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Graphical Output: Simple Drawing and Printing 5

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Handling Images
Printing

Handling Images

The Image class provides the base class for all the image classes in System::Drawing, especially the Bitmap class, which is used to represent and manipulate images in a number of formats. Bitmap class encapsulates a GDI+ bitmap, which consists of the pixel data for a graphics image and its attributes. A Bitmap is an object used to work with images defined by pixel data. The following tables list the members exposed by the Bitmap type.

Public Constructors
Symbol
Name	Description
Bitmap	Overloaded. Initializes a new instance of the Bitmap class.
Table 4

Public Properties
Symbol
Name	Description
Flags	Gets attribute flags for the pixel data of this Image. (Inherited from Image.)
FrameDimensionsList	Gets an array of GUIDs that represent the dimensions of frames within this Image. (Inherited from Image.)
Height	Gets the height, in pixels, of this Image. (Inherited from Image.)
HorizontalResolution	Gets the horizontal resolution, in pixels per inch, of this Image. (Inherited from Image.)
Palette	Gets or sets the color palette used for this Image. (Inherited from Image.)
PhysicalDimension	Gets the width and height of this image. (Inherited from Image.)
PixelFormat	Gets the pixel format for this Image. (Inherited from Image.)
PropertyIdList	Gets IDs of the property items stored in this Image. (Inherited from Image.)
PropertyItems	Gets all the property items (pieces of metadata) stored in this Image. (Inherited from Image.)
RawFormat	Gets the format of this Image. (Inherited from Image.)
Size	Gets the width and height, in pixels, of this image. (Inherited from Image.)
Tag	Gets or sets an object that provides additional data about the image. (Inherited from Image.)
VerticalResolution	Gets the vertical resolution, in pixels per inch, of this Image. (Inherited from Image.)
Width	Gets the width, in pixels, of this Image. (Inherited from Image.)
Table 5

Public Methods
Symbol
Name	Description
Clone	Overloaded. Creates a copy of the section of this Bitmap defined with a specified PixelFormat.
CreateObjRef	Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)
Dispose	Releases all resources used by this Image. (Inherited from Image.)
Equals	Overloaded. Determines whether two Object instances are equal. (Inherited from Object.)
FromFile	Overloaded. Creates an Image from the specified file. (Inherited from Image.)
FromHbitmap	Overloaded. Creates a Bitmap from a Windows handle. (Inherited from Image.)
FromHicon	Creates a Bitmap from a Windows handle to an icon.
FromResource	Creates a Bitmap from the specified Windows resource.
FromStream	Overloaded. Creates an Image from the specified data stream. (Inherited from Image.)
GetBounds	Gets the bounds of the image in the specified unit. (Inherited from Image.)
GetEncoderParameterList	Returns information about the parameters supported by the specified image encoder. (Inherited from Image.)
GetFrameCount	Returns the number of frames of the specified dimension. (Inherited from Image.)
GetHashCode	Serves as a hash function for a particular type. GetHashCode is suitable for use in hashing algorithms and data structures like a hash table. (Inherited from Object.)
GetHbitmap	Overloaded. Creates a GDI bitmap object from a GDI+ Bitmap.
GetHicon	Returns the handle to an icon.
GetHowFromImage	(Inherited from Image.)
GetLifetimeService	Retrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
GetPixel	Gets the color of the specified pixel in this Bitmap.
GetPixelFormatSize	Returns the color depth, in number of bits per pixel, of the specified pixel format. (Inherited from Image.)
GetPropertyItem	Gets the specified property item from this Image. (Inherited from Image.)
GetThumbnailImage	Returns a thumbnail for this Image. (Inherited from Image.)
GetType	Gets the Type of the current instance. (Inherited from Object.)
InitializeLifetimeService	Obtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)
IsAlphaPixelFormat	Returns a value that indicates whether the pixel format for this Image contains alpha information. (Inherited from Image.)
IsCanonicalPixelFormat	Returns a value that indicates whether the pixel format is 32 bits per pixel. (Inherited from Image.)
IsExtendedPixelFormat	Returns a value that indicates whether the pixel format is 64 bits per pixel. (Inherited from Image.)
LockBits	Overloaded. Locks a Bitmap into system memory.
MakeTransparent	Overloaded. Makes the default transparent color transparent for this Bitmap.
ReferenceEquals	Determines whether the specified Object instances are the same instance. (Inherited from Object.)
RemovePropertyItem	Removes the specified property item from this Image. (Inherited from Image.)
RotateFlip	This method rotates, flips, or rotates and flips the Image. (Inherited from Image.)
Save	Overloaded. Saves this image to the specified stream in the specified format. (Inherited from Image.)
SaveAdd	Overloaded. Adds the information in the specified Image to this Image. The specified EncoderParameters determine how the new information is incorporated into the existing image. (Inherited from Image.)
SelectActiveFrame	Selects the frame specified by the dimension and index. (Inherited from Image.)
SetPixel	Sets the color of the specified pixel in this Bitmap.
SetPropertyItem	Stores a property item (piece of metadata) in this Image. (Inherited from Image.)
SetResolution	Sets the resolution for this Bitmap.
ToString	Returns a String that represents the current Object. (Inherited from Object.)
UnlockBits	Unlocks this Bitmap from system memory.
Table 6

Protected Methods
Symbol
Name	Description
Finalize	Allows an Object to attempt to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
MemberwiseClone	Overloaded. (Inherited from MarshalByRefObject.)
Table 7

You can see the formats that are supported by looking at the ImageFormat enumeration. The following exercise illustrates how to display a bitmap on a form.

27. Find the Form1_Paint function that handles Paint events. You need to display the bitmap in the Paint event handler so that it gets redisplayed when the form needs to refresh itself. Add the following code to Form_Paint:

// Draw the image

Bitmap^ bmp = gcnew Bitmap(L"ramp1.gif");

gr->DrawImage(bmp, 10,10);

Adding codes to display the bitmap in the Paint event handler

The code creates a Bitmap object that reads data from a GIF file. The call to DrawImage then draws the image at position (10, 10) on the form. The image used forms a vertical stripe down the left side of the form. You’ll find the ramp1.gif file in the CppDraw project directory. Copy it into your CppDraw\CppDraw project directory to use it in this code.

28. Build and run the application. You’ll see a bitmap displayed on the form as shown below.

Bitmap displayed on the form

Printing

The System::Drawing::Printing namespace contains the classes that implement the printing functionality within GDI+. Printing isn’t particularly hard, but it can be a rather involved process because of the number of classes involved. The first class you’ll meet when printing is PrintDocument. A PrintDocument object represents your link with a printer and can be used for more than one print job. PrintDocument has four main properties:

DefaultPageSettings, which gets or sets a PageSettings object that represents the default page settings.
DocumentName, which represents the document name.
PrintController, which gets or sets a PrintController object that controls the printing process
PrinterSettings, which gets or sets a PrinterSettings object that controls where and how the document is printed.

The PrinterSettings and PageSettings classes hold data about the printer to be used such as whether different paper trays are available and PageSettings also holds data about the setup of the document, such as page orientation and number of copies.

System.Drawing.Printing Namespace

The System.Drawing.Printing namespace provides print-related services. Typically, you create a new instance of the PrintDocument class, set the properties that describe what to print, and call the Print method to actually print the document. Use the Graphics property to specify the output to print. If you are printing a text file, use StreamReader in the following manner: read one line at a time from the stream and call the DrawString method to draw the line in the graphics object. The DrawText methods of the TextRenderer class are not supported for printing. Instead, use the DrawString methods of the Graphics class. When implemented in a derived class, the PrintController controls how a PrintDocument is printed. The PrintDocument.Print method invokes the print controller's OnStartPrint, OnEndPrint, OnStartPage, and OnEndPage methods, which in turn tell the printer how to print the document. The print-preview process uses a specialized print controller, dialog box, and control. Classes within the System.Drawing.Printing namespace are not supported for use within a Windows service or ASP.NET application or service. Attempting to use these classes from within one of these application types may produce unexpected problems, such as diminished service performance and run-time exceptions.

Classes
Symbol
Class	Description
InvalidPrinterException	Represents the exception that is thrown when you try to access a printer using printer settings that are not valid.
Margins	Specifies the dimensions of the margins of a printed page.
MarginsConverter	Provides a MarginsConverter for Margins.
PageSettings	Specifies settings that apply to a single, printed page.
PaperSize	Specifies the size of a piece of paper.
PaperSource	Specifies the paper tray from which the printer gets paper.
PreviewPageInfo	Specifies print preview information for a single page. This class cannot be inherited.
PreviewPrintController	Specifies a print controller that displays a document on a screen as a series of images.
PrintController	Controls how a document is printed.
PrintDocument	Defines a reusable object that sends output to a printer.
PrinterResolution	Represents the resolution supported by a printer.
PrinterSettings	Specifies information about how a document is printed, including the printer that prints it.
PrinterSettings.PaperSizeCollection	Contains a collection of PaperSize objects.
PrinterSettings.PaperSourceCollection	Contains a collection of PaperSource objects.
PrinterSettings.PrinterResolutionCollection	Contains a collection of PrinterResolution objects.
PrinterSettings.StringCollection	Contains a collection of String objects.
PrinterUnitConvert	Specifies a series of conversion methods that are useful when interoperating with the Win32 printing API. This class cannot be inherited.
PrintEventArgs	Provides data for the BeginPrint and EndPrint events.
PrintingPermission	Controls access to printers. This class cannot be inherited.
PrintingPermissionAttribute	Allows declarative printing permission checks.
PrintPageEventArgs	Provides data for the PrintPage event.
QueryPageSettingsEventArgs	Provides data for the QueryPageSettings event.
StandardPrintController	Specifies a print controller that sends information to a printer.
Table 8

Delegates
Symbol
Delegate	Description
PrintEventHandler	Represents the method that will handle the BeginPrint or EndPrint event of a PrintDocument.
PrintPageEventHandler	Represents the method that will handle the PrintPage event of a PrintDocument.
QueryPageSettingsEventHandler	Represents the method that handles the QueryPageSettings event of a PrintDocument.
Table 9

Enumerations
Symbol
Enumeration	Description
Duplex	Specifies the printer's duplex setting.
PaperKind	Specifies the standard paper sizes.
PaperSourceKind	Standard paper sources.
PrintAction	Specifies the type of print operation occurring.
PrinterResolutionKind	Specifies a printer resolution.
PrinterUnit	Specifies several of the units of measure used for printing.
PrintingPermissionLevel	Specifies the type of printing that code is allowed to do.
PrintRange	Specifies the part of the document to print.
Table 10

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