gecko-dev/gfx/thebes/gfxUtils.cpp

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Corporation code.
 *
 * The Initial Developer of the Original Code is Mozilla Foundation.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Vladimir Vukicevic <vladimir@pobox.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
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 * ***** END LICENSE BLOCK ***** */

#include "gfxUtils.h"
#include "gfxContext.h"
#include "gfxPlatform.h"

#if defined(XP_WIN) || defined(WINCE)
#include "gfxWindowsPlatform.h"
#endif

static PRUint8 sUnpremultiplyTable[256*256];
static PRUint8 sPremultiplyTable[256*256];
static PRBool sTablesInitialized = PR_FALSE;

static const PRUint8 PremultiplyValue(PRUint8 a, PRUint8 v) {
    return sPremultiplyTable[a*256+v];
}

static const PRUint8 UnpremultiplyValue(PRUint8 a, PRUint8 v) {
    return sUnpremultiplyTable[a*256+v];
}

static void
CalculateTables()
{
    // It's important that the array be indexed first by alpha and then by rgb
    // value.  When we unpremultiply a pixel, we're guaranteed to do three
    // lookups with the same alpha; indexing by alpha first makes it likely that
    // those three lookups will be close to one another in memory, thus
    // increasing the chance of a cache hit.

    // Unpremultiply table

    // a == 0 case
    for (PRUint32 c = 0; c <= 255; c++) {
        sUnpremultiplyTable[c] = c;
    }

    for (int a = 1; a <= 255; a++) {
        for (int c = 0; c <= 255; c++) {
            sUnpremultiplyTable[a*256+c] = (PRUint8)((c * 255) / a);
        }
    }

    // Premultiply table

    for (int a = 0; a <= 255; a++) {
        for (int c = 0; c <= 255; c++) {
            sPremultiplyTable[a*256+c] = (a * c + 254) / 255;
        }
    }

    sTablesInitialized = PR_TRUE;
}

void
gfxUtils::PremultiplyImageSurface(gfxImageSurface *aSourceSurface,
                                  gfxImageSurface *aDestSurface)
{
    if (!aDestSurface)
        aDestSurface = aSourceSurface;

    NS_ASSERTION(aSourceSurface->Format() == aDestSurface->Format() &&
                 aSourceSurface->Width() == aDestSurface->Width() &&
                 aSourceSurface->Height() == aDestSurface->Height() &&
                 aSourceSurface->Stride() == aDestSurface->Stride(),
                 "Source and destination surfaces don't have identical characteristics");

    NS_ASSERTION(aSourceSurface->Stride() == aSourceSurface->Width() * 4,
                 "Source surface stride isn't tightly packed");

    // Only premultiply ARGB32
    if (aSourceSurface->Format() != gfxASurface::ImageFormatARGB32) {
        if (aDestSurface != aSourceSurface) {
            memcpy(aDestSurface->Data(), aSourceSurface->Data(),
                   aSourceSurface->Stride() * aSourceSurface->Height());
        }
        return;
    }

    if (!sTablesInitialized)
        CalculateTables();

    PRUint8 *src = aSourceSurface->Data();
    PRUint8 *dst = aDestSurface->Data();

    PRUint32 dim = aSourceSurface->Width() * aSourceSurface->Height();
    for (PRUint32 i = 0; i < dim; ++i) {
#ifdef IS_LITTLE_ENDIAN
        PRUint8 b = *src++;
        PRUint8 g = *src++;
        PRUint8 r = *src++;
        PRUint8 a = *src++;

        *dst++ = PremultiplyValue(a, b);
        *dst++ = PremultiplyValue(a, g);
        *dst++ = PremultiplyValue(a, r);
        *dst++ = a;
#else
        PRUint8 a = *src++;
        PRUint8 r = *src++;
        PRUint8 g = *src++;
        PRUint8 b = *src++;

        *dst++ = a;
        *dst++ = PremultiplyValue(a, r);
        *dst++ = PremultiplyValue(a, g);
        *dst++ = PremultiplyValue(a, b);
#endif
    }
}

void
gfxUtils::UnpremultiplyImageSurface(gfxImageSurface *aSourceSurface,
                                    gfxImageSurface *aDestSurface)
{
    if (!aDestSurface)
        aDestSurface = aSourceSurface;

    NS_ASSERTION(aSourceSurface->Format() == aDestSurface->Format() &&
                 aSourceSurface->Width() == aDestSurface->Width() &&
                 aSourceSurface->Height() == aDestSurface->Height() &&
                 aSourceSurface->Stride() == aDestSurface->Stride(),
                 "Source and destination surfaces don't have identical characteristics");

    NS_ASSERTION(aSourceSurface->Stride() == aSourceSurface->Width() * 4,
                 "Source surface stride isn't tightly packed");

    // Only premultiply ARGB32
    if (aSourceSurface->Format() != gfxASurface::ImageFormatARGB32) {
        if (aDestSurface != aSourceSurface) {
            memcpy(aDestSurface->Data(), aSourceSurface->Data(),
                   aSourceSurface->Stride() * aSourceSurface->Height());
        }
        return;
    }

    if (!sTablesInitialized)
        CalculateTables();

    PRUint8 *src = aSourceSurface->Data();
    PRUint8 *dst = aDestSurface->Data();

    PRUint32 dim = aSourceSurface->Width() * aSourceSurface->Height();
    for (PRUint32 i = 0; i < dim; ++i) {
#ifdef IS_LITTLE_ENDIAN
        PRUint8 b = *src++;
        PRUint8 g = *src++;
        PRUint8 r = *src++;
        PRUint8 a = *src++;

        *dst++ = UnpremultiplyValue(a, b);
        *dst++ = UnpremultiplyValue(a, g);
        *dst++ = UnpremultiplyValue(a, r);
        *dst++ = a;
#else
        PRUint8 a = *src++;
        PRUint8 r = *src++;
        PRUint8 g = *src++;
        PRUint8 b = *src++;

        *dst++ = a;
        *dst++ = UnpremultiplyValue(a, r);
        *dst++ = UnpremultiplyValue(a, g);
        *dst++ = UnpremultiplyValue(a, b);
#endif
    }
}

static PRBool
IsSafeImageTransformComponent(gfxFloat aValue)
{
  return aValue >= -32768 && aValue <= 32767;
}

static void
SetExtendAndFilterOnPattern(gfxPattern* aPattern,
                            const gfxMatrix& aDeviceToImage,
                            const gfxASurface::gfxSurfaceType aSurfaceType,
                            const gfxPattern::GraphicsFilter aDefaultFilter)
{
    // In theory we can handle this using cairo's EXTEND_PAD,
    // but implementation limitations mean we have to consult
    // the surface type.
    switch (aSurfaceType) {
        case gfxASurface::SurfaceTypeXlib:
        case gfxASurface::SurfaceTypeXcb:
        {
            // See bug 324698.  This is a workaround for EXTEND_PAD not being
            // implemented correctly on linux in the X server.
            //
            // Set the filter to CAIRO_FILTER_FAST --- otherwise,
            // pixman's sampling will sample transparency for the outside edges and we'll
            // get blurry edges.  CAIRO_EXTEND_PAD would also work here, if
            // available
            //
            // But don't do this for simple downscales because it's horrible.
            // Downscaling means that device-space coordinates are
            // scaled *up* to find the image pixel coordinates.
            //
            // aDeviceToImage is slightly stale because up above we may
            // have adjusted the pattern's matrix ... but the adjustment
            // is only a translation so the scale factors in aDeviceToImage
            // are still valid.
            PRBool isDownscale =
                aDeviceToImage.xx >= 1.0 && aDeviceToImage.yy >= 1.0 &&
                aDeviceToImage.xy == 0.0 && aDeviceToImage.yx == 0.0;
            if (!isDownscale) {
                aPattern->SetFilter(gfxPattern::FILTER_FAST);
            }
            break;
        }

        case gfxASurface::SurfaceTypeQuartz:
        case gfxASurface::SurfaceTypeQuartzImage:
            // Don't set EXTEND_PAD, Mac seems to be OK. Really?
            aPattern->SetFilter(aDefaultFilter);
            break;

        default:
            // turn on EXTEND_PAD.
            // This is what we really want for all surface types, if the
            // implementation was universally good.
            aPattern->SetExtend(gfxPattern::EXTEND_PAD);
            aPattern->SetFilter(aDefaultFilter);
            break;
    }
}

// EXTEND_PAD won't help us here; we have to create a temporary surface to hold
// the subimage of pixels we're allowed to sample.
static already_AddRefed<gfxPattern>
CreateSamplingRestrictedPattern(gfxASurface* aSurface,
                                gfxContext* aContext,
                                const gfxMatrix& aUserSpaceToImageSpace,
                                const gfxRect& aSourceRect,
                                const gfxRect& aSubimage,
                                const gfxImageSurface::gfxImageFormat aFormat)
{
    gfxRect userSpaceClipExtents = aContext->GetClipExtents();
    // This isn't optimal --- if aContext has a rotation then GetClipExtents
    // will have to do a bounding-box computation, and TransformBounds might
    // too, so we could get a better result if we computed image space clip
    // extents in one go --- but it doesn't really matter and this is easier
    // to understand.
    gfxRect imageSpaceClipExtents =
        aUserSpaceToImageSpace.TransformBounds(userSpaceClipExtents);
    // Inflate by one pixel because bilinear filtering will sample at most
    // one pixel beyond the computed image pixel coordinate.
    imageSpaceClipExtents.Outset(1.0);

    gfxRect needed = imageSpaceClipExtents.Intersect(aSourceRect);
    needed = needed.Intersect(aSubimage);
    needed.RoundOut();

    // if 'needed' is empty, nothing will be drawn since aFill
    // must be entirely outside the clip region, so it doesn't
    // matter what we do here, but we should avoid trying to
    // create a zero-size surface.
    if (needed.IsEmpty())
        return nsnull;

    gfxIntSize size(PRInt32(needed.Width()), PRInt32(needed.Height()));
    nsRefPtr<gfxASurface> temp =
        gfxPlatform::GetPlatform()->CreateOffscreenSurface(size, aFormat);
    if (!temp || temp->CairoStatus())
        return nsnull;

    nsRefPtr<gfxPattern> tmpPattern = new gfxPattern(aSurface);
    if (!tmpPattern)
        return nsnull;

    tmpPattern->SetExtend(gfxPattern::EXTEND_REPEAT);
    tmpPattern->SetMatrix(gfxMatrix().Translate(needed.pos));

    gfxContext tmpCtx(temp);
    tmpCtx.SetOperator(gfxContext::OPERATOR_SOURCE);
    tmpCtx.SetPattern(tmpPattern);
    tmpCtx.Paint();

    nsRefPtr<gfxPattern> resultPattern = new gfxPattern(temp);
    if (!resultPattern)
        return nsnull;

    resultPattern->SetMatrix(
        gfxMatrix(aUserSpaceToImageSpace).Multiply(gfxMatrix().Translate(-needed.pos)));
    return resultPattern.forget();
}

// working around cairo/pixman bug (bug 364968)
// Our device-space-to-image-space transform may not be acceptable to pixman.
struct NS_STACK_CLASS AutoCairoPixmanBugWorkaround
{
    AutoCairoPixmanBugWorkaround(gfxContext*      aContext,
                                 const gfxMatrix& aDeviceSpaceToImageSpace,
                                 const gfxRect&   aFill,
                                 const gfxASurface::gfxSurfaceType& aSurfaceType)
     : mContext(aContext), mSucceeded(PR_TRUE), mPushedGroup(PR_FALSE)
    {
        // Quartz's limits for matrix are much larger than pixman
        if (aSurfaceType == gfxASurface::SurfaceTypeQuartz)
            return;

        if (!IsSafeImageTransformComponent(aDeviceSpaceToImageSpace.xx) ||
            !IsSafeImageTransformComponent(aDeviceSpaceToImageSpace.xy) ||
            !IsSafeImageTransformComponent(aDeviceSpaceToImageSpace.yx) ||
            !IsSafeImageTransformComponent(aDeviceSpaceToImageSpace.yy)) {
            NS_WARNING("Scaling up too much, bailing out");
            mSucceeded = PR_FALSE;
            return;
        }

        if (IsSafeImageTransformComponent(aDeviceSpaceToImageSpace.x0) &&
            IsSafeImageTransformComponent(aDeviceSpaceToImageSpace.y0))
            return;

        // We'll push a group, which will hopefully reduce our transform's
        // translation so it's in bounds.
        gfxMatrix currentMatrix = mContext->CurrentMatrix();
        mContext->Save();

        // Clip the rounded-out-to-device-pixels bounds of the
        // transformed fill area. This is the area for the group we
        // want to push.
        mContext->IdentityMatrix();
        gfxRect bounds = currentMatrix.TransformBounds(aFill);
        bounds.RoundOut();
        mContext->Clip(bounds);
        mContext->SetMatrix(currentMatrix);
        mContext->PushGroup(gfxASurface::CONTENT_COLOR_ALPHA);
        mContext->SetOperator(gfxContext::OPERATOR_OVER);

        mPushedGroup = PR_TRUE;
    }

    ~AutoCairoPixmanBugWorkaround()
    {
        if (mPushedGroup) {
            mContext->PopGroupToSource();
            mContext->Paint();
            mContext->Restore();
        }
    }

    PRBool PushedGroup() { return mPushedGroup; }
    PRBool Succeeded() { return mSucceeded; }

private:
    gfxContext* mContext;
    PRPackedBool mSucceeded;
    PRPackedBool mPushedGroup;
};

/**
 * This returns the fastest operator to use for solid surfaces which have no
 * alpha channel or their alpha channel is uniformly opaque.
 * This differs per render mode.
 */
static gfxContext::GraphicsOperator
OptimalFillOperator()
{
#ifdef XP_WIN
    if (gfxWindowsPlatform::GetPlatform()->GetRenderMode() ==
        gfxWindowsPlatform::RENDER_DIRECT2D) {
        // D2D -really- hates operator source.
        return gfxContext::OPERATOR_OVER;
    } else {
#endif
        return gfxContext::OPERATOR_SOURCE;
#ifdef XP_WIN
    }
#endif
}

static gfxMatrix
DeviceToImageTransform(gfxContext* aContext,
                       const gfxMatrix& aUserSpaceToImageSpace)
{
    gfxFloat deviceX, deviceY;
    nsRefPtr<gfxASurface> currentTarget =
        aContext->CurrentSurface(&deviceX, &deviceY);
    gfxMatrix currentMatrix = aContext->CurrentMatrix();
    gfxMatrix deviceToUser = gfxMatrix(currentMatrix).Invert();
    deviceToUser.Translate(-gfxPoint(-deviceX, -deviceY));
    return gfxMatrix(deviceToUser).Multiply(aUserSpaceToImageSpace);
}

/* static */ void
gfxUtils::DrawPixelSnapped(gfxContext*      aContext,
                           gfxASurface*     aSurface,
                           const gfxMatrix& aUserSpaceToImageSpace,
                           const gfxRect&   aSubimage,
                           const gfxRect&   aSourceRect,
                           const gfxRect&   aImageRect,
                           const gfxRect&   aFill,
                           const gfxImageSurface::gfxImageFormat aFormat,
                           const gfxPattern::GraphicsFilter& aFilter)
{
    PRBool doTile = !aImageRect.Contains(aSourceRect);

    nsRefPtr<gfxASurface> currentTarget = aContext->CurrentSurface();
    gfxASurface::gfxSurfaceType surfaceType = currentTarget->GetType();
    gfxMatrix currentMatrix = aContext->CurrentMatrix();
    gfxMatrix deviceSpaceToImageSpace =
        DeviceToImageTransform(aContext, aUserSpaceToImageSpace);

    AutoCairoPixmanBugWorkaround workaround(aContext, deviceSpaceToImageSpace,
                                            aFill, surfaceType);
    if (!workaround.Succeeded())
        return;

    nsRefPtr<gfxPattern> pattern = new gfxPattern(aSurface);
    pattern->SetMatrix(aUserSpaceToImageSpace);

    // OK now, the hard part left is to account for the subimage sampling
    // restriction. If all the transforms involved are just integer
    // translations, then we assume no resampling will occur so there's
    // nothing to do.
    // XXX if only we had source-clipping in cairo!
    if (!currentMatrix.HasNonIntegerTranslation() &&
        !aUserSpaceToImageSpace.HasNonIntegerTranslation()) {
        if (doTile) {
            pattern->SetExtend(gfxPattern::EXTEND_REPEAT);
        }
    } else {
        if (doTile || !aSubimage.Contains(aImageRect)) {
            nsRefPtr<gfxPattern> restrictedPattern =
                CreateSamplingRestrictedPattern(aSurface, aContext,
                                                aUserSpaceToImageSpace,
                                                aSourceRect, aSubimage, aFormat);
            if (restrictedPattern) {
                pattern.swap(restrictedPattern);
            }
        }
        SetExtendAndFilterOnPattern(pattern, deviceSpaceToImageSpace, surfaceType,
                                    aFilter);
    }

    gfxContext::GraphicsOperator op = aContext->CurrentOperator();
    if ((op == gfxContext::OPERATOR_OVER || workaround.PushedGroup()) &&
        aFormat == gfxASurface::ImageFormatRGB24) {
        aContext->SetOperator(OptimalFillOperator());
    }

    // Phew! Now we can actually draw this image
    aContext->NewPath();
#ifdef MOZ_GFX_OPTIMIZE_MOBILE
    pattern->SetFilter(gfxPattern::FILTER_FAST); 
#endif
    aContext->SetPattern(pattern);
    aContext->Rectangle(aFill);
    aContext->Fill();

    aContext->SetOperator(op);
}