ttools: add transparency config item for histogram layer

Starlink · Nov 27, 2014 · 98cb02e · 98cb02e
1 parent ff84150
commit 98cb02e
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Showing 2 changed files with 12 additions and 1 deletion.
diff --git a/ttools/src/main/uk/ac/starlink/ttools/plot2/config/StyleKeys.java b/ttools/src/main/uk/ac/starlink/ttools/plot2/config/StyleKeys.java
@@ -90,6 +90,12 @@ public Specifier<Integer> createSpecifier() {
        .createSliderKey( new ConfigMeta( "translevel", "Transparency Level" ),
                          0.1, 0.001, 2, true );
 
+    /** Config key for "normal" transparency - it's just 1-alpha. */
+    public static final ConfigKey<Double> TRANSPARENCY =
+        DoubleConfigKey.createSliderKey( new ConfigMeta( "transparency",
+                                                         "Transparency" ),
+                                         0, 0, 1, false );
+
     /** Config key for line thickness. */
     private static final ConfigKey<Integer> THICKNESS = createThicknessKey( 1 );
 

diff --git a/ttools/src/main/uk/ac/starlink/ttools/plot2/layer/HistogramPlotter.java b/ttools/src/main/uk/ac/starlink/ttools/plot2/layer/HistogramPlotter.java
@@ -117,6 +117,7 @@ public CoordGroup getCoordGroup() {
     public ConfigKey[] getStyleKeys() {
         return new ConfigKey[] {
             StyleKeys.COLOR,
+            StyleKeys.TRANSPARENCY,
             BinSizer.BINSIZER_KEY,
             CUMULATIVE_KEY,
             NORM_KEY,
@@ -128,7 +129,11 @@ public ConfigKey[] getStyleKeys() {
     }
 
     public HistoStyle createStyle( ConfigMap config ) {
-        Color color = config.get( StyleKeys.COLOR );
+        Color baseColor = config.get( StyleKeys.COLOR );
+        double alpha = 1 - config.get( StyleKeys.TRANSPARENCY );
+        float[] rgba = baseColor.getRGBComponents( new float[ 4 ] );
+        rgba[ 3 ] *= alpha;
+        Color color = new Color( rgba[ 0 ], rgba[ 1 ], rgba[ 2 ], rgba[ 3 ] );
         BarStyle.Form barForm = config.get( StyleKeys.BAR_FORM );
         BarStyle.Placement placement = BarStyle.PLACE_OVER;
         boolean cumulative = config.get( CUMULATIVE_KEY );