Romain Guy 253f2c213f Linear blending, step 1
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
2016-10-11 17:47:58 -07:00

377 lines
13 KiB
C++

/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "EglManager.h"
#include "Caches.h"
#include "DeviceInfo.h"
#include "Properties.h"
#include "RenderThread.h"
#include "renderstate/RenderState.h"
#include "utils/StringUtils.h"
#include <cutils/log.h>
#include <cutils/properties.h>
#include <EGL/eglext.h>
#include <string>
#define GLES_VERSION 2
// Android-specific addition that is used to show when frames began in systrace
EGLAPI void EGLAPIENTRY eglBeginFrame(EGLDisplay dpy, EGLSurface surface);
namespace android {
namespace uirenderer {
namespace renderthread {
#define ERROR_CASE(x) case x: return #x;
static const char* egl_error_str(EGLint error) {
switch (error) {
ERROR_CASE(EGL_SUCCESS)
ERROR_CASE(EGL_NOT_INITIALIZED)
ERROR_CASE(EGL_BAD_ACCESS)
ERROR_CASE(EGL_BAD_ALLOC)
ERROR_CASE(EGL_BAD_ATTRIBUTE)
ERROR_CASE(EGL_BAD_CONFIG)
ERROR_CASE(EGL_BAD_CONTEXT)
ERROR_CASE(EGL_BAD_CURRENT_SURFACE)
ERROR_CASE(EGL_BAD_DISPLAY)
ERROR_CASE(EGL_BAD_MATCH)
ERROR_CASE(EGL_BAD_NATIVE_PIXMAP)
ERROR_CASE(EGL_BAD_NATIVE_WINDOW)
ERROR_CASE(EGL_BAD_PARAMETER)
ERROR_CASE(EGL_BAD_SURFACE)
ERROR_CASE(EGL_CONTEXT_LOST)
default:
return "Unknown error";
}
}
static const char* egl_error_str() {
return egl_error_str(eglGetError());
}
static struct {
bool bufferAge = false;
bool setDamage = false;
} EglExtensions;
void Frame::map(const SkRect& in, EGLint* out) const {
/* The rectangles are specified relative to the bottom-left of the surface
* and the x and y components of each rectangle specify the bottom-left
* position of that rectangle.
*
* HWUI does everything with 0,0 being top-left, so need to map
* the rect
*/
SkIRect idirty;
in.roundOut(&idirty);
EGLint y = mHeight - (idirty.y() + idirty.height());
// layout: {x, y, width, height}
out[0] = idirty.x();
out[1] = y;
out[2] = idirty.width();
out[3] = idirty.height();
}
EglManager::EglManager(RenderThread& thread)
: mRenderThread(thread)
, mEglDisplay(EGL_NO_DISPLAY)
, mEglConfig(nullptr)
, mEglContext(EGL_NO_CONTEXT)
, mPBufferSurface(EGL_NO_SURFACE)
, mCurrentSurface(EGL_NO_SURFACE) {
}
void EglManager::initialize() {
if (hasEglContext()) return;
ATRACE_NAME("Creating EGLContext");
mEglDisplay = eglGetDisplay(EGL_DEFAULT_DISPLAY);
LOG_ALWAYS_FATAL_IF(mEglDisplay == EGL_NO_DISPLAY,
"Failed to get EGL_DEFAULT_DISPLAY! err=%s", egl_error_str());
EGLint major, minor;
LOG_ALWAYS_FATAL_IF(eglInitialize(mEglDisplay, &major, &minor) == EGL_FALSE,
"Failed to initialize display %p! err=%s", mEglDisplay, egl_error_str());
ALOGI("Initialized EGL, version %d.%d", (int)major, (int)minor);
initExtensions();
// Now that extensions are loaded, pick a swap behavior
if (Properties::enablePartialUpdates) {
if (Properties::useBufferAge && EglExtensions.bufferAge) {
mSwapBehavior = SwapBehavior::BufferAge;
} else {
mSwapBehavior = SwapBehavior::Preserved;
}
}
loadConfig();
createContext();
createPBufferSurface();
makeCurrent(mPBufferSurface);
DeviceInfo::initialize();
mRenderThread.renderState().onGLContextCreated();
}
void EglManager::initExtensions() {
auto extensions = StringUtils::split(
eglQueryString(mEglDisplay, EGL_EXTENSIONS));
// For our purposes we don't care if EGL_BUFFER_AGE is a result of
// EGL_EXT_buffer_age or EGL_KHR_partial_update as our usage is covered
// under EGL_KHR_partial_update and we don't need the expanded scope
// that EGL_EXT_buffer_age provides.
EglExtensions.bufferAge = extensions.has("EGL_EXT_buffer_age")
|| extensions.has("EGL_KHR_partial_update");
EglExtensions.setDamage = extensions.has("EGL_KHR_partial_update");
LOG_ALWAYS_FATAL_IF(!extensions.has("EGL_KHR_swap_buffers_with_damage"),
"Missing required extension EGL_KHR_swap_buffers_with_damage");
}
bool EglManager::hasEglContext() {
return mEglDisplay != EGL_NO_DISPLAY;
}
void EglManager::loadConfig() {
ALOGD("Swap behavior %d", static_cast<int>(mSwapBehavior));
EGLint swapBehavior = (mSwapBehavior == SwapBehavior::Preserved)
? EGL_SWAP_BEHAVIOR_PRESERVED_BIT : 0;
EGLint attribs[] = {
EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
EGL_RED_SIZE, 8,
EGL_GREEN_SIZE, 8,
EGL_BLUE_SIZE, 8,
EGL_ALPHA_SIZE, 8,
EGL_DEPTH_SIZE, 0,
EGL_CONFIG_CAVEAT, EGL_NONE,
EGL_STENCIL_SIZE, Stencil::getStencilSize(),
EGL_SURFACE_TYPE, EGL_WINDOW_BIT | swapBehavior,
EGL_NONE
};
EGLint num_configs = 1;
if (!eglChooseConfig(mEglDisplay, attribs, &mEglConfig, num_configs, &num_configs)
|| num_configs != 1) {
if (mSwapBehavior == SwapBehavior::Preserved) {
// Try again without dirty regions enabled
ALOGW("Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...");
mSwapBehavior = SwapBehavior::Discard;
loadConfig();
} else {
// Failed to get a valid config
LOG_ALWAYS_FATAL("Failed to choose config, error = %s", egl_error_str());
}
}
}
void EglManager::createContext() {
EGLint attribs[] = {
EGL_CONTEXT_CLIENT_VERSION, GLES_VERSION,
EGL_NONE
};
mEglContext = eglCreateContext(mEglDisplay, mEglConfig, EGL_NO_CONTEXT, attribs);
LOG_ALWAYS_FATAL_IF(mEglContext == EGL_NO_CONTEXT,
"Failed to create context, error = %s", egl_error_str());
}
void EglManager::createPBufferSurface() {
LOG_ALWAYS_FATAL_IF(mEglDisplay == EGL_NO_DISPLAY,
"usePBufferSurface() called on uninitialized GlobalContext!");
if (mPBufferSurface == EGL_NO_SURFACE) {
EGLint attribs[] = { EGL_WIDTH, 1, EGL_HEIGHT, 1, EGL_NONE };
mPBufferSurface = eglCreatePbufferSurface(mEglDisplay, mEglConfig, attribs);
}
}
EGLSurface EglManager::createSurface(EGLNativeWindowType window) {
initialize();
EGLint attribs[] = {
#ifdef ANDROID_ENABLE_LINEAR_BLENDING
EGL_GL_COLORSPACE_KHR, EGL_GL_COLORSPACE_SRGB_KHR,
EGL_COLORSPACE, EGL_COLORSPACE_sRGB,
#endif
EGL_NONE
};
EGLSurface surface = eglCreateWindowSurface(mEglDisplay, mEglConfig, window, attribs);
LOG_ALWAYS_FATAL_IF(surface == EGL_NO_SURFACE,
"Failed to create EGLSurface for window %p, eglErr = %s",
(void*) window, egl_error_str());
if (mSwapBehavior != SwapBehavior::Preserved) {
LOG_ALWAYS_FATAL_IF(eglSurfaceAttrib(mEglDisplay, surface, EGL_SWAP_BEHAVIOR, EGL_BUFFER_DESTROYED) == EGL_FALSE,
"Failed to set swap behavior to destroyed for window %p, eglErr = %s",
(void*) window, egl_error_str());
}
return surface;
}
void EglManager::destroySurface(EGLSurface surface) {
if (isCurrent(surface)) {
makeCurrent(EGL_NO_SURFACE);
}
if (!eglDestroySurface(mEglDisplay, surface)) {
ALOGW("Failed to destroy surface %p, error=%s", (void*)surface, egl_error_str());
}
}
void EglManager::destroy() {
if (mEglDisplay == EGL_NO_DISPLAY) return;
mRenderThread.renderState().onGLContextDestroyed();
eglDestroyContext(mEglDisplay, mEglContext);
eglDestroySurface(mEglDisplay, mPBufferSurface);
eglMakeCurrent(mEglDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
eglTerminate(mEglDisplay);
eglReleaseThread();
mEglDisplay = EGL_NO_DISPLAY;
mEglContext = EGL_NO_CONTEXT;
mPBufferSurface = EGL_NO_SURFACE;
mCurrentSurface = EGL_NO_SURFACE;
}
bool EglManager::makeCurrent(EGLSurface surface, EGLint* errOut) {
if (isCurrent(surface)) return false;
if (surface == EGL_NO_SURFACE) {
// Ensure we always have a valid surface & context
surface = mPBufferSurface;
}
if (!eglMakeCurrent(mEglDisplay, surface, surface, mEglContext)) {
if (errOut) {
*errOut = eglGetError();
ALOGW("Failed to make current on surface %p, error=%s",
(void*)surface, egl_error_str(*errOut));
} else {
LOG_ALWAYS_FATAL("Failed to make current on surface %p, error=%s",
(void*)surface, egl_error_str());
}
}
mCurrentSurface = surface;
return true;
}
EGLint EglManager::queryBufferAge(EGLSurface surface) {
switch (mSwapBehavior) {
case SwapBehavior::Discard:
return 0;
case SwapBehavior::Preserved:
return 1;
case SwapBehavior::BufferAge:
EGLint bufferAge;
eglQuerySurface(mEglDisplay, surface, EGL_BUFFER_AGE_EXT, &bufferAge);
return bufferAge;
}
return 0;
}
Frame EglManager::beginFrame(EGLSurface surface) {
LOG_ALWAYS_FATAL_IF(surface == EGL_NO_SURFACE,
"Tried to beginFrame on EGL_NO_SURFACE!");
makeCurrent(surface);
Frame frame;
frame.mSurface = surface;
eglQuerySurface(mEglDisplay, surface, EGL_WIDTH, &frame.mWidth);
eglQuerySurface(mEglDisplay, surface, EGL_HEIGHT, &frame.mHeight);
frame.mBufferAge = queryBufferAge(surface);
eglBeginFrame(mEglDisplay, surface);
return frame;
}
void EglManager::damageFrame(const Frame& frame, const SkRect& dirty) {
#ifdef EGL_KHR_partial_update
if (EglExtensions.setDamage && mSwapBehavior == SwapBehavior::BufferAge) {
EGLint rects[4];
frame.map(dirty, rects);
if (!eglSetDamageRegionKHR(mEglDisplay, frame.mSurface, rects, 1)) {
LOG_ALWAYS_FATAL("Failed to set damage region on surface %p, error=%s",
(void*)frame.mSurface, egl_error_str());
}
}
#endif
}
bool EglManager::damageRequiresSwap() {
return EglExtensions.setDamage && mSwapBehavior == SwapBehavior::BufferAge;
}
bool EglManager::swapBuffers(const Frame& frame, const SkRect& screenDirty) {
if (CC_UNLIKELY(Properties::waitForGpuCompletion)) {
ATRACE_NAME("Finishing GPU work");
fence();
}
EGLint rects[4];
frame.map(screenDirty, rects);
eglSwapBuffersWithDamageKHR(mEglDisplay, frame.mSurface, rects,
screenDirty.isEmpty() ? 0 : 1);
EGLint err = eglGetError();
if (CC_LIKELY(err == EGL_SUCCESS)) {
return true;
}
if (err == EGL_BAD_SURFACE || err == EGL_BAD_NATIVE_WINDOW) {
// For some reason our surface was destroyed out from under us
// This really shouldn't happen, but if it does we can recover easily
// by just not trying to use the surface anymore
ALOGW("swapBuffers encountered EGL error %d on %p, halting rendering...",
err, frame.mSurface);
return false;
}
LOG_ALWAYS_FATAL("Encountered EGL error %d %s during rendering",
err, egl_error_str(err));
// Impossible to hit this, but the compiler doesn't know that
return false;
}
void EglManager::fence() {
EGLSyncKHR fence = eglCreateSyncKHR(mEglDisplay, EGL_SYNC_FENCE_KHR, NULL);
eglClientWaitSyncKHR(mEglDisplay, fence,
EGL_SYNC_FLUSH_COMMANDS_BIT_KHR, EGL_FOREVER_KHR);
eglDestroySyncKHR(mEglDisplay, fence);
}
bool EglManager::setPreserveBuffer(EGLSurface surface, bool preserve) {
if (mSwapBehavior != SwapBehavior::Preserved) return false;
bool preserved = eglSurfaceAttrib(mEglDisplay, surface, EGL_SWAP_BEHAVIOR,
preserve ? EGL_BUFFER_PRESERVED : EGL_BUFFER_DESTROYED);
if (!preserved) {
ALOGW("Failed to set EGL_SWAP_BEHAVIOR on surface %p, error=%s",
(void*) surface, egl_error_str());
// Maybe it's already set?
EGLint swapBehavior;
if (eglQuerySurface(mEglDisplay, surface, EGL_SWAP_BEHAVIOR, &swapBehavior)) {
preserved = (swapBehavior == EGL_BUFFER_PRESERVED);
} else {
ALOGW("Failed to query EGL_SWAP_BEHAVIOR on surface %p, error=%p",
(void*) surface, egl_error_str());
}
}
return preserved;
}
} /* namespace renderthread */
} /* namespace uirenderer */
} /* namespace android */