好的,所以我认为针对一般相机预览拉伸问题没有足够的答案。或者至少我没有找到一个。我的应用程序也遭受了这种拉伸综合症,花了我一段时间从所有用户在此门户网站和互联网上的答案中拼凑出一个解决方案。
我尝试过@Hesam的解决方案,但它并没有起作用,留下了我的相机预览严重失真。
首先,我展示我的解决方法的代码(代码的重要部分),然后解释为什么我采取了这些步骤。还有改进性能的空间。
主活动xml布局:
<RelativeLayout
android:id="@+id/main_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<FrameLayout
android:id="@+id/camera_preview"
android:layout_centerInParent="true"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</RelativeLayout>
摄像头预览:
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
private SurfaceHolder prHolder;
private Camera prCamera;
public List<Camera.Size> prSupportedPreviewSizes;
private Camera.Size prPreviewSize;
@SuppressWarnings("deprecation")
public YoCameraPreview(Context context, Camera camera) {
super(context);
prCamera = camera;
prSupportedPreviewSizes = prCamera.getParameters().getSupportedPreviewSizes();
prHolder = getHolder();
prHolder.addCallback(this);
prHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder holder) {
try {
prCamera.setPreviewDisplay(holder);
prCamera.startPreview();
} catch (IOException e) {
Log.d("Yologram", "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
if (prHolder.getSurface() == null){
return;
}
try {
prCamera.stopPreview();
} catch (Exception e){
}
try {
Camera.Parameters parameters = prCamera.getParameters();
List<String> focusModes = parameters.getSupportedFocusModes();
if (focusModes.contains(Camera.Parameters.FOCUS_MODE_AUTO)) {
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
}
parameters.setPreviewSize(prPreviewSize.width, prPreviewSize.height);
prCamera.setParameters(parameters);
prCamera.setPreviewDisplay(prHolder);
prCamera.startPreview();
} catch (Exception e){
Log.d("Yologram", "Error starting camera preview: " + e.getMessage());
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
setMeasuredDimension(width, height);
if (prSupportedPreviewSizes != null) {
prPreviewSize =
getOptimalPreviewSize(prSupportedPreviewSizes, width, height);
}
}
public Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int w, int h) {
final double ASPECT_TOLERANCE = 0.1;
double targetRatio = (double) h / w;
if (sizes == null)
return null;
Camera.Size optimalSize = null;
double minDiff = Double.MAX_VALUE;
int targetHeight = h;
for (Camera.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);
}
}
if (optimalSize == null) {
minDiff = Double.MAX_VALUE;
for (Camera.Size size : sizes) {
if (Math.abs(size.height - targetHeight) < minDiff) {
optimalSize = size;
minDiff = Math.abs(size.height - targetHeight);
}
}
}
return optimalSize;
}
}
主要活动:
public class MainActivity extends Activity {
...
@SuppressLint("NewApi")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
maCamera = getCameraInstance();
maLayoutPreview = (FrameLayout) findViewById(R.id.camera_preview);
maPreview = new CameraPreview(this, maCamera);
Point displayDim = getDisplayWH();
Point layoutPreviewDim = calcCamPrevDimensions(displayDim,
maPreview.getOptimalPreviewSize(maPreview.prSupportedPreviewSizes,
displayDim.x, displayDim.y));
if (layoutPreviewDim != null) {
RelativeLayout.LayoutParams layoutPreviewParams =
(RelativeLayout.LayoutParams) maLayoutPreview.getLayoutParams();
layoutPreviewParams.width = layoutPreviewDim.x;
layoutPreviewParams.height = layoutPreviewDim.y;
layoutPreviewParams.addRule(RelativeLayout.CENTER_IN_PARENT);
maLayoutPreview.setLayoutParams(layoutPreviewParams);
}
maLayoutPreview.addView(maPreview);
}
@SuppressLint("NewApi")
@SuppressWarnings("deprecation")
private Point getDisplayWH() {
Display display = this.getWindowManager().getDefaultDisplay();
Point displayWH = new Point();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
display.getSize(displayWH);
return displayWH;
}
displayWH.set(display.getWidth(), display.getHeight());
return displayWH;
}
private Point calcCamPrevDimensions(Point disDim, Camera.Size camDim) {
Point displayDim = disDim;
Camera.Size cameraDim = camDim;
double widthRatio = (double) displayDim.x / cameraDim.width;
double heightRatio = (double) displayDim.y / cameraDim.height;
if (widthRatio < heightRatio) {
Point calcDimensions = new Point();
calcDimensions.x = displayDim.x;
calcDimensions.y = (displayDim.x * cameraDim.height) / cameraDim.width;
return calcDimensions;
}
if (widthRatio > heightRatio) {
Point calcDimensions = new Point();
calcDimensions.x = (displayDim.y * cameraDim.width) / cameraDim.height;
calcDimensions.y = displayDim.y;
return calcDimensions;
}
return null;
}
}
我的评论:
这一切的关键在于,尽管您可以在getOptimalPreviewSize()
中计算出最佳相机尺寸,但是您只选择最接近屏幕比例的比例。因此,除非比例完全相同,否则预览将会被拉伸。
为什么会被拉伸?因为您在layout.xml
中设置了FrameLayout相机预览的宽度和高度匹配父容器。因此,预览将被拉伸到全屏。
需要做的是将相机预览布局的宽度和高度设置为与所选相机大小比例相匹配,以便预览保持其纵横比,不会失真。
我试图使用CameraPreview
类来执行所有计算和布局更改,但我无法理解。我试图应用此解决方案,但是SurfaceView
不认识getChildCount ()
或getChildAt(int index)
。我想,最终通过引用maLayoutPreview
解决了问题,但出现了问题,将设置的比例应用于整个应用程序,并在拍摄第一张照片后才这样做。因此,我放弃了它,并将布局修改移至MainActivity
。
在CameraPreview
中,我将prSupportedPreviewSizes
和getOptimalPreviewSize()
更改为public,以便在MainActivity
中使用。然后,我需要显示维度(如果有导航/状态栏,则减去其尺寸)和选择的最佳相机尺寸。我试图获取RelativeLayout(或FrameLayout)大小而不是显示大小,但它返回零值。此解决方案对我不起作用。布局在onWindowFocusChanged
之后获得了其值(在日志中检查)。
因此,我有了计算布局尺寸以匹配所选相机尺寸纵横比的方法。现在,您只需要设置相机预览布局的LayoutParams
。更改宽度,高度并将其居中于父容器。
有两种选择如何计算预览尺寸。要么您希望它适合具有黑色边条(如果windowBackground设置为null)的屏幕边缘或顶部/底部。要么您希望预览缩放到全屏。我在calcCamPrevDimensions()
中留下了更多信息的注释。