/**
 * Configures the necessary {@link Matrix} transformation.
 * This method should be called after the camera preview size is determined.
 *
 * @param displayRotation current rotation of default display
 * @param viewWidth  The width of `mTextureView`
 * @param viewHeight The height of `mTextureView`
 */
void configureTransform(
    int displayRotation, int viewWidth, int viewHeight, Size previewSize) {
  Matrix matrix = new Matrix();
  RectF viewRect = new RectF(0, 0, viewWidth, viewHeight);
  RectF bufferRect = new RectF(0, 0, previewSize.getHeight(), previewSize.getWidth());
  float centerX = viewRect.centerX();
  float centerY = viewRect.centerY();
  if (Surface.ROTATION_90 == displayRotation || Surface.ROTATION_270 == displayRotation) {
    bufferRect.offset(centerX - bufferRect.centerX(), centerY - bufferRect.centerY());
    matrix.setRectToRect(viewRect, bufferRect, ScaleToFit.FILL);
    float scale = Math.max(
        (float) viewHeight / previewSize.getHeight(),
        (float) viewWidth / previewSize.getWidth());
    matrix.postScale(scale, scale, centerX, centerY);
    matrix.postRotate(90 * (displayRotation - 2), centerX, centerY);
  } else if (Surface.ROTATION_180 == displayRotation) {
    matrix.postRotate(180, centerX, centerY);
  }
  setTransform(matrix);
}
 

private void calculateImageMatrixFromScale(float scale, @NonNull Matrix matrix) {
  matrix.reset();

  Drawable drawable = view.getDrawable();
  if (drawable != null && maxImageSize != 0) {
    // First make sure our image respects mMaxImageSize.
    RectF drawableBounds = tmpRectF1;
    RectF imageBounds = tmpRectF2;
    drawableBounds.set(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
    imageBounds.set(0, 0, maxImageSize, maxImageSize);
    matrix.setRectToRect(drawableBounds, imageBounds, ScaleToFit.CENTER);

    // Then scale it as requested.
    matrix.postScale(scale, scale, maxImageSize / 2f, maxImageSize / 2f);
  }
}
 

public void setFraming(final Rect frame, final RectF framePreview, final int displayRotation,
        final int cameraRotation, final boolean cameraFlip) {
    this.frame = frame;
    matrix.setRectToRect(framePreview, new RectF(frame), ScaleToFit.FILL);
    matrix.postRotate(-displayRotation, frame.exactCenterX(), frame.exactCenterY());
    matrix.postScale(cameraFlip ? -1 : 1, 1, frame.exactCenterX(), frame.exactCenterY());
    matrix.postRotate(cameraRotation, frame.exactCenterX(), frame.exactCenterY());

    invalidate();
}
 

protected void onBoundsChange(Rect bounds) {
    super.onBoundsChange(bounds);
    this.mRect.set((float) this.margin, (float) this.margin, (float) (bounds.width() - this.margin), (float) (bounds.height() - this.margin));
    Matrix shaderMatrix = new Matrix();
    shaderMatrix.setRectToRect(this.mBitmapRect, this.mRect, ScaleToFit.FILL);
    this.bitmapShader.setLocalMatrix(shaderMatrix);
}
 

public void setFraming(final Rect frame, final RectF framePreview, final int displayRotation,
                       final int cameraRotation, final boolean cameraFlip) {
    this.frame = frame;
    matrix.setRectToRect(framePreview, new RectF(frame), ScaleToFit.FILL);
    matrix.postRotate(-displayRotation, frame.exactCenterX(), frame.exactCenterY());
    matrix.postScale(cameraFlip ? -1 : 1, 1, frame.exactCenterX(), frame.exactCenterY());
    matrix.postRotate(cameraRotation, frame.exactCenterX(), frame.exactCenterY());

    invalidate();
}
 

public void setFraming(final Rect frame, final RectF framePreview, final int displayRotation,
        final int cameraRotation, final boolean cameraFlip) {
    this.frame = frame;
    matrix.setRectToRect(framePreview, new RectF(frame), ScaleToFit.FILL);
    matrix.postRotate(-displayRotation, frame.exactCenterX(), frame.exactCenterY());
    matrix.postScale(cameraFlip ? -1 : 1, 1, frame.exactCenterX(), frame.exactCenterY());
    matrix.postRotate(cameraRotation, frame.exactCenterX(), frame.exactCenterY());

    invalidate();
}