我想获得全屏肖像相机预览。使用 Google 的示例，预览在纵向屏幕上以横向格式显示。当我将预览设置为 480 x 864（工作横向尺寸的倒数）时，我收到 setParameters failed 错误。
我已经阅读了我能找到的所有 StackOverflow，但我不明白为什么横向支持的尺寸在纵向中失败。我也找不到强制全屏纵向预览的方法。手机上的相机应用程序提供全屏肖像预览，所以我知道这不是硬件限制。
我正在使用运行 Android 2.3.3 的 Droid 3 进行测试
我将不胜感激任何建议。
public class SimplePreview extends ViewGroup implements SurfaceHolder.Callback {
private final String TAG = "Preview";
SurfaceView mSurfaceView;
SurfaceHolder mHolder;
Size mPreviewSize;
List<Size> mSupportedPreviewSizes;
Camera mCamera;
int cameraId;
Activity activity;
public SimplePreview(Activity context, int defaultCamera) {
super(context);
activity = context;
cameraId = defaultCamera;
mSurfaceView = new SurfaceView(context);
addView(mSurfaceView);
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
mHolder = mSurfaceView.getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void setCamera(Camera camera) {
mCamera = camera;
if (mCamera != null) {
mSupportedPreviewSizes = mCamera.getParameters()
.getSupportedPreviewSizes();
requestLayout();
}
}
public void switchCamera(Camera camera) {
setCamera(camera);
try {
camera.setPreviewDisplay(mHolder);
} catch (IOException exception) {
Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
}
Camera.Parameters parameters = camera.getParameters();
parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
requestLayout();
camera.setParameters(parameters);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// We purposely disregard child measurements because act as a
// wrapper to a SurfaceView that centers the camera preview instead
// of stretching it.
final int width = resolveSize(getSuggestedMinimumWidth(),
widthMeasureSpec);
final int height = resolveSize(getSuggestedMinimumHeight(),
heightMeasureSpec);
Log.i(TAG, "setting View measured dimensions to width: " + width
+ " height: " + height);
setMeasuredDimension(width, height);
if (mSupportedPreviewSizes != null) {
mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width,
height);
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if (changed && getChildCount() > 0) {
final View child = getChildAt(0);
final int width = r - l;
final int height = b - t;
int previewWidth = width;
int previewHeight = height;
if (mPreviewSize != null) {
previewWidth = mPreviewSize.width;
previewHeight = mPreviewSize.height;
}
// Center the child SurfaceView within the parent.
if (width * previewHeight > height * previewWidth) {
final int scaledChildWidth = previewWidth * height
/ previewHeight;
child.layout((width - scaledChildWidth) / 2, 0,
(width + scaledChildWidth) / 2, height);
} else {
final int scaledChildHeight = previewHeight * width
/ previewWidth;
child.layout(0, (height - scaledChildHeight) / 2, width,
(height + scaledChildHeight) / 2);
}
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// Surface will be destroyed when we return, so stop the preview.
if (mCamera != null) {
mCamera.stopPreview();
}
}
private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
final double ASPECT_TOLERANCE = 0.1;
double targetRatio = (double) w / h;
if (sizes == null)
return null;
Size optimalSize = null;
double minDiff = Double.MAX_VALUE;
int targetHeight = h;
// Try to find an size match aspect ratio and size
for (Size size : sizes) {
Log.v(TAG, " width: " + size.width + " height: " + size.height);
double ratio = (double) size.width / size.height;
if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
continue;
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
// Cannot find the one match the aspect ratio, ignore the requirement
if (optimalSize == null) {
minDiff = Double.MAX_VALUE;
for (Size size : sizes) {
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
}
Log.i(TAG, "optimal preview width: " + optimalSize.width + " height: "
+ optimalSize.height);
return optimalSize;
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, acquire the camera and tell it where
// to draw.
try {
if (mCamera != null) {
final int width = getWidth();
final int height = getHeight();
Log.i(TAG, "view width: " + width + " height: " + height);
if (height > width) {
Log.i(TAG, "in portrait mode so rotate camera preview");
// THis line fixed the camera display orientation. seems to
// have to be called before setPreviewDisplay()
mCamera.setDisplayOrientation(90);
}
mCamera.setPreviewDisplay(holder);
}
} catch (IOException exception) {
Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
}
}
/**
* orientation and rotation work done here. Now that the size is known, set
* up the camera parameters and begin the preview.
*/
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
if (mCamera != null) {
mCamera.stopPreview();
Camera.Parameters parameters = mCamera.getParameters();
// mCamera.setDisplayOrientation(90);
final int width = getWidth();
final int height = getHeight();
Log.i(TAG, "view width: " + width + " height: " + height);
if (height > width) {
Log.i(TAG, "portrait: setting preview width: " + 480
+ " height: " + 864);
parameters.setPreviewSize(480, 864);
// had no effect
parameters.set("orientation", "portrait");
} else {
Log.i(TAG, "landscape: setting preview width: "
+ mPreviewSize.width + " height: "
+ mPreviewSize.height);
parameters.setPreviewSize(mPreviewSize.width,
mPreviewSize.height);
}
requestLayout();
// *** following line throws setParameters failed error ***
mCamera.setParameters(parameters);
mCamera.startPreview();
}
}
}
以及来自 Activity 的 onCreate() 的调用：
preview = new SimplePreview(this, defaultCameraId);
setContentView(preview);