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android - TextureView 的裁剪相机预览

转载 作者:IT老高 更新时间:2023-10-28 22:20:36 32 4
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我有一个具有固定宽度和高度的 TextureView,我想在其中显示一个相机预览。我需要裁剪相机预览,使其在我的 TextureView 中看起来不会被拉伸(stretch)。如何进行种植?如果我需要使用 OpenGL,如何将 Surface Texture 绑定(bind)到 OpenGL 以及如何使用 OpenGL 进行裁剪?

public class MyActivity extends Activity implements TextureView.SurfaceTextureListener 
{

private Camera mCamera;
private TextureView mTextureView;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_options);

mTextureView = (TextureView) findViewById(R.id.camera_preview);
mTextureView.setSurfaceTextureListener(this);
}

@Override
public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
mCamera = Camera.open();

try
{
mCamera.setPreviewTexture(surface);
mCamera.startPreview();
} catch (IOException ioe) {
// Something bad happened
}
}

@Override
public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
mCamera.stopPreview();
mCamera.release();
return true;
}

@Override
public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
}

@Override
public void onSurfaceTextureUpdated(SurfaceTexture surface)
{
// Invoked every time there's a new Camera preview frame
}
}

另外,在正确进行预览后,我需要能够实时读取裁剪图像中心的像素。

最佳答案

@Romanski 提供的早期解决方案效果很好,但它会随着裁剪而缩放。如果您需要缩放以适应,请使用以下解决方案。每次更改表面 View 时调用 updateTextureMatrix:即在 onSurfaceTextureAvailable 和 onSurfaceTextureSizeChanged 方法中。另请注意,此解决方案依赖于 Activity 忽略配置更改(即 android:configChanges="orientation|screenSize|keyboardHidden"或类似的东西):

private void updateTextureMatrix(int width, int height)
{
boolean isPortrait = false;

Display display = getWindowManager().getDefaultDisplay();
if (display.getRotation() == Surface.ROTATION_0 || display.getRotation() == Surface.ROTATION_180) isPortrait = true;
else if (display.getRotation() == Surface.ROTATION_90 || display.getRotation() == Surface.ROTATION_270) isPortrait = false;

int previewWidth = orgPreviewWidth;
int previewHeight = orgPreviewHeight;

if (isPortrait)
{
previewWidth = orgPreviewHeight;
previewHeight = orgPreviewWidth;
}

float ratioSurface = (float) width / height;
float ratioPreview = (float) previewWidth / previewHeight;

float scaleX;
float scaleY;

if (ratioSurface > ratioPreview)
{
scaleX = (float) height / previewHeight;
scaleY = 1;
}
else
{
scaleX = 1;
scaleY = (float) width / previewWidth;
}

Matrix matrix = new Matrix();

matrix.setScale(scaleX, scaleY);
textureView.setTransform(matrix);

float scaledWidth = width * scaleX;
float scaledHeight = height * scaleY;

float dx = (width - scaledWidth) / 2;
float dy = (height - scaledHeight) / 2;
textureView.setTranslationX(dx);
textureView.setTranslationY(dy);
}

您还需要以下字段:

private int orgPreviewWidth;
private int orgPreviewHeight;

在调用updateTextureMatrix之前在onSurfaceTextureAvailable方法中初始化它:

Camera.Parameters parameters = camera.getParameters();
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);

Pair<Integer, Integer> size = getMaxSize(parameters.getSupportedPreviewSizes());
parameters.setPreviewSize(size.first, size.second);

orgPreviewWidth = size.first;
orgPreviewHeight = size.second;

camera.setParameters(parameters);

getMaxSize 方法:

private static Pair<Integer, Integer> getMaxSize(List<Camera.Size> list)
{
int width = 0;
int height = 0;

for (Camera.Size size : list) {
if (size.width * size.height > width * height)
{
width = size.width;
height = size.height;
}
}

return new Pair<Integer, Integer>(width, height);
}

最后一件事 - 您需要更正相机旋转。所以在 Activity 的 onConfigurationChanged 方法中调用 setCameraDisplayOrientation 方法(同时在 onSurfaceTextureAvailable 方法中进行初始调用):

public static void setCameraDisplayOrientation(Activity activity, int cameraId, Camera camera)
{
Camera.CameraInfo info = new Camera.CameraInfo();
Camera.getCameraInfo(cameraId, info);
int rotation = activity.getWindowManager().getDefaultDisplay().getRotation();
int degrees = 0;
switch (rotation)
{
case Surface.ROTATION_0:
degrees = 0;
break;
case Surface.ROTATION_90:
degrees = 90;
break;
case Surface.ROTATION_180:
degrees = 180;
break;
case Surface.ROTATION_270:
degrees = 270;
break;
}

int result;
if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT)
{
result = (info.orientation + degrees) % 360;
result = (360 - result) % 360; // compensate the mirror
}
else
{ // back-facing
result = (info.orientation - degrees + 360) % 360;
}
camera.setDisplayOrientation(result);

Camera.Parameters params = camera.getParameters();
params.setRotation(result);
camera.setParameters(params);
}

关于android - TextureView 的裁剪相机预览,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/17019588/

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