Test: No new tests. This should not affect behavior; only dependencies.
Font.h does not need to include SkGlyphCache.h, and doing so requires
a transitive dependency on external/skia/src/utils, which was not
intended. Forward declare it instead, and fix the build errors that
resulted.
Change-Id: Ifd09430bb848d51b139df0f0c06c63e7e48711eb
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
Align x offset and width to 32, y offset and height to 4.
It improves the font texture upload performance.
Change-Id: I967eeed90658f2ce1eb08cb2740d5dc34c72f40b
Neither of these files need SkScalerContext.h. Remove those includes.
One really needs SkGlyph.h, so include it instead.
Change-Id: Ic7cfce9e7784c9290c5a2dfdd8385b65d32f9b76
bug:24584749
Fonts are only destroyed when the renderer is destroyed, this prevents
modifying the FontRenderer's LruCache while it's being iterated through
in FontRenderer::~FontRenderer.
Change-Id: I0e2c9f87981bfa50454ec8689df05851839e288e
bug:19062769
Glyphs were stored to the output buffer with the assumption of
non-overlap, which is incorrect for certain fonts/strings. Instead,
blend src into dst, so new glyphs don't clobber existing content.
Change-Id: I6e22037500e67d5348ee2a43d939416c23c4d1ea
Adds remaining missing overrides and nullptr usages, missed due to
an extreme failure in tool usage.
Change-Id: I56abd72975a3999ad13330003c348db40f59aebf
Changes generated with clang-modernize.
Additionally, fixed some struct-vs-class usage to make clang happy.
Change-Id: Ic6ef2427401ff1e794d26f21f7b44868fc75fb72
Remove Clang cutout for unused parameters. Fix warnings.
Remove Clang cutout for deprecated Skia function usage. Has been
fixed in the L push.
Change-Id: I7ea073ff67127cc1e14e798b655e2c50615fe8e7
bug:17702227
Add details useful to developers (such as layer size/View name), and
switch away from logging implementation names/details, since they
are generally not relevant to developers.
Change-Id: Iee605d182f241450f7e75a6d0c283d51fa1312f5
Narrow the use of #include directives in hwui, replacing with forward
declarations where straightforward. Speeds compiles; doesn't do any
restructuring of code.
Change-Id: Icac2baffb5896f55d8c6718e9bd9d4bfa02d3ca0
bug:14083128
Moves all of the font transform management into
OpenGLRenderer::findBestFontTransform(), and now simply passes down
final rasterization transforms into the FontRenderer.
Change-Id: Ie02752e6af863347b142367c7d628db5f9fc2998
the correct value to copy in bitmap is alpha component from
the cachebuffer. currently it is offset to red channel if format is
RGBA which is wrong.
this is followup fix for https://android-review.googlesource.com/#/c/93943/
Change-Id: I96b5ba35df5ccaef44caf2542d35d6585ba1df80
Signed-off-by: Digish Pandya <digishp@codeaurora.org>
