Allow setting transparency amout for transparent circle / hole (#902).

Author: PhilJay

MPChartExample/src/com/xxmassdeveloper/mpchartexample/PieChartActivity.java

@@ -67,8 +67,9 @@ protected void onCreate(Bundle savedInstanceState) {
 
         mChart.setDrawHoleEnabled(true);
         mChart.setHoleColorTransparent(true);
-        
+
         mChart.setTransparentCircleColor(Color.WHITE);
+        mChart.setTransparentCircleAlpha(110);
 
         mChart.setHoleRadius(58f);
         mChart.setTransparentCircleRadius(61f);

MPChartLib/src/com/github/mikephil/charting/charts/PieChart.java

@@ -3,6 +3,7 @@
 
 import android.content.Context;
 import android.graphics.Canvas;
+import android.graphics.Paint;
 import android.graphics.PointF;
 import android.graphics.PorterDuff;
 import android.graphics.PorterDuffXfermode;
@@ -66,7 +67,7 @@ public class PieChart extends PieRadarChartBase<PieData> {
     /**
      * the radius of the transparent circle next to the chart-hole in the center
      */
-    private float mTransparentCircleRadiusPercent = 55f;
+    protected float mTransparentCircleRadiusPercent = 55f;
 
     /** if enabled, centertext is drawn */
     private boolean mDrawCenterText = true;
@@ -455,8 +456,16 @@ public float getHoleRadius() {
         return mHoleRadiusPercent;
     }
 
+    /**
+     * Sets the color the transparent-circle should have.
+     * @param color
+     */
     public void setTransparentCircleColor(int color) {
-        ((PieChartRenderer) mRenderer).getPaintTransparentCircle().setColor(color);
+
+        Paint p = ((PieChartRenderer) mRenderer).getPaintTransparentCircle();
+        int alpha = p.getAlpha();
+        p.setColor(color);
+        p.setAlpha(alpha);
     }
 
     /**
@@ -475,6 +484,17 @@ public float getTransparentCircleRadius() {
         return mTransparentCircleRadiusPercent;
     }
 
+	/**
+	 * Sets the amount of transparency the transparent circle should have 0 = fully transparent, 255 = fully opaque.
+     * Default value is 100.
+	 * 
+	 * @param alpha
+	 *            0-255
+	 */
+	public void setTransparentCircleAlpha(int alpha) {
+		((PieChartRenderer) mRenderer).getPaintTransparentCircle().setAlpha(alpha);
+	}
+
     /**
      * set this to true to draw the x-value text into the pie slices
      * 

MPChartLib/src/com/github/mikephil/charting/renderer/PieChartRenderer.java

@@ -63,6 +63,7 @@ public PieChartRenderer(PieChart chart, ChartAnimator animator,
         mTransparentCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
         mTransparentCirclePaint.setColor(Color.WHITE);
         mTransparentCirclePaint.setStyle(Style.FILL);
+        mTransparentCirclePaint.setAlpha(100);
 
         mCenterTextPaint = new TextPaint(Paint.ANTI_ALIAS_FLAG);
         mCenterTextPaint.setColor(Color.BLACK);
@@ -260,16 +261,16 @@ protected void drawHole(Canvas c) {
             if (transparentCircleRadius > holeRadius && mAnimator.getPhaseX() >= 1f
                     && mAnimator.getPhaseY() >= 1f) {
 
-                int color = mTransparentCirclePaint.getColor();
+                //int color = mTransparentCirclePaint.getColor();
 
                 // make transparent
-                mTransparentCirclePaint.setColor(color & 0x60FFFFFF);
+                //mTransparentCirclePaint.setColor(color & 0x60FFFFFF);
 
                 // draw the transparent-circle
                 mBitmapCanvas.drawCircle(center.x, center.y,
                         radius / 100 * transparentCircleRadius, mTransparentCirclePaint);
 
-                mTransparentCirclePaint.setColor(color);
+                //mTransparentCirclePaint.setColor(color);
             }
 
             // draw the hole-circle