02 最简单的SurfaceFlinger应用程序

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已于 2023-11-03 16:27:02 修改

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分类专栏： SurfaceFlinger 文章标签：图形渲染 android 1024程序员节

于 2023-10-24 10:59:07 首次发布

本文链接：https://blog.youkuaiyun.com/fengchaochao123/article/details/134007375

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本文详细介绍了如何在Android中使用SurfaceFlinger创建Surface，设置属性，填充图像数据并进行推送，通过SurfaceTestDemo展示了从创建Surface到推送动态变化图片的过程。

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使用SurfaceFlinger送图，可以简单的按照如下几个步骤：

创建SurfaceComposerClient --->具体过程见《构造surfaceComposerClient》
获取要显示的屏幕，这里获取的是主屏SurfaceComposerClient::getInternalDisplayToken
获取屏幕大小 SurfaceComposerClient::getActiveDisplayMode(displayToken, &displayMode);
创建SurfaceControl
设置surface属性；setLayer，setPosition
创建surface
分配并map buffer；surface->lock
向buffer里填充图像数据
推图 surface->unlockAndPost()

源码如下，会在屏幕中间显示一个大小200x200，颜色rgb依次循环的方块。

#define LOG_TAG "SurfaceTestDemo"

#include <binder/IPCThreadState.h>
#include <binder/ProcessState.h>
#include <binder/IServiceManager.h>
#include <hardware/gralloc.h>
#include <ui/GraphicBuffer.h>
#include <utils/Log.h>
#include <gui/Surface.h>
#include <gui/SurfaceControl.h>
#include <gui/ISurfaceComposerClient.h>
#include <gui/SurfaceComposerClient.h>

#include <system/window.h>
#include <utils/RefBase.h>
using namespace android;

void fillRGBA8Buffer(uint8_t* img, int width, int height, int stride, int r, int g, int b) {
    for (int y = 0; y < height; y++) {
        for (int x = 0; x < width; x++) {
            uint8_t* pixel = img + (4 * (y*stride + x));
            pixel[0] = r;
            pixel[1] = g;
            pixel[2] = b;
            pixel[3] = 255;
        }
    }
}

int SurfaceTest() {
    status_t err = NO_ERROR;
    int countFrame = 0;
    ANativeWindow_Buffer nativeBuffer;

    sp<ProcessState> proc(ProcessState::self());
    ProcessState::self()->startThreadPool();

    sp<SurfaceComposerClient> surfaceComposerClient = new SurfaceComposerClient();
    err = surfaceComposerClient->initCheck();
    if (err != NO_ERROR) {
        ALOGD("SurfaceComposerClient::initCheck error: %#x\n", err);
        return -1;
    }

    // Get main display parameters.
    sp<IBinder> displayToken = SurfaceComposerClient::getInternalDisplayToken();
    if (displayToken == nullptr)
        return -1;

    ui::DisplayMode displayMode;
    const status_t error =
            SurfaceComposerClient::getActiveDisplayMode(displayToken, &displayMode);
    if (error != NO_ERROR)
        return -1;

    ui::Size resolution(200,200);
    // create the surface
    sp<SurfaceControl> surfaceControl = surfaceComposerClient->createSurface(String8("SurfaceTestDemo"), resolution.getWidth(), 
                                                                             resolution.getHeight(), PIXEL_FORMAT_RGBA_8888,
                                                                             ISurfaceComposerClient::eFXSurfaceBufferState,
                                                                             /*parent*/ nullptr);

    SurfaceComposerClient::Transaction{}
            .setLayer(surfaceControl, std::numeric_limits<int32_t>::max())
            .setPosition(surfaceControl, (displayMode.resolution.getWidth() - 200) / 2,
                (displayMode.resolution.getHeight() - 200) / 2)
            .show(surfaceControl)
            .apply();

    int mWidth = resolution.getWidth();
    int mHeight = resolution.getHeight();
    sp<Surface> surface = surfaceControl->getSurface();

    while(1) {
        countFrame = (countFrame+1)%3;
        surface->lock(&nativeBuffer, NULL);
        fillRGBA8Buffer((uint8_t *)nativeBuffer.bits, mWidth, mHeight, nativeBuffer.stride,
                        countFrame == 0 ? 255 : 0,
                        countFrame == 1 ? 255 : 0,
                        countFrame == 2 ? 255 : 0);
        surface->unlockAndPost();
        sleep(1);
    }

    return err;
}

int main() {
    SurfaceTest();
    return 0;
}

后面会根据这个简单的应用程序来一步一步剖析SurfaceFlinger的工作机制。

敬请期待。

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