samples/Support4Demos/src/com/example/android/supportv4/widget/ExploreByTouchHelperActivity.java - platform/development - Git at Google

 /*
  * Copyright (C) 2013 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.example.android.supportv4.widget;

 import android.annotation.TargetApi;
 import android.app.Activity;
 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
 import android.graphics.Paint.Align;
 import android.graphics.Paint.Style;
 import android.graphics.Rect;
 import android.graphics.RectF;
 import android.os.Build;
 import android.os.Bundle;
 import android.support.v4.view.ViewCompat;
 import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat;
 import android.support.v4.view.accessibility.AccessibilityNodeProviderCompat;
 import android.support.v4.widget.ExploreByTouchHelper;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.accessibility.AccessibilityEvent;
 import com.example.android.supportv4.R;

 import java.util.ArrayList;
 import java.util.List;

 /**
  * This example shows how to use the {@link ExploreByTouchHelper} class in the
  * Android support library to add accessibility support to a custom view that
  * represents multiple logical items.
  * <p>
  * The {@link ExploreByTouchHelper} class wraps
  * {@link AccessibilityNodeProviderCompat} and simplifies exposing information
  * about a custom view's logical structure to accessibility services.
  * <p>
  * The custom view in this example is responsible for:
  * <ul>
  * <li>Creating a helper class that extends {@link ExploreByTouchHelper}
  * <li>Setting the helper as the accessibility delegate using
  * {@link ViewCompat#setAccessibilityDelegate}
  * <li>Dispatching hover events to the helper in {@link View#dispatchHoverEvent}
  * </ul>
  * <p>
  * The helper class implementation in this example is responsible for:
  * <ul>
  * <li>Mapping hover event coordinates to logical items
  * <li>Exposing information about logical items to accessibility services
  * <li>Handling accessibility actions
  * <ul>
  */
 public class ExploreByTouchHelperActivity extends Activity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

         setContentView(R.layout.explore_by_touch_helper);

         final CustomView customView = (CustomView) findViewById(R.id.custom_view);

         // Adds an item at the top-left quarter of the custom view.
         customView.addItem(getString(R.string.sample_item_a), 0, 0, 0.5f, 0.5f);

         // Adds an item at the bottom-right quarter of the custom view.
         customView.addItem(getString(R.string.sample_item_b), 0.5f, 0.5f, 1, 1);
     }

     /**
      * Simple custom view that draws rectangular items to the screen. Each item
      * has a checked state that may be toggled by tapping on the item.
      */
     public static class CustomView extends View {
         private static final int NO_ITEM = -1;

         private final Paint mPaint = new Paint();
         private final Rect mTempBounds = new Rect();
         private final List<CustomItem> mItems = new ArrayList<CustomItem>();
         private CustomViewTouchHelper mTouchHelper;

         public CustomView(Context context, AttributeSet attrs) {
             super(context, attrs);

             // Set up accessibility helper class.
             mTouchHelper = new CustomViewTouchHelper(this);
             ViewCompat.setAccessibilityDelegate(this, mTouchHelper);
         }

         @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
         @Override
         public boolean dispatchHoverEvent(MotionEvent event) {
             // Always attempt to dispatch hover events to accessibility first.
             if (mTouchHelper.dispatchHoverEvent(event)) {
                 return true;
             }

             return super.dispatchHoverEvent(event);
         }

         @Override
         public boolean onTouchEvent(MotionEvent event) {
             switch (event.getAction()) {
                 case MotionEvent.ACTION_DOWN:
                     return true;
                 case MotionEvent.ACTION_UP:
                     final int itemIndex = getItemIndexUnder(event.getX(), event.getY());
                     if (itemIndex >= 0) {
                         onItemClicked(itemIndex);
                     }
                     return true;
             }

             return super.onTouchEvent(event);
         }

         /**
          * Adds an item to the custom view. The item is positioned relative to
          * the custom view bounds and its descriptions is drawn at its center.
          *
          * @param description The item's description.
          * @param top Top coordinate as a fraction of the parent height, range
          *            is [0,1].
          * @param left Left coordinate as a fraction of the parent width, range
          *            is [0,1].
          * @param bottom Bottom coordinate as a fraction of the parent height,
          *            range is [0,1].
          * @param right Right coordinate as a fraction of the parent width,
          *            range is [0,1].
          */
         public void addItem(String description, float top, float left, float bottom, float right) {
             final CustomItem item = new CustomItem();
             item.bounds = new RectF(top, left, bottom, right);
             item.description = description;
             item.checked = false;
             mItems.add(item);
         }

         @Override
         protected void onDraw(Canvas canvas) {
             super.onDraw(canvas);

             final Paint paint = mPaint;
             final Rect bounds = mTempBounds;
             final int height = getHeight();
             final int width = getWidth();

             for (CustomItem item : mItems) {
                 paint.setColor(item.checked ? Color.RED : Color.BLUE);
                 paint.setStyle(Style.FILL);
                 scaleRectF(item.bounds, bounds, width, height);
                 canvas.drawRect(bounds, paint);
                 paint.setColor(Color.WHITE);
                 paint.setTextAlign(Align.CENTER);
                 canvas.drawText(item.description, bounds.centerX(), bounds.centerY(), paint);
             }
         }

         protected boolean onItemClicked(int index) {
             final CustomItem item = getItem(index);
             if (item == null) {
                 return false;
             }

             item.checked = !item.checked;
             invalidate();

             // Since the item's checked state is exposed to accessibility
             // services through its AccessibilityNodeInfo, we need to invalidate
             // the item's virtual view. At some point in the future, the
             // framework will obtain an updated version of the virtual view.
             mTouchHelper.invalidateVirtualView(index);

             // We also need to let the framework know what type of event
             // happened. Accessibility services may use this event to provide
             // appropriate feedback to the user.
             mTouchHelper.sendEventForVirtualView(index, AccessibilityEvent.TYPE_VIEW_CLICKED);

             return true;
         }

         protected int getItemIndexUnder(float x, float y) {
             final float scaledX = (x / getWidth());
             final float scaledY = (y / getHeight());
             final int n = mItems.size();

             for (int i = 0; i < n; i++) {
                 final CustomItem item = mItems.get(i);
                 if (item.bounds.contains(scaledX, scaledY)) {
                     return i;
                 }
             }

             return NO_ITEM;
         }

         protected CustomItem getItem(int index) {
             if ((index < 0) || (index >= mItems.size())) {
                 return null;
             }

             return mItems.get(index);
         }

         protected static void scaleRectF(RectF in, Rect out, int width, int height) {
             out.top = (int) (in.top * height);
             out.bottom = (int) (in.bottom * height);
             out.left = (int) (in.left * width);
             out.right = (int) (in.right * width);
         }

         private class CustomViewTouchHelper extends ExploreByTouchHelper {
             private final Rect mTempRect = new Rect();

             public CustomViewTouchHelper(View forView) {
                 super(forView);
             }

             @Override
             protected int getVirtualViewAt(float x, float y) {
                 // We also perform hit detection in onTouchEvent(), and we can
                 // reuse that logic here. This will ensure consistency whether
                 // accessibility is on or off.
                 final int index = getItemIndexUnder(x, y);
                 if (index == NO_ITEM) {
                     return ExploreByTouchHelper.INVALID_ID;
                 }

                 return index;
             }

             @Override
             protected void getVisibleVirtualViews(List<Integer> virtualViewIds) {
                 // Since every item should be visible, and since we're mapping
                 // directly from item index to virtual view id, we can just add
                 // every available index in the item list.
                 final int n = mItems.size();
                 for (int i = 0; i < n; i++) {
                     virtualViewIds.add(i);
                 }
             }

             @Override
             protected void onPopulateEventForVirtualView(
                     int virtualViewId, AccessibilityEvent event) {
                 final CustomItem item = getItem(virtualViewId);
                 if (item == null) {
                     throw new IllegalArgumentException("Invalid virtual view id");
                 }

                 // The event must be populated with text, either using
                 // getText().add() or setContentDescription(). Since the item's
                 // description is displayed visually, we'll add it to the event
                 // text. If it was only used for accessibility, we would use
                 // setContentDescription().
                 event.getText().add(item.description);
             }

             @Override
             protected void onPopulateNodeForVirtualView(
                     int virtualViewId, AccessibilityNodeInfoCompat node) {
                 final CustomItem item = getItem(virtualViewId);
                 if (item == null) {
                     throw new IllegalArgumentException("Invalid virtual view id");
                 }

                 // Node and event text and content descriptions are usually
                 // identical, so we'll use the exact same string as before.
                 node.setText(item.description);

                 // Reported bounds should be consistent with those used to draw
                 // the item in onDraw(). They should also be consistent with the
                 // hit detection performed in getVirtualViewAt() and
                 // onTouchEvent().
                 final Rect bounds = mTempRect;
                 final int height = getHeight();
                 final int width = getWidth();
                 scaleRectF(item.bounds, bounds, width, height);
                 node.setBoundsInParent(bounds);

                 // Since the user can tap an item, add the CLICK action. We'll
                 // need to handle this later in onPerformActionForVirtualView.
                 node.addAction(AccessibilityNodeInfoCompat.ACTION_CLICK);

                 // This item has a checked state.
                 node.setCheckable(true);
                 node.setChecked(item.checked);
             }

             @Override
             protected boolean onPerformActionForVirtualView(
                     int virtualViewId, int action, Bundle arguments) {
                 switch (action) {
                     case AccessibilityNodeInfoCompat.ACTION_CLICK:
                         // Click handling should be consistent with
                         // onTouchEvent(). This ensures that the view works the
                         // same whether accessibility is turned on or off.
                         return onItemClicked(virtualViewId);
                 }

                 return false;
             }

         }

         public static class CustomItem {
             private String description;
             private RectF bounds;
             private boolean checked;
         }
     }
 }
	/*
	* Copyright (C) 2013 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.example.android.supportv4.widget;

	import android.annotation.TargetApi;
	import android.app.Activity;
	import android.content.Context;
	import android.graphics.Canvas;
	import android.graphics.Color;
	import android.graphics.Paint;
	import android.graphics.Paint.Align;
	import android.graphics.Paint.Style;
	import android.graphics.Rect;
	import android.graphics.RectF;
	import android.os.Build;
	import android.os.Bundle;
	import android.support.v4.view.ViewCompat;
	import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat;
	import android.support.v4.view.accessibility.AccessibilityNodeProviderCompat;
	import android.support.v4.widget.ExploreByTouchHelper;
	import android.util.AttributeSet;
	import android.view.MotionEvent;
	import android.view.View;
	import android.view.accessibility.AccessibilityEvent;
	import com.example.android.supportv4.R;

	import java.util.ArrayList;
	import java.util.List;

	/**
	* This example shows how to use the {@link ExploreByTouchHelper} class in the
	* Android support library to add accessibility support to a custom view that
	* represents multiple logical items.
	* <p>
	* The {@link ExploreByTouchHelper} class wraps
	* {@link AccessibilityNodeProviderCompat} and simplifies exposing information
	* about a custom view's logical structure to accessibility services.
	* <p>
	* The custom view in this example is responsible for:
	* <ul>
	* <li>Creating a helper class that extends {@link ExploreByTouchHelper}
	* <li>Setting the helper as the accessibility delegate using
	* {@link ViewCompat#setAccessibilityDelegate}
	* <li>Dispatching hover events to the helper in {@link View#dispatchHoverEvent}
	* </ul>
	* <p>
	* The helper class implementation in this example is responsible for:
	* <ul>
	* <li>Mapping hover event coordinates to logical items
	* <li>Exposing information about logical items to accessibility services
	* <li>Handling accessibility actions
	* <ul>
	*/
	public class ExploreByTouchHelperActivity extends Activity {
	@Override
	protected void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);

	setContentView(R.layout.explore_by_touch_helper);

	final CustomView customView = (CustomView) findViewById(R.id.custom_view);

	// Adds an item at the top-left quarter of the custom view.
	customView.addItem(getString(R.string.sample_item_a), 0, 0, 0.5f, 0.5f);

	// Adds an item at the bottom-right quarter of the custom view.
	customView.addItem(getString(R.string.sample_item_b), 0.5f, 0.5f, 1, 1);
	}

	/**
	* Simple custom view that draws rectangular items to the screen. Each item
	* has a checked state that may be toggled by tapping on the item.
	*/
	public static class CustomView extends View {
	private static final int NO_ITEM = -1;

	private final Paint mPaint = new Paint();
	private final Rect mTempBounds = new Rect();
	private final List<CustomItem> mItems = new ArrayList<CustomItem>();
	private CustomViewTouchHelper mTouchHelper;

	public CustomView(Context context, AttributeSet attrs) {
	super(context, attrs);

	// Set up accessibility helper class.
	mTouchHelper = new CustomViewTouchHelper(this);
	ViewCompat.setAccessibilityDelegate(this, mTouchHelper);
	}

	@TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH)
	@Override
	public boolean dispatchHoverEvent(MotionEvent event) {
	// Always attempt to dispatch hover events to accessibility first.
	if (mTouchHelper.dispatchHoverEvent(event)) {
	return true;
	}

	return super.dispatchHoverEvent(event);
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
	switch (event.getAction()) {
	case MotionEvent.ACTION_DOWN:
	return true;
	case MotionEvent.ACTION_UP:
	final int itemIndex = getItemIndexUnder(event.getX(), event.getY());
	if (itemIndex >= 0) {
	onItemClicked(itemIndex);
	}
	return true;
	}

	return super.onTouchEvent(event);
	}

	/**
	* Adds an item to the custom view. The item is positioned relative to
	* the custom view bounds and its descriptions is drawn at its center.
	*
	* @param description The item's description.
	* @param top Top coordinate as a fraction of the parent height, range
	* is [0,1].
	* @param left Left coordinate as a fraction of the parent width, range
	* is [0,1].
	* @param bottom Bottom coordinate as a fraction of the parent height,
	* range is [0,1].
	* @param right Right coordinate as a fraction of the parent width,
	* range is [0,1].
	*/
	public void addItem(String description, float top, float left, float bottom, float right) {
	final CustomItem item = new CustomItem();
	item.bounds = new RectF(top, left, bottom, right);
	item.description = description;
	item.checked = false;
	mItems.add(item);
	}

	@Override
	protected void onDraw(Canvas canvas) {
	super.onDraw(canvas);

	final Paint paint = mPaint;
	final Rect bounds = mTempBounds;
	final int height = getHeight();
	final int width = getWidth();

	for (CustomItem item : mItems) {
	paint.setColor(item.checked ? Color.RED : Color.BLUE);
	paint.setStyle(Style.FILL);
	scaleRectF(item.bounds, bounds, width, height);
	canvas.drawRect(bounds, paint);
	paint.setColor(Color.WHITE);
	paint.setTextAlign(Align.CENTER);
	canvas.drawText(item.description, bounds.centerX(), bounds.centerY(), paint);
	}
	}

	protected boolean onItemClicked(int index) {
	final CustomItem item = getItem(index);
	if (item == null) {
	return false;
	}

	item.checked = !item.checked;
	invalidate();

	// Since the item's checked state is exposed to accessibility
	// services through its AccessibilityNodeInfo, we need to invalidate
	// the item's virtual view. At some point in the future, the
	// framework will obtain an updated version of the virtual view.
	mTouchHelper.invalidateVirtualView(index);

	// We also need to let the framework know what type of event
	// happened. Accessibility services may use this event to provide
	// appropriate feedback to the user.
	mTouchHelper.sendEventForVirtualView(index, AccessibilityEvent.TYPE_VIEW_CLICKED);

	return true;
	}

	protected int getItemIndexUnder(float x, float y) {
	final float scaledX = (x / getWidth());
	final float scaledY = (y / getHeight());
	final int n = mItems.size();

	for (int i = 0; i < n; i++) {
	final CustomItem item = mItems.get(i);
	if (item.bounds.contains(scaledX, scaledY)) {
	return i;
	}
	}

	return NO_ITEM;
	}

	protected CustomItem getItem(int index) {
	if ((index < 0) \|\| (index >= mItems.size())) {
	return null;
	}

	return mItems.get(index);
	}

	protected static void scaleRectF(RectF in, Rect out, int width, int height) {
	out.top = (int) (in.top * height);
	out.bottom = (int) (in.bottom * height);
	out.left = (int) (in.left * width);
	out.right = (int) (in.right * width);
	}

	private class CustomViewTouchHelper extends ExploreByTouchHelper {
	private final Rect mTempRect = new Rect();

	public CustomViewTouchHelper(View forView) {
	super(forView);
	}

	@Override
	protected int getVirtualViewAt(float x, float y) {
	// We also perform hit detection in onTouchEvent(), and we can
	// reuse that logic here. This will ensure consistency whether
	// accessibility is on or off.
	final int index = getItemIndexUnder(x, y);
	if (index == NO_ITEM) {
	return ExploreByTouchHelper.INVALID_ID;
	}

	return index;
	}

	@Override
	protected void getVisibleVirtualViews(List<Integer> virtualViewIds) {
	// Since every item should be visible, and since we're mapping
	// directly from item index to virtual view id, we can just add
	// every available index in the item list.
	final int n = mItems.size();
	for (int i = 0; i < n; i++) {
	virtualViewIds.add(i);
	}
	}

	@Override
	protected void onPopulateEventForVirtualView(
	int virtualViewId, AccessibilityEvent event) {
	final CustomItem item = getItem(virtualViewId);
	if (item == null) {
	throw new IllegalArgumentException("Invalid virtual view id");
	}

	// The event must be populated with text, either using
	// getText().add() or setContentDescription(). Since the item's
	// description is displayed visually, we'll add it to the event
	// text. If it was only used for accessibility, we would use
	// setContentDescription().
	event.getText().add(item.description);
	}

	@Override
	protected void onPopulateNodeForVirtualView(
	int virtualViewId, AccessibilityNodeInfoCompat node) {
	final CustomItem item = getItem(virtualViewId);
	if (item == null) {
	throw new IllegalArgumentException("Invalid virtual view id");
	}

	// Node and event text and content descriptions are usually
	// identical, so we'll use the exact same string as before.
	node.setText(item.description);

	// Reported bounds should be consistent with those used to draw
	// the item in onDraw(). They should also be consistent with the
	// hit detection performed in getVirtualViewAt() and
	// onTouchEvent().
	final Rect bounds = mTempRect;
	final int height = getHeight();
	final int width = getWidth();
	scaleRectF(item.bounds, bounds, width, height);
	node.setBoundsInParent(bounds);

	// Since the user can tap an item, add the CLICK action. We'll
	// need to handle this later in onPerformActionForVirtualView.
	node.addAction(AccessibilityNodeInfoCompat.ACTION_CLICK);

	// This item has a checked state.
	node.setCheckable(true);
	node.setChecked(item.checked);
	}

	@Override
	protected boolean onPerformActionForVirtualView(
	int virtualViewId, int action, Bundle arguments) {
	switch (action) {
	case AccessibilityNodeInfoCompat.ACTION_CLICK:
	// Click handling should be consistent with
	// onTouchEvent(). This ensures that the view works the
	// same whether accessibility is turned on or off.
	return onItemClicked(virtualViewId);
	}

	return false;
	}

	}

	public static class CustomItem {
	private String description;
	private RectF bounds;
	private boolean checked;
	}
	}
	}