cmds/screencap/screencap.cpp

/*
 * Copyright (C) 2010 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 <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>

#include <linux/fb.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/wait.h>

#include <android/bitmap.h>

#include <binder/ProcessState.h>

#include <gui/ISurfaceComposer.h>
#include <gui/SurfaceComposerClient.h>
#include <gui/SyncScreenCaptureListener.h>

#include <ui/GraphicTypes.h>
#include <ui/PixelFormat.h>

#include <system/graphics.h>

using namespace android;

#define COLORSPACE_UNKNOWN    0
#define COLORSPACE_SRGB       1
#define COLORSPACE_DISPLAY_P3 2

static void usage(const char* pname, std::optional<PhysicalDisplayId> displayId)
{
    std::string defaultDisplayStr = "";
    if (!displayId) {
        defaultDisplayStr = "";
    } else {
        defaultDisplayStr = " (default: " + to_string(*displayId) + ")";
    }
    fprintf(stderr,
            "usage: %s [-hp] [-d display-id] [FILENAME]\n"
            "   -h: this message\n"
            "   -p: save the file as a png.\n"
            "   -d: specify the display ID to capture%s\n"
            "       see \"dumpsys SurfaceFlinger --display-id\" for valid display IDs.\n"
            "If FILENAME ends with .png it will be saved as a png.\n"
            "If FILENAME is not given, the results will be printed to stdout.\n",
            pname, defaultDisplayStr.c_str());
}

static int32_t flinger2bitmapFormat(PixelFormat f)
{
    switch (f) {
        case PIXEL_FORMAT_RGB_565:
            return ANDROID_BITMAP_FORMAT_RGB_565;
        default:
            return ANDROID_BITMAP_FORMAT_RGBA_8888;
    }
}

static uint32_t dataSpaceToInt(ui::Dataspace d)
{
    switch (d) {
        case ui::Dataspace::V0_SRGB:
            return COLORSPACE_SRGB;
        case ui::Dataspace::DISPLAY_P3:
            return COLORSPACE_DISPLAY_P3;
        default:
            return COLORSPACE_UNKNOWN;
    }
}

static status_t notifyMediaScanner(const char* fileName) {
    std::string filePath("file://");
    filePath.append(fileName);
    char *cmd[] = {
        (char*) "am",
        (char*) "broadcast",
        (char*) "-a",
        (char*) "android.intent.action.MEDIA_SCANNER_SCAN_FILE",
        (char*) "-d",
        &filePath[0],
        nullptr
    };

    int status;
    int pid = fork();
    if (pid < 0){
       fprintf(stderr, "Unable to fork in order to send intent for media scanner.\n");
       return UNKNOWN_ERROR;
    }
    if (pid == 0){
        int fd = open("/dev/null", O_WRONLY);
        if (fd < 0){
            fprintf(stderr, "Unable to open /dev/null for media scanner stdout redirection.\n");
            exit(1);
        }
        dup2(fd, 1);
        int result = execvp(cmd[0], cmd);
        close(fd);
        exit(result);
    }
    wait(&status);

    if (status < 0) {
        fprintf(stderr, "Unable to broadcast intent for media scanner.\n");
        return UNKNOWN_ERROR;
    }
    return NO_ERROR;
}

int main(int argc, char** argv)
{
    const std::vector<PhysicalDisplayId> ids = SurfaceComposerClient::getPhysicalDisplayIds();
    if (ids.empty()) {
        fprintf(stderr, "Failed to get ID for any displays.\n");
        return 1;
    }
    std::optional<PhysicalDisplayId> displayId;
    const char* pname = argv[0];
    bool png = false;
    int c;
    while ((c = getopt(argc, argv, "phd:")) != -1) {
        switch (c) {
            case 'p':
                png = true;
                break;
            case 'd':
                displayId = DisplayId::fromValue<PhysicalDisplayId>(atoll(optarg));
                if (!displayId) {
                    fprintf(stderr, "Invalid display ID: %s\n", optarg);
                    return 1;
                }
                break;
            case '?':
            case 'h':
                if (ids.size() == 1) {
                    displayId = ids.front();
                } 
                usage(pname, displayId);
                return 1;
        }
    }

    if (!displayId) { // no diplsay id is specified
        displayId = ids.front();
        if (ids.size() > 1) {
            fprintf(stderr,
                    "[Warning] Multiple displays were found, but no display id was specified! "
                    "Defaulting to the first display found, however this default is not guaranteed "
                    "to be consistent across captures. A display id should be specified.\n");
            fprintf(stderr, "A display ID can be specified with the [-d display-id] option.\n");
            fprintf(stderr, "See \"dumpsys SurfaceFlinger --display-id\" for valid display IDs.\n");
        }
    }

    argc -= optind;
    argv += optind;

    int fd = -1;
    const char* fn = NULL;
    if (argc == 0) {
        fd = dup(STDOUT_FILENO);
    } else if (argc == 1) {
        fn = argv[0];
        fd = open(fn, O_WRONLY | O_CREAT | O_TRUNC, 0664);
        if (fd == -1) {
            fprintf(stderr, "Error opening file: %s (%s)\n", fn, strerror(errno));
            return 1;
        }
        const int len = strlen(fn);
        if (len >= 4 && 0 == strcmp(fn+len-4, ".png")) {
            png = true;
        }
    }

    if (fd == -1) {
        usage(pname, displayId);
        return 1;
    }

    void const* mapbase = MAP_FAILED;
    ssize_t mapsize = -1;

    void* base = NULL;

    // setThreadPoolMaxThreadCount(0) actually tells the kernel it's
    // not allowed to spawn any additional threads, but we still spawn
    // a binder thread from userspace when we call startThreadPool().
    // See b/36066697 for rationale
    ProcessState::self()->setThreadPoolMaxThreadCount(0);
    ProcessState::self()->startThreadPool();

    sp<SyncScreenCaptureListener> captureListener = new SyncScreenCaptureListener();
    status_t result = ScreenshotClient::captureDisplay(*displayId, captureListener);
    if (result != NO_ERROR) {
        close(fd);
        return 1;
    }

    ScreenCaptureResults captureResults = captureListener->waitForResults();
    if (!captureResults.fenceResult.ok()) {
        close(fd);
        return 1;
    }
    ui::Dataspace dataspace = captureResults.capturedDataspace;
    sp<GraphicBuffer> buffer = captureResults.buffer;

    result = buffer->lock(GraphicBuffer::USAGE_SW_READ_OFTEN, &base);

    if (base == nullptr || result != NO_ERROR) {
        String8 reason;
        if (result != NO_ERROR) {
            reason.appendFormat(" Error Code: %d", result);
        } else {
            reason = "Failed to write to buffer";
        }
        fprintf(stderr, "Failed to take screenshot (%s)\n", reason.c_str());
        close(fd);
        return 1;
    }

    if (png) {
        AndroidBitmapInfo info;
        info.format = flinger2bitmapFormat(buffer->getPixelFormat());
        info.flags = ANDROID_BITMAP_FLAGS_ALPHA_PREMUL;
        info.width = buffer->getWidth();
        info.height = buffer->getHeight();
        info.stride = buffer->getStride() * bytesPerPixel(buffer->getPixelFormat());

        int result = AndroidBitmap_compress(&info, static_cast<int32_t>(dataspace), base,
                                            ANDROID_BITMAP_COMPRESS_FORMAT_PNG, 100, &fd,
                                            [](void* fdPtr, const void* data, size_t size) -> bool {
                                                int bytesWritten = write(*static_cast<int*>(fdPtr),
                                                                         data, size);
                                                return bytesWritten == size;
                                            });

        if (result != ANDROID_BITMAP_RESULT_SUCCESS) {
            fprintf(stderr, "Failed to compress PNG (error code: %d)\n", result);
        }

        if (fn != NULL) {
            notifyMediaScanner(fn);
        }
    } else {
        uint32_t w = buffer->getWidth();
        uint32_t h = buffer->getHeight();
        uint32_t s = buffer->getStride();
        uint32_t f = buffer->getPixelFormat();
        uint32_t c = dataSpaceToInt(dataspace);

        write(fd, &w, 4);
        write(fd, &h, 4);
        write(fd, &f, 4);
        write(fd, &c, 4);
        size_t Bpp = bytesPerPixel(f);
        for (size_t y=0 ; y<h ; y++) {
            write(fd, base, w*Bpp);
            base = (void *)((char *)base + s*Bpp);
        }
    }
    close(fd);
    if (mapbase != MAP_FAILED) {
        munmap((void *)mapbase, mapsize);
    }

    return 0;
}