我正在创建一个相机应用程序，它实现了自己的相机预览来拍照。该应用程序当前被强制进入纵向模式。
我的问题是相机的预览略微拉伸（纵横比有点偏离）。有趣的是，我将 SurfaceView 的大小设置为始终与预览大小匹配。这样可以确保始终保持纵横比……但事实并非如此……
这是我用来显示我的相机预览的布局：
public class Cp extends ViewGroup implements SurfaceHolder.Callback {
private final String TAG = "CameraPreview";
private boolean mPreviewRunning = false;
private SurfaceView mSurfaceView;
private SurfaceHolder mHolder;
private Size mPreviewSize;
private List<Size> mSupportedPreviewSizes;
private Camera mCamera;
public boolean IsPreviewRunning() {
return mPreviewRunning;
}
public Cp(Context context) {
this(context, null, 0);
}
public Cp(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public Cp(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
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) {
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);
setMeasuredDimension(width, height);
if (mSupportedPreviewSizes == null && mCamera != null) {
mSupportedPreviewSizes = mCamera.getParameters()
.getSupportedPreviewSizes();
}
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.height;
previewHeight = mPreviewSize.width;
}
if (previewWidth == 0) {
previewWidth = 1;
}
if (previewHeight == 0) {
previewHeight = 1;
}
// 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);
}
}
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, acquire the camera and tell it where to
// draw.
try {
if (mCamera != null) {
Parameters params = mCamera.getParameters();
mSupportedPreviewSizes = params.getSupportedPreviewSizes();
mCamera.setPreviewDisplay(holder);
}
} catch (IOException exception) {
Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// Surface will be destroyed when we return, so stop the preview.
stop();
}
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) {
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);
}
}
}
return optimalSize;
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
if (mCamera != null) {
// Now that the size is known, set up the camera parameters and
// begin the preview.
Camera.Parameters parameters = mCamera.getParameters();
if (mPreviewSize != null) {
parameters.setPreviewSize(mPreviewSize.width,
mPreviewSize.height);
}
requestLayout();
mCamera.setParameters(parameters);
mCamera.startPreview();
mPreviewRunning = true;
}
}
public void stop() {
if (mCamera != null) {
mCamera.stopPreview();
mPreviewRunning = false;
mCamera = null;
}
}
}
请注意，onLayout宽度和高度是交换的，因为应用程序始终以纵向运行。
我包括一些图片来向您展示问题的样子：
我已经调试了代码。预览大小被设置为 1280x720，并且布局的大小也被正确调整以匹配该大小。
我也尝试过不同的布局，但结果总是一样的......