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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.camera.ui.focus;
     18 
     19 import android.graphics.Matrix;
     20 import android.graphics.RectF;
     21 
     22 /**
     23  * Transform coordinates to and from preview coordinate space and camera driver
     24  * coordinate space.
     25  */
     26 public class CameraCoordinateTransformer {
     27     // http://developer.android.com/guide/topics/media/camera.html#metering-focus-areas
     28     private static final RectF CAMERA_DRIVER_RECT = new RectF(-1000, -1000, 1000, 1000);
     29 
     30     private final Matrix mCameraToPreviewTransform;
     31     private final Matrix mPreviewToCameraTransform;
     32 
     33     /**
     34      * Convert rectangles to / from camera coordinate and preview coordinate space.
     35      *
     36      * @param mirrorX if the preview is mirrored along the X axis.
     37      * @param displayOrientation orientation in degrees.
     38      * @param previewRect the preview rectangle size and position.
     39      */
     40     public CameraCoordinateTransformer(boolean mirrorX, int displayOrientation,
     41           RectF previewRect) {
     42         if (!hasNonZeroArea(previewRect)) {
     43             throw new IllegalArgumentException("previewRect");
     44         }
     45 
     46         mCameraToPreviewTransform = cameraToPreviewTransform(mirrorX, displayOrientation,
     47               previewRect);
     48         mPreviewToCameraTransform = inverse(mCameraToPreviewTransform);
     49     }
     50 
     51     /**
     52      * Transform a rectangle in camera space into a new rectangle in preview
     53      * view space.
     54      *
     55      * @param source the rectangle in camera space
     56      * @return the rectangle in preview view space.
     57      */
     58     public RectF toPreviewSpace(RectF source) {
     59         RectF result = new RectF();
     60         mCameraToPreviewTransform.mapRect(result, source);
     61         return result;
     62     }
     63 
     64     /**
     65      * Transform a rectangle in preview view space into a new rectangle in
     66      * camera view space.
     67      *
     68      * @param source the rectangle in preview view space
     69      * @return the rectangle in camera view space.
     70      */
     71     public RectF toCameraSpace(RectF source) {
     72         RectF result = new RectF();
     73         mPreviewToCameraTransform.mapRect(result, source);
     74         return result;
     75     }
     76 
     77     private Matrix cameraToPreviewTransform(boolean mirrorX, int displayOrientation,
     78           RectF previewRect) {
     79         Matrix transform = new Matrix();
     80 
     81         // Need mirror for front camera.
     82         transform.setScale(mirrorX ? -1 : 1, 1);
     83 
     84         // Apply a rotate transform.
     85         // This is the value for android.hardware.Camera.setDisplayOrientation.
     86         transform.postRotate(displayOrientation);
     87 
     88         // Map camera driver coordinates to preview rect coordinates
     89         Matrix fill = new Matrix();
     90         fill.setRectToRect(CAMERA_DRIVER_RECT,
     91               previewRect,
     92               Matrix.ScaleToFit.FILL);
     93 
     94         // Concat the previous transform on top of the fill behavior.
     95         transform.setConcat(fill, transform);
     96 
     97         return transform;
     98     }
     99 
    100     private Matrix inverse(Matrix source) {
    101         Matrix newMatrix = new Matrix();
    102         source.invert(newMatrix);
    103         return newMatrix;
    104     }
    105 
    106     private boolean hasNonZeroArea(RectF rect) {
    107         return rect.width() != 0 && rect.height() != 0;
    108     }
    109 }
    110