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NSGraphicsContext

Authors

Richard Frith-Macdonald (richard@brainstorm.co.uk)
Adam Fedor (fedor@gnu.org)
GNUstep drawing context class.

Copyright: (C) 1998,1999 Free Software Foundation, Inc.


Contents -

  1. NSGraphicsContext
  2. Software documentation for the NSGraphicsContext(GNUstep) category
  3. Software documentation for the NSGraphicsContext(NSGraphics) category
  4. Software documentation for the NSGraphicsContext(Ops) category

NSGraphicsContext

This is an abstract class which provides a framework for a device independant drawing.

In addition, this class provides methods to perform the actual drawing. As a convenience, you can also access these through various function interfaces. One is a Display Postscript interface using PS and DPS operations. Another is a Quartz interface (not yet written).

NSGraphicsContext : NSObject

Declared in:
AppKit/NSGraphicsContext.h
Standards:

Description forthcoming.



Instance Variables for NSGraphicsContext Class

_antialias

@protected BOOL _antialias;

Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.


_interp

@protected NSImageInterpolation _interp;

Warning the underscore at the start of the name of this instance variable indicates that, even though it is not technically private, it is intended for internal use within the package, and you should not use the variable in other code.


context_data

@protected NSMutableData* context_data;

Description forthcoming.


context_info

@protected NSDictionary* context_info;

Description forthcoming.


focus_stack

@protected NSMutableArray* focus_stack;

Description forthcoming.


methods

@public const gsMethodTable* methods;

Description forthcoming.


usedFonts

@protected NSMutableSet* usedFonts;

Description forthcoming.





Method summary

currentContext 

+ (NSGraphicsContext*) currentContext;

Returns the current context. Also see the convienience function GSCurrentContext()


currentContextDrawingToScreen 

+ (BOOL) currentContextDrawingToScreen;

Returns YES if the current context is a display context


graphicsContextWithAttributes: 

+ (NSGraphicsContext*) graphicsContextWithAttributes: (NSDictionary*)attributes;

Create a graphics context with attributes, which contains key/value pairs which describe the specifics of how the context is to be initialized.


graphicsContextWithWindow: 

+ (NSGraphicsContext*) graphicsContextWithWindow: (NSWindow*)aWindow;

Create graphics context with attributes speficied by aWindow's device description.


restoreGraphicsState 

+ (void) restoreGraphicsState;

Description forthcoming.


saveGraphicsState 

+ (void) saveGraphicsState;

Description forthcoming.


setCurrentContext: 

+ (void) setCurrentContext: (NSGraphicsContext*)context;

Set the current context that will handle drawing.


setGraphicsState: 

+ (void) setGraphicsState: (int)graphicsState;

Description forthcoming.


attributes 

- (NSDictionary*) attributes;

Description forthcoming.


flushGraphics 

- (void) flushGraphics;

Description forthcoming.


focusStack 

- (void*) focusStack;

Description forthcoming.


graphicsPort 

- (void*) graphicsPort;

Description forthcoming.


imageInterpolation 

- (NSImageInterpolation) imageInterpolation;

Description forthcoming.


isDrawingToScreen 

- (BOOL) isDrawingToScreen;

Description forthcoming.


restoreGraphicsState 

- (void) restoreGraphicsState;

Description forthcoming.


saveGraphicsState 

- (void) saveGraphicsState;

Description forthcoming.


setFocusStack: 

- (void) setFocusStack: (void*)stack;

Description forthcoming.


setImageInterpolation: 

- (void) setImageInterpolation: (NSImageInterpolation)interpolation;

Description forthcoming.


setShouldAntialias: 

- (void) setShouldAntialias: (BOOL)antialias;

Description forthcoming.


shouldAntialias 

- (BOOL) shouldAntialias;

Description forthcoming.


Software documentation for the NSGraphicsContext(GNUstep) category

NSGraphicsContext(GNUstep)

Declared in:
AppKit/NSGraphicsContext.h
Standards:

Description forthcoming.

Method summary

handleExposeRect: forDriver: 

+ (void) handleExposeRect: (NSRect)rect forDriver: (void*)driver;

Description forthcoming.


setDefaultContextClass: 

+ (void) setDefaultContextClass: (Class)defaultContextClass;

Description forthcoming.


focusView 

- (NSView*) focusView;

Description forthcoming.


initWithContextInfo: 

- (id) initWithContextInfo: (NSDictionary*)info;

Description forthcoming.


lockFocusView: inRect: 

- (void) lockFocusView: (NSView*)aView inRect: (NSRect)rect;

Description forthcoming.


resetUsedFonts 

- (void) resetUsedFonts;

Description forthcoming.


unlockFocusView: needsFlush: 

- (void) unlockFocusView: (NSView*)aView needsFlush: (BOOL)flush;

Description forthcoming.


useFont: 

- (void) useFont: (NSString*)fontName;

Description forthcoming.


usedFonts 

- (NSSet*) usedFonts;

Description forthcoming.


Software documentation for the NSGraphicsContext(NSGraphics) category

NSGraphicsContext(NSGraphics)

Declared in:
AppKit/NSGraphicsContext.h
Standards:

Description forthcoming.

Method summary

GSReadRect: 

- (NSDictionary*) GSReadRect: (NSRect)rect;

Read the data inside rect (defined in the current graphics state) and return the information as a bitmap. The dictionary contains the bitmap data plus various information about the size and format of the data. The dictionary keys include ImageSize, ImageBPS, ImageSPP, and ImageData.


GSWSetViewIsFlipped: 

- (void) GSWSetViewIsFlipped: (BOOL)flipped;

This method is used by the backend, but has been rendered obsolete. Do not use it in any code or in any backend implementation as it may disappear at any point.


GSWViewIsFlipped 

- (BOOL) GSWViewIsFlipped;

Returns YES if the current focused view is flipped. This is an obsolete method. Use [[NSView focusView] isFlipped] instead


NSBeep 

- (void) NSBeep;

Play the System Beep


NSDrawBitmap: : : : : : : : : : : 

- (void) NSDrawBitmap: (NSRect)rect : (int)pixelsWide : (int)pixelsHigh : (int)bitsPerSample : (int)samplesPerPixel : (int)bitsPerPixel : (int)bytesPerRow : (BOOL)isPlanar : (BOOL)hasAlpha : (NSString*)colorSpaceName : (const unsigned char*const[5])data;

Generic method to render bitmap images. This method shouldn't be used anywhere except in the AppKit itself. It will be replaced by the more flexible GSDrawImage method sometime in the future. (Quartz).


Software documentation for the NSGraphicsContext(Ops) category

NSGraphicsContext(Ops)

Declared in:
AppKit/NSGraphicsContext.h
Standards:

Description forthcoming.

Method summary

DPSPrintf: : 

- (void) DPSPrintf: (const char*)fmt : (va_list)args;

Write the string (with printf substitutions) to a PostScript context. Other output contexts will likely ignore this


DPSWriteData: : 

- (void) DPSWriteData: (const char*)buf : (unsigned int)count;

Write the encoded data to a PostScript context. Other output contexts will likely ignore this


DPSarc: : : : : 

- (void) DPSarc: (float)x : (float)y : (float)r : (float)angle1 : (float)angle2;

Description forthcoming.


DPSarcn: : : : : 

- (void) DPSarcn: (float)x : (float)y : (float)r : (float)angle1 : (float)angle2;

Description forthcoming.


DPSarct: : : : : 

- (void) DPSarct: (float)x1 : (float)y1 : (float)x2 : (float)y2 : (float)r;

Description forthcoming.


DPSashow: : : 

- (void) DPSashow: (float)x : (float)y : (const char*)s;

Displays a string as in the PostScript ashow operator. This operator is obsolete. You should instead use -DPSshow: with appropriate -DPSrmoveto:: operations and/or the -GSSetCharacterSpacing: method


DPSawidthshow: : : : : : 

- (void) DPSawidthshow: (float)cx : (float)cy : (int)c : (float)ax : (float)ay : (const char*)s;

Displays a string as in the PostScript awidthshow operator. This operator is obsolete. You should instead use -DPSshow: with appropriate -DPSrmoveto:: operations and/or the -GSSetCharacterSpacing: method


DPScharpath: : 

- (void) DPScharpath: (const char*)s : (int)b;

Appends to the current path a path that is equivalent to the outlines of the glyphs in the string. This results in a path that can be used for stroking, filling or clipping (DPS).


DPSclip 

- (void) DPSclip;

Clip to the current path. (DPS, Quartz).


DPSclosepath 

- (void) DPSclosepath;

Description forthcoming.


DPScomposite: : : : : : : : 

- (void) DPScomposite: (float)x : (float)y : (float)w : (float)h : (int)gstateNum : (float)dx : (float)dy : (int)op;

Description forthcoming.


DPScompositerect: : : : : 

- (void) DPScompositerect: (float)x : (float)y : (float)w : (float)h : (int)op;

Description forthcoming.


DPSconcat: 

- (void) DPSconcat: (const float*)m;

Concatenates the coordinate transform represented by the matrix m with the current coordinate transform. (DPS).


DPScurrentalpha: 

- (void) DPScurrentalpha: (float*)a;

Returns the current alpha component (DPS).


DPScurrentcmykcolor: : : : 

- (void) DPScurrentcmykcolor: (float*)c : (float*)m : (float*)y : (float*)k;

Returns the current color according to the CMYK color model (DPS).


DPScurrentflat: 

- (void) DPScurrentflat: (float*)flatness;

Returns the current flattness parameter, which controls how curved lines are drawn. (DPS, Quartz).


DPScurrentgray: 

- (void) DPScurrentgray: (float*)gray;

Returns the gray-level equivalent in the current color space. The value may depend on the current color space and may be 0 if the current color space has no notion of a gray value (DPS)


DPScurrenthsbcolor: : : 

- (void) DPScurrenthsbcolor: (float*)h : (float*)s : (float*)b;

Returns the current color according to the HSB color model (DPS).


DPScurrentlinecap: 

- (void) DPScurrentlinecap: (int*)linecap;

Returns the current linecap value. (DPS, Quartz).


DPScurrentlinejoin: 

- (void) DPScurrentlinejoin: (int*)linejoin;

Returns the current linejoin value. (DPS, Quartz).


DPScurrentlinewidth: 

- (void) DPScurrentlinewidth: (float*)width;

Returns the current line width. (DPS, Quartz).


DPScurrentmiterlimit: 

- (void) DPScurrentmiterlimit: (float*)limit;

Returns the current linecap value. (DPS, Quartz).


DPScurrentoffset: : 

- (void) DPScurrentoffset: (int*)x : (int*)y;

Description forthcoming.


DPScurrentpoint: : 

- (void) DPScurrentpoint: (float*)x : (float*)y;

Returns the current point. (DPS, Quartz).


DPScurrentrgbcolor: : : 

- (void) DPScurrentrgbcolor: (float*)r : (float*)g : (float*)b;

Returns the current color according to the RGB color model (DPS).


DPScurrentstrokeadjust: 

- (void) DPScurrentstrokeadjust: (int*)b;

Returns the strokeadjust value. (DPS).


DPScurveto: : : : : : 

- (void) DPScurveto: (float)x1 : (float)y1 : (float)x2 : (float)y2 : (float)x3 : (float)y3;

Description forthcoming.


DPSdissolve: : : : : : : : 

- (void) DPSdissolve: (float)x : (float)y : (float)w : (float)h : (int)gstateNum : (float)dx : (float)dy : (float)delta;

Description forthcoming.


DPSeoclip 

- (void) DPSeoclip;

Description forthcoming.


DPSeofill 

- (void) DPSeofill;

Description forthcoming.


DPSfill 

- (void) DPSfill;

Fill the current path. (DPS, Quartz).


DPSflattenpath 

- (void) DPSflattenpath;

Description forthcoming.


DPSgrestore 

- (void) DPSgrestore;

Pops a previously saved gstate from the gstate stack and makes it current. Drawing information in the previously saved gstate becomes the current information. (DPS, Quartz).


DPSgsave 

- (void) DPSgsave;

Saves (pushes) a copy of the current gstate information onto the gstate stack. This saves drawing information contained in the gstate, such as the current path, ctm and colors. (DPS, Quartz).


DPSinitclip 

- (void) DPSinitclip;

Description forthcoming.


DPSinitgraphics 

- (void) DPSinitgraphics;

Description forthcoming.


DPSinitmatrix 

- (void) DPSinitmatrix;

Sets the coordinate transform matrix to the initial values for the particular context


DPSlineto: : 

- (void) DPSlineto: (float)x : (float)y;

Description forthcoming.


DPSmoveto: : 

- (void) DPSmoveto: (float)x : (float)y;

Description forthcoming.


DPSnewpath 

- (void) DPSnewpath;

Description forthcoming.


DPSpathbbox: : : : 

- (void) DPSpathbbox: (float*)llx : (float*)lly : (float*)urx : (float*)ury;

Description forthcoming.


DPSrcurveto: : : : : : 

- (void) DPSrcurveto: (float)x1 : (float)y1 : (float)x2 : (float)y2 : (float)x3 : (float)y3;

Description forthcoming.


DPSrectclip: : : : 

- (void) DPSrectclip: (float)x : (float)y : (float)w : (float)h;

Description forthcoming.


DPSrectfill: : : : 

- (void) DPSrectfill: (float)x : (float)y : (float)w : (float)h;

Description forthcoming.


DPSrectstroke: : : : 

- (void) DPSrectstroke: (float)x : (float)y : (float)w : (float)h;

Description forthcoming.


DPSreversepath 

- (void) DPSreversepath;

Description forthcoming.


DPSrlineto: : 

- (void) DPSrlineto: (float)x : (float)y;

Description forthcoming.


DPSrmoveto: : 

- (void) DPSrmoveto: (float)x : (float)y;

Description forthcoming.


DPSrotate: 

- (void) DPSrotate: (float)angle;

Rotate the coordinate system. (DPS).


DPSscale: : 

- (void) DPSscale: (float)x : (float)y;

Scale the coordinate system. (DPS).


DPSsetalpha: 

- (void) DPSsetalpha: (float)a;

Sets the alpha drawing component. For this and other color setting commands that have no differentiation between fill and stroke colors, both the fill and stroke alpha are set (DPS).


DPSsetcmykcolor: : : : 

- (void) DPSsetcmykcolor: (float)c : (float)m : (float)y : (float)k;

Sets the current colorspace to Device CMYK and the current color based on the indicated values. For this and other color setting commands that have no differentiation between fill and stroke colors, both the fill and stroke colors are set (DPS).


DPSsetdash: : : 

- (void) DPSsetdash: (const float*)pat : (int)size : (float)offset;

Set the pattern for line dashes like the Postscript setdash operator. (DPS, Quartz).


DPSsetflat: 

- (void) DPSsetflat: (float)flatness;

Sets the current flattness parameter, which controls how curved lines are drawn. (DPS, Quartz).


DPSsetgray: 

- (void) DPSsetgray: (float)gray;

Sets the current colorspace to Device Gray and the current gray value (DPS).


DPSsetgstate: 

- (void) DPSsetgstate: (int)gst;

Makes the gstate indicated by the tag gst the current gstate. Note that the gstate is copied, so that changes to either gstate do not affect the other. (DPS, Quartz).


DPSsethalftonephase: : 

- (void) DPSsethalftonephase: (float)x : (float)y;

Description forthcoming.


DPSsethsbcolor: : : 

- (void) DPSsethsbcolor: (float)h : (float)s : (float)b;

Sets the current colorspace to Device RGB and the current color based on the indicated values (DPS).


DPSsetlinecap: 

- (void) DPSsetlinecap: (int)linecap;

Set the current linecap value. (DPS, Quartz).


DPSsetlinejoin: 

- (void) DPSsetlinejoin: (int)linejoin;

Set the current linejoin value. (DPS, Quartz).


DPSsetlinewidth: 

- (void) DPSsetlinewidth: (float)width;

Set the current line width. (DPS, Quartz).


DPSsetmiterlimit: 

- (void) DPSsetmiterlimit: (float)limit;

Set the current meter limit value. (DPS, Quartz).


DPSsetoffset: : 

- (void) DPSsetoffset: (short int)x : (short int)y;

Description forthcoming.


DPSsetrgbcolor: : : 

- (void) DPSsetrgbcolor: (float)r : (float)g : (float)b;

Sets the current colorspace to Device RGB and the current color based on the indicated values (DPS).


DPSsetstrokeadjust: 

- (void) DPSsetstrokeadjust: (int)b;

Description forthcoming.


DPSshfill: 

- (void) DPSshfill: (NSDictionary*)shaderDictionary;

Description forthcoming.


DPSshow: 

- (void) DPSshow: (const char*)s;

Display the string s using the current font (DPS).


DPSstroke 

- (void) DPSstroke;

Description forthcoming.


DPStranslate: : 

- (void) DPStranslate: (float)x : (float)y;

Translate the coordinate system. (DPS).


DPSwidthshow: : : : 

- (void) DPSwidthshow: (float)x : (float)y : (int)c : (const char*)s;

Displays a string as in the PostScript widthshow operator. This operator is obsolete. You should instead use -DPSshow: with appropriate -DPSrmoveto:: operations.


DPSxshow: : : 

- (void) DPSxshow: (const char*)s : (const float*)numarray : (int)size;

Displays a string as in the PostScript widthshow operator. This operator is obsolete. You should instead use -DPSshow: with appropriate -DPSrmoveto:: operations.


DPSxyshow: : : 

- (void) DPSxyshow: (const char*)s : (const float*)numarray : (int)size;

Displays a string as in the PostScript xyshow operator. This operator is obsolete. You should instead use -DPSshow: with appropriate -DPSrmoveto:: operations.


DPSyshow: : : 

- (void) DPSyshow: (const char*)s : (const float*)numarray : (int)size;

Displays a string as in the PostScript yshow operator. This operator is obsolete. You should instead use -DPSshow: with appropriate -DPSrmoveto:: operations.


GSConcatCTM: 

- (void) GSConcatCTM: (NSAffineTransform*)ctm;

Concatenates the matrix ctm onto the current coordinate transform matrix. (Quartz).


GSCurrentCTM 

- (NSAffineTransform*) GSCurrentCTM;

Returns the current coordinate transform matrix. (Quartz).


GSCurrentDevice: : : 

- (void) GSCurrentDevice: (void**)device : (int*)x : (int*)y;

This is a private method used between the window server and the context. It should not be used in any application. Typically used by the window server to find out what window the context is drawing graphics to. The device pointer is an opaque type that contains information about the window. The x and y pointers indicate the offset of the origin of the window from the lower left-hand corner


GSDefineGState 

- (int) GSDefineGState;

Creates a copy of the current gstate and associates it with a tag, which is given in the return value. This tag can later be used in -DPSsetgstate: to set the gstate as being current again. (DPS, Quartz).


GSDrawImage: : 

- (void) GSDrawImage: (NSRect)rect : (void*)imageref;

Generic method to draw an image into a rect. The image is defined by imageref, an opaque structure. Support for this method hasn't been implemented yet, so it should not be used anywhere.


GSGetTextCTM 

- (NSAffineTransform*) GSGetTextCTM;

Returns the transfer function for transforming text from text space to user space. See -GSSetTextCTM: for additiona information. (Quartz).


GSGetTextPosition 

- (NSPoint) GSGetTextPosition;

Returns the location at which text will be drawn. In text-space coordinates. (Quartz).


GSRectClipList: : 

- (void) GSRectClipList: (const NSRect*)rects : (int)count;

Append the array of rects to the current clip path (DPS, Quartz).


GSRectFillList: : 

- (void) GSRectFillList: (const NSRect*)rects : (int)count;

Draw and fill the array of rects. (DPS, Quartz)


GSReplaceGState: 

- (void) GSReplaceGState: (int)gst;

Replaces the gstate refered to by the tag gst with the current gstate. The former gstate is destroyed. (DPS, Quartz).


GSSendBezierPath: 

- (void) GSSendBezierPath: (NSBezierPath*)path;

Set the bezier path as the current path


GSSetCTM: 

- (void) GSSetCTM: (NSAffineTransform*)ctm;

Sets the coordinate transform matrix which describes how graphics will be transformed into device coordinates. (Quartz).


GSSetCharacterSpacing: 

- (void) GSSetCharacterSpacing: (float)extra;

Use this method to set the additional spacing between characters (glyphs). This spacing is added to the normal spacing for each character. Units are in text-space coordinate system. (Quartz).


GSSetDevice: : : 

- (void) GSSetDevice: (void*)device : (int)x : (int)y;

This is a private method used between the window server and the context. It should not be used in any application. Typically called by the window server to tell the context what window it should draw graphics to. The device pointer is an opaque type that contains information about the window. The x and y values tell the context that it should put the origin of the transform matrix at the indicated x and y values from the lower left-hand corner of the window


GSSetFillColor: 

- (void) GSSetFillColor: (const float*)values;

Sets the current color for fill operations. The values array should have n components, where n corresponds to the number of color components required to specify the color in the current colorspace (Quartz).


GSSetFillColorspace: 

- (void) GSSetFillColorspace: (void*)spaceref;

Sets the colorspace for fill operations based on values in the supplied dictionary dict.

For device colorspaces (GSDeviceGray, GSDeviceRGB, GSDeviceCMYK), only the name of the colorspace needs to be set using the GSColorSpaceName key.

Other colorspaces will be documented later (Quartz).


GSSetFont: 

- (void) GSSetFont: (void*)fontref;

Set the current font for drawing glyphs. (DPS, Quartz).


GSSetFontSize: 

- (void) GSSetFontSize: (float)size;

Set the font size of the current NSFont used for drawing glyphs. (DPS, Quartz).


GSSetStrokeColor: 

- (void) GSSetStrokeColor: (const float*)values;

Sets the current color for stroke operations. The values array should have n components, where n corresponds to the number of color components required to specify the color in the current colorspace (Quartz).


GSSetStrokeColorspace: 

- (void) GSSetStrokeColorspace: (void*)spaceref;

Sets the colorspace for stroke operations based on the values in the supplied dictionary. See -GSSetFillColorspace: for a description of the values that need to be supplied (Quartz).


GSSetTextCTM: 

- (void) GSSetTextCTM: (NSAffineTransform*)ctm;

Set the transfer function for transforming text from text space to user space. This transform is only applied to text objects and is in addition to the normal coordinate transform matrix. When drawing text, this transform is applied before the normal CTM.

The text matrix can be changed by either modifying it directly, or just by drawing text, in which case the tx and ty offset veriables are modified to point to the location of the next character that could be rendered (Quartz).


GSSetTextDrawingMode: 

- (void) GSSetTextDrawingMode: (GSTextDrawingMode)mode;

Set the current text drawing mode. The mode can be one of several values that fill/stroke the text or add it to the current clipping path. (Quartz).


GSSetTextPosition: 

- (void) GSSetTextPosition: (NSPoint)loc;

Set the location at which text will be drawn, in text-space coordinates. This routine updates the current text coordinate matrix. (Quartz).


GSShowGlyphs: : 

- (void) GSShowGlyphs: (const NSGlyph*)glyphs : (size_t)length;

Paints the glyphs using the current font. (Quartz).


GSShowText: : 

- (void) GSShowText: (const char*)string : (size_t)length;

Paints text represented by the characters in string in the current font. (Quartz).


GSUndefineGState: 

- (void) GSUndefineGState: (int)gst;

Disassociates the tag gst with it's gstate and destroys the gstate object. The tag will no longer be valid and should not be used to refer to the gstate again. (DPS, Quartz).



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