Merge commit 'alpha/update_2_12_for_2_11_2_series_merge^2' into HEAD

[jalview.git] / src / jalview / gui / Slider.java

diff --git a/src/jalview/gui/Slider.java b/src/jalview/gui/Slider.java
new file mode 100644 (file)
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+++ b/src/jalview/gui/Slider.java
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+package jalview.gui;
+
+import javax.swing.JSlider;
+
+/**
+ * A modified {@code javax.swing.JSlider} that
+ * <ul>
+ * <li>supports float valued numbers (by scaling up integer values)</li>
+ * <li>rescales 'true' value range to avoid negative values, as these are not
+ * rendered correctly by some look and feel libraries</li>
+ * </ul>
+ * 
+ * @author gmcarstairs
+ */
+@SuppressWarnings("serial")
+public class Slider extends JSlider
+{
+  /*
+   * the number of nominal positions the slider represents
+   * (higher number = more fine-grained positioning)
+   */
+  private static final int SCALE_TICKS = 1000;
+
+  /*
+   * 'true' value corresponding to zero on the slider
+   */
+  private float trueMin;
+
+  /*
+   * 'true' value corresponding to slider maximum
+   */
+  private float trueMax;
+
+  /*
+   * scaleFactor applied to true value range to give a
+   * slider range of 0 - 100
+   */
+  private float sliderScaleFactor;
+
+  /**
+   * Constructor that rescales min - max to 0 - 100 for the slider
+   * 
+   * @param min
+   * @param max
+   * @param value
+   */
+  public Slider(float min, float max, float value)
+  {
+    super();
+    setSliderModel(min, max, value);
+  }
+
+  /**
+   * Sets the min-max range and current value of the slider, with rescaling from
+   * true values to slider range as required
+   * 
+   * @param min
+   * @param max
+   * @param value
+   */
+  public void setSliderModel(float min, float max, float value)
+  {
+    trueMin = min;
+    trueMax = max;
+    setMinimum(0);
+    sliderScaleFactor = SCALE_TICKS / (max - min);
+    int sliderMax = (int) ((max - min) * sliderScaleFactor);
+    setMaximum(sliderMax);
+    setSliderValue(value);
+  }
+
+  /**
+   * Answers the value of the slider position (descaled to 'true' value)
+   * 
+   * @return
+   */
+  public float getSliderValue()
+  {
+    /*
+     * convert slider max to 'true max' in case of rounding errors
+     */
+    int value = getValue();
+    return value == getMaximum() ? trueMax
+            : value / sliderScaleFactor + trueMin;
+  }
+
+  /**
+   * Sets the slider value (scaled from the true value to the slider range)
+   * 
+   * @param value
+   */
+  public void setSliderValue(float value)
+  {
+    setValue(Math.round((value - trueMin) * sliderScaleFactor));
+  }
+
+  /**
+   * Answers the value of the slider position as a percentage between minimum and
+   * maximum of its range
+   * 
+   * @return
+   */
+  public float getSliderPercentageValue()
+  {
+    return (getValue() - getMinimum()) * 100f
+            / (getMaximum() - getMinimum());
+  }
+
+  /**
+   * Sets the slider position for a given percentage value of its min-max range
+   * 
+   * @param pct
+   */
+  public void setSliderPercentageValue(float pct)
+  {
+    float pc = pct / 100f * getMaximum();
+    setValue((int) pc);
+  }
+}