NOTE: Linear blending is currently disabled in this CL as the
feature is still a work in progress
Android currently performs all blending (any kind of linear math
on colors really) on gamma-encoded colors. Since Android assumes
that the default color space is sRGB, all bitmaps and colors
are encoded with the sRGB Opto-Electronic Conversion Function
(OECF, which can be approximated with a power function). Since
the power curve is not linear, our linear math is incorrect.
The result is that we generate colors that tend to be too dark;
this affects blending but also anti-aliasing, gradients, blurs,
etc.
The solution is to convert gamma-encoded colors back to linear
space before doing any math on them, using the sRGB Electo-Optical
Conversion Function (EOCF). This is achieved in different
ways in different parts of the pipeline:
- Using hardware conversions when sampling from OpenGL textures
or writing into OpenGL frame buffers
- Using software conversion functions, to translate app-supplied
colors to and from sRGB
- Using Skia's color spaces
Any type of processing on colors must roughly ollow these steps:
[sRGB input]->EOCF->[linear data]->[processing]->OECF->[sRGB output]
For the sRGB color space, the conversion functions are defined as
follows:
OECF(linear) :=
linear <= 0.0031308 ? linear * 12.92 : (pow(linear, 1/2.4) * 1.055) - 0.055
EOCF(srgb) :=
srgb <= 0.04045 ? srgb / 12.92 : pow((srgb + 0.055) / 1.055, 2.4)
The EOCF is simply the reciprocal of the OECF.
While it is highly recommended to use the exact sRGB conversion
functions everywhere possible, it is sometimes useful or beneficial
to rely on approximations:
- pow(x,2.2) and pow(x,1/2.2)
- x^2 and sqrt(x)
The latter is particularly useful in fragment shaders (for instance
to apply dithering in sRGB space), especially if the sqrt() can be
replaced with an inversesqrt().
Here is a fairly exhaustive list of modifications implemented
in this CL:
- Set TARGET_ENABLE_LINEAR_BLENDING := false in BoardConfig.mk
to disable linear blending. This is only for GLES 2.0 GPUs
with no hardware sRGB support. This flag is currently assumed
to be false (see note above)
- sRGB writes are disabled when entering a functor (WebView).
This will need to be fixed at some point
- Skia bitmaps are created with the sRGB color space
- Bitmaps using a 565 config are expanded to 888
- Linear blending is disabled when entering a functor
- External textures are not properly sampled (see below)
- Gradients are interpolated in linear space
- Texture-based dithering was replaced with analytical dithering
- Dithering is done in the quantization color space, which is
why we must do EOCF(OECF(color)+dither)
- Text is now gamma corrected differently depending on the luminance
of the source pixel. The asumption is that a bright pixel will be
blended on a dark background and the other way around. The source
alpha is gamma corrected to thicken dark on bright and thin
bright on dark to match the intended design of fonts. This also
matches the behavior of popular design/drawing applications
- Removed the asset atlas. It did not contain anything useful and
could not be sampled in sRGB without a yet-to-be-defined GL
extension
- The last column of color matrices is converted to linear space
because its value are added to linear colors
Missing features:
- Resource qualifier?
- Regeneration of goldeng images for automated tests
- Handle alpha8/grey8 properly
- Disable sRGB write for layers with external textures
Test: Manual testing while work in progress
Bug: 29940137
Change-Id: I6a07b15ab49b554377cd33a36b6d9971a15e9a0b
Bug: 30342017
Upload recents thumbnails in the
dead gaps between frames instead of
at the start of a frame. This eliminates
jank caused by the large texture
upload.
Change-Id: I507cd286d199109c7a9a1511d68ba5ab5d28069f
So that the native library isn't unloaded before we have a chance to
call the freeFunction.
Bug: 28406866
Change-Id: I889f1ccd91bba70e31fb8d09c0ec6d471fc35841
- Or to be specific, SurfaceFlinger can’t easily take 565 screenshots,
so convert them when creating the ashmem bitmap.
Bug: 28151300
Change-Id: Ic7586659a41cc19c322136f77a1c52ef68c22707
Bug: 22214367
Previous releases would let the getters on a recycle()'d bitmap to still
work despite being firmly in undefined behavior per the documentation
on Bitmap#recycle().
As there are apps relying on this, yell very loudly about this behavior
in the log and give them a bit of time to fix it
Change-Id: I857be7e74cb217877973d9c6f03eb761d12fd056
Bug: 20940526
Rather than throwing an exception on accessing a recycled()
bitmap let certain operations succeed and just return dummy
values. Apps appear to be relying on this.
Change-Id: I74df2efdc29d93facd8553ed31cda3addf0b28eb
Fix the issue where Bitmap requires two GC passes
to release its byte[] by using some questionable
ref-counting hacks to manage whether or not
native has a strong or weak ref to the byte[]
Change-Id: Ia90a883579f61c0b1904b5549a66bd0ef34b32c5
Fix a bunch of places where mNativeBitmap was being
poked at directly, switch them either to the NDK API
or to GraphicsJNI where it made sense
Change-Id: I6b3df3712d6497cba828c2d3012e725cb4ebb64d
Bug: 19035637
If an app tries to call recycle() on a Bitmap that has
already been finalized it will result in use-after-frees. This is
bad. Avoid this by setting the pointer to 0 and checking for this
Change-Id: I12d73703a0f95b05fe4c2fd8e9c01b6a3f2f023b
b/15856895
Nine patches now have outline round rect metadata stored as optional
png tags. aapt generates these automatically by inspecting the bitmap
pixels to estimate outline bounds and round rect radius, based on
opacity.
Change-Id: I226e328a97873010d9e1adb797ac48f93a31183c
Replace the Java variable with mRequestPremultiplied, to better
reflect what it represents. In both native and Java, the SkBitmap
is used as the decision maker of whether a Bitmap is premultiplied.
When changing other settings, mRequestedPremultiplied is used to
determine whether it should be premultiplied (if the new config/
hasAlpha-ness etc supports it).
ChooseFromColorProc now reads both the colortype (instead of the
deprecated Config) and alphatype on the SkBitmap. Same with
ChooseToColorProc. In the process, this caught a bug, where the
wrong procs were being used for Index8.
Replace instances of SkBitmap::Config with SkColorType where I
was already changing code.
Use the new versions of setConfig/allocPixels that take an SkImageInfo
as a parameter.
Document isPremultiplied's return value for ALPHA_8.
BUG:13618134
Change-Id: I91fc1f1e46e9294364b1af0ab4bdb37c68d7058e
This fixes CTS tests which are crashing on an SkASSERT due to a
mismatch of SkImageInfo between the SkPixelRef and SkBitmap.
Also directly call ref() and unref() instead of SkSafeRef/SkSafeUnref,
since we would already crash if the SkPixelRef in question was NULL.
Also if the user attempts to reconfigure to 4444, use 8888 instead.
Change-Id: I473ef225c6cd1c92d67ae103c53c6cff0dad92de
Bug: 13580771
The cached value mHasAlpha on Bitmap could get out of sync with the
real value stored in the SkBitmap. Fix this by just eliminating the
cached value. This adds an extra JNI call in copy(), createBitmap(),
and setPremultiplied(), none of which are going to be significantly
impacted by the extra JNI call.
Change-Id: I4fce069a77d9b3bbb47dde04275ff8510ce7e4f0
(These CLs are already in master.)
Bug: 13246311
This cherry-picks 7 CLs:
-----------------------------------------------------------------------
Remove calls to deprecated SkBitmap::setIsOpaque()
setIsOpaque() has been removed from ToT Skia.
Update setters for mIsPremultiplied and hasAlpha to take the
other into consideration.
cherry-pick from: I1b36b0b0ce7126031eb7b769b563c17dcd4b306a
-----------------------------------------------------------------------
Merge AssetStream with AssetStreamAdaptor.
Add enums to the constructor for AssetStreamAdaptor to choose the
different behaviors used by the (former) two different classes.
The old clients of AssetStream now get the following features of
AssetStreamAdaptor
- Debugging statements on error.
- The stream is an SkStreamRewindable.
- getLength() returns the correct value, and the old way of getting
the length (read(NULL, 0)) is no longer implemented, since it is
no longer used.
- isAtEnd() returns the correct value. ToT Skia makes it pure virtual,
so some implementation is necessary.
cherry-pick from: I2a5395914e4f53830aaefee396556459083a1c56
-----------------------------------------------------------------------
Deprecate Android-specific SkPaint functions.
The following functions were problematic:
const SkGlyph& getUnicharMetrics(SkUnichar, const SkMatrix*);
const SkGlyph& getGlyphMetrics(uint16_t, const SkMatrix*);
const void* findImage(const SkGlyph&, const SkMatrix*);
Replacing them with calls through SkGlyphCache solved a nasty crash
bug, so they have all been deprecated.
Bug: 11968757
cherry-pick from: Id746315d41aec5b211b78b172a883c2061130f08
-----------------------------------------------------------------------
pass SkGlyphCache into updateGlyphCache()
Doing so prevents us from double-locking the glyph cache, thereby
effectively locking ourselves out of reusing work that we'd just done.
Bug: 11968757
cherry-pick from: I5c552f2d0bbe30af2ce9054ba684e7da756a0d89
-----------------------------------------------------------------------
Updates to the Skia API needed to merge the WebView m33 version of Skia.
cherry-pick from: I0f63b53f2aae58871413b132742fc84138f069a3
Bugfix for screenshots (recent apps) due to incorrect rowBytes computation
bug: 12915192
cherry-pick from: I4d5fe2a2f75baf66099e0970fb646686a1992714
-----------------------------------------------------------------------
Fix bug in AndroidPixelRef where we did not store the correct imageInfo for a recycled bitmap.
cherry-pick from: I882483b78886e2f19fa4e43a86e69f5a82b3b7e5
-----------------------------------------------------------------------
Change-Id: Ie2b731a9f0795802418cfecddb4b684c92c64d33
Conflicts:
core/jni/android/graphics/Bitmap.cpp
core/jni/android/graphics/Graphics.cpp
core/jni/android/graphics/Typeface.cpp
graphics/java/android/graphics/Bitmap.java
