libs/hwui/Readback.cpp

/*
 * Copyright (C) 2016 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 "Readback.h"

#include "Caches.h"
#include "Image.h"
#include "GlopBuilder.h"
#include "renderstate/RenderState.h"
#include "renderthread/EglManager.h"
#include "utils/GLUtils.h"

#include <GLES2/gl2.h>
#include <ui/Fence.h>
#include <ui/GraphicBuffer.h>

namespace android {
namespace uirenderer {

bool Readback::copySurfaceInto(renderthread::RenderThread& renderThread,
        Surface& surface, SkBitmap* bitmap) {
    // TODO: Clean this up and unify it with LayerRenderer::copyLayer,
    // of which most of this is copied from.
    renderThread.eglManager().initialize();

    Caches& caches = Caches::getInstance();
    RenderState& renderState = renderThread.renderState();
    int destWidth = bitmap->width();
    int destHeight = bitmap->height();
    if (destWidth > caches.maxTextureSize
                || destHeight > caches.maxTextureSize) {
        ALOGW("Can't copy surface into bitmap, %dx%d exceeds max texture size %d",
                destWidth, destHeight, caches.maxTextureSize);
        return false;
    }
    GLuint fbo = renderState.createFramebuffer();
    if (!fbo) {
        ALOGW("Could not obtain an FBO");
        return false;
    }

    SkAutoLockPixels alp(*bitmap);

    GLuint texture;

    GLenum format;
    GLenum type;

    switch (bitmap->colorType()) {
        case kAlpha_8_SkColorType:
            format = GL_ALPHA;
            type = GL_UNSIGNED_BYTE;
            break;
        case kRGB_565_SkColorType:
            format = GL_RGB;
            type = GL_UNSIGNED_SHORT_5_6_5;
            break;
        case kARGB_4444_SkColorType:
            format = GL_RGBA;
            type = GL_UNSIGNED_SHORT_4_4_4_4;
            break;
        case kN32_SkColorType:
        default:
            format = GL_RGBA;
            type = GL_UNSIGNED_BYTE;
            break;
    }

    renderState.bindFramebuffer(fbo);

    // TODO: Use layerPool or something to get this maybe? But since we
    // need explicit format control we can't currently.

    // Setup the rendertarget
    glGenTextures(1, &texture);
    caches.textureState().activateTexture(0);
    caches.textureState().bindTexture(texture);
    glPixelStorei(GL_PACK_ALIGNMENT, bitmap->bytesPerPixel());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    glTexImage2D(GL_TEXTURE_2D, 0, format, destWidth, destHeight,
            0, format, type, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
            GL_TEXTURE_2D, texture, 0);

    // Setup the source
    sp<GraphicBuffer> sourceBuffer;
    sp<Fence> sourceFence;
    // FIXME: Waiting on an API from libgui for this
    // surface.getLastQueuedBuffer(&sourceBuffer, &sourceFence);
    if (!sourceBuffer.get()) {
        ALOGW("Surface doesn't have any previously queued frames, nothing to readback from");
        return false;
    }
    int err = sourceFence->wait(500 /* ms */);
    if (err != NO_ERROR) {
        ALOGE("Timeout (500ms) exceeded waiting for buffer fence, abandoning readback attempt");
        return false;
    }
    Image sourceImage(sourceBuffer);
    if (!sourceImage.getTexture()) {
        ALOGW("Failed to make an EGLImage from the GraphicBuffer");
        return false;
    }
    Texture sourceTexture(caches);
    sourceTexture.wrap(sourceImage.getTexture(),
            sourceBuffer->getWidth(), sourceBuffer->getHeight(), 0 /* total lie */);

    {
        // Draw & readback
        renderState.setViewport(destWidth, destHeight);
        renderState.scissor().setEnabled(false);
        renderState.blend().syncEnabled();
        renderState.stencil().disable();

        Rect destRect(destWidth, destHeight);
        Glop glop;
        GlopBuilder(renderState, caches, &glop)
                .setRoundRectClipState(nullptr)
                .setMeshTexturedUvQuad(nullptr, Rect(0, 1, 1, 0)) // TODO: simplify with VBO
                .setFillLayer(sourceTexture, nullptr, 1.0f, SkXfermode::kSrc_Mode,
                        Blend::ModeOrderSwap::NoSwap)
                .setTransform(Matrix4::identity(), TransformFlags::None)
                .setModelViewMapUnitToRect(destRect)
                .build();
        Matrix4 ortho;
        ortho.loadOrtho(destWidth, destHeight);
        renderState.render(glop, ortho);

        glReadPixels(0, 0, bitmap->width(), bitmap->height(), format,
                type, bitmap->getPixels());
    }

    // Cleanup
    caches.textureState().deleteTexture(texture);
    renderState.deleteFramebuffer(fbo);

    GL_CHECKPOINT(MODERATE);

    return true;
}

} // namespace uirenderer
} // namespace android