---

Inside Macintosh: Imaging with QuickDraw

Previous | Chapter Top | Chapter Contents | Next |

Using Pictures

To create a picture, you should

• use the OpenCPicture function to create a Picture record and begin defining the picture
• issue QuickDraw drawing commands, which are collected in the Picture record
• use the PicComment procedure to include picture comments in the picture definition (optional)
• use the ClosePicture procedure to conclude the picture definition

To open an existing picture, you should

• use File Manager routines to get a picture stored in a 'PICT' file
• use the GetPicture function to get a picture stored in a 'PICT' resource
• use the Scrap Manager function GetScrap to get a picture stored in the scrap

To draw a picture, you should use the DrawPicture procedure.

To save a picture, you should

• use File Manager routines to save the picture in a 'PICT' file
• use Resource Manager routines to save the picture in a 'PICT' resource
• use the Scrap Manager function PutScrap to place the picture in the scrap

To conserve memory, you can spool large pictures to and from disk storage; you should

• write your own low-level procedures--using File Manager routines--that read and write temporary 'PICT' files to disk
• use the SetStdCProcs procedure for a color graphics port (or the SetStdProcs procedure for a basic graphics port) and replace QuickDraw's standard low-level procedures StdGetPic and StdPutPic with your own procedures for reading and writing temporary 'PICT' files to disk

To gather information about a single picture, pixel map, or bitmap, you should

• use the GetPictInfo function to get information about a picture, or use the GetPixMapInfo function to get information about a pixel map or bitmap
• use the Palette record or the ColorTable record, the handles of which are returned by these functions in a PictInfo record, to examine the colors collected from the picture, pixel map, or bitmap
• use the FontSpec record, the handle of which is returned by GetPictInfo in a PictInfo record, to examine the fonts contained in the picture
• use the CommentSpec record, the handle of which is returned by GetPictInfo in a PictInfo record, to examine the picture comments contained in the picture
• examine the rest of the fields of the PictInfo record for additional information--such as pixel depth or optimal resolution--about the picture, pixel map, or bitmap
• use the Memory Manager procedure DisposeHandle to release the memory occupied by the PictInfo , FontSpec , and CommentSpec records; use the Palette Manager procedure DisposePalette to release the memory occupied by a Palette record; and use the Color QuickDraw procedure DisposeCTable to release the memory occupied by a ColorTable record when you are finished with the information collected by the GetPictInfo function

To gather information about multiple pictures, pixel maps, and bitmaps, you should

• use the NewPictInfo function to begin collecting pictures, pixel maps, and bitmaps for your survey
• use the RecordPictInfo function to add the information for a picture to your survey
• use the RecordPixMapInfo function to add the information for a pixel map or bitmap to your survey
• use the RetrievePictInfo function to return the collected information in a PictInfo record
• use the Palette record or the ColorTable record, the handles of which are returned in the PictInfo record, to examine the colors collected from the pictures, pixel maps, and bitmaps
• use the FontSpec record, the handle of which is returned in the PictInfo record, to examine the fonts contained in the collected pictures
• use the CommentSpec record, the handle of which is returned in the PictInfo record, to examine the picture comments contained in the collected pictures
• examine the rest of the fields of the PictInfo record for additional information about the pictures, pixel maps, and bitmaps in your survey
• use the DisposePictInfo function to dispose of the private data structures allocated by the NewPictInfo function; use the Memory Manager procedure DisposeHandle to release the memory occupied by PictInfo , FontSpec , and CommentSpec records; use the Palette Manager procedure DisposePalette to release the memory occupied by a Palette record; and use the Color QuickDraw procedure DisposeCTable to release the memory occupied by a ColorTable record when you are finished with the information collected by NewPictInfo

When you are finished using a picture (such as when you close the window containing it), you should

• release the memory it occupies by calling the KillPicture procedure if the picture is not stored in a 'PICT' resource
• release the memory it occupies by calling the Resource Manager procedure ReleaseResource if the picture is stored in a 'PICT' resource

Before using the routines described in this chapter, you must use the InitGraf procedure, described in the chapter "Basic QuickDraw" in this book, to initialize QuickDraw. The routines in this chapter are available on all computers running System 7--including those supporting only basic QuickDraw. To test for the existence of System 7, use the Gestalt function with the gestaltSystemVersion selector. Test the low-order word in the response parameter; if the value is $0700 or greater, all of the routines in this chapter are supported.

On computers running only basic QuickDraw, the Picture Utilities return NIL in place of handles to Palette and ColorTable records.

Creating and Drawing Pictures

Opening and Drawing Pictures

Saving Pictures

Gathering Picture Information

Previous | Chapter Top | Chapter Contents | Next