1 | package org.greenstone.applet.GsdlCollageApplet;
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2 |
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3 | import java.applet.*;
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4 | import java.awt.*;
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5 | import java.awt.image.*;
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6 | import java.awt.geom.*;
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7 | import java.util.*;
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8 |
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9 | /**
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10 | * @author Katrina Edgar
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11 | * @author David Bainbridge
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12 | *
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13 | * Retrieves images from the download thread, determines an appropriate position
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14 | * for thes images onscreen ensuring maximum whitespace coverage and minimal overlap
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15 | * when possible. Draws images using advanced image processing techniques when applicable,
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16 | * such as fading the edges of an image and discolouring backgrounds. Also re-uses images
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17 | * from those that have previously been displayed, or are aging onscreen, in order to
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18 | * to create movement when no new images have been downloaded. */
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19 | public class DisplayImages extends Thread {
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20 |
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21 |
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22 | /** Will fire a removal operation when 4 images in the collage overlap a single area */
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23 | static final int NO_IMAGES_OF_OVERLAP = 4;
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24 |
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25 | /** To determine if there are several images overlapped, can remove the
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26 | * layers underneath to save time in repainting */
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27 | boolean overlap = false;
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28 |
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29 | /** Refers to download thread */
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30 | DownloadImages download_images_ = null;
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31 |
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32 | /** Refers to applet */
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33 | GsdlCollageApplet app_ = null;
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34 |
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35 | /** Applets width on screen */
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36 | public static int app_x_dim_ = 0;
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37 |
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38 | /** Applets height on screen */
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39 | public static int app_y_dim_ = 0;
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40 |
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41 | /** Background colour of the applet screen */
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42 | protected Color bgcolor_ = null;
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43 |
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44 | /** Indicates whether java2 functionality should be used <br>
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45 | * If true will allow advanced image processing techniques to occur,
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46 | * such as fading and colouring using pixel manipulation <br>
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47 | * If false, images will maintain an alpha value of 1 (appear solid),
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48 | * newer images will simply be pasted on top of existing images <br> */
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49 | protected boolean is_java2_ = false;
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50 |
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51 |
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52 | /** Holds images currently on display in the applet */
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53 | protected Vector inuse_ = null;
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54 |
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55 | /** Holds images ready to be used */
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56 | protected Vector inuse_ready_ = null;
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57 |
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58 | /** Holds previously displayed images for re-use */
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59 | protected Vector notinuse_ = null;
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60 |
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61 | protected Image screen_buffer_ = null;
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62 | protected Graphics screen_graphic_ = null;
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63 | protected Image finished_buffer_ = null;
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64 | protected Graphics finished_graphic_ = null;
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65 |
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66 | Thread next_frame_ ;
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67 |
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68 | String dots[] = new String[]{" ",".","..","...","....",".....","......"};
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69 | int dots_nums=0;
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70 | boolean start_paint = false;
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71 | /** Used to determine where to place new images on the applet to optimize
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72 | * whitespace coverage <br>
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73 | * A co-ordinate in the applet has a value of zero if it is whitespace,
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74 | * one if it is covered by one image, two if it is covered by two images,
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75 | * and so on. New images will be placed such that they cover the largest
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76 | * area of whitespace (zero valued co-ordinates) */
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77 | public static int [] [] used_space = null;
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78 |
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79 |
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80 | /**
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81 | * Starts the display images thread. Initialises variables using parameters and
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82 | * static values. Creates the blank applet screen, initialises the used space
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83 | * 2D array to indicate that there are no images onscreen
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84 | *
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85 | * @param app the applet to display the images on
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86 | * @param download_images thread from which to retrieve downloaded images
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87 | * @param is_java2 whether advanced image processing techniques should be used
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88 | * @param bgcolor the background colour of the applet screen */
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89 | public DisplayImages(GsdlCollageApplet app, DownloadImages download_images,
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90 | boolean is_java2, Color bgcolor)
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91 | {
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92 | super("DisplayImages");
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93 |
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94 | final int xDim_fallback = 600;
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95 | final int yDim_fallback = 300;
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96 |
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97 | // parameters saved locally
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98 | app_ = app;
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99 | is_java2_ = is_java2;
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100 | bgcolor_ = bgcolor;
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101 |
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102 | inuse_ = new Vector();
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103 | notinuse_ = new Vector();
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104 | inuse_ready_ = new Vector();
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105 | download_images_ = download_images;
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106 | // sets width and height
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107 | if (is_java2_)
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108 | {
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109 | //app_x_dim_ = (app_.getWidth() == 0) ? xDim_fallback : app_.getWidth();
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110 | //app_y_dim_ = (app_.getHeight() == 0) ? yDim_fallback : app_.getHeight();
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111 | app_x_dim_ = app_.getWidth();
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112 | app_y_dim_ = app.getHeight();
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113 |
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114 | System.err.println("@@@ xDim: " + app_x_dim_);
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115 | System.err.println("@@@ yDim: " + app_y_dim_);
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116 | }
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117 | else
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118 | {
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119 | app_x_dim_ = xDim_fallback;
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120 | app_y_dim_ = yDim_fallback;
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121 | }
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122 |
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123 | // creates initial screen
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124 | screen_buffer_ = app_.createImage(app_x_dim_, app_y_dim_);
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125 | if(screen_buffer_ == null) {
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126 | System.err.println("### why is screen_buffer_ null?");
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127 | }
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128 | screen_graphic_ = screen_buffer_.getGraphics();
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129 | screen_graphic_.setColor(bgcolor_);
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130 | screen_graphic_.fillRect(0,0,app_x_dim_,app_y_dim_);
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131 |
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132 | finished_buffer_ = app_.createImage(app_x_dim_, app_y_dim_);
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133 | finished_graphic_ = finished_buffer_.getGraphics();
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134 |
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135 | // initialises used space array to indicate an empty screen
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136 | used_space = new int [app_x_dim_][app_y_dim_];
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137 | for (int n=0; n < app_x_dim_; n++)
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138 | for (int m=0; m < app_y_dim_; m++)
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139 | used_space[n][m] = 0;
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140 |
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141 | next_frame_ = new Thread(new Runnable(){
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142 | public void run() {
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143 |
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144 | Thread curr_thread = Thread.currentThread();
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145 |
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146 | while (curr_thread == next_frame_) {
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147 | try {
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148 | Runtime rt = Runtime.getRuntime();
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149 | //System.out.println("total: "+rt.totalMemory());
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150 | //System.out.println("free: "+rt.freeMemory());
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151 | rt.gc();
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152 | //System.out.println("**************next frame...");
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153 | next_frame();
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154 | Thread.sleep(app_. refreshDelay_);
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155 |
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156 | curr_thread = Thread.currentThread();
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157 | } catch (Exception e) {
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158 | e.printStackTrace();
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159 | break;
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160 | }
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161 | }
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162 |
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163 |
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164 | }
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165 |
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166 |
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167 | });
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168 |
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169 | next_frame_.start();
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170 |
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171 |
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172 | }
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173 |
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174 | /** Determines what the user has clicked on in the applet, either an image or whitespace
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175 | * @param x the x co-ordinate of the mouse
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176 | * @param y the y co-ordinate of the mouse
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177 | * @return the image that the user has clicked on or null if the user has clicked whitespace */
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178 | public CollageImage clickedOnImage(int x, int y)
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179 | {
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180 | if (app_.verbosity() > 1)
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181 | {
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182 | System.err.print("Checking for clicked on image: ("+x+","+y+")");
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183 | }
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184 |
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185 |
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186 | // checks from last image down, as last images place will be at the top of the collage
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187 | for (int i= inuse_.size() - 1; i >= 0; i--)
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188 | {
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189 | CollageImage collage_image = (CollageImage)inuse_.elementAt(i);
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190 | if (collage_image.inside(x,y))
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191 | {
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192 | return collage_image;
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193 | }
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194 | }
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195 | // no image at these co-ordinates, just whitespace
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196 | return null;
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197 | }
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198 |
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199 | /** Generates the images onscreen.
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200 | * Loops through the vector of currently displayed images and draws each one in turn.
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201 | * If the image is being drawn for the first time, its position will be determined
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202 | * and its alpha channel set as solid prior to drawing. <br>
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203 | * Drawing of the image will depend on whether or not java2 is enabled. If so then
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204 | * the image will be processed so that fading occurs with age, so that the edges
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205 | * fade faster than the rest of the image and so that white images are slightly
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206 | * discoloured to allow distinction. If java2 is not enabled, new images will simply
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207 | * be pasted on top of existing images without any special effects occuring<br>
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208 | * This function also deletes old images. If java2 is enabled then images are deleted
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209 | * once they have faded to a suitably low alpha value. If java2 is not enabled then
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210 | * images will be removed once there are greater than 25 images onscreen, to ensure
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211 | * the applet cannot be overloaded. */
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212 | public void display_collage()
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213 | {
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214 |
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215 | // if there is nothing new to add
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216 | if (inuse_.size()==0) return;
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217 |
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218 | // otherwise need to re-generate images
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219 | if (app_.verbosity() >= 2)
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220 | {
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221 | //system.err.println("Regenerating images");
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222 | }
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223 |
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224 | // get each image currently onscreen inturn
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225 | for (int i=0; i<inuse_.size();)
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226 | {
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227 | CollageImage collage_image = (CollageImage)inuse_.elementAt(i);
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228 |
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229 | if (!collage_image.isValid()){
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230 | continue;
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231 | }
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232 |
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233 | int[] pixels = null;
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234 | // the first time the image is painted, determine its position and size
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235 | if (collage_image.fresh == true)
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236 | {
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237 | collage_image.process();
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238 | }
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239 |
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240 | // advanced image processing may be used
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241 | if (is_java2_)
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242 | {
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243 | // conducts fading and colouring of image
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244 | pixels = collage_image.handlepixels(inuse_.size()-i);
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245 | }
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246 |
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247 | if (collage_image.fresh) {
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248 | collage_image.fresh = false;
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249 | }
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250 |
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251 |
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252 | // if we remove when images have faded too much
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253 | if (is_java2_) {
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254 | if (collage_image.checkFaded(pixels)|| overlap)
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255 | {
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256 | overlap = false;
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257 |
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258 | CollageImage removed_image = (CollageImage)inuse_.elementAt(i);
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259 | //System.out.println(removed_image.name_ + "is removed");
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260 | inuse_.remove(i);
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261 | // indicates space for this image is no longer used
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262 | for (int n = removed_image.xl_; n < (removed_image.xl_ + removed_image.image_x_dim_); n++)
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263 | for (int m = removed_image.yt_; m < (removed_image.yt_ + removed_image.image_y_dim_); m++)
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264 | if(used_space[n][m] != 0) {
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265 | used_space[n][m]--;
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266 | if (used_space[n][m] > NO_IMAGES_OF_OVERLAP)
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267 | overlap = true;
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268 | }
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269 |
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270 | // sets the image as fresh and adds it to the vector of images previously seen
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271 | removed_image.fresh = true;
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272 | notinuse_.addElement(removed_image);
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273 | }
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274 | else{
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275 | i++;
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276 | }
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277 | }
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278 | else
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279 | if (inuse_.size() > 25 || overlap) {
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280 | overlap = false;
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281 |
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282 | CollageImage removed_image = (CollageImage)inuse_.elementAt(i);
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283 | inuse_.remove(i);
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284 |
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285 | // indicates space for this image is no longer used
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286 | for (int n = removed_image.xl_; n < (removed_image.xl_ + removed_image.image_x_dim_); n++)
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287 | for (int m = removed_image.yt_; m < (removed_image.yt_ + removed_image.image_y_dim_); m++)
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288 | if(used_space[n][m] != 0) {
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289 | used_space[n][m]--;
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290 | if (used_space[n][m] > NO_IMAGES_OF_OVERLAP)
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291 | overlap = true;
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292 | }
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293 |
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294 | // sets the image as fresh and adds it to the vector of images previously seen
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295 | removed_image.fresh = true;
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296 | notinuse_.addElement(removed_image);
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297 | }
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298 | else{
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299 | i++;
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300 | }
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301 |
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302 | }
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303 | }
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304 |
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305 |
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306 | /** Alters the images currently on display in the applet <br>
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307 | * Changes are prioritised in the following way:
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308 | * 1. If there are images that have been downloaded and are yet to be displayed
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309 | * they will be added to the list of images in use. <br>
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310 | * 2. Otherwise if there are images that have previously been displayed but
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311 | * are not currently on the applet screen, re-use one of these images. <br>
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312 | * 3. Otherwise if there are any images on screen at all, take the oldest and
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313 | * repaint it as the newest. <br>
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314 | * Then the collage is asked to display and repaint with the new image set. */
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315 |
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316 | public void next_frame()
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317 | {
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318 | double random = Math.random();
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319 |
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320 |
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321 | if (inuse_ready_.size() > 0){
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322 | int pos = (int) ((inuse_ready_.size() - 1) * random);
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323 | CollageImage collage_image = (CollageImage) inuse_ready_.remove(pos);
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324 | inuse_.addElement(collage_image);
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325 | }
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326 | else if (notinuse_.size()>0)
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327 | {
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328 | int position = (int) ((notinuse_.size() - 1) * random);
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329 |
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330 | CollageImage collage_image = (CollageImage)notinuse_.elementAt(position);
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331 | notinuse_.remove(position);
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332 | inuse_.addElement(collage_image);
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333 |
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334 | if (app_.verbosity()>3)
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335 | {
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336 | System.err.println("Re-using an image not on screen");
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337 | }
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338 | }
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339 | else{
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340 | if (app_.verbosity()>=4)
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341 | System.err.println("No images in download area");
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342 | }
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343 |
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344 | display_collage();
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345 |
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346 | }
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347 |
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348 |
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349 |
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350 | /** Paints the applet on the screen */
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351 | public void paint(Graphics g)
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352 | {
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353 |
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354 | screen_graphic_.setColor(bgcolor_);
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355 | screen_graphic_.fillRect(0,0,app_x_dim_,app_y_dim_);
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356 |
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357 | // get each image currently onscreen inturn
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358 |
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359 | for (int i=0; i < inuse_.size(); i++)
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360 | {
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361 |
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362 | CollageImage collage_image =null;
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363 | try{
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364 | collage_image = (CollageImage)inuse_.elementAt(i);
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365 | start_paint = true;
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366 | }
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367 | catch(Exception e){
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368 | System.out.println("exception in paint");
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369 | break;
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370 | }
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371 | // don't paint new images yet
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372 | if (collage_image.fresh) {
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373 | if (app_.verbosity()>=1) {
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374 | System.err.println("doing nothing... "+ collage_image.name_ +" is fresh.");
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375 | }
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376 | }
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377 |
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378 | // advanced image processing may be used
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379 | else if (is_java2_) {
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380 |
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381 | //the alphacomposite controls the blending of these two images.
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382 | Graphics2D sg2d = (Graphics2D)screen_graphic_;
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383 | sg2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
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384 | sg2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
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385 | RenderingHints.VALUE_ANTIALIAS_ON);
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386 | collage_image.expand();
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387 | sg2d.drawImage(collage_image.image_, collage_image.af_, app_);
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388 | }
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389 | // simple image collage
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390 | else
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391 | { // add the image to the collage
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392 |
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393 | screen_graphic_.drawImage(collage_image.image_,
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394 | collage_image.xl_, collage_image.yt_,
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395 | collage_image.xr_, collage_image.yb_,
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396 | 0,0,collage_image.image_x_dim_-1,
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397 | collage_image.image_y_dim_-1, app_);
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398 | }
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399 |
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400 | }
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401 |
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402 |
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403 | finished_graphic_.drawImage(screen_buffer_,0,0,app_);
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404 |
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405 |
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406 | if (finished_buffer_ != null)
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407 | {
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408 | g.drawImage(finished_buffer_, 0, 0, app_);
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409 | if (!start_paint){
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410 | g.setColor(Color.white);
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411 | g.setFont(new Font("font",Font.PLAIN+Font.BOLD,30));
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412 | g.drawString("Downloading" + dots[(dots_nums++)%dots.length],app_x_dim_/3-20,app_y_dim_/2-2);
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413 | }
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414 | }
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415 |
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416 |
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417 | }
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418 |
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419 | /** Runs display thread by repeatedly calling the next frame,
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420 | * waiting for a specified delay period between calls */
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421 | public void run() {
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422 | try {
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423 |
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424 | Thread curr_thread = Thread.currentThread();
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425 |
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426 | while (curr_thread == this) {
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427 | if (inuse_ready_.size() >= 1){
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428 | Thread.sleep(1000);
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429 | continue;
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430 | }
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431 | CollageImage collage_image = download_images_.getCollageImage();
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432 |
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433 | if (collage_image !=null){
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434 | inuse_ready_.addElement(collage_image);
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435 | }
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436 | curr_thread = Thread.currentThread();
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437 | }
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438 |
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439 | } catch (Exception e) {
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440 | e.printStackTrace();
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441 | System.out.println("Display images thread is interrupted");
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442 | }
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443 |
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444 | System.out.println("Display images thread stoped");
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445 |
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446 | }
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447 |
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448 | }
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