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     // Variables --------------------------------------------------------------
  42     // ------------------------------------------------------------------------
  43
  44     /**
  45      * Value that corresponds to being on the top edge of the scroll bar.
  46      */
  47     private int topValue = 0;
  48
  49     /**
  50      * Value that corresponds to being on the bottom edge of the scroll bar.
  51      */
  52     private int bottomValue = 100;
  53
  54     /**
  55      * Current value of the scroll.
  56      */
  57     private int value = 0;
  58
  59     /**
  60      * The increment for clicking on an arrow.
  61      */
  62     private int smallChange = 1;
  63
  64     /**
  65      * The increment for clicking in the bar between the box and an arrow.
  66      */
  67     private int bigChange = 20;
  68
  69     /**
  70      * When true, the user is dragging the scroll box.
  71      */
  72     private boolean inScroll = false;
  73
  74     // ------------------------------------------------------------------------
  75     // Constructors -----------------------------------------------------------
  76     // ------------------------------------------------------------------------
  77
  78     /**
  79      * Public constructor.
  80      *
  81      * @param parent parent widget
  82      * @param x column relative to parent
  83      * @param y row relative to parent
  84      * @param height height of scroll bar
  85      */
  86     public TVScroller(final TWidget parent, final int x, final int y,
  87         final int height) {
  88
  89         // Set parent and window
  90         super(parent, x, y, 1, height);
  91     }
  92
  93     // ------------------------------------------------------------------------
  94     // Event handlers ---------------------------------------------------------
  95     // ------------------------------------------------------------------------
  96
  97     /**
  98      * Handle mouse button releases.
  99      *
 100      * @param mouse mouse button release event
 101      */
 102     @Override
 103     public void onMouseUp(final TMouseEvent mouse) {
 104         if (bottomValue == topValue) {
 105             return;
 106         }
 107
 108         if (inScroll) {
 109             inScroll = false;
 110             return;
 111         }
 112
 113         if ((mouse.getX() == 0)
 114             && (mouse.getY() == 0)
 115         ) {
 116             // Clicked on the top arrow
 117             decrement();
 118             return;
 119         }
 120
 121         if ((mouse.getX() == 0)
 122             && (mouse.getY() == getHeight() - 1)
 123         ) {
 124             // Clicked on the bottom arrow
 125             increment();
 126             return;
 127         }
 128
 129         if ((mouse.getX() == 0)
 130             && (mouse.getY() > 0)
 131             && (mouse.getY() < boxPosition())
 132         ) {
 133             // Clicked between the top arrow and the box
 134             value -= bigChange;
 135             if (value < topValue) {
 136                 value = topValue;
 137             }
 138             return;
 139         }
 140
 141         if ((mouse.getX() == 0)
 142             && (mouse.getY() > boxPosition())
 143             && (mouse.getY() < getHeight() - 1)
 144         ) {
 145             // Clicked between the box and the bottom arrow
 146             value += bigChange;
 147             if (value > bottomValue) {
 148                 value = bottomValue;
 149             }
 150             return;
 151         }
 152     }
 153
 154     /**
 155      * Handle mouse movement events.
 156      *
 157      * @param mouse mouse motion event
 158      */
 159     @Override
 160     public void onMouseMotion(final TMouseEvent mouse) {
 161         if (bottomValue == topValue) {
 162             return;
 163         }
 164
 165         if ((mouse.isMouse1())
 166             && (inScroll)
 167             && (mouse.getY() > 0)
 168             && (mouse.getY() < getHeight() - 1)
 169         ) {
 170             // Recompute value based on new box position
 171             value = (bottomValue - topValue)
 172                 * (mouse.getY()) / (getHeight() - 3) + topValue;
 173             if (value > bottomValue) {
 174                 value = bottomValue;
 175             }
 176             if (value < topValue) {
 177                 value = topValue;
 178             }
 179             return;
 180         }
 181
 182         inScroll = false;
 183     }
 184
 185     /**
 186      * Handle mouse press events.
 187      *
 188      * @param mouse mouse button press event
 189      */
 190     @Override
 191     public void onMouseDown(final TMouseEvent mouse) {
 192         if (bottomValue == topValue) {
 193             return;
 194         }
 195
 196         if ((mouse.getX() == 0)
 197             && (mouse.getY() == boxPosition())
 198         ) {
 199             inScroll = true;
 200             return;
 201         }
 202     }
 203
 204     // ------------------------------------------------------------------------
 205     // TWidget ----------------------------------------------------------------
 206     // ------------------------------------------------------------------------
 207
 208     /**
 209      * Draw a vertical scroll bar.
 210      */
 211     @Override
 212     public void draw() {
 213         CellAttributes arrowColor = getTheme().getColor("tscroller.arrows");
 214         CellAttributes barColor = getTheme().getColor("tscroller.bar");
 215         getScreen().putCharXY(0, 0, GraphicsChars.CP437[0x1E], arrowColor);
 216         getScreen().putCharXY(0, getHeight() - 1, GraphicsChars.CP437[0x1F],
 217             arrowColor);
 218
 219         // Place the box
 220         if (bottomValue > topValue) {
 221             getScreen().vLineXY(0, 1, getHeight() - 2,
 222                 GraphicsChars.CP437[0xB1], barColor);
 223             getScreen().putCharXY(0, boxPosition(), GraphicsChars.BOX,
 224                 arrowColor);
 225         } else {
 226             getScreen().vLineXY(0, 1, getHeight() - 2, GraphicsChars.HATCH,
 227                 barColor);
 228         }
 229
 230     }
 231
 232     // ------------------------------------------------------------------------
 233     // TVScroller -------------------------------------------------------------
 234     // ------------------------------------------------------------------------
 235
 236     /**
 237      * Get the value that corresponds to being on the top edge of the scroll
 238      * bar.
 239      *
 240      * @return the scroll value
 241      */
 242     public int getTopValue() {
 243         return topValue;
 244     }
 245
 246     /**
 247      * Set the value that corresponds to being on the top edge of the scroll
 248      * bar.
 249      *
 250      * @param topValue the new scroll value
 251      */
 252     public void setTopValue(final int topValue) {
 253         this.topValue = topValue;
 254     }
 255
 256     /**
 257      * Get the value that corresponds to being on the bottom edge of the
 258      * scroll bar.
 259      *
 260      * @return the scroll value
 261      */
 262     public int getBottomValue() {
 263         return bottomValue;
 264     }
 265
 266     /**
 267      * Set the value that corresponds to being on the bottom edge of the
 268      * scroll bar.
 269      *
 270      * @param bottomValue the new scroll value
 271      */
 272     public void setBottomValue(final int bottomValue) {
 273         this.bottomValue = bottomValue;
 274     }
 275
 276     /**
 277      * Get current value of the scroll.
 278      *
 279      * @return the scroll value
 280      */
 281     public int getValue() {
 282         return value;
 283     }
 284
 285     /**
 286      * Set current value of the scroll.
 287      *
 288      * @param value the new scroll value
 289      */
 290     public void setValue(final int value) {
 291         this.value = value;
 292     }
 293
 294     /**
 295      * Get the increment for clicking on an arrow.
 296      *
 297      * @return the increment value
 298      */
 299     public int getSmallChange() {
 300         return smallChange;
 301     }
 302
 303     /**
 304      * Set the increment for clicking on an arrow.
 305      *
 306      * @param smallChange the new increment value
 307      */
 308     public void setSmallChange(final int smallChange) {
 309         this.smallChange = smallChange;
 310     }
 311
 312     /**
 313      * Set the increment for clicking in the bar between the box and an
 314      * arrow.
 315      *
 316      * @return the increment value
 317      */
 318     public int getBigChange() {
 319         return bigChange;
 320     }
 321
 322     /**
 323      * Set the increment for clicking in the bar between the box and an
 324      * arrow.
 325      *
 326      * @param bigChange the new increment value
 327      */
 328     public void setBigChange(final int bigChange) {
 329         this.bigChange = bigChange;
 330     }
 331
 332     /**
 333      * Compute the position of the scroll box (a.k.a. grip, thumb).
 334      *
 335      * @return Y position of the box, between 1 and height - 2
 336      */
 337     private int boxPosition() {
 338         return (getHeight() - 3) * (value - topValue) / (bottomValue - topValue) + 1;
 339     }
 340
 341     /**
 342      * Perform a small step change up.
 343      */
 344     public void decrement() {
 345         if (bottomValue == topValue) {
 346             return;
 347         }
 348         value -= smallChange;
 349         if (value < topValue) {
 350             value = topValue;
 351         }
 352     }
 353
 354     /**
 355      * Perform a small step change down.
 356      */
 357     public void increment() {
 358         if (bottomValue == topValue) {
 359             return;
 360         }
 361         value += smallChange;
 362         if (value > bottomValue) {
 363             value = bottomValue;
 364         }
 365     }
 366
 367     /**
 368      * Perform a big step change up.
 369      */
 370     public void bigDecrement() {
 371         if (bottomValue == topValue) {
 372             return;
 373         }
 374         value -= bigChange;
 375         if (value < topValue) {
 376             value = topValue;
 377         }
 378     }
 379
 380     /**
 381      * Perform a big step change down.
 382      */
 383     public void bigIncrement() {
 384         if (bottomValue == topValue) {
 385             return;
 386         }
 387         value += bigChange;
 388         if (value > bottomValue) {
 389             value = bottomValue;
 390         }
 391     }
 392
 393     /**
 394      * Go to the top edge of the scroller.
 395      */
 396     public void toTop() {
 397         value = topValue;
 398     }
 399
 400     /**
 401      * Go to the bottom edge of the scroller.
 402      */
 403     public void toBottom() {
 404         value = bottomValue;
 405     }
 406
 407 }