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      1 /*
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     30 
     31 #include "config.h"
     32 #include "TransparencyWin.h"
     33 
     34 #include "AffineTransform.h"
     35 #include "ImageBuffer.h"
     36 
     37 #include <gtest/gtest.h>
     38 #include <windows.h>
     39 
     40 namespace WebCore {
     41 
     42 static FloatRect RECTToFloatRect(const RECT* rect)
     43 {
     44     return FloatRect(static_cast<float>(rect->left),
     45                      static_cast<float>(rect->top),
     46                      static_cast<float>(rect->right - rect->left),
     47                      static_cast<float>(rect->bottom - rect->top));
     48 }
     49 
     50 static void drawNativeRect(GraphicsContext* context,
     51                            int x, int y, int w, int h)
     52 {
     53     SkCanvas* canvas = context->platformContext()->canvas();
     54     HDC dc = skia::BeginPlatformPaint(canvas);
     55 
     56     RECT innerRc;
     57     innerRc.left = x;
     58     innerRc.top = y;
     59     innerRc.right = x + w;
     60     innerRc.bottom = y + h;
     61     FillRect(dc, &innerRc,
     62              reinterpret_cast<HBRUSH>(GetStockObject(BLACK_BRUSH)));
     63 
     64     skia::EndPlatformPaint(canvas);
     65 }
     66 
     67 static Color getPixelAt(GraphicsContext* context, int x, int y)
     68 {
     69     const SkBitmap& bitmap = context->platformContext()->canvas()->getTopDevice()->accessBitmap(false);
     70     return Color(*reinterpret_cast<const RGBA32*>(bitmap.getAddr32(x, y)));
     71 }
     72 
     73 // Resets the top layer's alpha channel to 0 for each pixel. This simulates
     74 // Windows messing it up.
     75 static void clearTopLayerAlphaChannel(GraphicsContext* context)
     76 {
     77     SkBitmap& bitmap = const_cast<SkBitmap&>(context->platformContext()->canvas()->getTopDevice()->accessBitmap(false));
     78     for (int y = 0; y < bitmap.height(); y++) {
     79         uint32_t* row = bitmap.getAddr32(0, y);
     80         for (int x = 0; x < bitmap.width(); x++)
     81             row[x] &= 0x00FFFFFF;
     82     }
     83 }
     84 
     85 // Clears the alpha channel on the specified pixel.
     86 static void clearTopLayerAlphaPixel(GraphicsContext* context, int x, int y)
     87 {
     88     SkBitmap& bitmap = const_cast<SkBitmap&>(context->platformContext()->canvas()->getTopDevice()->accessBitmap(false));
     89     *bitmap.getAddr32(x, y) &= 0x00FFFFFF;
     90 }
     91 
     92 static std::ostream& operator<<(std::ostream& out, const Color& c)
     93 {
     94     std::ios_base::fmtflags oldFlags = out.flags(std::ios_base::hex |
     95                                                  std::ios_base::showbase);
     96     out << c.rgb();
     97     out.flags(oldFlags);
     98     return out;
     99 }
    100 
    101 TEST(TransparencyWin, NoLayer)
    102 {
    103     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(17, 16), ColorSpaceDeviceRGB));
    104 
    105     // KeepTransform
    106     {
    107         TransparencyWin helper;
    108         helper.init(src->context(),
    109                     TransparencyWin::NoLayer,
    110                     TransparencyWin::KeepTransform,
    111                     IntRect(1, 1, 14, 12));
    112 
    113         EXPECT_TRUE(src->context() == helper.context());
    114         EXPECT_TRUE(IntSize(14, 12) == helper.m_layerSize);
    115         EXPECT_TRUE(IntRect(1, 1, 14, 12) == helper.drawRect());
    116     }
    117 
    118     // Untransform is not allowed for NoLayer.
    119 
    120     // ScaleTransform
    121     src->context()->save();
    122     src->context()->scale(FloatSize(2.0, 0.5));
    123     {
    124         TransparencyWin helper;
    125         helper.init(src->context(),
    126                     TransparencyWin::NoLayer,
    127                     TransparencyWin::ScaleTransform,
    128                     IntRect(2, 2, 6, 6));
    129         helper.composite();
    130 
    131         // The coordinate system should be based in the upper left of our box.
    132         // It should be post-transformed.
    133         EXPECT_TRUE(src->context() == helper.context());
    134         EXPECT_TRUE(IntSize(12, 3) == helper.m_layerSize);
    135         EXPECT_TRUE(IntRect(4, 1, 12, 3) == helper.drawRect());
    136     }
    137     src->context()->restore();
    138 }
    139 
    140 TEST(TransparencyWin, WhiteLayer)
    141 {
    142     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    143 
    144     // KeepTransform
    145     {
    146         TransparencyWin helper;
    147         helper.init(src->context(),
    148                     TransparencyWin::WhiteLayer,
    149                     TransparencyWin::KeepTransform,
    150                     IntRect(1, 1, 14, 12));
    151         helper.composite();
    152 
    153         EXPECT_TRUE(src->context() != helper.context());
    154         EXPECT_TRUE(IntSize(14, 12) == helper.m_layerSize);
    155         EXPECT_TRUE(IntRect(1, 1, 14, 12) == helper.drawRect());
    156     }
    157 
    158     // Untransform
    159     {
    160         TransparencyWin helper;
    161         helper.init(src->context(),
    162                     TransparencyWin::WhiteLayer,
    163                     TransparencyWin::Untransform,
    164                     IntRect(1, 1, 14, 12));
    165         helper.composite();
    166 
    167         EXPECT_TRUE(src->context() != helper.context());
    168         EXPECT_TRUE(IntSize(14, 12) == helper.m_layerSize);
    169         EXPECT_TRUE(IntRect(0, 0, 14, 12) == helper.drawRect());
    170     }
    171 
    172     // ScaleTransform
    173     src->context()->save();
    174     src->context()->scale(FloatSize(2.0, 0.5));
    175     {
    176         TransparencyWin helper;
    177         helper.init(src->context(),
    178                     TransparencyWin::WhiteLayer,
    179                     TransparencyWin::ScaleTransform,
    180                     IntRect(2, 2, 6, 6));
    181         helper.composite();
    182 
    183         // The coordinate system should be based in the upper left of our box.
    184         // It should be post-transformed.
    185         EXPECT_TRUE(src->context() != helper.context());
    186         EXPECT_TRUE(IntSize(12, 3) == helper.m_layerSize);
    187         EXPECT_TRUE(IntRect(0, 0, 12, 3) == helper.drawRect());
    188     }
    189     src->context()->restore();
    190 }
    191 
    192 TEST(TransparencyWin, TextComposite)
    193 {
    194     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    195 
    196     // KeepTransform is the only valid transform mode for TextComposite.
    197     {
    198         TransparencyWin helper;
    199         helper.init(src->context(),
    200                     TransparencyWin::TextComposite,
    201                     TransparencyWin::KeepTransform,
    202                     IntRect(1, 1, 14, 12));
    203         helper.composite();
    204 
    205         EXPECT_TRUE(src->context() != helper.context());
    206         EXPECT_TRUE(IntSize(14, 12) == helper.m_layerSize);
    207         EXPECT_TRUE(IntRect(1, 1, 14, 12) == helper.drawRect());
    208     }
    209 }
    210 
    211 TEST(TransparencyWin, OpaqueCompositeLayer)
    212 {
    213     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    214 
    215     // KeepTransform
    216     {
    217         TransparencyWin helper;
    218         helper.init(src->context(),
    219                     TransparencyWin::OpaqueCompositeLayer,
    220                     TransparencyWin::KeepTransform,
    221                     IntRect(1, 1, 14, 12));
    222         helper.composite();
    223 
    224         EXPECT_TRUE(src->context() != helper.context());
    225         EXPECT_TRUE(IntSize(14, 12) == helper.m_layerSize);
    226         EXPECT_TRUE(IntRect(1, 1, 14, 12) == helper.drawRect());
    227     }
    228 
    229     // KeepTransform with scroll applied.
    230     src->context()->save();
    231     src->context()->translate(0, -1);
    232     {
    233         TransparencyWin helper;
    234         helper.init(src->context(),
    235                     TransparencyWin::OpaqueCompositeLayer,
    236                     TransparencyWin::KeepTransform,
    237                     IntRect(1, 1, 14, 14));
    238         helper.composite();
    239 
    240         EXPECT_TRUE(src->context() != helper.context());
    241         EXPECT_TRUE(IntSize(14, 14) == helper.m_layerSize);
    242         EXPECT_TRUE(IntRect(1, 1, 14, 14) == helper.drawRect());
    243     }
    244     src->context()->restore();
    245 
    246     // Untransform
    247     {
    248         TransparencyWin helper;
    249         helper.init(src->context(),
    250                     TransparencyWin::OpaqueCompositeLayer,
    251                     TransparencyWin::Untransform,
    252                     IntRect(1, 1, 14, 12));
    253         helper.composite();
    254 
    255         EXPECT_TRUE(src->context() != helper.context());
    256         EXPECT_TRUE(IntSize(14, 12) == helper.m_layerSize);
    257         EXPECT_TRUE(IntRect(0, 0, 14, 12) == helper.drawRect());
    258     }
    259 
    260     // ScaleTransform
    261     src->context()->save();
    262     src->context()->scale(FloatSize(2.0, 0.5));
    263     {
    264         TransparencyWin helper;
    265         helper.init(src->context(),
    266                     TransparencyWin::OpaqueCompositeLayer,
    267                     TransparencyWin::ScaleTransform,
    268                     IntRect(2, 2, 6, 6));
    269         helper.composite();
    270 
    271         // The coordinate system should be based in the upper left of our box.
    272         // It should be post-transformed.
    273         EXPECT_TRUE(src->context() != helper.context());
    274         EXPECT_TRUE(IntSize(12, 3) == helper.m_layerSize);
    275         EXPECT_TRUE(IntRect(0, 0, 12, 3) == helper.drawRect());
    276     }
    277     src->context()->restore();
    278 }
    279 
    280 TEST(TransparencyWin, WhiteLayerPixelTest)
    281 {
    282     // Make a total transparent buffer, and draw the white layer inset by 1 px.
    283     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    284 
    285     {
    286         TransparencyWin helper;
    287         helper.init(src->context(),
    288                     TransparencyWin::WhiteLayer,
    289                     TransparencyWin::KeepTransform,
    290                     IntRect(1, 1, 14, 14));
    291 
    292         // Coordinates should be in the original space, not the layer.
    293         drawNativeRect(helper.context(), 3, 3, 1, 1);
    294         clearTopLayerAlphaChannel(helper.context());
    295         helper.composite();
    296     }
    297 
    298     // The final image should be transparent around the edges for 1 px, white
    299     // in the middle, with (3,3) (what we drew above) being opaque black.
    300     EXPECT_EQ(Color(Color::transparent), getPixelAt(src->context(), 0, 0));
    301     EXPECT_EQ(Color(Color::white), getPixelAt(src->context(), 2, 2));
    302     EXPECT_EQ(Color(Color::black), getPixelAt(src->context(), 3, 3));
    303     EXPECT_EQ(Color(Color::white), getPixelAt(src->context(), 4, 4));
    304 }
    305 
    306 TEST(TransparencyWin, OpaqueCompositeLayerPixel)
    307 {
    308     Color red(0xFFFF0000), darkRed(0xFFBF0000);
    309     Color green(0xFF00FF00);
    310 
    311     // Make a red bottom layer, followed by a half green next layer @ 50%.
    312     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    313 
    314     FloatRect fullRect(0, 0, 16, 16);
    315     src->context()->fillRect(fullRect, red, ColorSpaceDeviceRGB);
    316     src->context()->beginTransparencyLayer(0.5);
    317     FloatRect rightHalf(8, 0, 8, 16);
    318     src->context()->fillRect(rightHalf, green, ColorSpaceDeviceRGB);
    319 
    320     // Make a transparency layer inset by one pixel, and fill it inset by
    321     // another pixel with 50% black.
    322     {
    323         TransparencyWin helper;
    324         helper.init(src->context(),
    325                     TransparencyWin::OpaqueCompositeLayer,
    326                     TransparencyWin::KeepTransform,
    327                     IntRect(1, 1, 14, 14));
    328 
    329         FloatRect inner(2, 2, 12, 12);
    330         helper.context()->fillRect(inner, Color(0x7f000000), ColorSpaceDeviceRGB);
    331         // These coordinates are relative to the layer, whish is inset by 1x1
    332         // pixels from the top left. So we're actually clearing (2, 2) and
    333         // (13,13), which are the extreme corners of the black area (and which
    334         // we check below).
    335         clearTopLayerAlphaPixel(helper.context(), 1, 1);
    336         clearTopLayerAlphaPixel(helper.context(), 12, 12);
    337         helper.composite();
    338     }
    339 
    340     // Finish the compositing.
    341     src->context()->endTransparencyLayer();
    342 
    343     // Check that we got the right values, it should be like the rectangle was
    344     // drawn with half opacity even though the alpha channel got messed up.
    345     EXPECT_EQ(red, getPixelAt(src->context(), 0, 0));
    346     EXPECT_EQ(red, getPixelAt(src->context(), 1, 1));
    347     EXPECT_EQ(darkRed, getPixelAt(src->context(), 2, 2));
    348 
    349     // The dark result is:
    350     //   (black @ 50% atop green) @ 50% atop red = 0xFF804000
    351     // which is 0xFFA02000 (Skia computes 0xFFA11F00 due to rounding).
    352     Color darkGreenRed(0xFF803f00);
    353     EXPECT_EQ(darkGreenRed, getPixelAt(src->context(), 13, 13));
    354 
    355     // 50% green on top of red = FF808000 (rounded to what Skia will produce).
    356     Color greenRed(0xFF807F00);
    357     EXPECT_EQ(greenRed, getPixelAt(src->context(), 14, 14));
    358     EXPECT_EQ(greenRed, getPixelAt(src->context(), 15, 15));
    359 }
    360 
    361 // Tests that translations are properly handled when using KeepTransform.
    362 TEST(TransparencyWin, TranslateOpaqueCompositeLayer)
    363 {
    364     // Fill with white.
    365     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    366     Color white(0xFFFFFFFF);
    367     FloatRect fullRect(0, 0, 16, 16);
    368     src->context()->fillRect(fullRect, white, ColorSpaceDeviceRGB);
    369 
    370     // Scroll down by 8 (coordinate system goes up).
    371     src->context()->save();
    372     src->context()->translate(0, -8);
    373 
    374     Color red(0xFFFF0000);
    375     Color green(0xFF00FF00);
    376     {
    377         // Make the transparency layer after translation will be @ (0, -8) with
    378         // size 16x16.
    379         TransparencyWin helper;
    380         helper.init(src->context(),
    381                     TransparencyWin::OpaqueCompositeLayer,
    382                     TransparencyWin::KeepTransform,
    383                     IntRect(0, 0, 16, 16));
    384 
    385         // Draw a red pixel at (15, 15). This should be the at (15, 7) after
    386         // the transform.
    387         FloatRect bottomRight(15, 15, 1, 1);
    388         helper.context()->fillRect(bottomRight, green, ColorSpaceDeviceRGB);
    389         helper.composite();
    390     }
    391 
    392     src->context()->restore();
    393 
    394     // Check the pixel we wrote.
    395     EXPECT_EQ(green, getPixelAt(src->context(), 15, 7));
    396 }
    397 
    398 // Same as OpaqueCompositeLayer, but the canvas has a rotation applied. This
    399 // tests that the propert transform is applied to the copied layer.
    400 TEST(TransparencyWin, RotateOpaqueCompositeLayer)
    401 {
    402     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    403 
    404     // The background is white.
    405     Color white(0xFFFFFFFF);
    406     FloatRect fullRect(0, 0, 16, 16);
    407     src->context()->fillRect(fullRect, white, ColorSpaceDeviceRGB);
    408 
    409     // Rotate the image by 90 degrees. This matrix is the same as
    410     // cw90.rotate(90); but avoids rounding errors. Rounding errors can cause
    411     // Skia to think that !rectStaysRect() and it will fall through to path
    412     // drawing mode, which in turn gives us antialiasing. We want no
    413     // antialiasing or other rounding problems since we're testing exact pixel
    414     // values.
    415     src->context()->save();
    416     AffineTransform cw90(0, 1, -1, 0, 0, 0);
    417     src->context()->concatCTM(cw90);
    418 
    419     // Make a transparency layer consisting of a horizontal line of 50% black.
    420     // Since the rotation is applied, this will actually be a vertical line
    421     // down the middle of the image.
    422     src->context()->beginTransparencyLayer(0.5);
    423     FloatRect blackRect(0, -9, 16, 2);
    424     Color black(0xFF000000);
    425     src->context()->fillRect(blackRect, black, ColorSpaceDeviceRGB);
    426 
    427     // Now draw 50% red square.
    428     {
    429         // Create a transparency helper inset one pixel in the buffer. The
    430         // coordinates are before transforming into this space, and maps to
    431         // IntRect(1, 1, 14, 14).
    432         TransparencyWin helper;
    433         helper.init(src->context(),
    434                     TransparencyWin::OpaqueCompositeLayer,
    435                     TransparencyWin::Untransform,
    436                     IntRect(1, -15, 14, 14));
    437 
    438         // Fill with red.
    439         helper.context()->fillRect(helper.drawRect(), Color(0x7f7f0000), ColorSpaceDeviceRGB);
    440         clearTopLayerAlphaChannel(helper.context());
    441         helper.composite();
    442     }
    443 
    444     // Finish the compositing.
    445     src->context()->endTransparencyLayer();
    446 
    447     // Top corner should be the original background.
    448     EXPECT_EQ(white, getPixelAt(src->context(), 0, 0));
    449 
    450     // Check the stripe down the middle, first at the top...
    451     Color gray(0xFF808080);
    452     EXPECT_EQ(white, getPixelAt(src->context(), 6, 0));
    453     EXPECT_EQ(gray, getPixelAt(src->context(), 7, 0));
    454     EXPECT_EQ(gray, getPixelAt(src->context(), 8, 0));
    455     EXPECT_EQ(white, getPixelAt(src->context(), 9, 0));
    456 
    457     // ...now at the bottom.
    458     EXPECT_EQ(white, getPixelAt(src->context(), 6, 15));
    459     EXPECT_EQ(gray, getPixelAt(src->context(), 7, 15));
    460     EXPECT_EQ(gray, getPixelAt(src->context(), 8, 15));
    461     EXPECT_EQ(white, getPixelAt(src->context(), 9, 15));
    462 
    463     // Our red square should be 25% red over the top of those two.
    464     Color redwhite(0xFFdfbfbf);
    465     Color redgray(0xFF9f8080);
    466     EXPECT_EQ(white, getPixelAt(src->context(), 0, 1));
    467     EXPECT_EQ(redwhite, getPixelAt(src->context(), 1, 1));
    468     EXPECT_EQ(redwhite, getPixelAt(src->context(), 6, 1));
    469     EXPECT_EQ(redgray, getPixelAt(src->context(), 7, 1));
    470     EXPECT_EQ(redgray, getPixelAt(src->context(), 8, 1));
    471     EXPECT_EQ(redwhite, getPixelAt(src->context(), 9, 1));
    472     EXPECT_EQ(redwhite, getPixelAt(src->context(), 14, 1));
    473     EXPECT_EQ(white, getPixelAt(src->context(), 15, 1));
    474 
    475     // Complete the 50% transparent layer.
    476     src->context()->restore();
    477 }
    478 
    479 TEST(TransparencyWin, TranslateScaleOpaqueCompositeLayer)
    480 {
    481     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    482 
    483     // The background is white on top with red on bottom.
    484     Color white(0xFFFFFFFF);
    485     FloatRect topRect(0, 0, 16, 8);
    486     src->context()->fillRect(topRect, white, ColorSpaceDeviceRGB);
    487     Color red(0xFFFF0000);
    488     FloatRect bottomRect(0, 8, 16, 8);
    489     src->context()->fillRect(bottomRect, red, ColorSpaceDeviceRGB);
    490 
    491     src->context()->save();
    492 
    493     // Translate left by one pixel.
    494     AffineTransform left;
    495     left.translate(-1, 0);
    496 
    497     // Scale by 2x.
    498     AffineTransform scale;
    499     scale.scale(2.0);
    500     src->context()->concatCTM(scale);
    501 
    502     // Then translate up by one pixel (which will actually be 2 due to scaling).
    503     AffineTransform up;
    504     up.translate(0, -1);
    505     src->context()->concatCTM(up);
    506 
    507     // Now draw 50% red square.
    508     {
    509         // Create a transparency helper inset one pixel in the buffer. The
    510         // coordinates are before transforming into this space, and maps to
    511         // IntRect(1, 1, 14, 14).
    512         TransparencyWin helper;
    513         helper.init(src->context(),
    514                     TransparencyWin::OpaqueCompositeLayer,
    515                     TransparencyWin::KeepTransform,
    516                     IntRect(1, -15, 14, 14));
    517 
    518         // Fill with red.
    519         helper.context()->fillRect(helper.drawRect(), Color(0x7f7f0000), ColorSpaceDeviceRGB);
    520         clearTopLayerAlphaChannel(helper.context());
    521         helper.composite();
    522     }
    523 }
    524 
    525 // Tests scale mode with no additional copy.
    526 TEST(TransparencyWin, Scale)
    527 {
    528     // Create an opaque white buffer.
    529     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    530     FloatRect fullBuffer(0, 0, 16, 16);
    531     src->context()->fillRect(fullBuffer, Color::white, ColorSpaceDeviceRGB);
    532 
    533     // Scale by 2x.
    534     src->context()->save();
    535     AffineTransform scale;
    536     scale.scale(2.0);
    537     src->context()->concatCTM(scale);
    538 
    539     // Start drawing a rectangle from 1->4. This should get scaled to 2->8.
    540     {
    541         TransparencyWin helper;
    542         helper.init(src->context(),
    543                     TransparencyWin::NoLayer,
    544                     TransparencyWin::ScaleTransform,
    545                     IntRect(1, 1, 3, 3));
    546 
    547         // The context should now have the identity transform and the returned
    548         // rect should be scaled.
    549         EXPECT_TRUE(helper.context()->getCTM().isIdentity());
    550         EXPECT_EQ(2, helper.drawRect().x());
    551         EXPECT_EQ(2, helper.drawRect().y());
    552         EXPECT_EQ(8, helper.drawRect().maxX());
    553         EXPECT_EQ(8, helper.drawRect().maxY());
    554 
    555         // Set the pixel at (2, 2) to be transparent. This should be fixed when
    556         // the helper goes out of scope. We don't want to call
    557         // clearTopLayerAlphaChannel because that will actually clear the whole
    558         // canvas (since we have no extra layer!).
    559         SkBitmap& bitmap = const_cast<SkBitmap&>(helper.context()->platformContext()->canvas()->getTopDevice()->accessBitmap(false));
    560         *bitmap.getAddr32(2, 2) &= 0x00FFFFFF;
    561         helper.composite();
    562     }
    563 
    564     src->context()->restore();
    565 
    566     // Check the pixel we previously made transparent, it should have gotten
    567     // fixed back up to white.
    568 
    569     // The current version doesn't fixup transparency when there is no layer.
    570     // This seems not to be necessary, so we don't bother, but if it becomes
    571     // necessary, this line should be uncommented.
    572     // EXPECT_EQ(Color(Color::white), getPixelAt(src->context(), 2, 2));
    573 }
    574 
    575 // Tests scale mode with an additional copy for transparency. This will happen
    576 // if we have a scaled textbox, for example. WebKit will create a new
    577 // transparency layer, draw the text field, then draw the text into it, then
    578 // composite this down with an opacity.
    579 TEST(TransparencyWin, ScaleTransparency)
    580 {
    581     // Create an opaque white buffer.
    582     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    583     FloatRect fullBuffer(0, 0, 16, 16);
    584     src->context()->fillRect(fullBuffer, Color::white, ColorSpaceDeviceRGB);
    585 
    586     // Make another layer (which duplicates how WebKit will make this). We fill
    587     // the top half with red, and have the layer be 50% opaque.
    588     src->context()->beginTransparencyLayer(0.5);
    589     FloatRect topHalf(0, 0, 16, 8);
    590     src->context()->fillRect(topHalf, Color(0xFFFF0000), ColorSpaceDeviceRGB);
    591 
    592     // Scale by 2x.
    593     src->context()->save();
    594     AffineTransform scale;
    595     scale.scale(2.0);
    596     src->context()->concatCTM(scale);
    597 
    598     // Make a layer inset two pixels (because of scaling, this is 2->14). And
    599     // will it with 50% black.
    600     {
    601         TransparencyWin helper;
    602         helper.init(src->context(),
    603                     TransparencyWin::OpaqueCompositeLayer,
    604                     TransparencyWin::ScaleTransform,
    605                     IntRect(1, 1, 6, 6));
    606 
    607         helper.context()->fillRect(helper.drawRect(), Color(0x7f000000), ColorSpaceDeviceRGB);
    608         clearTopLayerAlphaChannel(helper.context());
    609         helper.composite();
    610     }
    611 
    612     // Finish the layer.
    613     src->context()->restore();
    614     src->context()->endTransparencyLayer();
    615 
    616     Color redBackground(0xFFFF8080); // 50% red composited on white.
    617     EXPECT_EQ(redBackground, getPixelAt(src->context(), 0, 0));
    618     EXPECT_EQ(redBackground, getPixelAt(src->context(), 1, 1));
    619 
    620     // Top half (minus two pixel border) should be 50% gray atop opaque
    621     // red = 0xFF804141. Then that's composited with 50% transparency on solid
    622     // white = 0xFFC0A1A1.
    623     Color darkRed(0xFFBF8080);
    624     EXPECT_EQ(darkRed, getPixelAt(src->context(), 2, 2));
    625     EXPECT_EQ(darkRed, getPixelAt(src->context(), 7, 7));
    626 
    627     // Bottom half (minus a two pixel border) should be a layer with 5% gray
    628     // with another 50% opacity composited atop white.
    629     Color darkWhite(0xFFBFBFBF);
    630     EXPECT_EQ(darkWhite, getPixelAt(src->context(), 8, 8));
    631     EXPECT_EQ(darkWhite, getPixelAt(src->context(), 13, 13));
    632 
    633     Color white(0xFFFFFFFF); // Background in the lower-right.
    634     EXPECT_EQ(white, getPixelAt(src->context(), 14, 14));
    635     EXPECT_EQ(white, getPixelAt(src->context(), 15, 15));
    636 }
    637 
    638 TEST(TransparencyWin, Text)
    639 {
    640     OwnPtr<ImageBuffer> src(ImageBuffer::create(IntSize(16, 16), ColorSpaceDeviceRGB));
    641 
    642     // Our text should end up 50% transparent blue-green.
    643     Color fullResult(0x80008080);
    644 
    645     {
    646         TransparencyWin helper;
    647         helper.init(src->context(),
    648                     TransparencyWin::TextComposite,
    649                     TransparencyWin::KeepTransform,
    650                     IntRect(0, 0, 16, 16));
    651         helper.setTextCompositeColor(fullResult);
    652 
    653         // Write several different squares to simulate ClearType. These should
    654         // all reduce to 2/3 coverage.
    655         FloatRect pixel(0, 0, 1, 1);
    656         helper.context()->fillRect(pixel, 0xFFFF0000, ColorSpaceDeviceRGB);
    657         pixel.move(1.0f, 0.0f);
    658         helper.context()->fillRect(pixel, 0xFF00FF00, ColorSpaceDeviceRGB);
    659         pixel.move(1.0f, 0.0f);
    660         helper.context()->fillRect(pixel, 0xFF0000FF, ColorSpaceDeviceRGB);
    661         pixel.move(1.0f, 0.0f);
    662         helper.context()->fillRect(pixel, 0xFF008080, ColorSpaceDeviceRGB);
    663         pixel.move(1.0f, 0.0f);
    664         helper.context()->fillRect(pixel, 0xFF800080, ColorSpaceDeviceRGB);
    665         pixel.move(1.0f, 0.0f);
    666         helper.context()->fillRect(pixel, 0xFF808000, ColorSpaceDeviceRGB);
    667 
    668         // Try one with 100% coverage (opaque black).
    669         pixel.move(1.0f, 0.0f);
    670         helper.context()->fillRect(pixel, 0xFF000000, ColorSpaceDeviceRGB);
    671 
    672         // Now mess with the alpha channel.
    673         clearTopLayerAlphaChannel(helper.context());
    674         helper.composite();
    675     }
    676 
    677     Color oneThirdResult(0x55005555); // = fullResult * 2 / 3
    678     EXPECT_EQ(oneThirdResult, getPixelAt(src->context(), 0, 0));
    679     EXPECT_EQ(oneThirdResult, getPixelAt(src->context(), 1, 0));
    680     EXPECT_EQ(oneThirdResult, getPixelAt(src->context(), 2, 0));
    681     EXPECT_EQ(oneThirdResult, getPixelAt(src->context(), 3, 0));
    682     EXPECT_EQ(oneThirdResult, getPixelAt(src->context(), 4, 0));
    683     EXPECT_EQ(oneThirdResult, getPixelAt(src->context(), 5, 0));
    684     EXPECT_EQ(fullResult, getPixelAt(src->context(), 6, 0));
    685     EXPECT_EQ(Color::transparent, getPixelAt(src->context(), 7, 0));
    686 }
    687 
    688 } // namespace WebCore
    689