Added Accessibility Support for Screenreaders

MPChartLib/src/main/java/com/github/mikephil/charting/charts/BarChart.java

@@ -8,12 +8,15 @@
 import com.github.mikephil.charting.components.YAxis;
 import com.github.mikephil.charting.data.BarData;
 import com.github.mikephil.charting.data.BarEntry;
+import com.github.mikephil.charting.formatter.ValueFormatter;
 import com.github.mikephil.charting.highlight.BarHighlighter;
 import com.github.mikephil.charting.highlight.Highlight;
 import com.github.mikephil.charting.interfaces.dataprovider.BarDataProvider;
 import com.github.mikephil.charting.interfaces.datasets.IBarDataSet;
 import com.github.mikephil.charting.renderer.BarChartRenderer;
 
+import java.util.Locale;
+
 /**
  * Chart that draws bars.
  *
@@ -255,4 +258,33 @@ public void groupBars(float fromX, float groupSpace, float barSpace) {
             notifyDataSetChanged();
         }
     }
+
+    @Override
+    public String getAccessibilityDescription() {
+
+        BarData barData = getBarData();
+
+        int entryCount = barData.getEntryCount();
+
+        // Find the min and max index
+        ValueFormatter yAxisValueFormmater = getAxisLeft().getValueFormatter();
+        String minVal = yAxisValueFormmater.getFormattedValue(barData.getYMin());
+        String maxVal = yAxisValueFormmater.getFormattedValue(barData.getYMax());
+
+        // Data range...
+        ValueFormatter xAxisValueFormatter = getXAxis().getValueFormatter();
+        String minRange = xAxisValueFormatter.getFormattedValue(barData.getXMin());
+        String maxRange = xAxisValueFormatter.getFormattedValue(barData.getXMax());
+
+        String entries = entryCount == 1 ? "entry" : "entries";
+
+        // Format the values of min and max; to recite them back
+
+        String description = String.format(Locale.getDefault(), "The bar chart has %d %s. " +
+                        "The minimum value is %s and maximum value is %s." +
+                        "Data ranges from %s to %s.",
+                entryCount, entries, minVal, maxVal, minRange, maxRange);
+
+        return description;
+    }
 }

MPChartLib/src/main/java/com/github/mikephil/charting/charts/BubbleChart.java

@@ -40,4 +40,9 @@ protected void init() {
     public BubbleData getBubbleData() {
         return mData;
     }
+
+    @Override
+    public String getAccessibilityDescription() {
+        return "This is bubble chart";
+    }
 }

MPChartLib/src/main/java/com/github/mikephil/charting/charts/CandleStickChart.java

@@ -41,4 +41,9 @@ protected void init() {
     public CandleData getCandleData() {
         return mData;
     }
+
+    @Override
+    public String getAccessibilityDescription() {
+        return "This is a candlestick";
+    }
 }

MPChartLib/src/main/java/com/github/mikephil/charting/charts/Chart.java

@@ -23,6 +23,7 @@
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.ViewParent;
+import android.view.accessibility.AccessibilityEvent;
 
 import com.github.mikephil.charting.animation.ChartAnimator;
 import com.github.mikephil.charting.animation.Easing;
@@ -176,6 +177,16 @@ public abstract class Chart<T extends ChartData<? extends IDataSet<? extends Ent
             mExtraBottomOffset = 0.f,
             mExtraLeftOffset = 0.f;
 
+    /**
+     * Tag for logging accessibility related content
+     */
+    private String TAG = "abilityTag";
+
+    /**
+     * Additional data on top of dynamically generated description. This can be set by the user.
+     */
+    private String accessibilitySummaryDescription = "";
+
     /**
      * default constructor for initialization in code
      */
@@ -237,6 +248,9 @@ public void onAnimationUpdate(ValueAnimator animation) {
 
         if (mLogEnabled)
             Log.i("", "Chart.init()");
+
+        // enable being detected by ScreenReader
+        setFocusable(true);
     }
 
     // public void initWithDummyData() {
@@ -1818,4 +1832,38 @@ private void unbindDrawables(View view) {
     public void setUnbindEnabled(boolean enabled) {
         this.mUnbind = enabled;
     }
+
+    // region accessibility
+
+    /**
+     *
+     * @return accessibility description must be created for each chart
+     */
+    public abstract String getAccessibilityDescription();
+
+    public String getAccessibilitySummaryDescription() {
+        return accessibilitySummaryDescription;
+    }
+
+    public void setAccessibilitySummaryDescription(String accessibilitySummaryDescription) {
+        this.accessibilitySummaryDescription = accessibilitySummaryDescription;
+    }
+
+    @Override
+    public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
+
+        boolean completed = super.dispatchPopulateAccessibilityEvent(event);
+        Log.d(TAG, "Dispatch called for Chart <View> and completed as " + completed);
+
+        event.getText().add(getAccessibilityDescription());
+
+        // Add the user generated summary after the dynamic summary is complete.
+        if (!TextUtils.isEmpty(this.getAccessibilitySummaryDescription())) {
+            event.getText().add(this.getAccessibilitySummaryDescription());
+        }
+
+        return true;
+    }
+
+    // endregion
 }

MPChartLib/src/main/java/com/github/mikephil/charting/charts/CombinedChart.java

@@ -269,4 +269,8 @@ protected void drawMarkers(Canvas canvas) {
         }
     }
 
+    @Override
+    public String getAccessibilityDescription() {
+        return "This is a combined chart";
+    }
 }

MPChartLib/src/main/java/com/github/mikephil/charting/charts/LineChart.java

@@ -5,9 +5,12 @@
 import android.util.AttributeSet;
 
 import com.github.mikephil.charting.data.LineData;
+import com.github.mikephil.charting.formatter.ValueFormatter;
 import com.github.mikephil.charting.interfaces.dataprovider.LineDataProvider;
 import com.github.mikephil.charting.renderer.LineChartRenderer;
 
+import java.util.Locale;
+
 /**
  * Chart that draws lines, surfaces, circles, ...
  *
@@ -47,4 +50,32 @@ protected void onDetachedFromWindow() {
         }
         super.onDetachedFromWindow();
     }
+
+    @Override
+    public String getAccessibilityDescription() {
+
+        LineData lineData = getLineData();
+
+        int numberOfPoints = lineData.getEntryCount();
+
+        // Min and max values...
+        ValueFormatter yAxisValueFormmater = getAxisLeft().getValueFormatter();
+        String minVal = yAxisValueFormmater.getFormattedValue(lineData.getYMin());
+        String maxVal = yAxisValueFormmater.getFormattedValue(lineData.getYMax());
+
+        // Data range...
+        ValueFormatter xAxisValueFormatter = getXAxis().getValueFormatter();
+        String minRange = xAxisValueFormatter.getFormattedValue(lineData.getXMin());
+        String maxRange = xAxisValueFormatter.getFormattedValue(lineData.getXMax());
+
+        String entries = numberOfPoints == 1 ? "entry" : "entries";
+
+        String description = String.format(Locale.getDefault(), "The line chart has %d %s. " +
+                        "The minimum value is %s and maximum value is %s." +
+                        "Data ranges from %s to %s.",
+                numberOfPoints, entries, minVal, maxVal, minRange, maxRange);
+
+
+        return description;
+    }
 }

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

@@ -6,18 +6,23 @@
 import android.graphics.Paint;
 import android.graphics.RectF;
 import android.graphics.Typeface;
+import android.text.TextUtils;
 import android.util.AttributeSet;
 
 import com.github.mikephil.charting.components.XAxis;
 import com.github.mikephil.charting.data.PieData;
+import com.github.mikephil.charting.data.PieEntry;
+import com.github.mikephil.charting.formatter.ValueFormatter;
 import com.github.mikephil.charting.highlight.Highlight;
 import com.github.mikephil.charting.highlight.PieHighlighter;
 import com.github.mikephil.charting.interfaces.datasets.IPieDataSet;
 import com.github.mikephil.charting.renderer.PieChartRenderer;
 import com.github.mikephil.charting.utils.MPPointF;
 import com.github.mikephil.charting.utils.Utils;
 
+import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 /**
  * View that represents a pie chart. Draws cake like slices.
@@ -801,4 +806,27 @@ protected void onDetachedFromWindow() {
         }
         super.onDetachedFromWindow();
     }
+
+    @Override
+    public String getAccessibilityDescription() {
+
+        PieData pieData = getData();
+
+        int entryCount = pieData.getEntryCount();
+
+        StringBuilder builder = new StringBuilder();
+
+        builder.append(String.format(Locale.getDefault(), "The pie chart has %d entries.",
+                entryCount));
+
+        for (int i = 0; i < entryCount; i++) {
+            PieEntry entry = pieData.getDataSet().getEntryForIndex(i);
+            float percentage = (entry.getValue() / pieData.getYValueSum()) * 100;
+            builder.append(String.format(Locale.getDefault(), "%s has %.2f percent pie taken",
+                    (TextUtils.isEmpty(entry.getLabel()) ? "No Label" : entry.getLabel()),
+                    percentage));
+        }
+
+        return builder.toString();
+    }
 }

MPChartLib/src/main/java/com/github/mikephil/charting/charts/RadarChart.java

@@ -359,4 +359,9 @@ public float getYChartMin() {
     public float getYRange() {
         return mYAxis.mAxisRange;
     }
+
+    @Override
+    public String getAccessibilityDescription() {
+        return "This is a Radar chart";
+    }
 }

MPChartLib/src/main/java/com/github/mikephil/charting/charts/ScatterChart.java

@@ -74,4 +74,9 @@ public static ScatterShape[] getAllDefaultShapes() {
             return new ScatterShape[]{SQUARE, CIRCLE, TRIANGLE, CROSS, X, CHEVRON_UP, CHEVRON_DOWN};
         }
     }
+
+    @Override
+    public String getAccessibilityDescription() {
+        return "This is scatter chart";
+    }
 }