DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (b6057e17f856)

VCS Links

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsDeviceContext.h"
#include <algorithm>                    // for max
#include "gfxASurface.h"                // for gfxASurface, etc
#include "gfxFont.h"                    // for gfxFontGroup
#include "gfxImageSurface.h"            // for gfxImageSurface
#include "gfxPoint.h"                   // for gfxSize
#include "mozilla/Attributes.h"         // for MOZ_FINAL
#include "mozilla/Preferences.h"        // for Preferences
#include "mozilla/Services.h"           // for GetObserverService
#include "mozilla/mozalloc.h"           // for operator new
#include "nsCRT.h"                      // for nsCRT
#include "nsDebug.h"                    // for NS_NOTREACHED, NS_ASSERTION, etc
#include "nsFont.h"                     // for nsFont
#include "nsFontMetrics.h"              // for nsFontMetrics
#include "nsIAtom.h"                    // for nsIAtom, do_GetAtom
#include "nsID.h"
#include "nsIDeviceContextSpec.h"       // for nsIDeviceContextSpec
#include "nsILanguageAtomService.h"     // for nsILanguageAtomService, etc
#include "nsIObserver.h"                // for nsIObserver, etc
#include "nsIObserverService.h"         // for nsIObserverService
#include "nsIScreen.h"                  // for nsIScreen
#include "nsIScreenManager.h"           // for nsIScreenManager
#include "nsISupportsImpl.h"            // for MOZ_COUNT_CTOR, etc
#include "nsISupportsUtils.h"           // for NS_ADDREF, NS_RELEASE
#include "nsIWidget.h"                  // for nsIWidget, NS_NATIVE_WINDOW
#include "nsRect.h"                     // for nsRect
#include "nsRenderingContext.h"         // for nsRenderingContext
#include "nsServiceManagerUtils.h"      // for do_GetService
#include "nsString.h"               // for nsDependentString
#include "nsTArray.h"                   // for nsTArray, nsTArray_Impl
#include "nsThreadUtils.h"              // for NS_IsMainThread

#if !XP_MACOSX
#include "gfxPDFSurface.h"
#endif

#ifdef MOZ_WIDGET_GTK
#include "gfxPSSurface.h"
#elif XP_WIN
#include "gfxWindowsSurface.h"
#elif XP_MACOSX
#include "gfxQuartzSurface.h"
#endif

using namespace mozilla;
using mozilla::services::GetObserverService;

class nsFontCache MOZ_FINAL : public nsIObserver
{
public:
    nsFontCache()   { MOZ_COUNT_CTOR(nsFontCache); }
    ~nsFontCache()  { MOZ_COUNT_DTOR(nsFontCache); }

    NS_DECL_ISUPPORTS
    NS_DECL_NSIOBSERVER

    void Init(nsDeviceContext* aContext);
    void Destroy();

    nsresult GetMetricsFor(const nsFont& aFont, nsIAtom* aLanguage,
                           gfxUserFontSet* aUserFontSet,
                           gfxTextPerfMetrics* aTextPerf,
                           nsFontMetrics*& aMetrics);

    void FontMetricsDeleted(const nsFontMetrics* aFontMetrics);
    void Compact();
    void Flush();

protected:
    nsDeviceContext*          mContext; // owner
    nsCOMPtr<nsIAtom>         mLocaleLanguage;
    nsTArray<nsFontMetrics*>  mFontMetrics;
};

NS_IMPL_ISUPPORTS(nsFontCache, nsIObserver)

// The Init and Destroy methods are necessary because it's not
// safe to call AddObserver from a constructor or RemoveObserver
// from a destructor.  That should be fixed.
void
nsFontCache::Init(nsDeviceContext* aContext)
{
    mContext = aContext;
    // register as a memory-pressure observer to free font resources
    // in low-memory situations.
    nsCOMPtr<nsIObserverService> obs = GetObserverService();
    if (obs)
        obs->AddObserver(this, "memory-pressure", false);

    nsCOMPtr<nsILanguageAtomService> langService;
    langService = do_GetService(NS_LANGUAGEATOMSERVICE_CONTRACTID);
    if (langService) {
        mLocaleLanguage = langService->GetLocaleLanguage();
    }
    if (!mLocaleLanguage) {
        mLocaleLanguage = do_GetAtom("x-western");
    }
}

void
nsFontCache::Destroy()
{
    nsCOMPtr<nsIObserverService> obs = GetObserverService();
    if (obs)
        obs->RemoveObserver(this, "memory-pressure");
    Flush();
}

NS_IMETHODIMP
nsFontCache::Observe(nsISupports*, const char* aTopic, const char16_t*)
{
    if (!nsCRT::strcmp(aTopic, "memory-pressure"))
        Compact();
    return NS_OK;
}

nsresult
nsFontCache::GetMetricsFor(const nsFont& aFont, nsIAtom* aLanguage,
                           gfxUserFontSet* aUserFontSet,
                           gfxTextPerfMetrics* aTextPerf,
                           nsFontMetrics*& aMetrics)
{
    if (!aLanguage)
        aLanguage = mLocaleLanguage;

    // First check our cache
    // start from the end, which is where we put the most-recent-used element

    nsFontMetrics* fm;
    int32_t n = mFontMetrics.Length() - 1;
    for (int32_t i = n; i >= 0; --i) {
        fm = mFontMetrics[i];
        if (fm->Font().Equals(aFont) && fm->GetUserFontSet() == aUserFontSet &&
            fm->Language() == aLanguage) {
            if (i != n) {
                // promote it to the end of the cache
                mFontMetrics.RemoveElementAt(i);
                mFontMetrics.AppendElement(fm);
            }
            fm->GetThebesFontGroup()->UpdateFontList();
            NS_ADDREF(aMetrics = fm);
            return NS_OK;
        }
    }

    // It's not in the cache. Get font metrics and then cache them.

    fm = new nsFontMetrics();
    NS_ADDREF(fm);
    nsresult rv = fm->Init(aFont, aLanguage, mContext, aUserFontSet, aTextPerf);
    if (NS_SUCCEEDED(rv)) {
        // the mFontMetrics list has the "head" at the end, because append
        // is cheaper than insert
        mFontMetrics.AppendElement(fm);
        aMetrics = fm;
        NS_ADDREF(aMetrics);
        return NS_OK;
    }
    fm->Destroy();
    NS_RELEASE(fm);

    // One reason why Init() fails is because the system is running out of
    // resources. e.g., on Win95/98 only a very limited number of GDI
    // objects are available. Compact the cache and try again.

    Compact();
    fm = new nsFontMetrics();
    NS_ADDREF(fm);
    rv = fm->Init(aFont, aLanguage, mContext, aUserFontSet, aTextPerf);
    if (NS_SUCCEEDED(rv)) {
        mFontMetrics.AppendElement(fm);
        aMetrics = fm;
        return NS_OK;
    }
    fm->Destroy();
    NS_RELEASE(fm);

    // could not setup a new one, send an old one (XXX search a "best
    // match"?)

    n = mFontMetrics.Length() - 1; // could have changed in Compact()
    if (n >= 0) {
        aMetrics = mFontMetrics[n];
        NS_ADDREF(aMetrics);
        return NS_OK;
    }

    NS_POSTCONDITION(NS_SUCCEEDED(rv),
                     "font metrics should not be null - bug 136248");
    return rv;
}

void
nsFontCache::FontMetricsDeleted(const nsFontMetrics* aFontMetrics)
{
    mFontMetrics.RemoveElement(aFontMetrics);
}

void
nsFontCache::Compact()
{
    // Need to loop backward because the running element can be removed on
    // the way
    for (int32_t i = mFontMetrics.Length()-1; i >= 0; --i) {
        nsFontMetrics* fm = mFontMetrics[i];
        nsFontMetrics* oldfm = fm;
        // Destroy() isn't here because we want our device context to be
        // notified
        NS_RELEASE(fm); // this will reset fm to nullptr
        // if the font is really gone, it would have called back in
        // FontMetricsDeleted() and would have removed itself
        if (mFontMetrics.IndexOf(oldfm) != mFontMetrics.NoIndex) {
            // nope, the font is still there, so let's hold onto it too
            NS_ADDREF(oldfm);
        }
    }
}

void
nsFontCache::Flush()
{
    for (int32_t i = mFontMetrics.Length()-1; i >= 0; --i) {
        nsFontMetrics* fm = mFontMetrics[i];
        // Destroy() will unhook our device context from the fm so that we
        // won't waste time in triggering the notification of
        // FontMetricsDeleted() in the subsequent release
        fm->Destroy();
        NS_RELEASE(fm);
    }
    mFontMetrics.Clear();
}

nsDeviceContext::nsDeviceContext()
    : mWidth(0), mHeight(0), mDepth(0),
      mAppUnitsPerDevPixel(-1), mAppUnitsPerDevNotScaledPixel(-1),
      mAppUnitsPerPhysicalInch(-1),
      mPixelScale(1.0f), mPrintingScale(1.0f),
      mFontCache(nullptr)
{
    MOZ_ASSERT(NS_IsMainThread(), "nsDeviceContext created off main thread");
}

// Note: we use a bare pointer for mFontCache so that nsFontCache
// can be an incomplete type in nsDeviceContext.h.
// Therefore we have to do all the refcounting by hand.
nsDeviceContext::~nsDeviceContext()
{
    if (mFontCache) {
        mFontCache->Destroy();
        NS_RELEASE(mFontCache);
    }
}

nsresult
nsDeviceContext::GetMetricsFor(const nsFont& aFont,
                               nsIAtom* aLanguage,
                               gfxUserFontSet* aUserFontSet,
                               gfxTextPerfMetrics* aTextPerf,
                               nsFontMetrics*& aMetrics)
{
    if (!mFontCache) {
        mFontCache = new nsFontCache();
        NS_ADDREF(mFontCache);
        mFontCache->Init(this);
    }

    return mFontCache->GetMetricsFor(aFont, aLanguage, aUserFontSet,
                                     aTextPerf, aMetrics);
}

nsresult
nsDeviceContext::FlushFontCache(void)
{
    if (mFontCache)
        mFontCache->Flush();
    return NS_OK;
}

nsresult
nsDeviceContext::FontMetricsDeleted(const nsFontMetrics* aFontMetrics)
{
    if (mFontCache) {
        mFontCache->FontMetricsDeleted(aFontMetrics);
    }
    return NS_OK;
}

bool
nsDeviceContext::IsPrinterSurface()
{
    return mPrintingSurface != nullptr;
}

void
nsDeviceContext::SetDPI()
{
    float dpi = -1.0f;

    // PostScript, PDF and Mac (when printing) all use 72 dpi
    // Use a printing DC to determine the other dpi values
    if (mPrintingSurface) {
        switch (mPrintingSurface->GetType()) {
        case gfxSurfaceType::PDF:
        case gfxSurfaceType::PS:
        case gfxSurfaceType::Quartz:
            dpi = 72.0f;
            break;
#ifdef XP_WIN
        case gfxSurfaceType::Win32:
        case gfxSurfaceType::Win32Printing: {
            HDC dc = reinterpret_cast<gfxWindowsSurface*>(mPrintingSurface.get())->GetDC();
            int32_t OSVal = GetDeviceCaps(dc, LOGPIXELSY);
            dpi = 144.0f;
            mPrintingScale = float(OSVal) / dpi;
            break;
        }
#endif
        default:
            NS_NOTREACHED("Unexpected printing surface type");
            break;
        }

        mAppUnitsPerDevNotScaledPixel =
            NS_lround((AppUnitsPerCSSPixel() * 96) / dpi);
    } else {
        // A value of -1 means use the maximum of 96 and the system DPI.
        // A value of 0 means use the system DPI. A positive value is used as the DPI.
        // This sets the physical size of a device pixel and thus controls the
        // interpretation of physical units.
        int32_t prefDPI = Preferences::GetInt("layout.css.dpi", -1);

        if (prefDPI > 0) {
            dpi = prefDPI;
        } else if (mWidget) {
            dpi = mWidget->GetDPI();

            if (prefDPI < 0) {
                dpi = std::max(96.0f, dpi);
            }
        } else {
            dpi = 96.0f;
        }

        CSSToLayoutDeviceScale scale = mWidget ? mWidget->GetDefaultScale()
                                               : CSSToLayoutDeviceScale(1.0);
        double devPixelsPerCSSPixel = scale.scale;

        mAppUnitsPerDevNotScaledPixel =
            std::max(1, NS_lround(AppUnitsPerCSSPixel() / devPixelsPerCSSPixel));
    }

    NS_ASSERTION(dpi != -1.0, "no dpi set");

    mAppUnitsPerPhysicalInch = NS_lround(dpi * mAppUnitsPerDevNotScaledPixel);
    UpdateScaledAppUnits();
}

nsresult
nsDeviceContext::Init(nsIWidget *aWidget)
{
    if (mScreenManager && mWidget == aWidget)
        return NS_OK;

    mWidget = aWidget;
    SetDPI();

    if (mScreenManager)
        return NS_OK;

    mScreenManager = do_GetService("@mozilla.org/gfx/screenmanager;1");

    return NS_OK;
}

already_AddRefed<nsRenderingContext>
nsDeviceContext::CreateRenderingContext()
{
    nsRefPtr<gfxASurface> printingSurface = mPrintingSurface;
#ifdef XP_MACOSX
    // CreateRenderingContext() can be called (on reflow) after EndPage()
    // but before BeginPage().  On OS X (and only there) mPrintingSurface
    // will in this case be null, because OS X printing surfaces are
    // per-page, and therefore only truly valid between calls to BeginPage()
    // and EndPage().  But we can get away with fudging things here, if need
    // be, by using a cached copy.
    if (!printingSurface) {
      printingSurface = mCachedPrintingSurface;
    }
#endif
    nsRefPtr<nsRenderingContext> pContext = new nsRenderingContext();

    RefPtr<gfx::DrawTarget> dt =
      gfxPlatform::GetPlatform()->CreateDrawTargetForSurface(printingSurface,
                                                             gfx::IntSize(mWidth, mHeight));

    pContext->Init(this, dt);
    pContext->ThebesContext()->SetFlag(gfxContext::FLAG_DISABLE_SNAPPING);
    pContext->Scale(mPrintingScale, mPrintingScale);

    return pContext.forget();
}

nsresult
nsDeviceContext::GetDepth(uint32_t& aDepth)
{
    if (mDepth == 0) {
        nsCOMPtr<nsIScreen> primaryScreen;
        mScreenManager->GetPrimaryScreen(getter_AddRefs(primaryScreen));
        primaryScreen->GetColorDepth(reinterpret_cast<int32_t *>(&mDepth));
    }

    aDepth = mDepth;
    return NS_OK;
}

nsresult
nsDeviceContext::GetDeviceSurfaceDimensions(nscoord &aWidth, nscoord &aHeight)
{
    if (mPrintingSurface) {
        // we have a printer device
        aWidth = mWidth;
        aHeight = mHeight;
    } else {
        nsRect area;
        ComputeFullAreaUsingScreen(&area);
        aWidth = area.width;
        aHeight = area.height;
    }

    return NS_OK;
}

nsresult
nsDeviceContext::GetRect(nsRect &aRect)
{
    if (mPrintingSurface) {
        // we have a printer device
        aRect.x = 0;
        aRect.y = 0;
        aRect.width = mWidth;
        aRect.height = mHeight;
    } else
        ComputeFullAreaUsingScreen ( &aRect );

    return NS_OK;
}

nsresult
nsDeviceContext::GetClientRect(nsRect &aRect)
{
    if (mPrintingSurface) {
        // we have a printer device
        aRect.x = 0;
        aRect.y = 0;
        aRect.width = mWidth;
        aRect.height = mHeight;
    }
    else
        ComputeClientRectUsingScreen(&aRect);

    return NS_OK;
}

nsresult
nsDeviceContext::InitForPrinting(nsIDeviceContextSpec *aDevice)
{
    NS_ENSURE_ARG_POINTER(aDevice);

    mDeviceContextSpec = aDevice;

    nsresult rv = aDevice->GetSurfaceForPrinter(getter_AddRefs(mPrintingSurface));
    if (NS_FAILED(rv))
        return NS_ERROR_FAILURE;

    Init(nullptr);

    CalcPrintingSize();

    return NS_OK;
}

nsresult
nsDeviceContext::BeginDocument(const nsAString& aTitle,
                               char16_t*       aPrintToFileName,
                               int32_t          aStartPage,
                               int32_t          aEndPage)
{
    static const char16_t kEmpty[] = { '\0' };
    nsresult rv;

    rv = mPrintingSurface->BeginPrinting(aTitle,
                                         nsDependentString(aPrintToFileName ? aPrintToFileName : kEmpty));

    if (NS_SUCCEEDED(rv) && mDeviceContextSpec)
        rv = mDeviceContextSpec->BeginDocument(aTitle, aPrintToFileName, aStartPage, aEndPage);

    return rv;
}


nsresult
nsDeviceContext::EndDocument(void)
{
    nsresult rv = NS_OK;

    if (mPrintingSurface) {
        rv = mPrintingSurface->EndPrinting();
        if (NS_SUCCEEDED(rv))
            mPrintingSurface->Finish();
    }

    if (mDeviceContextSpec)
        mDeviceContextSpec->EndDocument();

    return rv;
}


nsresult
nsDeviceContext::AbortDocument(void)
{
    nsresult rv = mPrintingSurface->AbortPrinting();

    if (mDeviceContextSpec)
        mDeviceContextSpec->EndDocument();

    return rv;
}


nsresult
nsDeviceContext::BeginPage(void)
{
    nsresult rv = NS_OK;

    if (mDeviceContextSpec)
        rv = mDeviceContextSpec->BeginPage();

    if (NS_FAILED(rv)) return rv;

#ifdef XP_MACOSX
    // We need to get a new surface for each page on the Mac, as the
    // CGContextRefs are only good for one page.
    mDeviceContextSpec->GetSurfaceForPrinter(getter_AddRefs(mPrintingSurface));
#endif

    rv = mPrintingSurface->BeginPage();

    return rv;
}

nsresult
nsDeviceContext::EndPage(void)
{
    nsresult rv = mPrintingSurface->EndPage();

#ifdef XP_MACOSX
    // We need to release the CGContextRef in the surface here, plus it's
    // not something you would want anyway, as these CGContextRefs are only
    // good for one page.  But we need to keep a cached reference to it, since
    // CreateRenderingContext() may try to access it when mPrintingSurface
    // would normally be null.  See bug 665218.  If we just stop nulling out
    // mPrintingSurface here (and thereby make that our cached copy), we'll
    // break all our null checks on mPrintingSurface.  See bug 684622.
    mCachedPrintingSurface = mPrintingSurface;
    mPrintingSurface = nullptr;
#endif

    if (mDeviceContextSpec)
        mDeviceContextSpec->EndPage();

    return rv;
}

void
nsDeviceContext::ComputeClientRectUsingScreen(nsRect* outRect)
{
    // we always need to recompute the clientRect
    // because the window may have moved onto a different screen. In the single
    // monitor case, we only need to do the computation if we haven't done it
    // once already, and remember that we have because we're assured it won't change.
    nsCOMPtr<nsIScreen> screen;
    FindScreen (getter_AddRefs(screen));
    if (screen) {
        int32_t x, y, width, height;
        screen->GetAvailRect(&x, &y, &width, &height);

        // convert to device units
        outRect->y = NSIntPixelsToAppUnits(y, AppUnitsPerDevPixel());
        outRect->x = NSIntPixelsToAppUnits(x, AppUnitsPerDevPixel());
        outRect->width = NSIntPixelsToAppUnits(width, AppUnitsPerDevPixel());
        outRect->height = NSIntPixelsToAppUnits(height, AppUnitsPerDevPixel());
    }
}

void
nsDeviceContext::ComputeFullAreaUsingScreen(nsRect* outRect)
{
    // if we have more than one screen, we always need to recompute the clientRect
    // because the window may have moved onto a different screen. In the single
    // monitor case, we only need to do the computation if we haven't done it
    // once already, and remember that we have because we're assured it won't change.
    nsCOMPtr<nsIScreen> screen;
    FindScreen ( getter_AddRefs(screen) );
    if ( screen ) {
        int32_t x, y, width, height;
        screen->GetRect ( &x, &y, &width, &height );

        // convert to device units
        outRect->y = NSIntPixelsToAppUnits(y, AppUnitsPerDevPixel());
        outRect->x = NSIntPixelsToAppUnits(x, AppUnitsPerDevPixel());
        outRect->width = NSIntPixelsToAppUnits(width, AppUnitsPerDevPixel());
        outRect->height = NSIntPixelsToAppUnits(height, AppUnitsPerDevPixel());

        mWidth = outRect->width;
        mHeight = outRect->height;
    }
}

//
// FindScreen
//
// Determines which screen intersects the largest area of the given surface.
//
void
nsDeviceContext::FindScreen(nsIScreen** outScreen)
{
    if (mWidget && mWidget->GetNativeData(NS_NATIVE_WINDOW))
        mScreenManager->ScreenForNativeWidget(mWidget->GetNativeData(NS_NATIVE_WINDOW),
                                              outScreen);
    else
        mScreenManager->GetPrimaryScreen(outScreen);
}

void
nsDeviceContext::CalcPrintingSize()
{
    if (!mPrintingSurface)
        return;

    bool inPoints = true;

    gfxSize size(0, 0);
    switch (mPrintingSurface->GetType()) {
    case gfxSurfaceType::Image:
        inPoints = false;
        size = reinterpret_cast<gfxImageSurface*>(mPrintingSurface.get())->GetSize();
        break;

#if defined(MOZ_PDF_PRINTING)
    case gfxSurfaceType::PDF:
        inPoints = true;
        size = reinterpret_cast<gfxPDFSurface*>(mPrintingSurface.get())->GetSize();
        break;
#endif

#ifdef MOZ_WIDGET_GTK
    case gfxSurfaceType::PS:
        inPoints = true;
        size = reinterpret_cast<gfxPSSurface*>(mPrintingSurface.get())->GetSize();
        break;
#endif

#ifdef XP_MACOSX
    case gfxSurfaceType::Quartz:
        inPoints = true; // this is really only true when we're printing
        size = reinterpret_cast<gfxQuartzSurface*>(mPrintingSurface.get())->GetSize();
        break;
#endif

#ifdef XP_WIN
    case gfxSurfaceType::Win32:
    case gfxSurfaceType::Win32Printing:
        {
            inPoints = false;
            HDC dc = reinterpret_cast<gfxWindowsSurface*>(mPrintingSurface.get())->GetDC();
            if (!dc)
                dc = GetDC((HWND)mWidget->GetNativeData(NS_NATIVE_WIDGET));
            size.width = NSFloatPixelsToAppUnits(::GetDeviceCaps(dc, HORZRES)/mPrintingScale, AppUnitsPerDevPixel());
            size.height = NSFloatPixelsToAppUnits(::GetDeviceCaps(dc, VERTRES)/mPrintingScale, AppUnitsPerDevPixel());
            mDepth = (uint32_t)::GetDeviceCaps(dc, BITSPIXEL);
            if (dc != reinterpret_cast<gfxWindowsSurface*>(mPrintingSurface.get())->GetDC())
                ReleaseDC((HWND)mWidget->GetNativeData(NS_NATIVE_WIDGET), dc);
            break;
        }
#endif

    default:
        NS_ERROR("trying to print to unknown surface type");
    }

    if (inPoints) {
        // For printing, CSS inches and physical inches are identical
        // so it doesn't matter which we use here
        mWidth = NSToCoordRound(float(size.width) * AppUnitsPerPhysicalInch() / 72);
        mHeight = NSToCoordRound(float(size.height) * AppUnitsPerPhysicalInch() / 72);
    } else {
        mWidth = NSToIntRound(size.width);
        mHeight = NSToIntRound(size.height);
    }
}

bool nsDeviceContext::CheckDPIChange() {
    int32_t oldDevPixels = mAppUnitsPerDevNotScaledPixel;
    int32_t oldInches = mAppUnitsPerPhysicalInch;

    SetDPI();

    return oldDevPixels != mAppUnitsPerDevNotScaledPixel ||
        oldInches != mAppUnitsPerPhysicalInch;
}

bool
nsDeviceContext::SetPixelScale(float aScale)
{
    if (aScale <= 0) {
        NS_NOTREACHED("Invalid pixel scale value");
        return false;
    }
    int32_t oldAppUnitsPerDevPixel = mAppUnitsPerDevPixel;
    mPixelScale = aScale;
    UpdateScaledAppUnits();
    return oldAppUnitsPerDevPixel != mAppUnitsPerDevPixel;
}

void
nsDeviceContext::UpdateScaledAppUnits()
{
    mAppUnitsPerDevPixel =
        std::max(1, NSToIntRound(float(mAppUnitsPerDevNotScaledPixel) / mPixelScale));
    // adjust mPixelScale to reflect appunit rounding
    mPixelScale = float(mAppUnitsPerDevNotScaledPixel) / mAppUnitsPerDevPixel;
}