src/jexer/THScroller.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  * THScroller implements a simple horizontal scroll bar.
  37  */
  38 public final class THScroller extends TWidget {
  39
  40     /**
  41      * Value that corresponds to being on the left edge of the scroll bar.
  42      */
  43     private int leftValue = 0;
  44
  45     /**
  46      * Get the value that corresponds to being on the left edge of the scroll
  47      * bar.
  48      *
  49      * @return the scroll value
  50      */
  51     public int getLeftValue() {
  52         return leftValue;
  53     }
  54
  55     /**
  56      * Set the value that corresponds to being on the left edge of the
  57      * scroll bar.
  58      *
  59      * @param leftValue the new scroll value
  60      */
  61     public void setLeftValue(final int leftValue) {
  62         this.leftValue = leftValue;
  63     }
  64
  65     /**
  66      * Value that corresponds to being on the right edge of the scroll bar.
  67      */
  68     private int rightValue = 100;
  69
  70     /**
  71      * Get the value that corresponds to being on the right edge of the
  72      * scroll bar.
  73      *
  74      * @return the scroll value
  75      */
  76     public int getRightValue() {
  77         return rightValue;
  78     }
  79
  80     /**
  81      * Set the value that corresponds to being on the right edge of the
  82      * scroll bar.
  83      *
  84      * @param rightValue the new scroll value
  85      */
  86     public void setRightValue(final int rightValue) {
  87         this.rightValue = rightValue;
  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 width height of scroll bar
 173      */
 174     public THScroller(final TWidget parent, final int x, final int y,
 175         final int width) {
 176
 177         // Set parent and window
 178         super(parent, x, y, width, 1);
 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 width - 2
 185      */
 186     private int boxPosition() {
 187         return (getWidth() - 3) * (value - leftValue) / (rightValue - leftValue) + 1;
 188     }
 189
 190     /**
 191      * Draw a horizontal 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[0x11], arrowColor);
 198         getScreen().putCharXY(getWidth() - 1, 0, GraphicsChars.CP437[0x10],
 199             arrowColor);
 200
 201         // Place the box
 202         if (rightValue > leftValue) {
 203             getScreen().hLineXY(1, 0, getWidth() - 2, GraphicsChars.CP437[0xB1],
 204                 barColor);
 205             getScreen().putCharXY(boxPosition(), 0, GraphicsChars.BOX,
 206                 arrowColor);
 207         } else {
 208             getScreen().hLineXY(1, 0, getWidth() - 2, GraphicsChars.HATCH,
 209                 barColor);
 210         }
 211
 212     }
 213
 214     /**
 215      * Perform a small step change left.
 216      */
 217     public void decrement() {
 218         if (leftValue == rightValue) {
 219             return;
 220         }
 221         value -= smallChange;
 222         if (value < leftValue) {
 223             value = leftValue;
 224         }
 225     }
 226
 227     /**
 228      * Perform a small step change right.
 229      */
 230     public void increment() {
 231         if (leftValue == rightValue) {
 232             return;
 233         }
 234         value += smallChange;
 235         if (value > rightValue) {
 236             value = rightValue;
 237         }
 238     }
 239
 240     /**
 241      * Perform a big step change left.
 242      */
 243     public void bigDecrement() {
 244         if (leftValue == rightValue) {
 245             return;
 246         }
 247         value -= bigChange;
 248         if (value < leftValue) {
 249             value = leftValue;
 250         }
 251     }
 252
 253     /**
 254      * Perform a big step change right.
 255      */
 256     public void bigIncrement() {
 257         if (rightValue == leftValue) {
 258             return;
 259         }
 260         value += bigChange;
 261         if (value > rightValue) {
 262             value = rightValue;
 263         }
 264     }
 265
 266     /**
 267      * Go to the left edge of the scroller.
 268      */
 269     public void toLeft() {
 270         value = leftValue;
 271     }
 272
 273     /**
 274      * Go to the right edge of the scroller.
 275      */
 276     public void toRight() {
 277         value = rightValue;
 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
 288         if (inScroll) {
 289             inScroll = false;
 290             return;
 291         }
 292
 293         if (rightValue == leftValue) {
 294             return;
 295         }
 296
 297         if ((mouse.getX() == 0)
 298             && (mouse.getY() == 0)
 299         ) {
 300             // Clicked on the left arrow
 301             decrement();
 302             return;
 303         }
 304
 305         if ((mouse.getY() == 0)
 306             && (mouse.getX() == getWidth() - 1)
 307         ) {
 308             // Clicked on the right arrow
 309             increment();
 310             return;
 311         }
 312
 313         if ((mouse.getY() == 0)
 314             && (mouse.getX() > 0)
 315             && (mouse.getX() < boxPosition())
 316         ) {
 317             // Clicked between the left arrow and the box
 318             value -= bigChange;
 319             if (value < leftValue) {
 320                 value = leftValue;
 321             }
 322             return;
 323         }
 324
 325         if ((mouse.getY() == 0)
 326             && (mouse.getX() > boxPosition())
 327             && (mouse.getX() < getWidth() - 1)
 328         ) {
 329             // Clicked between the box and the right arrow
 330             value += bigChange;
 331             if (value > rightValue) {
 332                 value = rightValue;
 333             }
 334             return;
 335         }
 336     }
 337
 338     /**
 339      * Handle mouse movement events.
 340      *
 341      * @param mouse mouse motion event
 342      */
 343     @Override
 344     public void onMouseMotion(final TMouseEvent mouse) {
 345
 346         if (rightValue == leftValue) {
 347             inScroll = false;
 348             return;
 349         }
 350
 351         if ((mouse.isMouse1())
 352             && (inScroll)
 353             && (mouse.getX() > 0)
 354             && (mouse.getX() < getWidth() - 1)
 355         ) {
 356             // Recompute value based on new box position
 357             value = (rightValue - leftValue)
 358                 * (mouse.getX()) / (getWidth() - 3) + leftValue;
 359             return;
 360         }
 361         inScroll = false;
 362     }
 363
 364     /**
 365      * Handle mouse button press events.
 366      *
 367      * @param mouse mouse button press event
 368      */
 369     @Override
 370     public void onMouseDown(final TMouseEvent mouse) {
 371         if (rightValue == leftValue) {
 372             inScroll = false;
 373             return;
 374         }
 375
 376         if ((mouse.getY() == 0)
 377             && (mouse.getX() == boxPosition())
 378         ) {
 379             inScroll = true;
 380             return;
 381         }
 382
 383     }
 384
 385 }