a device context with a metafile.

CDC provides two member functions, GetLayout and SetLayout, for reversing the layout of a device context, which does not inherit its layout from a window. Such right-to-left orientation is necessary for applications written for cultures, such as Arabic or Hebrew, where the character layout is not the European standard.

CDC contains two device contexts, m_hDC and m_hAttribDC, which, on creation of a CDC object, refer to the same device. CDC directs all output GDI calls to m_hDC and most attribute GDI calls to m_hAttribDC. (An example of an attribute call is GetTextColor, while SetTextColor is an output call.)

For example, the framework uses these two device contexts to implement a CMetaFileDC object that will send output to a metafile while reading attributes from a physical device. Print preview is implemented in the framework in a similar fashion. You can also use the two device contexts in a similar way in your application-specific code.

There are times when you may need text-metric information from both the m_hDC and m_hAttribDC device contexts. The following pairs of functions provide this capability:

Uses m_hAttribDC	Uses m_hDC
GetTextExtent	GetOutputTextExtent
GetTabbedTextExtent	GetOutputTabbedTextExtent
GetTextMetrics	GetOutputTextMetrics
GetCharWidth	GetOutputCharWidth

For more information on CDC, see Device Contexts.

Inheritance Hierarchy

CObject

CDC

Requirements

Header: afxwin.h