Plumbing maxTouchPoints for Android.

ui/android/java/src/org/chromium/ui/base/TouchDevice.java

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.ui.base;
+
+import android.content.Context;
+import android.content.pm.PackageManager;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+
+/**
+ * Simple proxy to let us query the touch device from C++
+ */
+@JNINamespace("ui")
+public class TouchDevice {
+
+    /**
+     * Static methods only so make constructor private.
+     */
+    private TouchDevice() { }
+
+    /**
+     * Returns the number of supported touch points.
+     *
+     * @return Maximum supported touch points.
+     */
+    @CalledByNative
+    private static int maxTouchPoints(Context context) {
+        // Android only tells us if the device belongs to a "Touchscreen Class"
+        // which only guarantees a minimum number of touch points. Be
+        // conservative and return the minimum, checking membership from the
+        // highest class down.
+        if (context.getPackageManager().hasSystemFeature(
+                PackageManager.FEATURE_TOUCHSCREEN_MULTITOUCH_JAZZHAND)) {
+            return 5;
+        } else if (context.getPackageManager().hasSystemFeature(
+                PackageManager.FEATURE_TOUCHSCREEN_MULTITOUCH_DISTINCT)) {
+            return 2;
+        } else if (context.getPackageManager().hasSystemFeature(
+                PackageManager.FEATURE_TOUCHSCREEN_MULTITOUCH)) {
+            return 2;
+        } else if (context.getPackageManager().hasSystemFeature(
+                PackageManager.FEATURE_TOUCHSCREEN)) {
+            return 1;
+        } else {
+            return 0;
+        }
+    }
+}