如何在libGDX中调用android摄像头
turbo_timo
8年前
<h2><strong>开发背景</strong></h2> <p>简单介绍下自己，目前在人脸识别从事android开发与测试，公司的产品是人脸识别SDK，成品就是各种终端上的人脸识别设备，总监大人希望最好能有一个跨平台的开发框架，能够以一种语言为主，输出各种app。于是他找到了libGDX，一个多平台开发游戏的框架， 语言为java。libGDX是一个游戏开发工具，确切的说也就是一个java框架，按他的套路进行编写即可。</p> <p>开始稍微看看游戏，有些误入歧途，然后他说要看看怎么掉摄像头。然后我又误入歧途的寻找寻找了一些有意思的东西：一个是抓幽灵的游戏ChaseWhisplyProject。</p> <p><img src="https://simg.open-open.com/show/2b29feaf440ade632b28689a960aaa0f.png"></p> <p style="text-align:center">ChaseWhisplyProject</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/5eb0cddea72a12f4f3fce2ef8d89d7bb.jpg"></p> <p style="text-align:center">beyondar</p> <p>当然，上边两个多事在Android内实现的，而非在libgdx中实现，感谢Github，在libGDX的介绍中，有达人分享了他使用libGDX调用android摄像头的实例，他在libGDX中调用摄像头的目的简单来说就是AR，使用者可以通过APP看到设备背后的路面，或者和真实世界有交互，就像PokemonGO一样，当然全部的这些也需要算法支持。但是时间是2013年，我拷贝下来，进行了微调，发现是可以实现的，鉴于目前网络上还真没有许多的实例说明如何在LibGDX中调用android摄像头，我搜索libgdx camera 大部分给我的结果都是libgdx中的镜头，就是跟随演员的镜头，而不是设备摄像头，这里也对这个实例进行一个记录和补充，以及简单的实现。</p> <p>下面我也是基于这篇文章进行翻译，顺序当然有所改变，还有原代码中有包含一个类似初始页面的SplashActivity的我没有实现，目前还没有去了解libGDX的三维编程，代码的源码已上传至GitHub，再好的文字也比不上源码。</p> <h3><strong>libGDX中到底是如何实现调用摄像头</strong></h3> <p>很简单，就是在一个透明的画布上绘制libGDX的舞台演员，在画布的后边放置摄像头的预览画面。而文章主要解决的问题就是如何显示摄像头预览画面，和如何调用摄像头。</p> <h3><strong>如何显示摄像头预览画面</strong></h3> <p>我们知道，libGDX的代码主要全部在core项目中，其他各个平台的代码都是经过一个简单的代码启动启动然后，剩下的就去调用core项目中的代码，首先在libGDX初始化时，要进行一定的设置，才能让摄像头的预览画面显示在libGDX框架生成的app中，进入android项目组，修改AndroidLauncher.class代码如下</p> <pre> <code class="language-java">AndroidApplicationConfiguration cfg = new AndroidApplicationConfiguration(); cfg.r = 8; cfg.g = 8; cfg.b = 8; cfg.a = 8; DeviceCameraControl cameraControl = new AndroidDeviceCameraController(this); initialize(new MyGdxGame0606(cameraControl), cfg);</code></pre> <p>你可以点击进入AndroidApplicationConfiguration去看看r,g,b,a原来数值如下</p> <pre> <code class="language-java">/** number of bits per color channel **/ public int r = 5, g = 6, b = 5, a = 0;</code></pre> <p>rgba的具体值指的是每种颜色的比特位数，这里改为8位，大概的意思就是每种颜色深度为8位，也就是2的8次幂，也就是256，和photoshop中意义一样。这么设置的原因是为了libGDX中的画布的后边能够正常的显示android的摄像头，不然颜色和在android上调用摄像头有出入，色彩不会同样的丰富。</p> <p>同样在AndroidLauncher.class中，将OpenGL surface 模式设置成TRANSLUCENT</p> <pre> <code class="language-java">if (graphics.getView() instanceof SurfaceView) { SurfaceView glView = (SurfaceView) graphics.getView(); // force alpha channel - I'm not sure we need this as the GL surface // is already using alpha channel glView.getHolder().setFormat(PixelFormat.TRANSLUCENT); }</code></pre> <p>然后是，在AndroidLauncher.class新建一个post方法，用来帮助唤起一些异步线程</p> <pre> <code class="language-java">public void post(Runnable r) { handler.post(r); }</code></pre> <p>以上就是AndroidLauncher.class所要完成的全部内容。</p> <h3><strong>如何让屏幕透明</strong></h3> <pre> <code class="language-java">很简单，在core项目中MyGdxGame0606.class主类中的render()渲染方法中，要注意使用glClearColor()清屏时，参数的选择必须全部是0，这样相机预览的画面才会显示在render画面的后边</code></pre> <pre> <code class="language-java">Gdx.gl20.glClearColor(0f, 0.0f, 0.0f, 0.0f);</code></pre> <p>清屏准备完毕，现在就是要调用android摄像头的时候到了</p> <p>首先了解一下，把大象装冰箱中总共分几步？对于调用android摄像头的步骤则可以分如下几部？Android相机有特别的工作顺序必须遵守，通过application的callbacks回调函数能管理相机的状态，机器的工作状态将由AndroidDeviceCameraController.class进行管理（desktop没有实现，Android已实现）。</p> <p>相机的工作状态一次是 Ready -> Preview -> autoFocusing -> ShutterCalled -> Raw PictureData -> Postview PictureData -> Jpeg PictureData -> Ready （可以做一个表格）</p> <p>本实例代码实现的顺序也可以概括为 Ready -> Preview -> autoFocusing -> Jpeg PictureData -> Ready</p> <h3><strong>新建AndroidDeviceCameraController</strong></h3> <p>在core项目中，新建一个DeviceCameraController类,而为了配合core中DeviceCameraControl，在android项目中，新建一个AndroidDeviceCameraController 类，来控制设备的摄像头，它要继承DeviceCameraControl，同时还要实现Camera.PictureCallback：(android.hardware.Camera.PictureCallback)Camera.AutoFocusCallback(android.hardware.Camera.AutoFocusCallback)，共计三个接口，来实现android摄像头从准备到拍摄的过程。</p> <pre> <code class="language-java">public class AndroidDeviceCameraController implements DeviceCameraControl, Camera.PictureCallback, Camera.AutoFocusCallback { . . . }</code></pre> <p>AndroidDeviceCameraController 新建后，逐步实现摄像头该有的各个功能。</p> <p><strong>1.准备显示预览信息的CameraSurface</strong></p> <p>我们产生一个CameraSurface类来负责管理摄像头和它收集的图像，这里我和android摄像相关的代码一致</p> <pre> <code class="language-java">public class CameraSurface extends SurfaceView implements SurfaceHolder.Callback { private Camera camera; public CameraSurface( Context context ) { super( context ); // We're implementing the Callback interface and want to get notified // about certain surface events. getHolder().addCallback( this ); // We're changing the surface to a PUSH surface, meaning we're receiving // all buffer data from another component - the camera, in this case. getHolder().setType( SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS ); } public void surfaceCreated( SurfaceHolder holder ) { // Once the surface is created, simply open a handle to the camera hardware. camera = Camera.open(); } public void surfaceChanged( SurfaceHolder holder, int format, int width, int height ) { // This method is called when the surface changes, e.g. when it's size is set. // We use the opportunity to initialize the camera preview display dimensions. Camera.Parameters p = camera.getParameters(); p.setPreviewSize( width, height ); camera.setParameters( p ); // We also assign the preview display to this surface... try { camera.setPreviewDisplay( holder ); } catch( IOException e ) { e.printStackTrace(); } } public void surfaceDestroyed( SurfaceHolder holder ) { // Once the surface gets destroyed, we stop the preview mode and release // the whole camera since we no longer need it. camera.stopPreview(); camera.release(); camera = null; } public Camera getCamera() { return camera; } }</code></pre> <p><strong>2.在android项目中增加相机预览视图</strong></p> <p>在android项目的AndroidDeviceController类，使用activity.addContentView，直接将cameraSurface显示在android设备的屏幕上</p> <pre> <code class="language-java">@Override public void prepareCamera() { if (cameraSurface == null) { cameraSurface = new CameraSurface(activity); } activity.addContentView( cameraSurface, new LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT ) ); }</code></pre> <pre> <code class="language-java">@Override public synchronized void prepareCamera() { if (cameraSurface == null) { cameraSurface = new CameraSurface(activity); } FrameLayout.LayoutParams params = new FrameLayout.LayoutParams (680,680); params.rightMargin=150;//可以通过设置rightMargin控制组件的实际位置 params.leftMargin=200;//可以通过设置rightMargin控制组件的实际位置 params.topMargin=100; activity.addContentView(cameraSurface, params); }</code></pre> <p>prepareCamera方法应该在libgdx渲染过程中异步调用</p> <pre> <code class="language-java">@Override public void prepareCameraAsync() { Runnable r = new Runnable() { public void run() { prepareCamera(); } }; activity.post(r); } @Override public void prepareCameraAsync() { Runnable r = new Runnable() { public void run() { prepareCamera(); } }; activity.post(r); }</code></pre> <p>当CameraSurface和camera 对象准备好了的时候（通过检测cameraSurface!=null && cameraSurface.getCamera() != null），就可以让相机由准备状态进入预览模式</p> <pre> <code class="language-java">@Override public boolean isReady() { if (cameraSurface!=null && cameraSurface.getCamera() != null) { return true; } return false; }</code></pre> <pre> <code class="language-java">@Override public boolean isReady() { if (cameraSurface != null && cameraSurface.getCamera() != null) { return true; } return false; }</code></pre> <p>异步调用开启预览</p> <pre> <code class="language-java">@Override public synchronized void startPreviewAsync() { Runnable r = new Runnable() { public void run() { startPreview(); } }; activity.post(r); } @Override public synchronized void startPreview() { // ...and start previewing. From now on, the camera keeps pushing preview // images to the surface. if (cameraSurface != null && cameraSurface.getCamera() != null) { cameraSurface.getCamera().startPreview(); } }</code></pre> <p><strong>3.由预览模式进行拍照</strong></p> <p>拍照前还要AndroidDeviceCameraController类设置下相机合适的参数</p> <pre> <code class="language-java">public void setCameraParametersForPicture(Camera camera) { // Before we take the picture - we make sure all camera parameters are as we like them // Use max resolution and auto focus Camera.Parameters p = camera.getParameters(); List<Camera.Size> supportedSizes = p.getSupportedPictureSizes(); int maxSupportedWidth = -1; int maxSupportedHeight = -1; for (Camera.Size size : supportedSizes) { if (size.width > maxSupportedWidth) { maxSupportedWidth = size.width; maxSupportedHeight = size.height; } } p.setPictureSize(maxSupportedWidth, maxSupportedHeight); p.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO); camera.setParameters( p ); }</code></pre> <p>接下来，我们将通过设置相机的参数，设置聚焦为自动模式，</p> <pre> <code class="language-java">@Override public synchronized void takePicture() { // the user request to take a picture - start the process by requesting focus setCameraParametersForPicture(cameraSurface.getCamera()); cameraSurface.getCamera().autoFocus(this); }</code></pre> <p>当聚焦完成后，我们就要拍照了，仅仅实现JPG回调实现</p> <pre> <code class="language-java">@Override public synchronized void onAutoFocus(boolean success, Camera camera) { // Focus process finished, we now have focus (or not) if (success) { if (camera != null) { camera.stopPreview(); // We now have focus take the actual picture camera.takePicture(null, null, null, this); } } } @Override public synchronized void onPictureTaken(byte[] pictureData, Camera camera) { this.pictureData = pictureData; } @Override public synchronized void onAutoFocus(boolean success, Camera camera) { // Focus process finished, we now have focus (or not) if (success) { if (camera != null) { camera.stopPreview(); /*增加三个回调函数shutterCallback, rawPictureCallback, jpegPictureCallback后，可以进行拍照，并且成功保存*/ // We now have focus take the actual picture camera.takePicture(shutterCallback, rawPictureCallback, jpegPictureCallback);//54wall camera.startPreview(); } } } @Override public synchronized void onPictureTaken(byte[] pictureData, Camera camera) { // We got the picture data - keep it this.pictureData = pictureData; } ShutterCallback shutterCallback = new ShutterCallback() { @Override public void onShutter() { } }; PictureCallback rawPictureCallback = new PictureCallback() { @Override public void onPictureTaken(byte[] arg0, Camera arg1) { } }; PictureCallback jpegPictureCallback = new PictureCallback() { @Override public void onPictureTaken(byte[] arg0, Camera arg1) { /*可以在Android项目中中生成图片*/ // String fileName = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM) // .toString() // + File.separator // + "PicTest_" + System.currentTimeMillis() + ".jpg"; // File file = new File(fileName); // if (!file.getParentFile().exists()) { // file.getParentFile().mkdir(); // } // // try { // BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file)); // bos.write(arg0); // bos.flush(); // bos.close(); // // } catch (Exception e) { // // } pictureData=arg0; }; };</code></pre> <p>以上就是拍照的具体步骤，之后照片完成后，需要将图像数据进行保存到存储器上</p> <p>拍照的具体功能实现了，为了在libgdx中能够看到摄像头，当然需要在实现ApplicationListener的主类的render（）进行设置了，我这里设置了三个按钮，功能分别是开启相机，进行拍摄，和一个控制人物移动的按钮（算是证明是在libgdx框架内部的）。</p> <p>原代码时触控进入相机预览，松开则进行拍照，我开始还没太理解，render中因为涉及到相机的功能切换，所以在libgdx主类中定义了相机的这几种状态</p> <pre> <code class="language-java">public enum Mode { normal, prepare, preview, takePicture, waitForPictureReady, }，</code></pre> <p>render（）中的代码非常长，不过就是在相机的各个状态中切换，具体代码如下：</p> <pre> <code class="language-java">@Override public void render() { // Gdx.gl20.glClearColor(0.0f, 0f, 0.0f, 0.0f);//黑 // Gdx.gl.glClearColor(1, 1, 1, 1);//背景为白色 Gdx.gl.glClearColor(0.57f, 0.40f, 0.55f, 1.0f);// 紫色 Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);// 清屏 render_preview(); } public void render_preview() { /* 我已经将preview变为takePicture状态移动到click中，实现先预览再拍照，这样便于理解相机的运行步骤 */ Gdx.gl20.glHint(GL20.GL_GENERATE_MIPMAP_HINT, GL20.GL_NICEST); if (mode == Mode.takePicture) { Gdx.gl20.glClearColor(0f, 0.0f, 0.0f, 0.0f); if (deviceCameraControl != null) { deviceCameraControl.takePicture(); } mode = Mode.waitForPictureReady; } else if (mode == Mode.waitForPictureReady) { Gdx.gl20.glClearColor(0.0f, 0f, 0.0f, 0.0f); } else if (mode == Mode.prepare) { Gdx.gl20.glClearColor(0.0f, 0.0f, 0f, 0.6f); if (deviceCameraControl != null) { if (deviceCameraControl.isReady()) { deviceCameraControl.startPreviewAsync(); mode = Mode.preview; } } } else if (mode == Mode.preview) { Gdx.gl20.glClearColor(0.0f, 0.0f, 0.0f, 0f); } else { /* mode = normal */ Gdx.gl20.glClearColor(0.0f, 0.0f, 0.6f, 1.0f); } Gdx.gl20.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT); /* 下边放到texture.bind();时效果一致 */ batch.begin(); stage.act(); // 更新舞台逻辑 batch.draw(texture, 0, 0, 3f*texture.getWidth(), 3f*texture.getHeight()); Gdx.app.log("", String.valueOf(texture.getWidth())); //先绘制的就先出现，所以演员在texture上边，而不是被覆盖 //batch.draw(actorTexture, firstActor.getX(), firstActor.getY());//原大小 batch.draw(actorTexture, firstActor.getX(), firstActor.getY(),4*actorTexture.getWidth(),4*actorTexture.getWidth());//可控制绘制图像大小 button_move.draw(batch, 1.0f); stage.draw();// 绘制舞台 batch.end(); Gdx.gl20.glEnable(GL20.GL_DEPTH_TEST); Gdx.gl20.glEnable(GL20.GL_TEXTURE); Gdx.gl20.glEnable(GL20.GL_TEXTURE_2D); // Gdx.gl20.glEnable(GL20.GL_LINE_SMOOTH);//old Gdx.gl20.glEnable(GL20.GL_LINE_LOOP);//54wall Gdx.gl20.glDepthFunc(GL20.GL_LEQUAL); Gdx.gl20.glClearDepthf(1.0F); camera.update(true); // camera.apply(Gdx.gl20);//old texture.bind(); if (mode == Mode.waitForPictureReady) { /*注意deviceCameraControl.getPictureData()得到的是byte[]，可见整体思路就是， *将Android摄像头得到byte[],然后将byte[]转换为Pixmap，最后将pixmap存为jpg,这样不适用Android端图片保存模式， *byte[]----Pixmap----jpg */ if (deviceCameraControl.getPictureData() != null) { // camera picture was actually takentake Gdx Screenshot Pixmap screenshotPixmap = getScreenshot(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), true); Pixmap cameraPixmap = new Pixmap( deviceCameraControl.getPictureData(), 0, deviceCameraControl.getPictureData().length); merge2Pixmaps(cameraPixmap, screenshotPixmap); // we could call PixmapIO.writePNG(pngfile, cameraPixmap); //仅保存screenshot，对同一时间的图片进行保存然后进行比较 Pixmap screenshotPixmap_test = getScreenshot(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), true); FileHandle jpgfile_screenshot = Gdx.files .external("a_SDK_fail/libGdxSnapshot" + "_" + date + "_screenshot.jpg"); deviceCameraControl.saveAsJpeg(jpgfile_screenshot, screenshotPixmap_test); //仅保存cameraPixma，对同一时间的图片进行保存然后进行比较 Pixmap cameraPixmap_test = new Pixmap( deviceCameraControl.getPictureData(), 0, deviceCameraControl.getPictureData().length); FileHandle jpgfile_cameraPixmap = Gdx.files .external("a_SDK_fail/libGdxSnapshot" + "_" + date + "_camera.jpg"); deviceCameraControl.saveAsJpeg(jpgfile_cameraPixmap, cameraPixmap_test); //保存混合之后的相片 FileHandle jpgfile = Gdx.files .external("a_SDK_fail/libGdxSnapshot" + "_" + date + ".jpg"); Gdx.app.log("FileHandle", date); time_1 = System.currentTimeMillis(); deviceCameraControl.saveAsJpeg(jpgfile, cameraPixmap); time_2 = System.currentTimeMillis(); //可以得到35830ms=35s，所以非常忙，导致Mode非常缓慢的回到Mode.normal Gdx.app.log("cost", String.valueOf(time_2 - time_1)); deviceCameraControl.stopPreviewAsync(); //保存文件后，mode回到normal继续render循环，所以中间停顿和logcat长时间未动的其实是卡住了Org mode = Mode.normal; } } // 这个log将会一直出现，所以render其实是一直在执行 // Gdx.app.log("mode", String.valueOf(i_render++)); }</code></pre> <h3><strong>如何实现libgdx端的截图</strong></h3> <p>因为AndroidDeviceCameraController 实现两个接口: Camera.PictureCallback，所以可以直接调用，而deviceCameraControl.getPictureData()的byte[]数据则来自AndroidDeviceCameraController,如下</p> <pre> <code class="language-java">@Override public synchronized byte[] getPictureData() { // Give to picture data to whom ever requested it return pictureData; } if (deviceCameraControl.getPictureData() != null) { // camera picture was actually taken Pixmap cameraPixmap = new Pixmap(deviceCameraControl.getPictureData(), 0, deviceCameraControl.getPictureData().length); }</code></pre> <p>下面是截图的具体操作过程是保存为pixmap，libgdx中保存格式都是pixmap，而非android中的bitmap</p> <pre> <code class="language-java">public Pixmap getScreenshot(int x, int y, int w, int h, boolean flipY) { Gdx.gl.glPixelStorei(GL10.GL_PACK_ALIGNMENT, 1); final Pixmap pixmap = new Pixmap(w, h, Format.RGBA8888); ByteBuffer pixels = pixmap.getPixels(); Gdx.gl.glReadPixels(x, y, w, h, GL10.GL_RGBA, GL10.GL_UNSIGNED_BYTE, pixels); final int numBytes = w * h * 4; byte[] lines = new byte[numBytes]; if (flipY) { final int numBytesPerLine = w * 4; for (int i = 0; i < h; i++) { pixels.position((h - i - 1) * numBytesPerLine); pixels.get(lines, i * numBytesPerLine, numBytesPerLine); } pixels.clear(); pixels.put(lines); } else { pixels.clear(); pixels.get(lines); } return pixmap; }</code></pre> <p>接下来的操作都是需要消耗大量时间和CPU资源的，首先不应放到UI线程中，应该新开线程去执行，并且最好加一个进度条，在代码示例中，我们并没有那么做，所以屏幕在这个过程中会出现卡死的状况。我这里则直接保存了三分文件，分别是截图，android摄像头的拍摄相片，还有二者混合之后的图片，代码如下</p> <pre> <code class="language-java">/* 仅保存screenshot，对同一时间的图片进行保存然后进行比较 */ Pixmap screenshotPixmap_test = getScreenshot(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), true); FileHandle jpgfile_screenshot = Gdx.files .external("a_SDK_fail/libGdxSnapshot" + "_" + date + "_screenshot.jpg"); deviceCameraControl.saveAsJpeg(jpgfile_screenshot, screenshotPixmap_test); /* 仅保存cameraPixma，对同一时间的图片进行保存然后进行比较 */ Pixmap cameraPixmap_test = new Pixmap( deviceCameraControl.getPictureData(), 0, deviceCameraControl.getPictureData().length); FileHandle jpgfile_cameraPixmap = Gdx.files .external("a_SDK_fail/libGdxSnapshot" + "_" + date + "_camera.jpg"); deviceCameraControl.saveAsJpeg(jpgfile_cameraPixmap, cameraPixmap_test); /* 保存混合之后的相片 */ FileHandle jpgfile = Gdx.files .external("a_SDK_fail/libGdxSnapshot" + "_" + date + ".jpg"); Gdx.app.log("FileHandle", date); time_1 = System.currentTimeMillis(); deviceCameraControl.saveAsJpeg(jpgfile, cameraPixmap); time_2 = System.currentTimeMillis(); /* 可以得到35830ms=35s，所以非常忙，导致Mode非常缓慢的回到Mode.normal */ Gdx.app.log("cost", String.valueOf(time_2 - time_1)); deviceCameraControl.stopPreviewAsync();</code></pre> <h3><strong>混合两个pixmap</strong></h3> <p>接下来是整合两个PIxmap对象，LibGDX Pixmap对象可以帮助我们实现这个功能，但是因为相机的相片可能有不同的aspect ratio，所以我们也需要分别对待处理</p> <pre> <code class="language-java">private void merge2Pixmaps(Pixmap mainPixmap, Pixmap overlayedPixmap) { // merge to data and Gdx screen shot - but fix Aspect Ratio issues between the screen and the camera Pixmap.setFilter(Filter.BiLinear); float mainPixmapAR = (float)mainPixmap.getWidth() / mainPixmap.getHeight(); float overlayedPixmapAR = (float)overlayedPixmap.getWidth() / overlayedPixmap.getHeight(); if (overlayedPixmapAR < mainPixmapAR) { int overlayNewWidth = (int)(((float)mainPixmap.getHeight() / overlayedPixmap.getHeight()) * overlayedPixmap.getWidth()); int overlayStartX = (mainPixmap.getWidth() - overlayNewWidth)/2; mainPixmap.drawPixmap(overlayedPixmap, 0, 0, overlayedPixmap.getWidth(), overlayedPixmap.getHeight(), overlayStartX, 0, overlayNewWidth, mainPixmap.getHeight()); } else { int overlayNewHeight = (int)(((float)mainPixmap.getWidth() / overlayedPixmap.getWidth()) * overlayedPixmap.getHeight()); int overlayStartY = (mainPixmap.getHeight() - overlayNewHeight)/2; mainPixmap.drawPixmap(overlayedPixmap, 0, 0, overlayedPixmap.getWidth(), overlayedPixmap.getHeight(), 0, overlayStartY, mainPixmap.getWidth(), overlayNewHeight); } }</code></pre> <h3><strong>将图片保存为jpg</strong></h3> <p>所以我们选择JPG格式进行保存，一种方式就是使用Android的bitmap类对图片进行jpg格式的保存，这个功能可以在AndroidDeviceController类中实现，因为它是Android特有的功能，所以我们想不用它。</p> <p>尽量将大部分代码全部放到libgdx框架中，就是大部分实现的代码要在core中，然而libgdx的pixel格式是RGBA，而bitmap的Pixmap格式是ARGB，所以我们需要一bit一bit的将颜色转换过来</p> <pre> <code class="language-java">@Override public void saveAsJpeg(FileHandle jpgfile, Pixmap pixmap) { FileOutputStream fos; int x=0,y=0; int xl=0,yl=0; try { Bitmap bmp = Bitmap.createBitmap(pixmap.getWidth(), pixmap.getHeight(), Bitmap.Config.ARGB_8888); // we need to switch between LibGDX RGBA format to Android ARGB format for (x=0,xl=pixmap.getWidth(); x<xl;x++) { for (y=0,yl=pixmap.getHeight(); y<yl;y++) { int color = pixmap.getPixel(x, y); // RGBA => ARGB int RGB = color >> 8; int A = (color & 0x000000ff) << 24; int ARGB = A | RGB; bmp.setPixel(x, y, ARGB); } } // Finished Color format conversion fos = new FileOutputStream(jpgfile.file()); bmp.compress(CompressFormat.JPEG, 90, fos); // Finished Comression to JPEG file fos.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (IllegalArgumentException e) { e.printStackTrace(); } }</code></pre> <h3><strong>停止预览</strong></h3> <p>在完成保存图片后，我们将停止预览窗口，并且从Activity窗口中移去CameraSurface，我们同样也将停止camera继续想camera surface继续发送preview，我们同样异步执行这些。</p> <pre> <code class="language-java">@Override public synchronized void stopPreviewAsync() { Runnable r = new Runnable() { public void run() { stopPreview(); } }; activity.post(r); } @Override public synchronized void stopPreview() { // stop previewing. if (cameraSurface != null) { if (cameraSurface.getCamera() != null) { cameraSurface.getCamera().stopPreview(); } ViewParent parentView = cameraSurface.getParent(); if (parentView instanceof ViewGroup) { ViewGroup viewGroup = (ViewGroup) parentView; viewGroup.removeView(cameraSurface); } } }</code></pre> <p>注意在合成两张pixmap也就是混合相机取景和libgdx截图时分辨率有差异。在我们的Pixmaps整合过程中依然还存在一个问题，就是相机的分辨率和我们的截图分辨率也许是不同的（我在我的三星手机上，我把一个480x320屏幕截图延伸到2560x1920 大小的图片）。一个围绕它的解决方法就是扩大Libgdx视图的尺寸到更大，比实际物理设备的尺寸要大，要实现他需要使用setFixedSize()功能。真实的屏幕尺寸是根据BPU内存。</p> <p>然而，在这个时间中我设法去设置虚拟屏幕尺寸为960x640（可能因为GPU显存已经被origin的带下分配了）</p> <pre> <code class="language-java">public void setFixedSize(int width, int height) { if (graphics.getView() instanceof SurfaceView) { SurfaceView glView = (SurfaceView) graphics.getView(); glView.getHolder().setFixedSize(width, height); glView.getHolder().setFormat(PixelFormat.TRANSLUCENT); } } public void restoreFixedSize() { if (graphics.getView() instanceof SurfaceView) { SurfaceView glView = (SurfaceView) graphics.getView(); glView.getHolder().setFixedSize(origWidth, origHeight); glView.getHolder().setFormat(PixelFormat.TRANSLUCENT); } }</code></pre> <p>一些小提示</p> <ol> <li> <p>提示1<br> 注意，代码仅仅适用于Android平台，并非跨平台解决方法，但是我觉得至少在桌面端，应该可以提供类似功能的代码</p> </li> <li> <p>提示2<br> 在整合图片，并将图片数据保存到存储器上时，会花大量的时间，是因为libgdx颜色方案是RGBA而bitmap颜色方案是ARGB</p> </li> <li> <p>提示3<br> 最后需要注意的<br> 我仅仅测试了一部分Android设备，不同的GPU会产生不同的现象。<br> 最后的截图，按下camera可以开启相机，看下shot，就是进行拍摄，move可以控制猫向右侧移动</p> </li> </ol> <p style="text-align:center"><br> <img src="https://simg.open-open.com/show/0a6abe807a2cde42e1a83f0ef5ef0b1c.jpg"></p> <p style="text-align:center">4.jpg</p> <p> </p> <p>来自：http://www.jianshu.com/p/081a63afe95d</p> <p> </p>