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      * Set the increment for clicking on an arrow.
 120      *
 121      * @param smallChange the new increment value
 122      */
 123     public void setSmallChange(final int smallChange) {
 124         this.smallChange = smallChange;
 125     }
 126
 127     /**
 128      * The increment for clicking in the bar between the box and an arrow.
 129      */
 130     private int bigChange = 20;
 131
 132     /**
 133      * Set the increment for clicking in the bar between the box and an
 134      * arrow.
 135      *
 136      * @param bigChange the new increment value
 137      */
 138     public void setBigChange(final int bigChange) {
 139         this.bigChange = bigChange;
 140     }
 141
 142     /**
 143      * When true, the user is dragging the scroll box.
 144      */
 145     private boolean inScroll = false;
 146
 147     /**
 148      * Public constructor.
 149      *
 150      * @param parent parent widget
 151      * @param x column relative to parent
 152      * @param y row relative to parent
 153      * @param width height of scroll bar
 154      */
 155     public THScroller(final TWidget parent, final int x, final int y,
 156         final int width) {
 157
 158         // Set parent and window
 159         super(parent, x, y, width, 1);
 160     }
 161
 162     /**
 163      * Compute the position of the scroll box (a.k.a. grip, thumb).
 164      *
 165      * @return Y position of the box, between 1 and width - 2
 166      */
 167     private int boxPosition() {
 168         return (getWidth() - 3) * (value - leftValue) / (rightValue - leftValue) + 1;
 169     }
 170
 171     /**
 172      * Draw a horizontal scroll bar.
 173      */
 174     @Override
 175     public void draw() {
 176         CellAttributes arrowColor = getTheme().getColor("tscroller.arrows");
 177         CellAttributes barColor = getTheme().getColor("tscroller.bar");
 178         getScreen().putCharXY(0, 0, GraphicsChars.CP437[0x11], arrowColor);
 179         getScreen().putCharXY(getWidth() - 1, 0, GraphicsChars.CP437[0x10],
 180             arrowColor);
 181
 182         // Place the box
 183         if (rightValue > leftValue) {
 184             getScreen().hLineXY(1, 0, getWidth() - 2, GraphicsChars.CP437[0xB1],
 185                 barColor);
 186             getScreen().putCharXY(boxPosition(), 0, GraphicsChars.BOX,
 187                 arrowColor);
 188         } else {
 189             getScreen().hLineXY(1, 0, getWidth() - 2, GraphicsChars.HATCH,
 190                 barColor);
 191         }
 192
 193     }
 194
 195     /**
 196      * Perform a small step change left.
 197      */
 198     public void decrement() {
 199         if (leftValue == rightValue) {
 200             return;
 201         }
 202         value -= smallChange;
 203         if (value < leftValue) {
 204             value = leftValue;
 205         }
 206     }
 207
 208     /**
 209      * Perform a small step change right.
 210      */
 211     public void increment() {
 212         if (leftValue == rightValue) {
 213             return;
 214         }
 215         value += smallChange;
 216         if (value > rightValue) {
 217             value = rightValue;
 218         }
 219     }
 220
 221     /**
 222      * Handle mouse button releases.
 223      *
 224      * @param mouse mouse button release event
 225      */
 226     @Override
 227     public void onMouseUp(final TMouseEvent mouse) {
 228
 229         if (inScroll) {
 230             inScroll = false;
 231             return;
 232         }
 233
 234         if (rightValue == leftValue) {
 235             return;
 236         }
 237
 238         if ((mouse.getX() == 0)
 239             && (mouse.getY() == 0)
 240         ) {
 241             // Clicked on the left arrow
 242             decrement();
 243             return;
 244         }
 245
 246         if ((mouse.getY() == 0)
 247             && (mouse.getX() == getWidth() - 1)
 248         ) {
 249             // Clicked on the right arrow
 250             increment();
 251             return;
 252         }
 253
 254         if ((mouse.getY() == 0)
 255             && (mouse.getX() > 0)
 256             && (mouse.getX() < boxPosition())
 257         ) {
 258             // Clicked between the left arrow and the box
 259             value -= bigChange;
 260             if (value < leftValue) {
 261                 value = leftValue;
 262             }
 263             return;
 264         }
 265
 266         if ((mouse.getY() == 0)
 267             && (mouse.getX() > boxPosition())
 268             && (mouse.getX() < getWidth() - 1)
 269         ) {
 270             // Clicked between the box and the right arrow
 271             value += bigChange;
 272             if (value > rightValue) {
 273                 value = rightValue;
 274             }
 275             return;
 276         }
 277     }
 278
 279     /**
 280      * Handle mouse movement events.
 281      *
 282      * @param mouse mouse motion event
 283      */
 284     @Override
 285     public void onMouseMotion(final TMouseEvent mouse) {
 286
 287         if (rightValue == leftValue) {
 288             inScroll = false;
 289             return;
 290         }
 291
 292         if ((mouse.isMouse1())
 293             && (inScroll)
 294             && (mouse.getX() > 0)
 295             && (mouse.getX() < getWidth() - 1)
 296         ) {
 297             // Recompute value based on new box position
 298             value = (rightValue - leftValue)
 299                 * (mouse.getX()) / (getWidth() - 3) + leftValue;
 300             return;
 301         }
 302         inScroll = false;
 303     }
 304
 305     /**
 306      * Handle mouse button press events.
 307      *
 308      * @param mouse mouse button press event
 309      */
 310     @Override
 311     public void onMouseDown(final TMouseEvent mouse) {
 312         if (rightValue == leftValue) {
 313             inScroll = false;
 314             return;
 315         }
 316
 317         if ((mouse.getY() == 0)
 318             && (mouse.getX() == boxPosition())
 319         ) {
 320             inScroll = true;
 321             return;
 322         }
 323
 324     }
 325
 326 }