src/jexer/TVScroller.java

   1 /*
   2  * Jexer - Java Text User Interface
   3  *
   4  * The MIT License (MIT)
   5  *
   6  * Copyright (C) 2019 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 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         putCharXY(0, 0, GraphicsChars.CP437[0x1E], arrowColor);
 216         putCharXY(0, getHeight() - 1, GraphicsChars.CP437[0x1F], arrowColor);
 217
 218         // Place the box
 219         if (bottomValue > topValue) {
 220             vLineXY(0, 1, getHeight() - 2, GraphicsChars.CP437[0xB1], barColor);
 221             putCharXY(0, boxPosition(), GraphicsChars.BOX, arrowColor);
 222         } else {
 223             vLineXY(0, 1, getHeight() - 2, GraphicsChars.HATCH, barColor);
 224         }
 225     }
 226
 227     // ------------------------------------------------------------------------
 228     // TVScroller -------------------------------------------------------------
 229     // ------------------------------------------------------------------------
 230
 231     /**
 232      * Get the value that corresponds to being on the top edge of the scroll
 233      * bar.
 234      *
 235      * @return the scroll value
 236      */
 237     public int getTopValue() {
 238         return topValue;
 239     }
 240
 241     /**
 242      * Set the value that corresponds to being on the top edge of the scroll
 243      * bar.
 244      *
 245      * @param topValue the new scroll value
 246      */
 247     public void setTopValue(final int topValue) {
 248         this.topValue = topValue;
 249     }
 250
 251     /**
 252      * Get the value that corresponds to being on the bottom edge of the
 253      * scroll bar.
 254      *
 255      * @return the scroll value
 256      */
 257     public int getBottomValue() {
 258         return bottomValue;
 259     }
 260
 261     /**
 262      * Set the value that corresponds to being on the bottom edge of the
 263      * scroll bar.
 264      *
 265      * @param bottomValue the new scroll value
 266      */
 267     public void setBottomValue(final int bottomValue) {
 268         this.bottomValue = bottomValue;
 269     }
 270
 271     /**
 272      * Get current value of the scroll.
 273      *
 274      * @return the scroll value
 275      */
 276     public int getValue() {
 277         return value;
 278     }
 279
 280     /**
 281      * Set current value of the scroll.
 282      *
 283      * @param value the new scroll value
 284      */
 285     public void setValue(final int value) {
 286         this.value = value;
 287     }
 288
 289     /**
 290      * Get the increment for clicking on an arrow.
 291      *
 292      * @return the increment value
 293      */
 294     public int getSmallChange() {
 295         return smallChange;
 296     }
 297
 298     /**
 299      * Set the increment for clicking on an arrow.
 300      *
 301      * @param smallChange the new increment value
 302      */
 303     public void setSmallChange(final int smallChange) {
 304         this.smallChange = smallChange;
 305     }
 306
 307     /**
 308      * Set the increment for clicking in the bar between the box and an
 309      * arrow.
 310      *
 311      * @return the increment value
 312      */
 313     public int getBigChange() {
 314         return bigChange;
 315     }
 316
 317     /**
 318      * Set the increment for clicking in the bar between the box and an
 319      * arrow.
 320      *
 321      * @param bigChange the new increment value
 322      */
 323     public void setBigChange(final int bigChange) {
 324         this.bigChange = bigChange;
 325     }
 326
 327     /**
 328      * Compute the position of the scroll box (a.k.a. grip, thumb).
 329      *
 330      * @return Y position of the box, between 1 and height - 2
 331      */
 332     private int boxPosition() {
 333         return (getHeight() - 3) * (value - topValue) / (bottomValue - topValue) + 1;
 334     }
 335
 336     /**
 337      * Perform a small step change up.
 338      */
 339     public void decrement() {
 340         if (bottomValue == topValue) {
 341             return;
 342         }
 343         value -= smallChange;
 344         if (value < topValue) {
 345             value = topValue;
 346         }
 347     }
 348
 349     /**
 350      * Perform a small step change down.
 351      */
 352     public void increment() {
 353         if (bottomValue == topValue) {
 354             return;
 355         }
 356         value += smallChange;
 357         if (value > bottomValue) {
 358             value = bottomValue;
 359         }
 360     }
 361
 362     /**
 363      * Perform a big step change up.
 364      */
 365     public void bigDecrement() {
 366         if (bottomValue == topValue) {
 367             return;
 368         }
 369         value -= bigChange;
 370         if (value < topValue) {
 371             value = topValue;
 372         }
 373     }
 374
 375     /**
 376      * Perform a big step change down.
 377      */
 378     public void bigIncrement() {
 379         if (bottomValue == topValue) {
 380             return;
 381         }
 382         value += bigChange;
 383         if (value > bottomValue) {
 384             value = bottomValue;
 385         }
 386     }
 387
 388     /**
 389      * Go to the top edge of the scroller.
 390      */
 391     public void toTop() {
 392         value = topValue;
 393     }
 394
 395     /**
 396      * Go to the bottom edge of the scroller.
 397      */
 398     public void toBottom() {
 399         value = bottomValue;
 400     }
 401
 402 }