src/jexer/TVScroller.java

   1 /*
   2  * Jexer - Java Text User Interface
   3  *
   4  * The MIT License (MIT)
   5  *
   6  * Copyright (C) 2017 Kevin Lamonte
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  21  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  24  * DEALINGS IN THE SOFTWARE.
  25  *
  26  * @author Kevin Lamonte [kevin.lamonte@gmail.com]
  27  * @version 1
  28  */
  29 package jexer;
  30
  31 import jexer.bits.CellAttributes;
  32 import jexer.bits.GraphicsChars;
  33 import jexer.event.TMouseEvent;
  34
  35 /**
  36  * TVScroller implements a simple vertical scroll bar.
  37  */
  38 public final class TVScroller extends TWidget {
  39
  40     /**
  41      * Value that corresponds to being on the top edge of the scroll bar.
  42      */
  43     private int topValue = 0;
  44
  45     /**
  46      * Get the value that corresponds to being on the top edge of the scroll
  47      * bar.
  48      *
  49      * @return the scroll value
  50      */
  51     public int getTopValue() {
  52         return topValue;
  53     }
  54
  55     /**
  56      * Set the value that corresponds to being on the top edge of the scroll
  57      * bar.
  58      *
  59      * @param topValue the new scroll value
  60      */
  61     public void setTopValue(final int topValue) {
  62         this.topValue = topValue;
  63     }
  64
  65     /**
  66      * Value that corresponds to being on the bottom edge of the scroll bar.
  67      */
  68     private int bottomValue = 100;
  69
  70     /**
  71      * Get the value that corresponds to being on the bottom edge of the
  72      * scroll bar.
  73      *
  74      * @return the scroll value
  75      */
  76     public int getBottomValue() {
  77         return bottomValue;
  78     }
  79
  80     /**
  81      * Set the value that corresponds to being on the bottom edge of the
  82      * scroll bar.
  83      *
  84      * @param bottomValue the new scroll value
  85      */
  86     public void setBottomValue(final int bottomValue) {
  87         this.bottomValue = bottomValue;
  88     }
  89
  90     /**
  91      * Current value of the scroll.
  92      */
  93     private int value = 0;
  94
  95     /**
  96      * Get current value of the scroll.
  97      *
  98      * @return the scroll value
  99      */
 100     public int getValue() {
 101         return value;
 102     }
 103
 104     /**
 105      * Set current value of the scroll.
 106      *
 107      * @param value the new scroll value
 108      */
 109     public void setValue(final int value) {
 110         this.value = value;
 111     }
 112
 113     /**
 114      * The increment for clicking on an arrow.
 115      */
 116     private int smallChange = 1;
 117
 118     /**
 119      * Get the increment for clicking on an arrow.
 120      *
 121      * @return the increment value
 122      */
 123     public int getSmallChange() {
 124         return smallChange;
 125     }
 126
 127     /**
 128      * Set the increment for clicking on an arrow.
 129      *
 130      * @param smallChange the new increment value
 131      */
 132     public void setSmallChange(final int smallChange) {
 133         this.smallChange = smallChange;
 134     }
 135
 136     /**
 137      * The increment for clicking in the bar between the box and an arrow.
 138      */
 139     private int bigChange = 20;
 140
 141     /**
 142      * Set the increment for clicking in the bar between the box and an
 143      * arrow.
 144      *
 145      * @return the increment value
 146      */
 147     public int getBigChange() {
 148         return bigChange;
 149     }
 150
 151     /**
 152      * Set the increment for clicking in the bar between the box and an
 153      * arrow.
 154      *
 155      * @param bigChange the new increment value
 156      */
 157     public void setBigChange(final int bigChange) {
 158         this.bigChange = bigChange;
 159     }
 160
 161     /**
 162      * When true, the user is dragging the scroll box.
 163      */
 164     private boolean inScroll = false;
 165
 166     /**
 167      * Public constructor.
 168      *
 169      * @param parent parent widget
 170      * @param x column relative to parent
 171      * @param y row relative to parent
 172      * @param height height of scroll bar
 173      */
 174     public TVScroller(final TWidget parent, final int x, final int y,
 175         final int height) {
 176
 177         // Set parent and window
 178         super(parent, x, y, 1, height);
 179     }
 180
 181     /**
 182      * Compute the position of the scroll box (a.k.a. grip, thumb).
 183      *
 184      * @return Y position of the box, between 1 and height - 2
 185      */
 186     private int boxPosition() {
 187         return (getHeight() - 3) * (value - topValue) / (bottomValue - topValue) + 1;
 188     }
 189
 190     /**
 191      * Draw a vertical scroll bar.
 192      */
 193     @Override
 194     public void draw() {
 195         CellAttributes arrowColor = getTheme().getColor("tscroller.arrows");
 196         CellAttributes barColor = getTheme().getColor("tscroller.bar");
 197         getScreen().putCharXY(0, 0, GraphicsChars.CP437[0x1E], arrowColor);
 198         getScreen().putCharXY(0, getHeight() - 1, GraphicsChars.CP437[0x1F],
 199             arrowColor);
 200
 201         // Place the box
 202         if (bottomValue > topValue) {
 203             getScreen().vLineXY(0, 1, getHeight() - 2,
 204                 GraphicsChars.CP437[0xB1], barColor);
 205             getScreen().putCharXY(0, boxPosition(), GraphicsChars.BOX,
 206                 arrowColor);
 207         } else {
 208             getScreen().vLineXY(0, 1, getHeight() - 2, GraphicsChars.HATCH,
 209                 barColor);
 210         }
 211
 212     }
 213
 214     /**
 215      * Perform a small step change up.
 216      */
 217     public void decrement() {
 218         if (bottomValue == topValue) {
 219             return;
 220         }
 221         value -= smallChange;
 222         if (value < topValue) {
 223             value = topValue;
 224         }
 225     }
 226
 227     /**
 228      * Perform a small step change down.
 229      */
 230     public void increment() {
 231         if (bottomValue == topValue) {
 232             return;
 233         }
 234         value += smallChange;
 235         if (value > bottomValue) {
 236             value = bottomValue;
 237         }
 238     }
 239
 240     /**
 241      * Perform a big step change up.
 242      */
 243     public void bigDecrement() {
 244         if (bottomValue == topValue) {
 245             return;
 246         }
 247         value -= bigChange;
 248         if (value < topValue) {
 249             value = topValue;
 250         }
 251     }
 252
 253     /**
 254      * Perform a big step change down.
 255      */
 256     public void bigIncrement() {
 257         if (bottomValue == topValue) {
 258             return;
 259         }
 260         value += bigChange;
 261         if (value > bottomValue) {
 262             value = bottomValue;
 263         }
 264     }
 265
 266     /**
 267      * Go to the top edge of the scroller.
 268      */
 269     public void toTop() {
 270         value = topValue;
 271     }
 272
 273     /**
 274      * Go to the bottom edge of the scroller.
 275      */
 276     public void toBottom() {
 277         value = bottomValue;
 278     }
 279
 280     /**
 281      * Handle mouse button releases.
 282      *
 283      * @param mouse mouse button release event
 284      */
 285     @Override
 286     public void onMouseUp(final TMouseEvent mouse) {
 287         if (bottomValue == topValue) {
 288             return;
 289         }
 290
 291         if (inScroll) {
 292             inScroll = false;
 293             return;
 294         }
 295
 296         if ((mouse.getX() == 0)
 297             && (mouse.getY() == 0)
 298         ) {
 299             // Clicked on the top arrow
 300             decrement();
 301             return;
 302         }
 303
 304         if ((mouse.getX() == 0)
 305             && (mouse.getY() == getHeight() - 1)
 306         ) {
 307             // Clicked on the bottom arrow
 308             increment();
 309             return;
 310         }
 311
 312         if ((mouse.getX() == 0)
 313             && (mouse.getY() > 0)
 314             && (mouse.getY() < boxPosition())
 315         ) {
 316             // Clicked between the top arrow and the box
 317             value -= bigChange;
 318             if (value < topValue) {
 319                 value = topValue;
 320             }
 321             return;
 322         }
 323
 324         if ((mouse.getX() == 0)
 325             && (mouse.getY() > boxPosition())
 326             && (mouse.getY() < getHeight() - 1)
 327         ) {
 328             // Clicked between the box and the bottom arrow
 329             value += bigChange;
 330             if (value > bottomValue) {
 331                 value = bottomValue;
 332             }
 333             return;
 334         }
 335     }
 336
 337     /**
 338      * Handle mouse movement events.
 339      *
 340      * @param mouse mouse motion event
 341      */
 342     @Override
 343     public void onMouseMotion(final TMouseEvent mouse) {
 344         if (bottomValue == topValue) {
 345             return;
 346         }
 347
 348         if ((mouse.isMouse1())
 349             && (inScroll)
 350             && (mouse.getY() > 0)
 351             && (mouse.getY() < getHeight() - 1)
 352         ) {
 353             // Recompute value based on new box position
 354             value = (bottomValue - topValue)
 355                 * (mouse.getY()) / (getHeight() - 3) + topValue;
 356             return;
 357         }
 358
 359         inScroll = false;
 360     }
 361
 362     /**
 363      * Handle mouse press events.
 364      *
 365      * @param mouse mouse button press event
 366      */
 367     @Override
 368     public void onMouseDown(final TMouseEvent mouse) {
 369         if (bottomValue == topValue) {
 370             return;
 371         }
 372
 373         if ((mouse.getX() == 0)
 374             && (mouse.getY() == boxPosition())
 375         ) {
 376             inScroll = true;
 377             return;
 378         }
 379     }
 380
 381 }