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
17package com.android.camera.ui.focus;
18
19import android.graphics.Matrix;
20import android.graphics.RectF;
21
22/**
23 * Transform coordinates to and from preview coordinate space and camera driver
24 * coordinate space.
25 */
26public 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