Android相机效果不起作用
我正在尝试为Android构建一个图像编辑应用程序，我刚刚开始，我已经遇到了麻烦。 好吧，我可以拍照并保存到SD卡。 但我尝试做一些应用程序运行的效果，但效果不会出现在预览中。 下面是我使用的完整代码：
package com.example.camerademo; import java.io.IOException; import android.app.Activity; import android.hardware.Camera; import android.os.Bundle; import android.view.SurfaceHolder; import android.view.SurfaceView; public class MainActivity extends Activity implements SurfaceHolder.Callback { SurfaceView cameraView; SurfaceHolder surfaceHolder; Camera camera; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); cameraView = (SurfaceView) this.findViewById(R.id.CameraView); surfaceHolder = cameraView.getHolder(); surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); surfaceHolder.addCallback(this); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width,int height) { // TODO Auto-generated method stub camera.startPreview(); } @Override public void surfaceCreated(SurfaceHolder holder) { // TODO Auto-generated method stub camera = Camera.open(); try { camera.setPreviewDisplay(holder); Camera.Parameters parameters = camera.getParameters(); parameters.setColorEffect(Camera.Parameters.EFFECT_NEGATIVE); camera.setParameters(parameters); } catch (IOException exception) { camera.release(); } } @Override public void surfaceDestroyed(SurfaceHolder holder) { // TODO Auto-generated method stub camera.stopPreview(); camera.release(); }} 谁能告诉我我的效果代码有什么问题。 这是另一种做法吗？
下面是我用来获得支持的效果并循环遍历的代码。
List colorEffects = parameters.getSupportedColorEffects(); Iterator cei = colorEffects.iterator(); while (cei.hasNext()) { String currentEffect = cei.next(); if (currentEffect.equals(Camera.Parameters.EFFECT_NEGATIVE)) { parameters.setColorEffect(Camera.Parameters.EFFECT_NEGATIVE); break; } }
这给了我一个空指针exception..所以我试图看看colorEffects是否包含任何数据或效果。 我使用了这样的if循环
if(colorEffects == null){ editText.setText("Null"); }
它是空的。 为什么？ 下载的sdk是否有问题。 我应该下载android 2.3 SDK。 目前我已经下载了2.2 SDK。 顺便说一句，即使只是打字
parameters.setColorEffect(Camera.Parameters.EFFECT_NEGATIVE);
如果不使用getSupportedColorEffects（）方法，它运行时没有错误，但效果不会在预览中显示。
Log Cat信息：
01-01 00:08:17.588: E/AndroidRuntime(297): FATAL EXCEPTION: main 01-01 00:08:17.588: E/AndroidRuntime(297): java.lang.NullPointerException 01-01 00:08:17.588: E/AndroidRuntime(297): at com.example.camerademo.MainActivity.surfaceCreated(MainActivity.java:56) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.SurfaceView.updateWindow(SurfaceView.java:532) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.SurfaceView.dispatchDraw(SurfaceView.java:339) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewGroup.drawChild(ViewGroup.java:1638) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1367) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewGroup.drawChild(ViewGroup.java:1638) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1367) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.View.draw(View.java:6743) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.widget.FrameLayout.draw(FrameLayout.java:352) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewGroup.drawChild(ViewGroup.java:1640) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1367) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewGroup.drawChild(ViewGroup.java:1638) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1367) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.View.draw(View.java:6743) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.widget.FrameLayout.draw(FrameLayout.java:352) 01-01 00:08:17.588: E/AndroidRuntime(297): at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1842) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewRoot.draw(ViewRoot.java:1407) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewRoot.performTraversals(ViewRoot.java:1163) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.view.ViewRoot.handleMessage(ViewRoot.java:1727) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.os.Handler.dispatchMessage(Handler.java:99) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.os.Looper.loop(Looper.java:123) 01-01 00:08:17.588: E/AndroidRuntime(297): at android.app.ActivityThread.main(ActivityThread.java:4627) 01-01 00:08:17.588: E/AndroidRuntime(297): at java.lang.reflect.Method.invokeNative(Native Method) 01-01 00:08:17.588: E/AndroidRuntime(297): at java.lang.reflect.Method.invoke(Method.java:521) 01-01 00:08:17.588: E/AndroidRuntime(297): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 01-01 00:08:17.588: E/AndroidRuntime(297): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 01-01 00:08:17.588: E/AndroidRuntime(297): at dalvik.system.NativeStart.main(Native Method)
当我输入以下代码行时会发生此错误：
List colorEffects = parameters.getSupportedColorEffects(); Iterator cei = colorEffects.iterator(); while (cei.hasNext()) { String currentEffect = cei.next(); if (currentEffect.equals(Camera.Parameters.EFFECT_NEGATIVE)) { parameters.setColorEffect(Camera.Parameters.EFFECT_NEGATIVE); break; } }
你可以尝试把这些行：
Camera.Parameters parameters = camera.getParameters(); parameters.setColorEffect(Camera.Parameters.EFFECT_NEGATIVE); camera.setParameters(parameters);
进入surfaceChanged方法？
这是我从Android Developers Reference中复制的示例代码：
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) { // If your preview can change or rotate, take care of those events here. // Make sure to stop the preview before resizing or reformatting it. if (mHolder.getSurface() == null){ // preview surface does not exist return; } // stop preview before making changes try { mCamera.stopPreview(); } catch (Exception e){ // ignore: tried to stop a non-existent preview } // set preview size and make any resize, rotate or // reformatting changes here // start preview with new settings try { mCamera.setPreviewDisplay(mHolder); mCamera.startPreview(); } catch (Exception e){ Log.d(TAG, "Error starting camera preview: " + e.getMessage()); } }
根据这篇参考文献，建议对surfaceChanged方法进行任何更改，就像评论所说的那样。
我有类似的应用程序，将改变预览的大小，我按照指南。 那么你可以尝试这种方法吗？