NAME
OpenScreen -- Open an Intuition screen.
SYNOPSIS
Screen = OpenScreen( NewScreen )
D0 A0
struct Screen *OpenScreen( struct NewScreen * );
or
struct Screen *OpenScreen( struct ExtNewScreen * );Links: Screen NewScreen Screen NewScreen Screen ExtNewScreen
FUNCTION
Opens an Intuition screen according to the specified parameters found in the NewScreen structure.
Does all the allocations, sets up the screen structure and all substructures completely, and links this screen's viewport into Intuition's View structure.
Before you call OpenScreen(), you must initialize an instance of a NewScreen structure. NewScreen is a structure that contains all of the arguments needed to open a screen. The NewScreen structure may be discarded immediately after OpenScreen() returns.
The SHOWTITLE flag is set to TRUE by default when a screen is opened. To change this, you must call the routine ShowTitle.
INPUTS
NewScreen = pointer to an instance of a NewScreen structure.
New for V36: In addition to the information contained in the NewScreen structure, Intuition now recognizes extended data passed in the form of an array of TagItem structures (from <utility/tagitem.h>), commonly called a "tag list."
There are two ways to provide this array. The first is to use the new Intuition entry point OpenScreenTagList and pass the tag list as a parameter. This is the recommended method, and has a convenient format variation for C programs using a variable number of arguments.
An older way used for some V36 development uses the OpenScreen() entry point, and an extension of the NewScreen structure named ExtNewScreen. See the documentation of the flag NS_EXTENDED, below.
While we recommend that you use OpenScreenTagList rather than OpenScreen() when using the extension tag list, we document the tag ID values here, so that all parameters for opening a screen can be found in one place.
NewScreen is initialized with the following information:
Left = initial x-position of your screen (should be zero for releases prior to V36)
Top = initial y-position of the opening screen (Note: Left and Top are specified relative to the Intuition's view, in same resolution as the screen pixels.)
Width = the width for this screen's RastPort
Height = the height for his screen's RastPort, or the constant STDSCREENHEIGHT to get the current default height (at this time guaranteed to be at least 200 rows). The normal width and height for a particular system is stored by the graphics.library in GfxBase->NormalDisplayRows and GfxBase->NormalDisplayColumns. These values will be different depending on factors such as PAL video and overscan.
For V36, a new constant STDSCREENWIDTH is introduced. It serves the similar function for screen width. Both STDSCREENWIDTH and STDSCREENHEIGHT indicate that your screen RastPort is to be the same dimensions as your DisplayClip rectangle. If you do not specify either a standard or custom DisplayClip, the OSCAN_TEXT region will be used, which corresponds to the standard dimensions of V35 and earlier.
Furthermore, if you are using OpenScreenTagList, and you specify STDSCREENWIDTH, and you DO NOT provide a NewScreen pointer, and you DO NOT provide SA_Left, then Intuition will automatically set the LeftEdge of the screen to be the left edge of the screen's DisplayClip region. Likewise for STDSCREENHEIGHT and the screen's TopEdge.
Depth = number of bitplanes
DetailPen = pen number for details (like gadgets or text in title bar) The common value for this pen is 0.
BlockPen = pen number for block fills (like title bar) The common value for this pen is 1.
Type = screen type values Set these flags as desired from the set: CUSTOMSCREEN -- this is your own screen, not a system screen. CUSTOMBITMAP -- this custom screen has bit maps supplied in the bitmap field of the NewScreen structure. Intuition is not to allocate any raster bitmaps. SCREENBEHIND -- your screen will be created behind all other open screens. This allows a program to prepare imagery in the screen, change its colors, and so on, bringing it to the front when it is presentable. SCREENQUIET -- Intuition will not render system screen gadgets or screen title. In concert with the WFLG_RMBTRAP flag on all your screen's windows, this flag will prevent Intuition from rendering into your screen's bitplanes. Without WFLG_RMBTRAP (or using the IDCMP_MENUVERIFY facility to cancel menu operations), this flag will prevent Intuition from clearing your menu bar, which is probably unacceptable. The menu bar layer may still overwrite a portion of your screen bitmap when the screen is opened. (V36: it won't clobber your bits any more.) NS_EXTENDED for this screen to use extended attributes pointed to by the 'Extended' field, below.
ViewModes = the appropriate argument for the data type ViewPort.Modes. These include: HIRES for this screen to be HIRES width. INTERLACE for the display to switch to interlace. SPRITES for this screen to use sprites (the pointer sprite is always displayed) DUALPF for dual-playfield mode (not supported yet) [For V36: The ViewModes field is superceded by a TagItem with tag value SA_DisplayID.]
Font = pointer to the default TextAttr structure for text in this screen and all windows that open in this screen. Text that uses this TextAttr includes title bars of both screen and windows, string gadgets, and menu titles. Of course, IntuiText that specifies a NULL TextAttr field will use the screen/window default fonts. NOTE: Intuition will NOT call OpenDiskFont, so the TextAttr you supply must be in memory. The ways to ensure that are to either use a ROM font (Topaz 8 or 9) or first call OpenDiskFont to load the font, and don't close it until after your screen is successfully opened. [For V36: this is superceded by SA_Font and SA_SysFont.]
DefaultTitle = pointer to a line of text that will be displayed along the screen's title bar. Null terminated, or just a NULL pointer to get no text [For V36: superceded by SA_Title.]
Gadgets = This field should be set to NULL, since no user gadgets may be attached to a screen with the current versions of Intuition.
CustomBitMap = if you're not supplying a custom bitmap, this value is ignored. However, if you have your own display memory that you want used for this screen, the CustomBitMap field should point to the BitMap structure that describes your display memory. See the "Screens" chapter and the "Amiga ROM Kernel Manual" for more information about bitmaps. [For V36: this is superceded by SA_BitMap.]
[ All TagItem extensions below are new for V36.] Extension = if NS_EXTENDED is set in NewScreen.Type, this pointer should point to an array (or chain of arrays) of TagItems, as defined in the include file <utility/tagitem.h>. This field is only defined in the structure ExtNewScreen. The values to use for TagItem.ti_Tag are defined below. We recommend that V36-specific applications use the new Intuition entry point OpenScreenTagList, rather than using this field. The ExtNewScreen structure is a convenient way to give V36 Intuition some information that V34 and earlier Intuition will ignore.
Each TagItem is an optional tagged data structure which identifies an additional parameter to OpenScreen(). The applicable tag ID values for TagItem.ti_Tag and their corresponding data follow.
Several of the tag items are alternative (and overriding) versions to familiar fields in NewScreen. They are:
SA_Left SA_Top SA_Width SA_Height SA_Depth SA_DetailPen SA_BlockPen SA_Title SA_Font SA_Type SA_BitMap (whose existence also implies CUSTOMBITMAP).
Several tags are Booleans, which means that depending on whether their corresponding ti_Data field is zero (FALSE) or non-zero (TRUE), they specify Boolean attributes. The ones corresponding to Boolean flags in the NewScreen.Type field are:
SA_ShowTitle SA_Behind (equiv. to SCREENBEHIND) SA_Quiet (equiv. to SCREENQUIET)
The following tags provide extended information to Intuition when creating a screen:
SA_DisplayID: ti_Data is a 32-bit extended display mode ID as defined in <graphics/displayinfo.h>
SA_Overscan: ti_Data contains a defined constant specifying one of the system standard overscan dimensions appropriate for the display mode of the screen. Used with the Width and Height dimensions STDSCREENWIDTH and STDSCREEN, this makes it trivial to open an overscanned or standard dimension screen. You may also hand-pick your various dimensions for overscanned or other screens, by specifying screen position and dimensions explicitly, and by using SA_DClip to explicitly specify an overscanned DisplayClip region.
The values for ti_Data of this tag are as follows:
OSCAN_TEXT - Text Overscan region. A region which is completely on screen and readable ("text safe"). A preferences data setting, this is backward equivalent with the old MoreRows, and specifies the DisplayClip and default dimensions of the Workbench screen. This is the default.
OSCAN_STANDARD - Also a preferences setting, this specifies a rectangle whose edges are "just out of view." This yields the most efficient position and dimensions of on-monitor presentations, such as games and artwork.
OSCAN_MAX - This is the largest rectangular region that the graphics library can handle "comfortably" for a given mode. Screens can smoothly scroll (hardware pan) within this region, and any DisplayClip or Screen region within this rectangle is also legal. It is not a preferences item, but reflects the limits of the graphics hardware and software.
OSCAN_VIDEO - This is the largest region that the graphics library can display, comfortable or not. There is no guarantee that all smaller rectangles are valid. This region is typically out of sight on any monitor or TV, but provides our best shot at "edge-to-edge" video generation.
Remember, using overscan drastically effects memory use and chip memory bandwidth. Always use the smallest (standard) overscan region that works for your application.
SA_DClip: ti_Data is a pointer to a rectangle which explicitly defines a DisplayClip region for this screen. See QueryOverscan for the role of the DisplayClip region.
Except for overscan display screens, this parameter is unnecessary, and specifying a standard value using SA_Overscan is normally an easier way to get overscan.
SA_AutoScroll: this is a Boolean tag item, which specifies that this screens is to scroll automatically when the mouse pointer reaches the edge of the screen. The operation of this requires that the screen dimensions be larger than its DisplayClip region.
SA_PubName: If this field is present (and ti_Data is non-NULL), it means that the screen is a public screen, and that the public screen name string is pointed to by ti_Data. Public screens are opened in "PRIVATE" mode and must be made public using PubScreenStatus.
SA_Pens: The ti_Data field (if non-NULL) points to a UWORD array of pen specification, as defined for struct DrawInfo. This array will be used to initialize the screen's DrawInfo.dri_Pens array.
SA_Pens is also used to decide that a screen is ready to support the full-blown "new look" graphics. If you want the 3D embossed look, you must provide this tag, and the ti_Data value cannot be NULL. If it points to a "minimal" array, containing just the terminator ~0, you can specify "new look" without providing any values for the pen array.
The following two tag items specify the task and signal to be issued to notify when the last "visitor" window closes on a public screen. This support is to assist envisioned public screen manager programs.
SA_PubTask: Task to be signalled. If absent (and SA_PubSig is valid), use the task which called OpenScreen() or OpenScreenTagList).
SA_PubSig: Data is a UBYTE signal number (not flag) used to notify a task when the last visitor window closes on a public screen.
SA_Colors: ti_Data points to an array of ColorSpec structures (terminated with ColorIndex = -1) which specify initial values of the screen's color palette.
SA_FullPalette: this is a Boolean attribute. Prior to V36, there were just 7 RGB color values that Intuition maintained in its user preferences (playfield colors 0-3, and colors 17-19 for the sprite). When opening a screen, the color map for the screens viewport is first initialized by graphics (graphics.library/GetColorMap()) then these seven values are overridden to take the preferences values.
In V36, Intuition maintains a full set of 32 preferences colors. If you specify TRUE for SA_FullPalette, Intuition will override ALL color map entries with its full suite of preferred colors.
SA_ErrorCode: ti_Data points to a ULONG in which Intuition will stick an extended error code if OpenScreenTagList fails. Values are of this include 0, for success, and: OSERR_NOMONITOR - monitor for display mode not available. OSERR_NOCHIPS - you need newer custom chips for display mode. OSERR_NOMEM - couldn't get normal memory OSERR_NOCHIPMEM - couldn't get chip memory OSERR_PUBNOTUNIQUE - public screen name already used OSERR_UNKNOWNMODE - don't recognize display mode requested
NOTE: These values are not the same as some similar return values defined in graphics.library/ModeNotAvailable.
SA_SysFont: ti_Data selects one of the system standard fonts specified in preferences. This tag item overrides the NewScreen.Font field and the SA_Font tag item.
Values recognized in ti_Data at present are: 0 - old DefaultFont, fixed-width, the default. 1 - Workbench screen preferred font. You have to be very font sensitive to handle a proportional or larger than traditional screen font.
NOTE WELL: if you select sysfont 1, windows opened on your screen will not inherit the screen font, but rather the window RastPort will be initialized to the old-style DefaultFont (sysfont 0).
RESULT If all is well, returns the pointer to your new screen If anything goes wrong, returns NULL, with further error specification in the variable pointed to by the SA_ErrorCode data field (V36 and later).
NOTE By default, AmigaDOS requesters related to your process are put on the Workbench screen (these are messages like "Disk Full"). If you wish them to show up on custom screens, DOS must be told. This fragment shows the procedure. More information is available in the AmigaDOS manuals. Sample code fragment:
#include "libraries/dosextens.h" ... struct Process *process; struct Window *window; APTR temp; ... process = (struct Process *) FindTask(NULL); temp = process->pr_WindowPtr; (save old value) process->pr_WindowPtr = (APTR) window; ( use a pointer to any open window on your screen ) ... your code goes here ... process->pr_WindowPtr = temp; ( restore value BEFORE CloseWindow ) CloseWindow(window);
BUGS
SEE ALSO
OpenScreenTagList, OpenWindow, PrintIText, CloseScreen, QueryOverscan PubScreenStatus, The Intuition Reference Manual, utility/tagitem.h, graphics.library/ModeNotAvailable, diskfont.library/OpenDiskFont, graphics.library/GetColorMap