SwitchAnimManager.java revision 76507a9fd2581694942a662a57fbdd46d7a20036 
1/*
2 * Copyright (C) 2012 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;
18
19import android.os.SystemClock;
20import android.util.Log;
21
22import com.android.gallery3d.ui.GLCanvas;
23import com.android.gallery3d.ui.RawTexture;
24
25/**
26 * Class to handle the animation when switching between back and front cameras.
27 * An image of the previous camera zooms in and fades out. The preview of the
28 * new camera zooms in and fades in. The image of the previous camera is called
29 * review in this class.
30 */
31public class SwitchAnimManager {
32    private static final String TAG = "SwitchAnimManager";
33    // The amount of change for zooming in and out.
34    private static final float ZOOM_DELTA_PREVIEW = 0.2f;
35    private static final float ZOOM_DELTA_REVIEW = 0.5f;
36    private static final float ANIMATION_DURATION = 400;  // ms
37    public static final float INITIAL_DARKEN_ALPHA = 0.8f;
38
39    private long mAnimStartTime;  // milliseconds.
40    // The drawing width and height of the review image. This is saved when the
41    // texture is copied.
42    private int mReviewDrawingWidth;
43    private int mReviewDrawingHeight;
44    // The maximum width of the camera screen nail width from onDraw. We need to
45    // know how much the preview is scaled and scale the review the same amount.
46    // For example, the preview is not full screen in film strip mode.
47    private int mPreviewFrameLayoutWidth;
48
49    public SwitchAnimManager() {
50    }
51
52    public void setReviewDrawingSize(int width, int height) {
53        mReviewDrawingWidth = width;
54        mReviewDrawingHeight = height;
55    }
56
57    // width: the width of PreviewFrameLayout view.
58    // height: the height of PreviewFrameLayout view. Not used. Kept for
59    //         consistency.
60    public void setPreviewFrameLayoutSize(int width, int height) {
61        mPreviewFrameLayoutWidth = width;
62    }
63
64    // w and h: the rectangle area where the animation takes place.
65    public void startAnimation() {
66        mAnimStartTime = SystemClock.uptimeMillis();
67    }
68
69    // Returns true if the animation has been drawn.
70    // preview: camera preview view.
71    // review: snapshot of the preview before switching the camera.
72    public boolean drawAnimation(GLCanvas canvas, int x, int y, int width,
73            int height, CameraScreenNail preview, RawTexture review) {
74        long timeDiff = SystemClock.uptimeMillis() - mAnimStartTime;
75        if (timeDiff > ANIMATION_DURATION) return false;
76        float fraction = timeDiff / ANIMATION_DURATION;
77
78        // Calculate the position and the size of the preview.
79        float centerX = x + width / 2f;
80        float centerY = y + height / 2f;
81        float previewAnimScale = 1 - ZOOM_DELTA_PREVIEW * (1 - fraction);
82        float previewWidth = width * previewAnimScale;
83        float previewHeight = height * previewAnimScale;
84        int previewX = Math.round(centerX - previewWidth / 2);
85        int previewY = Math.round(centerY - previewHeight / 2);
86
87        // Calculate the position and the size of the review.
88        float reviewAnimScale = 1 + ZOOM_DELTA_REVIEW * fraction;
89
90        // Calculate how much preview is scaled.
91        // The scaling is done by PhotoView in Gallery so we don't have the
92        // scaling information but only the width and the height passed to this
93        // method. The inference of the scale ratio is done by matching the
94        // current width and the original width we have at first when the camera
95        // layout is inflated.
96        float scaleRatio = 1;
97        if (mPreviewFrameLayoutWidth != 0) {
98            scaleRatio = (float) width / mPreviewFrameLayoutWidth;
99        } else {
100            Log.e(TAG, "mPreviewFrameLayoutWidth is 0.");
101        }
102        float reviewWidth = mReviewDrawingWidth * reviewAnimScale * scaleRatio;
103        float reviewHeight = mReviewDrawingHeight * reviewAnimScale * scaleRatio;
104        int reviewX = Math.round(centerX - reviewWidth / 2);
105        int reviewY = Math.round(centerY - reviewHeight / 2);
106
107        // Draw the preview.
108        float alpha = canvas.getAlpha();
109        canvas.setAlpha(fraction); // fade in
110        preview.directDraw(canvas, previewX, previewY, Math.round(previewWidth),
111                Math.round(previewHeight));
112
113        // Draw the review.
114        canvas.setAlpha((1f - fraction) * INITIAL_DARKEN_ALPHA); // fade out
115        review.draw(canvas, reviewX, reviewY, Math.round(reviewWidth),
116                Math.round(reviewHeight));
117        canvas.setAlpha(alpha);
118        return true;
119    }
120}
121