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      1 /*
      2  * Copyright (C) 2011 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.gallery3d.ui;
     18 
     19 import android.content.Context;
     20 import android.opengl.Matrix;
     21 
     22 // EdgeView draws EdgeEffect (blue glow) at four sides of the view.
     23 public class EdgeView extends GLView {
     24     private static final String TAG = "EdgeView";
     25 
     26     public static final int INVALID_DIRECTION = -1;
     27     public static final int TOP = 0;
     28     public static final int LEFT = 1;
     29     public static final int BOTTOM = 2;
     30     public static final int RIGHT = 3;
     31 
     32     // Each edge effect has a transform matrix, and each matrix has 16 elements.
     33     // We put all the elements in one array. These constants specify the
     34     // starting index of each matrix.
     35     private static final int TOP_M = TOP * 16;
     36     private static final int LEFT_M = LEFT * 16;
     37     private static final int BOTTOM_M = BOTTOM * 16;
     38     private static final int RIGHT_M = RIGHT * 16;
     39 
     40     private EdgeEffect[] mEffect = new EdgeEffect[4];
     41     private float[] mMatrix = new float[4 * 16];
     42 
     43     public EdgeView(Context context) {
     44         for (int i = 0; i < 4; i++) {
     45             mEffect[i] = new EdgeEffect(context);
     46         }
     47     }
     48 
     49     @Override
     50     protected void onLayout(
     51             boolean changeSize, int left, int top, int right, int bottom) {
     52         if (!changeSize) return;
     53 
     54         int w = right - left;
     55         int h = bottom - top;
     56         for (int i = 0; i < 4; i++) {
     57             if ((i & 1) == 0) {  // top or bottom
     58                 mEffect[i].setSize(w, h);
     59             } else {  // left or right
     60                 mEffect[i].setSize(h, w);
     61             }
     62         }
     63 
     64         // Set up transforms for the four edges. Without transforms an
     65         // EdgeEffect draws the TOP edge from (0, 0) to (w, Y * h) where Y
     66         // is some factor < 1. For other edges we need to move, rotate, and
     67         // flip the effects into proper places.
     68         Matrix.setIdentityM(mMatrix, TOP_M);
     69         Matrix.setIdentityM(mMatrix, LEFT_M);
     70         Matrix.setIdentityM(mMatrix, BOTTOM_M);
     71         Matrix.setIdentityM(mMatrix, RIGHT_M);
     72 
     73         Matrix.rotateM(mMatrix, LEFT_M, 90, 0, 0, 1);
     74         Matrix.scaleM(mMatrix, LEFT_M, 1, -1, 1);
     75 
     76         Matrix.translateM(mMatrix, BOTTOM_M, 0, h, 0);
     77         Matrix.scaleM(mMatrix, BOTTOM_M, 1, -1, 1);
     78 
     79         Matrix.translateM(mMatrix, RIGHT_M, w, 0, 0);
     80         Matrix.rotateM(mMatrix, RIGHT_M, 90, 0, 0, 1);
     81     }
     82 
     83     @Override
     84     protected void render(GLCanvas canvas) {
     85         super.render(canvas);
     86         boolean more = false;
     87         for (int i = 0; i < 4; i++) {
     88             canvas.save(GLCanvas.SAVE_FLAG_MATRIX);
     89             canvas.multiplyMatrix(mMatrix, i * 16);
     90             more |= mEffect[i].draw(canvas);
     91             canvas.restore();
     92         }
     93         if (more) {
     94             invalidate();
     95         }
     96     }
     97 
     98     // Called when the content is pulled away from the edge.
     99     // offset is in pixels. direction is one of {TOP, LEFT, BOTTOM, RIGHT}.
    100     public void onPull(int offset, int direction) {
    101         int fullLength = ((direction & 1) == 0) ? getWidth() : getHeight();
    102         mEffect[direction].onPull((float)offset / fullLength);
    103         if (!mEffect[direction].isFinished()) {
    104             invalidate();
    105         }
    106     }
    107 
    108     // Call when the object is released after being pulled.
    109     public void onRelease() {
    110         boolean more = false;
    111         for (int i = 0; i < 4; i++) {
    112             mEffect[i].onRelease();
    113             more |= !mEffect[i].isFinished();
    114         }
    115         if (more) {
    116             invalidate();
    117         }
    118     }
    119 
    120     // Call when the effect absorbs an impact at the given velocity.
    121     // Used when a fling reaches the scroll boundary. velocity is in pixels
    122     // per second. direction is one of {TOP, LEFT, BOTTOM, RIGHT}.
    123     public void onAbsorb(int velocity, int direction) {
    124         mEffect[direction].onAbsorb(velocity);
    125         if (!mEffect[direction].isFinished()) {
    126             invalidate();
    127         }
    128     }
    129 }
    130