[6816] | 1 | package org.nzdl.gsdl.GsdlCollageApplet;
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| 2 |
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| 3 | public class MyAffineTransform {
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| 4 |
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| 5 | public double scaleX = 0;
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| 6 | public double scaleY = 0;
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| 7 | public double translateX = 0;
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| 8 | public double translateY = 0;
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| 9 | public boolean overlap = false;
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| 10 |
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| 11 | public MyAffineTransform (int image_x_dim, int image_y_dim) {
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| 12 |
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| 13 | random_set_pos(image_x_dim, image_y_dim);
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| 14 | }
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| 15 |
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| 16 | /** The amount to adjust the size of an image so that it fits into the applet screen
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| 17 | * @param image_x_dim the width of the image to scale
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| 18 | * @param image_y_dim the height of the image to scale
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| 19 | * @return a value by which to scale the image to ensure it will fit in the applet */
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| 20 | private double scaleFactor (int image_x_dim, int image_y_dim) {
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| 21 |
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| 22 | double scale_factor = 1.0;
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| 23 |
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| 24 | // three quarters of the application width & height
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| 25 | int tol_app_x_dim = 3*DisplayImages.app_x_dim_/4;
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| 26 | int tol_app_y_dim = 3*DisplayImages.app_y_dim_/4;
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| 27 |
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| 28 | // if the image is too big, calculate a fraction
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| 29 | // by which to reduce the image
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| 30 | if (image_x_dim>tol_app_x_dim)
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| 31 | {
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| 32 | scale_factor = image_x_dim/tol_app_x_dim + 1;
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| 33 | }
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| 34 |
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| 35 | if (image_y_dim>tol_app_y_dim)
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| 36 | {
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| 37 | int y_scale_factor = image_y_dim/tol_app_y_dim + 1;
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| 38 | // take the biggest of the two as the same fraction must
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| 39 | // be applied to both the x and y values to keep the image
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| 40 | // in proportion
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| 41 | if (y_scale_factor>scale_factor)
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| 42 | {
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| 43 | scale_factor = y_scale_factor;
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| 44 | }
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| 45 | }
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| 46 |
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| 47 | return scale_factor;
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| 48 | }
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| 49 |
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| 50 | /** Determines the placement of new images on the applet screen <br>
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| 51 | * First the image is scaled, then the function loops until a satisfactory
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| 52 | * image position is found. This is done by randomly selecting an x and y
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| 53 | * co-ordinate for the image, then determining how much whitespace will be
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| 54 | * covered if the image were to be placed at this position in the collage.
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| 55 | * The standards for loop termination are as follows:<br>
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| 56 | * 1. On any occasion a whitespace coverage of greater than 70% will result
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| 57 | * in the loop being terminated.<br>
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| 58 | * 2. After three times through the loop, a whitespace coverage of 50% will
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| 59 | * also allow the loop to terminate (a less stringent condition). <br>
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| 60 | * 3. After seven times through, the loop will terminate and the best
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| 61 | * position will be used by default.<br>
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| 62 | * This function also updates the used space array after image position has been selected.
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| 63 | *
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| 64 | * @param image_x_dim the width of the image
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| 65 | * @param image_y_dim the height of the image
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| 66 | * @return a transform operation by which to move the image from the origin */
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| 67 | protected void random_set_pos(int image_x_dim, int image_y_dim)
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| 68 | {
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| 69 |
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| 70 | double scale_factor = scaleFactor(image_x_dim, image_y_dim);
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| 71 |
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| 72 | // scale the image (will be 1 and therefore no change as a default)
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| 73 | image_x_dim/=scale_factor;
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| 74 | image_y_dim/=scale_factor;
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| 75 |
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| 76 | // initialise variables required to determine image placement
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| 77 | int image_x_pos = 0;
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| 78 | int image_y_pos = 0;
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| 79 | int best_x = 0;
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| 80 | int best_y = 0;
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| 81 | double best_clear = 0;
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| 82 | double clear = 100;
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| 83 | int stoploop = 0;
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| 84 |
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| 85 | do {
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| 86 | // increment the loop counter
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| 87 | stoploop++;
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| 88 |
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| 89 | // the number of positions that the image could occupy on the x axis
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| 90 | int safe_x_dim = DisplayImages.app_x_dim_ - image_x_dim;
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| 91 | double rx = Math.random();
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| 92 | // randomly pick an x co-ordinate for the image
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| 93 | image_x_pos= ((int)(rx*safe_x_dim));
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| 94 |
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| 95 | // same process as for the x co-ordinate
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| 96 | // ensuring the y co-ordinate will fit on the screen
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| 97 | int safe_y_dim = DisplayImages.app_y_dim_ - image_y_dim;
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| 98 | double ry = Math.random();
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| 99 | // randomly pick a y co-ordinate for the image
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| 100 | image_y_pos= ((int)(ry*safe_y_dim));
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| 101 |
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| 102 | double whitespace = 0;
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| 103 | double space = 0;
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| 104 |
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| 105 | // determine how much whitespace the image will cover if placed in the
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| 106 | // current position and how much overlap will occur
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| 107 | for (int n = image_x_pos; n < (image_x_pos + image_x_dim); n++) {
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| 108 | for (int m = image_y_pos; m < (image_y_pos + image_y_dim); m++) {
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| 109 | if (DisplayImages.used_space[n][m] == 0)
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| 110 | whitespace++;
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| 111 | space++;
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| 112 | }
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| 113 | }
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| 114 |
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| 115 | // divide the amount of whitespace covered by the amount of overlap
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| 116 | clear = whitespace/space;
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| 117 | // if this value is better than previous calculations, save these co-ordinates
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| 118 | if (clear > best_clear) {
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| 119 | best_x = image_x_pos;
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| 120 | best_y = image_y_pos;
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| 121 | best_clear = clear;
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| 122 | }
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| 123 |
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| 124 | if ((image_x_dim > (DisplayImages.app_x_dim_ / 2)) || (image_y_dim > (DisplayImages.app_y_dim_ / 2)))
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| 125 | break;
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| 126 |
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| 127 | } while ((clear < 0.70 || (stoploop > 3 && clear < 0.50)) && stoploop < 7);
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| 128 |
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| 129 | // if we only terminated because we went through so many times,
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| 130 | // then we set the position to the best value possible
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| 131 | if (stoploop == 7) {
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| 132 | image_x_pos = best_x;
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| 133 | image_y_pos = best_y;
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| 134 | }
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| 135 |
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| 136 | // indicate that the space where the image is to be placed is now used
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| 137 | for (int n = image_x_pos; n < (image_x_pos + image_x_dim); n++)
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| 138 | for (int m = image_y_pos; m < (image_y_pos + image_y_dim); m++) {
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| 139 | DisplayImages.used_space[n][m]++;
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| 140 | if (DisplayImages.used_space[n][m] > DisplayImages.NO_IMAGES_OF_OVERLAP)
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| 141 | overlap = true;
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| 142 | }
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| 143 |
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| 144 | translateX = image_x_pos;
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| 145 | translateY = image_y_pos;
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| 146 |
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| 147 | // scale the image appropriately
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| 148 | scaleX = 1.0/scale_factor;
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| 149 | scaleY = 1.0/scale_factor;
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| 150 |
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| 151 | return;
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| 152 | }
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| 153 |
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| 154 | }
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