Intuition Screens - Revision history

Costel Mincea: Text replacement - "" to ""

2025-01-26T19:24:32Z

Text replacement - "<syntaxhighlight>" to "<syntaxhighlight lang="C" line>"

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	Whenever a new screen is created, Intuition also creates an auxiliary data structure called a DrawInfo. The DrawInfo structure provides information Intuition uses to support the 3D look and specifies graphical information for applications that use the screen. The information includes such items as aspect ratio (resolution), font, number of colors and drawing pens.		Whenever a new screen is created, Intuition also creates an auxiliary data structure called a DrawInfo. The DrawInfo structure provides information Intuition uses to support the 3D look and specifies graphical information for applications that use the screen. The information includes such items as aspect ratio (resolution), font, number of colors and drawing pens.

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	struct DrawInfo		struct DrawInfo
	{		{
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	Using the pen specification of an existing public screen is a bit more involved. First, the application must get a pointer to the screen structure of the public screen using the LockPubScreen() call. A copy of the screen's DrawInfo structure may then be obtained by calling GetScreenDrawInfo(). The DrawInfo structure contains a copy of the pen specification for the screen that can be used in the OpenScreenTagList() call with the SA_Pens tag. The pen array is copied to the data structures of the new screen (it is not kept as a pointer to the information passed), so the application may immediately call FreeScreenDrawInfo() and UnlockPubScreen() after the new screen is open.		Using the pen specification of an existing public screen is a bit more involved. First, the application must get a pointer to the screen structure of the public screen using the LockPubScreen() call. A copy of the screen's DrawInfo structure may then be obtained by calling GetScreenDrawInfo(). The DrawInfo structure contains a copy of the pen specification for the screen that can be used in the OpenScreenTagList() call with the SA_Pens tag. The pen array is copied to the data structures of the new screen (it is not kept as a pointer to the information passed), so the application may immediately call FreeScreenDrawInfo() and UnlockPubScreen() after the new screen is open.

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	/* publicscreen.c		/* publicscreen.c
	** open a screen with the pens from a public screen.		** open a screen with the pens from a public screen.
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	When opening a window in an overscanned screen, it is often useful to open it relative to the visible part of the screen rather than relative to the entire screen. Use QueryOverscan() to find the overscan region and where the screen is positioned relative to it.		When opening a window in an overscanned screen, it is often useful to open it relative to the visible part of the screen rather than relative to the entire screen. Use QueryOverscan() to find the overscan region and where the screen is positioned relative to it.

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	LONG QueryOverscan(ULONG displayID, struct Rectangle *rect, WORD overscanType );		LONG QueryOverscan(ULONG displayID, struct Rectangle *rect, WORD overscanType );
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	This example was taken from [[Intuition_Windows\|Intuition Windows]] in the section "Visible Display Sized Window Example". The complete example is reproduced there.		This example was taken from [[Intuition_Windows\|Intuition Windows]] in the section "Visible Display Sized Window Example". The complete example is reproduced there.

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	/* this technique returns the text overscan rectangle of the screen that we		/* this technique returns the text overscan rectangle of the screen that we
	** are opening on. If you really need the actual value set into the display		** are opening on. If you really need the actual value set into the display
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	==== doublebuffer.c ====		==== doublebuffer.c ====

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	/*		/*
	* doublebuffer.c - shows double-buffering, attached screens, menu lending		* doublebuffer.c - shows double-buffering, attached screens, menu lending
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	ScreenToFront() and ScreenToBack() make a screen either the frontmost or the backmost screen. If an application needs to render into a screen before the screen becomes visible to the user, the screen may be opened behind all other screens and later moved to the front when ready with ScreenToFront().		ScreenToFront() and ScreenToBack() make a screen either the frontmost or the backmost screen. If an application needs to render into a screen before the screen becomes visible to the user, the screen may be opened behind all other screens and later moved to the front when ready with ScreenToFront().

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	VOID ScreenToFront( struct Screen * );		VOID ScreenToFront( struct Screen * );
	VOID ScreenToBack ( struct Screen * );		VOID ScreenToBack ( struct Screen * );
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	The MoveScreen() function moves the screen origin by the number of pixels specified in dx and dy.		The MoveScreen() function moves the screen origin by the number of pixels specified in dx and dy.

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	VOID MoveScreen( struct Screen *myscreen, WORD dx, WORD dy );		VOID MoveScreen( struct Screen *myscreen, WORD dx, WORD dy );
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	Three other functions used with screens are DisplayBeep(), ShowTitle() and GetScreenData(). DisplayBeep() flashes the screen colors to inform the user of an error or problem.		Three other functions used with screens are DisplayBeep(), ShowTitle() and GetScreenData(). DisplayBeep() flashes the screen colors to inform the user of an error or problem.

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	VOID DisplayBeep( struct Screen *myscreen );		VOID DisplayBeep( struct Screen *myscreen );
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	ShowTitle() determines whether the screen's title bar will be displayed in front of or behind any backdrop windows on the screen.		ShowTitle() determines whether the screen's title bar will be displayed in front of or behind any backdrop windows on the screen.

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	VOID ShowTitle( struct Screen *myscreen, BOOL infront );		VOID ShowTitle( struct Screen *myscreen, BOOL infront );
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Daniel Jedlicka: /* Function Reference */

2017-04-14T07:08:53Z

Function Reference

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	\| Query a screen attribute.		\| Query a screen attribute.
	\|-		\|-
	\| GetScreenAttr()/GetScreenAttrsA()		\| GetScreenAttr() / GetScreenAttrsA()
	\| Query screen attributes.		\| Query screen attributes.
	\|-		\|-

Steven Solie: /* Preset Overscan Values */

2015-11-03T20:39:55Z

Preset Overscan Values

← Older revision		Revision as of 20:39, 3 November 2015
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	** clip of the screen, use the VideoControl() command of the graphics library		** clip of the screen, use the VideoControl() command of the graphics library
	** to return a copy of the ViewPortExtra structure. See the Graphics		** to return a copy of the ViewPortExtra structure. See the Graphics
	** library ~~chapter~~ and Autodocs for more details.		** library articles and Autodocs for more details.
	**		**
	** GetVPModeID() is a graphics call...		** GetVPModeID() is a graphics call...

Steven Solie: /* The Pen Specification in DrawInfo */

2015-11-03T20:39:27Z

The Pen Specification in DrawInfo

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	: Custom screens that do not provide the SA_Pens tag are assumed to have no knowledge of the pen array. They are rendered in a special version of the monochrome new look, which uses the screen's DetailPen and BlockPen to get its colors. This is provided for compatibility with V34 and older versions of the operating system.		: Custom screens that do not provide the SA_Pens tag are assumed to have no knowledge of the pen array. They are rendered in a special version of the monochrome new look, which uses the screen's DetailPen and BlockPen to get its colors. This is provided for compatibility with V34 and older versions of the operating system.

	It is very easy for an application to use the default pen specification. Simply specify an empty pen specification (in C, {~0}), and Intuition will fill in all of the values with defaults appropriate for the screen. This technique is demonstrated in the first two examples listed earlier in this ~~chapter~~.		It is very easy for an application to use the default pen specification. Simply specify an empty pen specification (in C, {~0}), and Intuition will fill in all of the values with defaults appropriate for the screen. This technique is demonstrated in the first two examples listed earlier in this article.

	For certain applications, a custom pen specification is required. A custom pen specification is set up when the screen is opened by using the SA_Pens tag and a pointer to a pen array. Currently, Intuition uses nine pens to support the 3D look. The application can specify all of these, or only a few pens and Intuition will fill in the rest. Intuition will only fill in pens that are past the end of those specified by the application, there is no facility for using default values for "leading" pens (those at the beginning of the array) without using the defaults for the rest of the pens.		For certain applications, a custom pen specification is required. A custom pen specification is set up when the screen is opened by using the SA_Pens tag and a pointer to a pen array. Currently, Intuition uses nine pens to support the 3D look. The application can specify all of these, or only a few pens and Intuition will fill in the rest. Intuition will only fill in pens that are past the end of those specified by the application, there is no facility for using default values for "leading" pens (those at the beginning of the array) without using the defaults for the rest of the pens.

Steven Solie: /* Direct Screen Access */

2015-11-03T20:39:05Z

Direct Screen Access

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	{{Note\|title=Do Not Perform Layers Operations Directly\|text=While layers are not part of the graphics library, it is appropriate to mention them here. Certain types of layers operations are not allowed with Intuition. You may not, for example, call SizeLayer() on a window (use SizeWindow() instead). To access layers library features with screens, use Intuition windows!}}		{{Note\|title=Do Not Perform Layers Operations Directly\|text=While layers are not part of the graphics library, it is appropriate to mention them here. Certain types of layers operations are not allowed with Intuition. You may not, for example, call SizeLayer() on a window (use SizeWindow() instead). To access layers library features with screens, use Intuition windows!}}

	A custom screen may be created to allow for modification of the screen's Copper list. The Copper is the display synchronized co-processor that handles the actual video display by directly affecting the hardware registers. See the ''Amiga Hardware Reference Manual'' or the graphics library ~~chapters~~ for more information on programming the Copper.		A custom screen may be created to allow for modification of the screen's Copper list. The Copper is the display synchronized co-processor that handles the actual video display by directly affecting the hardware registers. See the ''Amiga Hardware Reference Manual'' or the graphics library articles for more information on programming the Copper.

	=== Limitations of the Graphics Subsystem ===		=== Limitations of the Graphics Subsystem ===

Steven Solie: /* Overscan and the Display Clip */

2015-10-30T22:29:13Z

Overscan and the Display Clip

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	If custom clipping is required, a display clip may be explicitly specified using the SA_DClip tag and a Rectangle structure specification. This custom rectangle must fit within the OSCAN_MAX rectangle, offset included. It is not permitted to specify custom rectangles whose values are in between OSCAN_MAX and OSCAN_VIDEO, nor is it permitted to specify rectangles larger than OSCAN_VIDEO. For an example of how to open a centered overscan screen based on user preferences, see the "module/screen.c" listing in the [[IFF_Source_Code\|IFF Source Code]].		If custom clipping is required, a display clip may be explicitly specified using the SA_DClip tag and a Rectangle structure specification. This custom rectangle must fit within the OSCAN_MAX rectangle, offset included. It is not permitted to specify custom rectangles whose values are in between OSCAN_MAX and OSCAN_VIDEO, nor is it permitted to specify rectangles larger than OSCAN_VIDEO. For an example of how to open a centered overscan screen based on user preferences, see the "module/screen.c" listing in the [[IFF_Source_Code\|IFF Source Code]].

	Use the Graphics library call VideoControl() to find the true display clip of a screen. See the Graphics Autodocs and ~~the chapter "~~Graphics Primitives" for more information on VideoControl(). The ViewPortExtra structure contains the display clip information.		Use the Graphics library call VideoControl() to find the true display clip of a screen. See the Graphics Autodocs and [[Graphics_Primitives\|Graphics Primitives]] for more information on VideoControl(). The ViewPortExtra structure contains the display clip information.

	If any dimension of a screen is not equal to the equivalent display clip dimension, then the screen may be scrolled. If the screen's dimensions are smaller than the display clip, then the screen may be positioned within the display clip. If the screen is larger than the display clip, then it may be positioned such that any part of the screen is visible.		If any dimension of a screen is not equal to the equivalent display clip dimension, then the screen may be scrolled. If the screen's dimensions are smaller than the display clip, then the screen may be positioned within the display clip. If the screen is larger than the display clip, then it may be positioned such that any part of the screen is visible.
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	</syntaxhighlight>		</syntaxhighlight>

	This example was taken from ~~the chapter "~~Intuition Windows" in the section "Visible Display Sized Window Example". The complete example is reproduced there.		This example was taken from [[Intuition_Windows\|Intuition Windows]] in the section "Visible Display Sized Window Example". The complete example is reproduced there.

	<syntaxhighlight>		<syntaxhighlight>

Steven Solie: /* Screen Attributes */

2015-10-30T22:24:38Z

Screen Attributes

← Older revision		Revision as of 22:24, 30 October 2015
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	; SA_DisplayID		; SA_DisplayID
	: Extended display mode key for the screen. Data is a long, unsigned value. By using DisplayIDs and the display database, applications can open a screen in any display mode available on a user's system, including PAL and NTSC modes. See the discussion of the display database in ~~the~~ ~~"Graphics Primitives" chapter~~ and the include file <graphics/displayinfo.h> for more information.		: Extended display mode key for the screen. Data is a long, unsigned value. By using DisplayIDs and the display database, applications can open a screen in any display mode available on a user's system, including PAL and NTSC modes. See the discussion of the display database in [[Display_Database\|Display Database]] and the include file <graphics/displayinfo.h> for more information.

	; SA_Pens		; SA_Pens

Steven Solie: /* Screen Components */

2015-10-30T22:22:31Z

Screen Components

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	[[File:LibFig3-1.png\|frame\|center\|An Intuition Screen (Workbench)]]		[[File:LibFig3-1.png\|frame\|center\|An Intuition Screen (Workbench)]]

	Screens are always rectangular, and the areas at the sides and bottom of the display that are not within the screen's limits are filled with the background color. The area above all visible screens is filled with the background color of the highest screen. These areas surrounding the screen (normally unused) are known as the ''overscan'' area. The Amiga display system allows the overscan area to be used for graphics under special circumstances (see the section on "Overscan and the Display Clip~~" later in this chapter~~).		Screens are always rectangular, and the areas at the sides and bottom of the display that are not within the screen's limits are filled with the background color. The area above all visible screens is filled with the background color of the highest screen. These areas surrounding the screen (normally unused) are known as the ''overscan'' area. The Amiga display system allows the overscan area to be used for graphics under special circumstances (see the section on [[Intuition_Screens#Overscan_and_the_Display_Clip\|Overscan and the Display Clip]]).

	== Screen Attributes ==		== Screen Attributes ==

Steven Solie at 22:14, 30 October 2015

2015-10-30T22:14:42Z

← Older revision		Revision as of 22:14, 30 October 2015
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	{{WIP}}
	== Intuition Screens ==		== Intuition Screens ==

Steven Solie: /* Public Screens and Custom Screens */

2014-03-14T19:06:18Z

Public Screens and Custom Screens

← Older revision		Revision as of 19:06, 14 March 2014
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	An application may choose to use an existing screen or to create its own screen. For instance, the normal Amiga startup process opens the Workbench screen (Workbench is the Amiga's default user interface). Any application is free to use the Workbench screen instead of opening a new one. Screens that can be shared this way are called ''public'' screens.		An application may choose to use an existing screen or to create its own screen. For instance, the normal Amiga startup process opens the Workbench screen (Workbench is the Amiga's default user interface). Any application is free to use the Workbench screen instead of opening a new one. Screens that can be shared this way are called ''public'' screens.

	''Public screens'' allow applications to open windows on them. Any screen may be set up as a public screen so that other applications may use it.		[[Public_Screen_Type\|Public screens]] allow applications to open windows on them. Any screen may be set up as a public screen so that other applications may use it.

	The use of an existing public screen, like the Workbench screen, requires little effort by the application and does not use up any memory. However, using Workbench or another existing public screen means some flexibility is lost; the resolution, maximum number of colors and other attributes are already set. If the application cannot function under these limitations, it may open its own ''custom'' screen.		The use of an existing public screen, like the Workbench screen, requires little effort by the application and does not use up any memory. However, using Workbench or another existing public screen means some flexibility is lost; the resolution, maximum number of colors and other attributes are already set. If the application cannot function under these limitations, it may open its own ''custom'' screen.

	''Custom screens'' allow for complete control of the display space so an application can get exactly the kind of display it wants. However, since creating a new, custom screen uses up memory, they should only be used when there are no suitable public screens available.		[[Custom_Screen_Type\|Custom screens]] allow for complete control of the display space so an application can get exactly the kind of display it wants. However, since creating a new, custom screen uses up memory, they should only be used when there are no suitable public screens available.

	Owners of a custom screen can keep their screen private, or they may allow other applications to share their screen by registering the screen with the operating system as a public screen. See the section on ~~"Public~~ ~~Screen Functions" below~~ for more about public screens and Workbench.		Owners of a custom screen can keep their screen private, or they may allow other applications to share their screen by registering the screen with the operating system as a public screen. See the section on [[Public_Screen_Type\|public screens]] for more about public screens and Workbench.

	=== Screen Components ===		=== Screen Components ===