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Manual Pages for UNIX Operating System command usage for man Tk_GetImageMasterData

Tk Library Procedures Tk_CreateImageType(3TK)

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NAME

Tk_CreateImageType, Tk_GetImageMasterData, Tk_InitImageArgs

- define new kind of image

SYNOPSIS

#include

Tk_CreateImageType(typePtr)

ClientData |

Tk_GetImageMasterData(interp, name, typePtrPtr) |

Tk_InitImageArgs(interp, argc, argvPtr) |

ARGUMENTS |

Tk_ImageType *typePtr (in) ||

Tcl_Interp *interp (in) ||

Interpreter in which | image was created. | CONST char *name (in) || Name of existing | image. |

Tk_ImageType **typePtrPtr (out) ||

Points to word in | which to store a | pointer to type | information for the | given image, if it | exists. | int argc (in) || Number of arguments | char ***argvPtr (in/out) || Pointer to argument | list

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Tk Last change: 8.3 1

Tk Library Procedures Tk_CreateImageType(3TK)

DESCRIPTION

Tk_CreateImageType is invoked to define a new kind of image.

An image type corresponds to a particular value of the type argument for the image create command. There may exist any number of different image types, and new types may be

defined dynamically by calling Tk_CreateImageType. For

example, there might be one type for 2-color bitmaps,

another for multi-color images, another for dithered images,

another for video, and so on. The code that implements a new image type is called an image manager. It consists of a collection of procedures plus three different kinds of data structures. The first data

structure is a Tk_ImageType structure, which contains the

name of the image type and pointers to five procedures pro-

vided by the image manager to deal with images of this type:

typedef struct Tk_ImageType {

char *name;

Tk_ImageCreateProc *createProc;

Tk_ImageGetProc *getProc;

Tk_ImageDisplayProc *displayProc;

Tk_ImageFreeProc *freeProc;

Tk_ImageDeleteProc *deleteProc;

} Tk_ImageType;

The fields of this structure will be described in later sub-

sections of this entry. The second major data structure manipulated by an image manager is called an image master; it contains overall information about a particular image, such as the values of

the configuration options specified in an image create com-

mand. There will usually be one of these structures for each invocation of the image create command. The third data structure related to images is an image instance. There will usually be one of these structures for

each usage of an image in a particular widget. It is possi-

ble for a single image to appear simultaneously in multiple

widgets, or even multiple times in the same widget. Furth-

ermore, different instances may be on different screens or displays. The image instance data structure describes things that may vary from instance to instance, such as

colors and graphics contexts for redisplay. There is usu-

ally one instance structure for each -image option specified

for a widget or canvas item. The following subsections describe the fields of a

Tk_ImageType in more detail.

NAME

Tk Last change: 8.3 2

Tk Library Procedures Tk_CreateImageType(3TK)

typePtr->name provides a name for the image type. Once

Tk_CreateImageType returns, this name may be used in image

create commands to create images of the new type. If there already existed an image type by this name then the new image type replaces the old one. PORTABILITY In Tk 8.2 and earlier, the createProc below had a different signature. If you want to compile an image type using the

old interface which should still run on all Tcl/Tk versions,

compile it with the flag -DUSE_OLD_IMAGE. Further on, if you

are using Stubs, you need to call the function

Tk_InitImageArgs(interp, argc, &argv) first in your

createProc. See below for a description of this function. CREATEPROC

typePtr->createProc provides the address of a procedure for

Tk to call whenever image create is invoked to create an

image of the new type. typePtr->createProc must match the

following prototype:

typedef int Tk_ImageCreateProc(

Tcl_Interp *interp,

char *name, int objc,

Tcl_Obj *CONST objv[],

Tk_ImageType *typePtr,

Tk_ImageMaster master,

ClientData *masterDataPtr); The interp argument is the interpreter in which the image command was invoked, and name is the name for the new image, which was either specified explicitly in the image command or generated automatically by the image command. The objc and objv arguments describe all the configuration options for the new image (everything after the name argument to image). The master argument is a token that refers to Tk's information about this image; the image manager must return

this token to Tk when invoking the Tk_ImageChanged pro-

cedure. Typically createProc will parse objc and objv and create an image master data structure for the new image.

createProc may store an arbitrary one-word value at *master-

DataPtr, which will be passed back to the image manager when other callbacks are invoked. Typically the value is a pointer to the master data structure for the image. If createProc encounters an error, it should leave an error

message in interp->result and return TCL_ERROR; otherwise

it should return TCL_OK.

createProc should call Tk_ImageChanged in order to set the

size of the image and request an initial redisplay. Tk Last change: 8.3 3

Tk Library Procedures Tk_CreateImageType(3TK)

GETPROC

typePtr->getProc is invoked by Tk whenever a widget calls

Tk_GetImage to use a particular image. This procedure must

match the following prototype:

typedef ClientData Tk_ImageGetProc(

Tk_Window tkwin,

ClientData masterData); The tkwin argument identifies the window in which the image will be used and masterData is the value returned by createProc when the image master was created. getProc will usually create a data structure for the new instance, including such things as the resources needed to display the

image in the given window. getProc returns a one-word token

for the instance, which is typically the address of the instance data structure. Tk will pass this value back to the image manager when invoking its displayProc and freeProc procedures. DISPLAYPROC

typePtr->displayProc is invoked by Tk whenever an image

needs to be displayed (i.e., whenever a widget calls

Tk_RedrawImage). displayProc must match the following pro-

totype:

typedef void Tk_ImageDisplayProc(

ClientData instanceData, Display *display, Drawable drawable, int imageX, int imageY, int width, int height, int drawableX, int drawableY); The instanceData will be the same as the value returned by getProc when the instance was created. display and drawable

indicate where to display the image; drawable may be a pix-

map rather than the window specified to getProc (this is

usually the case, since most widgets double-buffer their

redisplay to get smoother visual effects). imageX, imageY, width, and height identify the region of the image that must be redisplayed. This region will always be within the size of the image as specified in the most recent call to

Tk_ImageChanged. drawableX and drawableY indicate where in

drawable the image should be displayed; displayProc should display the given region of the image so that point (imageX, imageY) in the image appears at (drawableX, drawableY) in drawable. FREEPROC Tk Last change: 8.3 4

Tk Library Procedures Tk_CreateImageType(3TK)

typePtr->freeProc contains the address of a procedure that

Tk will invoke when an image instance is released (i.e.,

when Tk_FreeImage is invoked). This can happen, for exam-

ple, when a widget is deleted or a image item in a canvas is deleted, or when the image displayed in a widget or canvas

item is changed. freeProc must match the following proto-

type:

typedef void Tk_ImageFreeProc(

ClientData instanceData, Display *display); The instanceData will be the same as the value returned by getProc when the instance was created, and display is the display containing the window for the instance. freeProc should release any resources associated with the image instance, since the instance will never be used again. DELETEPROC

typePtr->deleteProc is a procedure that Tk invokes when an

image is being deleted (i.e. when the image delete command is invoked). Before invoking deleteProc Tk will invoke freeProc for each of the image's instances. deleteProc must match the following prototype:

typedef void Tk_ImageDeleteProc(

ClientData masterData); The masterData argument will be the same as the value stored in *masterDataPtr by createProc when the image was created. deleteProc should release any resources associated with the image.

TK_GETIMAGEMASTERDATA

The procedure Tk_GetImageMasterData may be invoked to |

retrieve information about an image. For example, an image | manager can use this procedure to locate its image master | data for an image. If there exists an image named name in | the interpreter given by interp, then *typePtrPtr is filled | in with type information for the image (the typePtr value |

passed to Tk_CreateImageType when the image type was |

registered) and the return value is the ClientData value | returned by the createProc when the image was created (this | is typically a pointer to the image master data structure). | If no such image exists then NULL is returned and NULL is | stored at *typePtrPtr.

TK_INITIMAGEARGS

The function Tk_InitImageArgs converts the arguments of the |

createProc from objects to strings when necessary. When not | using stubs, not using the old interface, or running under |

an older (pre-8.3) Tk version, this function has no effect. |

This function makes porting older image handlers to the new | Tk Last change: 8.3 5

Tk Library Procedures Tk_CreateImageType(3TK)

interface a lot easier: After running this function, the | arguments are guaranteed to be in string format, no matter | how Tk deliverd them. |

ATTRIBUTES |

See attributes(5) for descriptions of the following attri- |

butes: |

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| ATTRIBUTE TYPE | ATTRIBUTE VALUE| |

|____________________|__________________|_ |

| Availability | runtime/tk-8 | |

|____________________|__________________|_ |

| Interface Stability| Uncommitted | |

|____________________|_________________| ||||

NOTES | Source for Tk is available on http://opensolaris.org. | Tk Last change: 8.3 6

Manual Pages for UNIX Operating System command usage for man Tk_GetImageMasterData

NAME

Tk_CreateImageType, Tk_GetImageMasterData, Tk_InitImageArgs

SYNOPSIS

Tk_GetImageMasterData(interp, name, typePtrPtr) |

DESCRIPTION

NAME

message in interp->result and return TCL_ERROR; otherwise

The procedure Tk_GetImageMasterData may be invoked to |

SEE ALSO |

ATTRIBUTES |

| ATTRIBUTE TYPE | ATTRIBUTE VALUE| |