Android几种特殊绘制方框方法

Shocker · 发表于 2022-2-14 17:08

本帖最后由 Shocker 于 2022-2-14 17:13 编辑

简介

除了之前介绍的用悬浮窗绘制方框之外,还有几种比较特殊的绘制方框的方法.

可执行文件

首先需要搭建aosp环境,雷电模拟器以Android5.1为例

编译aosp可以参考这个视频:

Android开源项目AOSP

编译系统后,在external目录将test拷贝过来.

代码逻辑如下:

1.创建surface

sp<SurfaceControl> surfaceControl = client->createSurface(String8("test"),
                                                        display.w, display.h, PIXEL_FORMAT_RGBA_8888, ISurfaceComposerClient::eHidden);

2.设置surface属性

SurfaceComposerClient::openGlobalTransaction();
surfaceControl->setLayer(100000);
surfaceControl->setPosition(0, 0);
surfaceControl->show();
SurfaceComposerClient::closeGlobalTransaction();

3.结合skia绘制

SkCanvas surfaceCanvas(surfaceBitmap);
SkPaint paint;
SkRect rect{i, i, display.w - i, display.h - i};

paint.setColor(SK_ColorRED);
paint.setStrokeWidth(2);
paint.setStyle(SkPaint::kStroke_Style);
surfaceCanvas.drawRect(rect, paint);

示例代码见github:

https://github.com/PShocker/Android_executable_draw

注意,每个Android版本的skia代码都可能不一样,所以该示例编译的文件仅仅适用于Android5.1

Hook Surfaceflinger进程的eglSwapBuffers函数

替换Surfaceflinger进程的Surfaceflinger.so的eglSwapBuffers为自己的new_eglSwapBuffers函数,并在new_eglSwapBuffers的函数内调用opengl相关函数实现绘制.

EGLBoolean new_eglSwapBuffers(EGLDisplay dpy, EGLSurface surface)
{
    LOGD("New eglSwapBuffers\n");
    // glClearColor(0, 255, 0, 1);
    // glClear(GL_COLOR_BUFFER_BIT);

    eglQuerySurface(dpy, surface, EGL_WIDTH, &w);
    eglQuerySurface(dpy, surface, EGL_HEIGHT, &h);
    // LOGD("EGL_WIDTH:%d\n",w);
    // LOGD("EGL_HEIGHT:%d\n",h);

    glUseProgram(gProgram);
    glLineWidth(2);
    glEnableVertexAttribArray(0);
    // glVertexAttribPointer(gvPositionHandle, 2, GL_FLOAT, GL_FALSE, 0, gTriangleVertices);
    // glEnableVertexAttribArray(gvPositionHandle);

    // glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, vVertices);
    // glDrawArrays(GL_LINE_LOOP, 0, 4);
    // drawRect(100,10,200,200);
    drawRect(0,0,200,200);

    return eglSwapBuffers(dpy, surface);
}

github示例:

x86模拟器版本:
https://github.com/PShocker/Android_hook_sf_draw_x86

arm64版本:
https://github.com/PShocker/Android_hook_sf_draw_arm64

参考:
https://blog.csdn.net/jinzhuojun/article/details/10428435
https://github.com/MelonWXD/ELFHooker
https://blog.csdn.net/jinzhuojun/article/details/9900105
https://github.com/android/ndk-samples/tree/main/hello-gl2