content/public/android/java/src/org/chromium/content/browser/TouchEventSynthesizer.java

// Copyright 2013 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.content.browser;

import android.view.MotionEvent;
import android.view.MotionEvent.PointerCoords;
import android.view.MotionEvent.PointerProperties;

import org.chromium.base.CalledByNative;
import org.chromium.base.JNINamespace;

/**
 * Provides a Java-side implementation for injecting synthetic touch events.
 */
@JNINamespace("content")
public class TouchEventSynthesizer {
    private static final int MAX_NUM_POINTERS = 16;

    private static final int ACTION_START = 0;
    private static final int ACTION_MOVE = 1;
    private static final int ACTION_CANCEL = 2;
    private static final int ACTION_END = 3;

    private final ContentViewCore mContentViewCore;
    private final PointerProperties[] mPointerProperties;
    private final PointerCoords[] mPointerCoords;
    private long mDownTimeInMs;

    TouchEventSynthesizer(ContentViewCore contentViewCore) {
        mContentViewCore = contentViewCore;
        mPointerProperties = new PointerProperties[MAX_NUM_POINTERS];
        mPointerCoords = new PointerCoords[MAX_NUM_POINTERS];
    }

    @CalledByNative
    void setPointer(int index, int x, int y, int id) {
        assert (0 <= index && index < MAX_NUM_POINTERS);

        // Convert coordinates from density independent pixels to density dependent pixels.
        float scaleFactor = mContentViewCore.getRenderCoordinates().getDeviceScaleFactor();

        PointerCoords coords = new PointerCoords();
        coords.x = scaleFactor * x;
        coords.y = scaleFactor * y;
        coords.pressure = 1.0f;
        mPointerCoords[index] = coords;

        PointerProperties properties = new PointerProperties();
        properties.id = id;
        mPointerProperties[index] = properties;
    }

    @CalledByNative
    void inject(int action, int pointerCount, long timeInMs) {
        switch (action) {
            case ACTION_START: {
                mDownTimeInMs = timeInMs;
                MotionEvent event = MotionEvent.obtain(
                        mDownTimeInMs, timeInMs, MotionEvent.ACTION_DOWN, 1,
                        mPointerProperties, mPointerCoords,
                        0, 0, 1, 1, 0, 0, 0, 0);
                mContentViewCore.onTouchEvent(event);
                event.recycle();

                if (pointerCount > 1) {
                    event = MotionEvent.obtain(
                            mDownTimeInMs, timeInMs,
                            MotionEvent.ACTION_POINTER_DOWN, pointerCount,
                            mPointerProperties, mPointerCoords,
                            0, 0, 1, 1, 0, 0, 0, 0);
                    mContentViewCore.onTouchEvent(event);
                    event.recycle();
                }
                break;
            }
            case ACTION_MOVE: {
                MotionEvent event = MotionEvent.obtain(mDownTimeInMs, timeInMs,
                        MotionEvent.ACTION_MOVE,
                        pointerCount, mPointerProperties, mPointerCoords,
                        0, 0, 1, 1, 0, 0, 0, 0);
                mContentViewCore.onTouchEvent(event);
                event.recycle();
                break;
            }
            case ACTION_CANCEL: {
                MotionEvent event = MotionEvent.obtain(
                        mDownTimeInMs, timeInMs, MotionEvent.ACTION_CANCEL, 1,
                        mPointerProperties, mPointerCoords,
                        0, 0, 1, 1, 0, 0, 0, 0);
                mContentViewCore.onTouchEvent(event);
                event.recycle();
                break;
            }
            case ACTION_END: {
                if (pointerCount > 1) {
                    MotionEvent event = MotionEvent.obtain(
                        mDownTimeInMs, timeInMs, MotionEvent.ACTION_POINTER_UP,
                        pointerCount, mPointerProperties, mPointerCoords,
                        0, 0, 1, 1, 0, 0, 0, 0);
                    mContentViewCore.onTouchEvent(event);
                    event.recycle();
                }

                MotionEvent event = MotionEvent.obtain(
                        mDownTimeInMs, timeInMs, MotionEvent.ACTION_UP, 1,
                        mPointerProperties, mPointerCoords,
                        0, 0, 1, 1, 0, 0, 0, 0);
                mContentViewCore.onTouchEvent(event);
                event.recycle();
                break;
            }
        }
    }
}