JAL-2438 FeatureColourFinder refactored from FeatureRenderer, fr not

[jalview.git] / src / jalview / renderer / seqfeatures / FeatureColourFinder.java

diff --git a/src/jalview/renderer/seqfeatures/FeatureColourFinder.java b/src/jalview/renderer/seqfeatures/FeatureColourFinder.java
new file mode 100644 (file)
index 0000000..5055ed5
--- /dev/null
+++ b/src/jalview/renderer/seqfeatures/FeatureColourFinder.java
@@ -0,0 +1,79 @@
+package jalview.renderer.seqfeatures;
+
+import jalview.api.FeaturesDisplayedI;
+import jalview.datamodel.SequenceI;
+import jalview.viewmodel.seqfeatures.FeatureRendererModel;
+
+import java.awt.Color;
+import java.awt.Graphics;
+import java.awt.image.BufferedImage;
+
+/**
+ * A helper class to find feature colour using an associated FeatureRenderer
+ * 
+ * @author gmcarstairs
+ *
+ */
+public class FeatureColourFinder
+{
+  /*
+   * the class we delegate feature finding to
+   */
+  private jalview.api.FeatureRenderer featureRenderer;
+
+  /*
+   * a 1-pixel image on which features can be drawn, for the case where
+   * transparency allows 'see-through' of multiple feature colours
+   */
+  private BufferedImage offscreenImage;
+
+  /**
+   * Constructor
+   * 
+   * @param fr
+   */
+  public FeatureColourFinder(jalview.api.FeatureRenderer fr)
+  {
+    featureRenderer = fr;
+    offscreenImage = new BufferedImage(1, 1, BufferedImage.TYPE_INT_ARGB);
+  }
+
+  /**
+   * Answers the feature colour to show for the given sequence and column
+   * position. This delegates to the FeatureRenderer to find the colour, which
+   * will depend on feature location, visibility, ordering, and whether or not
+   * transparency is applied. For feature rendering with transparency, this
+   * class provides a dummy 'offscreen' graphics context where multiple feature
+   * colours can be overlaid and the combined colour read back.
+   * 
+   * @param defaultColour
+   * @param seq
+   * @param column
+   * @return
+   */
+  public Color findFeatureColour(Color defaultColour, SequenceI seq,
+          int column)
+  {
+    if (!((FeatureRendererModel) featureRenderer).hasRenderOrder())
+    {
+      return defaultColour;
+    }
+
+    FeaturesDisplayedI displayed = featureRenderer.getFeaturesDisplayed();
+    if (displayed == null || displayed.getVisibleFeatureCount() == 0)
+    {
+      return defaultColour; // nothing to see here folks
+    }
+
+    Graphics g = featureRenderer.getTransparency() == 1f ? null
+            : offscreenImage.getGraphics();
+
+    Color c = featureRenderer.findFeatureColour(defaultColour, seq, column,
+            g);
+    if (c != null && g != null)
+    {
+      c = new Color(offscreenImage.getRGB(0, 0));
+    }
+    return c == null ? defaultColour : c;
+  }
+}