请帮助正确配置 Android 相机（在 HTC Desire 2.3.3 上测试）以在旋转（人像）模式下从相机预览。预览必须占不到一半的屏幕，宽度必须等于设备宽度，并且比例必须根据相机纵横比动态设置。我当前的代码：
public class CameraSurface extends SurfaceView implements SurfaceHolder.Callback {
…
public void surfaceCreated(SurfaceHolder holder) {
try {
if (camera != null) {
try {
camera.stopPreview();
} catch (Exception ignore) {
}
try {
camera.release();
} catch (Exception ignore) {
}
camera = null;
}
camera = Camera.open();
camera.setPreviewDisplay(holder);
} catch (Exception ex) {
try {
if (camera != null) {
try {
camera.stopPreview();
} catch (Exception ignore) {
}
try {
camera.release();
} catch (Exception ignore) {
}
camera = null;
}
} catch (Exception ignore) {
}
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
try {
if (camera != null) {
try {
camera.stopPreview();
} catch (Exception ignore) {
}
try {
camera.release();
} catch (Exception ignore) {
}
camera = null;
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
try {
Camera.Parameters parameters = camera.getParameters();
float bff = 0;
try {
List<Camera.Size> supportedSizes = null;
//maximize supported resizes, TODO remove as hardcode
w*=1.5;
h*=1.5;
// On older devices (<1.6) the following will fail
// the camera will work nevertheless
supportedSizes = Compatibility.getSupportedPreviewSizes(parameters);
// preview form factor
float ff = (float) w / h;
Log.d("TAG", "Screen res: w:" + w + " h:" + h
+ " aspect ratio:" + ff);
// holder for the best form factor and size
int bestw = 0;
int besth = 0;
Iterator<Camera.Size> itr = supportedSizes.iterator();
// we look for the best preview size, it has to be the closest
// to the
// screen form factor
while (itr.hasNext()) {
Camera.Size element = itr.next();
// current form factor
float cff = (float) element.width / element.height;
// check if the current element is a candidate to replace
// the best match so far
// current form factor should be closer to the bff
// preview width should be less than screen width
// preview width should be more than current bestw
// this combination will ensure that the highest resolution
// will win
Log.d("TAG", "Candidate camera element: w:"
+ element.width + " h:" + element.height
+ " aspect ratio:" + cff);
if ((ff - cff <= ff - bff) && (element.width <= w)
&& (element.width >= bestw)) {
bff = cff;
bestw = element.width;
besth = element.height;
}
}
Log.d("TAG", "Chosen camera element: w:" + bestw + " h:"
+ besth + " aspect ratio:" + bff);
// Some Samsung phones will end up with bestw and besth = 0
// because their minimum preview size is bigger then the screen
// size.
// In this case, we use the default values: 480x320
if ((bestw == 0) || (besth == 0)) {
Log.d("Mixare", "Using default camera parameters!");
bestw = 480;
besth = 320;
}
parameters.setPreviewSize(bestw,besth);
} catch (Exception ex) {
parameters.setPreviewSize(480,320);
bff=1.5f;
}
makeResizeForCameraAspect(bff);
camera.setDisplayOrientation(90);//only Android 2.2 and later
camera.setParameters(parameters);
camera.startPreview();
} catch (Exception ex) {
Log.e(TAG,"",ex);
}
}
private void makeResizeForCameraAspect(float cameraAspectRatio){
LayoutParams layoutParams=this.getLayoutParams();
int matchParentWidth=this.getWidth();
int newHeight=(int)(matchParentWidth/cameraAspectRatio);
if(newHeight!=layoutParams.height){
layoutParams.height=newHeight;
layoutParams.width=matchParentWidth;
this.setLayoutParams(layoutParams);
this.invalidate();
}
}
}
活动布局：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<org.mixare.CameraSurface
android:id="@+id/camera_surface"
android:layout_width="match_parent"
android:layout_height="150dp"
android:layout_alignParentTop="true"
/>
<!--CameraSurface layout_height will be changed during it's loading process -->
</RelativeLayout>
AndroidManifest 配置为纵向：
<activity android:label="@string/app_name" android:name=".MixView"
android:screenOrientation="portrait"
android:launchMode="singleTop" >
实际图片：
- 设备旋转肖像
- 设备旋转景观
在相同的主题中发现：Android - Camera preview is sideways，Android camera rotate，但我的代码得到了相同的结果
在这里你可以看到图像的错误比例。如何以适当的比例显示旋转和缩放的相机预览？
部分代码取自 Mixare 开源项目，http://www.mixare.org/