gfx/public/nsIDeviceContext.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
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  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is mozilla.org code.
  16  *
  17  * The Initial Developer of the Original Code is
  18  * Netscape Communications Corporation.
  19  * Portions created by the Initial Developer are Copyright (C) 1998
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *   Roland Mainz <roland.mainz@informatik.med.uni-giessen.de>
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * either of the GNU General Public License Version 2 or later (the "GPL"),
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  28  * in which case the provisions of the GPL or the LGPL are applicable instead
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  36  *
  37  * ***** END LICENSE BLOCK ***** */
  38
  39 #ifndef nsIDeviceContext_h___
  40 #define nsIDeviceContext_h___
  41
  42 #include "nsISupports.h"
  43 #include "nsCoord.h"
  44 #include "nsRect.h"
  45 #include "nsIWidget.h"
  46 #include "nsIRenderingContext.h"
  47 // XXX we need only gfxTypes.h, but we cannot include it directly.
  48 #include "gfxPoint.h"
  49
  50 class nsIView;
  51 class nsIFontMetrics;
  52 class nsIWidget;
  53 class nsIDeviceContextSpec;
  54 class nsIAtom;
  55 class gfxUserFontSet;
  56
  57 struct nsFont;
  58
  59 //a cross platform way of specifying a native device context
  60 typedef void * nsNativeDeviceContext;
  61
  62 /* error codes for printer device contexts */
  63 #define NS_ERROR_GFX_PRINTER_BASE (1) /* adjustable :-) */
  64 /* Unix: print command (lp/lpr) not found */
  65 #define NS_ERROR_GFX_PRINTER_CMD_NOT_FOUND          \
  66   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+1)
  67 /* Unix: print command returned an error */
  68 #define NS_ERROR_GFX_PRINTER_CMD_FAILURE            \
  69   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+2)
  70 /* no printer available (e.g. cannot find _any_ printer) */
  71 #define NS_ERROR_GFX_PRINTER_NO_PRINTER_AVAILABLE  \
  72   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+3)
  73 /* _specified_ (by name) printer not found */
  74 #define NS_ERROR_GFX_PRINTER_NAME_NOT_FOUND         \
  75   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+4)
  76 /* access to printer denied */
  77 #define NS_ERROR_GFX_PRINTER_ACCESS_DENIED          \
  78   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+5)
  79 /* invalid printer attribute (for example: unsupported paper size etc.) */
  80 #define NS_ERROR_GFX_PRINTER_INVALID_ATTRIBUTE      \
  81   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+6)
  82 /* printer not "ready" (offline ?) */
  83 #define NS_ERROR_GFX_PRINTER_PRINTER_NOT_READY     \
  84   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+8)
  85 /* printer out of paper */
  86 #define NS_ERROR_GFX_PRINTER_OUT_OF_PAPER           \
  87   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+9)
  88 /* generic printer I/O error */
  89 #define NS_ERROR_GFX_PRINTER_PRINTER_IO_ERROR       \
  90   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+10)
  91 /* print-to-file: could not open output file */
  92 #define NS_ERROR_GFX_PRINTER_COULD_NOT_OPEN_FILE    \
  93   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+11)
  94 /* print-to-file: I/O error while printing to file */
  95 #define NS_ERROR_GFX_PRINTER_FILE_IO_ERROR          \
  96   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+12)
  97 /* print preview: needs at least one printer */
  98 #define NS_ERROR_GFX_PRINTER_PRINTPREVIEW          \
  99   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+13)
 100 /* print: starting document */
 101 #define NS_ERROR_GFX_PRINTER_STARTDOC          \
 102   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+14)
 103 /* print: ending document */
 104 #define NS_ERROR_GFX_PRINTER_ENDDOC          \
 105   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+15)
 106 /* print: starting page */
 107 #define NS_ERROR_GFX_PRINTER_STARTPAGE          \
 108   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+16)
 109 /* print: ending page */
 110 #define NS_ERROR_GFX_PRINTER_ENDPAGE          \
 111   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+17)
 112 /* print: print while in print preview */
 113 #define NS_ERROR_GFX_PRINTER_PRINT_WHILE_PREVIEW          \
 114   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+18)
 115 /* requested page size not supported by printer */
 116 #define NS_ERROR_GFX_PRINTER_PAPER_SIZE_NOT_SUPPORTED \
 117   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+19)
 118 /* requested page orientation not supported */
 119 #define NS_ERROR_GFX_PRINTER_ORIENTATION_NOT_SUPPORTED \
 120   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+20)
 121 /* requested colorspace not supported (like printing "color" on a "grayscale"-only printer) */
 122 #define NS_ERROR_GFX_PRINTER_COLORSPACE_NOT_SUPPORTED \
 123   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+21)
 124 /* too many copies requested */
 125 #define NS_ERROR_GFX_PRINTER_TOO_MANY_COPIES \
 126   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+22)
 127 /* driver configuration error */
 128 #define NS_ERROR_GFX_PRINTER_DRIVER_CONFIGURATION_ERROR \
 129   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+23)
 130 /* The document is still being loaded, can't Print Preview */
 131 #define NS_ERROR_GFX_PRINTER_DOC_IS_BUSY_PP \
 132   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+24)
 133 /* The document was asked to be destroyed while we were preparing printing */
 134 #define NS_ERROR_GFX_PRINTER_DOC_WAS_DESTORYED \
 135   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+25)
 136 /* Cannot Print or Print Preview XUL Documents */
 137 #define NS_ERROR_GFX_PRINTER_NO_XUL \
 138   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+26)
 139 /* The toolkit no longer supports the Print Dialog (for embedders) */
 140 #define NS_ERROR_GFX_NO_PRINTDIALOG_IN_TOOLKIT \
 141   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+27)
 142 /* The was wasn't any Print Prompt service registered (this shouldn't happen) */
 143 #define NS_ERROR_GFX_NO_PRINTROMPTSERVICE \
 144   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+28)
 145 /* requested plex mode not supported by printer */
 146 #define NS_ERROR_GFX_PRINTER_PLEX_NOT_SUPPORTED \
 147   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+29)
 148 /* The document is still being loaded */
 149 #define NS_ERROR_GFX_PRINTER_DOC_IS_BUSY \
 150   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+30)
 151 /* Printing is not implemented */
 152 #define NS_ERROR_GFX_PRINTING_NOT_IMPLEMENTED \
 153   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+31)
 154 /* Cannot load the matching print module */
 155 #define NS_ERROR_GFX_COULD_NOT_LOAD_PRINT_MODULE \
 156   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+32)
 157 /* requested resolution/quality mode not supported by printer */
 158 #define NS_ERROR_GFX_PRINTER_RESOLUTION_NOT_SUPPORTED \
 159   NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_GFX,NS_ERROR_GFX_PRINTER_BASE+33)
 160
 161 /**
 162  * Conts need for Print Preview
 163  */
 164 #ifdef NS_PRINT_PREVIEW
 165 const PRUint8 kUseAltDCFor_NONE            = 0x00; // Do not use the AltDC for anything
 166 const PRUint8 kUseAltDCFor_FONTMETRICS     = 0x01; // Use it for only getting the font metrics
 167 const PRUint8 kUseAltDCFor_CREATERC_REFLOW = 0x02; // Use when creating RenderingContexts for Reflow
 168 const PRUint8 kUseAltDCFor_CREATERC_PAINT  = 0x04; // Use when creating RenderingContexts for Painting
 169 const PRUint8 kUseAltDCFor_SURFACE_DIM     = 0x08; // Use it for getting the Surface Dimensions
 170 #endif
 171
 172 // eca27eb2-ef6f-4142-bf77-89c14e595171
 173 #define NS_IDEVICE_CONTEXT_IID   \
 174 { 0xeca27eb2, 0xef6f, 0x4142, \
 175   { 0xbf, 0x77, 0x89, 0xc1, 0x4e, 0x59, 0x51, 0x71 } }
 176
 177 //a cross platform way of specifying a native palette handle
 178 typedef void * nsPalette;
 179
 180   //structure used to return information about a device's palette capabilities
 181   struct nsPaletteInfo {
 182      PRPackedBool  isPaletteDevice;
 183      PRUint16      sizePalette;  // number of entries in the palette
 184      PRUint16      numReserved;  // number of reserved palette entries
 185      nsPalette     palette;      // native palette handle
 186   };
 187
 188   typedef enum {
 189     eSystemFont_Caption,         // css2
 190     eSystemFont_Icon,
 191     eSystemFont_Menu,
 192     eSystemFont_MessageBox,
 193     eSystemFont_SmallCaption,
 194     eSystemFont_StatusBar,
 195
 196     eSystemFont_Window,          // css3
 197     eSystemFont_Document,
 198     eSystemFont_Workspace,
 199     eSystemFont_Desktop,
 200     eSystemFont_Info,
 201     eSystemFont_Dialog,
 202     eSystemFont_Button,
 203     eSystemFont_PullDownMenu,
 204     eSystemFont_List,
 205     eSystemFont_Field,
 206
 207     eSystemFont_Tooltips,        // moz
 208     eSystemFont_Widget
 209   } nsSystemFontID;
 210
 211 class nsIDeviceContext : public nsISupports
 212 {
 213 public:
 214   NS_DECLARE_STATIC_IID_ACCESSOR(NS_IDEVICE_CONTEXT_IID)
 215
 216   /**
 217    * Initialize the device context from a widget
 218    * @param aWidget a native widget to initialize the device context from
 219    * @return error status
 220    */
 221   NS_IMETHOD  Init(nsNativeWidget aWidget) = 0;
 222
 223   /**
 224    * Initialize the device context from a device context spec
 225    * @param aDevSpec the specification of the printng device (platform-specific)
 226    * @return error status
 227    */
 228   NS_IMETHOD  InitForPrinting(nsIDeviceContextSpec* aDevSpec) = 0;
 229
 230   /**
 231    * Create a rendering context and initialize it from an nsIView
 232    * @param aView view to initialize context from
 233    * @param aContext out parameter for new rendering context
 234    * @return error status
 235    */
 236   NS_IMETHOD  CreateRenderingContext(nsIView *aView, nsIRenderingContext *&aContext) = 0;
 237
 238   /**
 239    * Create a rendering context and initialize it from an nsIWidget
 240    * @param aWidget widget to initialize context from
 241    * @param aContext out parameter for new rendering context
 242    * @return error status
 243    */
 244   NS_IMETHOD  CreateRenderingContext(nsIWidget *aWidget, nsIRenderingContext *&aContext) = 0;
 245
 246   /**
 247    * Create a rendering context and initialize it. This API should *only* be called
 248    * on device contexts whose SupportsNativeWidgets() method return PR_FALSE.
 249    * @param aContext out parameter for new rendering context
 250    * @return error status
 251    */
 252   NS_IMETHOD  CreateRenderingContext(nsIRenderingContext *&aContext) = 0;
 253
 254   /**
 255    * Create an uninitalised rendering context.
 256    * @param aContext out parameter for new rendering context
 257    * @return error status
 258    */
 259   NS_IMETHOD  CreateRenderingContextInstance(nsIRenderingContext *&aContext) = 0;
 260
 261   /**
 262    * Query the device to see if it supports native widgets. If not, then
 263    * nsIWidget->Create() calls should be avoided.
 264    * @param aSupportsWidgets out paramater. If PR_TRUE, then native widgets
 265    *        can be created.
 266    * @return error status
 267    */
 268   NS_IMETHOD  SupportsNativeWidgets(PRBool &aSupportsWidgets) = 0;
 269
 270   /**
 271    * We are in the process of creating the native widget for aWidget.
 272    * Do any device-specific processing required to initialize the
 273    * native widget for this device. A pointer to some platform-specific data is
 274    * returned in aOut.
 275    *
 276    * GTK2 calls this to get the required visual for the window.
 277    */
 278   NS_IMETHOD PrepareNativeWidget(nsIWidget* aWidget, void** aOut) = 0;
 279
 280   /**
 281    * Gets the number of app units in one CSS pixel; this number is global,
 282    * not unique to each device context.
 283    */
 284   static PRInt32 AppUnitsPerCSSPixel() { return 60; }
 285
 286   /**
 287    * Convert app units to CSS pixels which is used in gfx/thebes.
 288    */
 289   static gfxFloat AppUnitsToGfxCSSPixels(nscoord aAppUnits)
 290   { return gfxFloat(aAppUnits) / AppUnitsPerCSSPixel(); }
 291
 292   /**
 293    * Gets the number of app units in one device pixel; this number is usually
 294    * a factor of AppUnitsPerCSSPixel(), although that is not guaranteed.
 295    */
 296   PRInt32 AppUnitsPerDevPixel() const { return mAppUnitsPerDevPixel; }
 297
 298   /**
 299    * Convert device pixels which is used for gfx/thebes to nearest (rounded)
 300    * app units
 301    */
 302   nscoord GfxUnitsToAppUnits(gfxFloat aGfxUnits) const
 303   { return nscoord(NS_round(aGfxUnits * AppUnitsPerDevPixel())); }
 304
 305   /**
 306    * Convert app units to device pixels which is used for gfx/thebes.
 307    */
 308   gfxFloat AppUnitsToGfxUnits(nscoord aAppUnits) const
 309   { return gfxFloat(aAppUnits) / AppUnitsPerDevPixel(); }
 310
 311   /**
 312    * Gets the number of app units in one inch; this is the device's DPI
 313    * times AppUnitsPerDevPixel().
 314    */
 315   PRInt32 AppUnitsPerInch() const { return mAppUnitsPerInch; }
 316
 317   /**
 318    * Fill in an nsFont based on the ID of a system font.  This function
 319    * may or may not fill in the size, so the size should be set to a
 320    * reasonable default before calling.
 321    *
 322    * @param aID    The system font ID.
 323    * @param aInfo  The font structure to be filled in.
 324    * @return error status
 325    */
 326   NS_IMETHOD  GetSystemFont(nsSystemFontID aID, nsFont *aFont) const = 0;
 327
 328   /**
 329    * Get the nsIFontMetrics that describe the properties of
 330    * an nsFont.
 331    * @param aFont font description to obtain metrics for
 332    * @param aLangGroup the language group of the document
 333    * @param aMetrics out parameter for font metrics
 334    * @param aUserFontSet user font set
 335    * @return error status
 336    */
 337   NS_IMETHOD  GetMetricsFor(const nsFont& aFont, nsIAtom* aLangGroup,
 338                             gfxUserFontSet* aUserFontSet,
 339                             nsIFontMetrics*& aMetrics) = 0;
 340
 341   /**
 342    * Get the nsIFontMetrics that describe the properties of
 343    * an nsFont.
 344    * @param aFont font description to obtain metrics for
 345    * @param aMetrics out parameter for font metrics
 346    * @param aUserFontSet user font set
 347    * @return error status
 348    */
 349   NS_IMETHOD  GetMetricsFor(const nsFont& aFont, gfxUserFontSet* aUserFontSet,
 350                             nsIFontMetrics*& aMetrics) = 0;
 351
 352   /**
 353    * Check to see if a particular named font exists.
 354    * @param aFontName character string of font face name
 355    * @return NS_OK if font is available, else font is unavailable
 356    */
 357   NS_IMETHOD CheckFontExistence(const nsString& aFaceName) = 0;
 358   NS_IMETHOD FirstExistingFont(const nsFont& aFont, nsString& aFaceName) = 0;
 359
 360   NS_IMETHOD GetLocalFontName(const nsString& aFaceName, nsString& aLocalName,
 361                               PRBool& aAliased) = 0;
 362
 363   /**
 364    * Notification when a font metrics instance created for this device is
 365    * about to be deleted
 366    */
 367   NS_IMETHOD FontMetricsDeleted(const nsIFontMetrics* aFontMetrics) = 0;
 368
 369   /**
 370    * Attempt to free up resoruces by flushing out any fonts no longer
 371    * referenced by anything other than the font cache itself.
 372    * @return error status
 373    */
 374   NS_IMETHOD FlushFontCache(void) = 0;
 375
 376   /**
 377    * Return the bit depth of the device.
 378    */
 379   NS_IMETHOD GetDepth(PRUint32& aDepth) = 0;
 380
 381   /**
 382    * Returns information about the device's palette capabilities.
 383    */
 384   NS_IMETHOD GetPaletteInfo(nsPaletteInfo& aPaletteInfo) = 0;
 385
 386   /**
 387    * Get the size of the displayable area of the output device
 388    * in app units.
 389    * @param aWidth out parameter for width
 390    * @param aHeight out parameter for height
 391    * @return error status
 392    */
 393   NS_IMETHOD GetDeviceSurfaceDimensions(nscoord &aWidth, nscoord &aHeight) = 0;
 394
 395   /**
 396    * Get the size of the content area of the output device in app units.
 397    * This corresponds on a screen device, for instance, to the entire screen.
 398    * @param aRect out parameter for full rect. Position (x,y) will be (0,0) or
 399    *              relative to the primary monitor if this is not the primary.
 400    * @return error status
 401    */
 402   NS_IMETHOD GetRect ( nsRect &aRect ) = 0;
 403
 404   /**
 405    * Get the size of the content area of the output device in app units.
 406    * This corresponds on a screen device, for instance, to the area reported
 407    * by GetDeviceSurfaceDimensions, minus the taskbar (Windows) or menubar
 408    * (Macintosh).
 409    * @param aRect out parameter for client rect. Position (x,y) will be (0,0)
 410    *              adjusted for any upper/left non-client space if present or
 411    *              relative to the primary monitor if this is not the primary.
 412    * @return error status
 413    */
 414   NS_IMETHOD GetClientRect(nsRect &aRect) = 0;
 415
 416   /**
 417    * This is enables the DeviceContext to anything it needs to do for Printing
 418    * before Reflow and BeginDocument is where work can be done after reflow.
 419    * @param aTitle - itle of Document
 420    * @param aPrintToFileName - name of file to print to, if NULL then don't print to file
 421    *
 422    * @return error status
 423    */
 424   NS_IMETHOD PrepareDocument(PRUnichar * aTitle,
 425                              PRUnichar*  aPrintToFileName) = 0;
 426
 427   //XXX need to work out re-entrancy issues for these APIs... MMP
 428   /**
 429    * Inform the output device that output of a document is beginning
 430    * Used for print related device contexts. Must be matched 1:1 with
 431    * EndDocument().
 432    * XXX needs to take parameters so that feedback can be given to the
 433    * app regarding pagination progress and aborting print operations?
 434    *
 435    * @param aTitle - itle of Document
 436    * @param aPrintToFileName - name of file to print to, if NULL then don't print to file
 437    * @param aStartPage - starting page number (must be greater than zero)
 438    * @param aEndPage - ending page number     (must be less than or equal to number of pages)
 439    *
 440    * @return error status
 441    */
 442   NS_IMETHOD BeginDocument(PRUnichar*  aTitle,
 443                            PRUnichar*  aPrintToFileName,
 444                            PRInt32     aStartPage,
 445                            PRInt32     aEndPage) = 0;
 446
 447   /**
 448    * Inform the output device that output of a document is ending.
 449    * Used for print related device contexts. Must be matched 1:1 with
 450    * BeginDocument()
 451    * @return error status
 452    */
 453   NS_IMETHOD EndDocument(void) = 0;
 454
 455   /**
 456    * Inform the output device that output of a document is being aborted.
 457    * Must be matched 1:1 with BeginDocument()
 458    * @return error status
 459    */
 460   NS_IMETHOD AbortDocument(void) = 0;
 461
 462   /**
 463    * Inform the output device that output of a page is beginning
 464    * Used for print related device contexts. Must be matched 1:1 with
 465    * EndPage() and within a BeginDocument()/EndDocument() pair.
 466    * @return error status
 467    */
 468   NS_IMETHOD BeginPage(void) = 0;
 469
 470   /**
 471    * Inform the output device that output of a page is ending
 472    * Used for print related device contexts. Must be matched 1:1 with
 473    * BeginPage() and within a BeginDocument()/EndDocument() pair.
 474    * @return error status
 475    */
 476   NS_IMETHOD EndPage(void) = 0;
 477
 478   /**
 479    * Clear cached system fonts (refresh from theme when
 480    * requested).  This method is effectively static,
 481    * and can be called on a new DeviceContext instance
 482    * without any initialization.  Only really used by
 483    * Gtk native theme stuff.
 484    */
 485   NS_IMETHOD ClearCachedSystemFonts() = 0;
 486
 487   /**
 488    * Check to see if the DPI has changed
 489    * @return whether there was actually a change in the DPI
 490    *         (whether AppUnitsPerDevPixel() or AppUnitsPerInch() changed)
 491   */
 492   virtual PRBool CheckDPIChange() = 0;
 493
 494   /**
 495    * Set the pixel scaling factor: all lengths are multiplied by this factor
 496    * when we convert them to device pixels. Returns whether the ratio of
 497    * app units to dev pixels changed because of the scale factor.
 498    */
 499   virtual PRBool SetPixelScale(float aScale) = 0;
 500
 501   /**
 502    * Get the pixel scaling factor; defaults to 1.0, but can be changed with
 503    * SetPixelScale.
 504    */
 505   float GetPixelScale() const { return mPixelScale; }
 506
 507   /**
 508    * Get the unscaled ratio of app units to dev pixels; useful if something
 509    * needs to be converted from to unscaled pixels
 510    */
 511   PRInt32 UnscaledAppUnitsPerDevPixel() const { return mAppUnitsPerDevNotScaledPixel; }
 512
 513 protected:
 514   PRInt32 mAppUnitsPerDevPixel;
 515   PRInt32 mAppUnitsPerInch;
 516   PRInt32 mAppUnitsPerDevNotScaledPixel;
 517   float  mPixelScale;
 518 };
 519
 520 NS_DEFINE_STATIC_IID_ACCESSOR(nsIDeviceContext, NS_IDEVICE_CONTEXT_IID)
 521
 522 #endif /* nsIDeviceContext_h___ */