content/browser/android/touch_point.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/android/touch_point.h"
   6
   7 #include "base/debug/debugger.h"
   8 #include "base/logging.h"
   9 #include "base/time/time.h"
  10
  11 #include "jni/TouchPoint_jni.h"
  12
  13 using WebKit::WebTouchEvent;
  14 using WebKit::WebTouchPoint;
  15
  16 namespace {
  17
  18 void MaybeAddTouchPoint(JNIEnv* env,
  19                         jobject pt,
  20                         float dpi_scale,
  21                         WebKit::WebTouchEvent& event) {
  22   WebTouchPoint::State state = static_cast<WebTouchPoint::State>(
  23       Java_TouchPoint_getState(env, pt));
  24   if (state == WebTouchPoint::StateUndefined)
  25     return;
  26
  27   // When generating a cancel event from an event of a different type, the
  28   // touch points are out of sync, so we ensure the points are marked as
  29   // canceled as well.
  30   if (event.type == WebTouchEvent::TouchCancel)
  31     state = WebTouchPoint::StateCancelled;
  32
  33   // Record the current number of points in the WebTouchEvent
  34   const int idx = event.touchesLength;
  35   DCHECK_LT(idx, WebKit::WebTouchEvent::touchesLengthCap);
  36
  37   WebTouchPoint wtp;
  38   wtp.id = Java_TouchPoint_getId(env, pt);
  39   wtp.state = state;
  40   wtp.position.x = Java_TouchPoint_getX(env, pt) / dpi_scale;
  41   wtp.position.y = Java_TouchPoint_getY(env, pt) / dpi_scale;
  42   // TODO(joth): Raw event co-ordinates.
  43   wtp.screenPosition = wtp.position;
  44   wtp.force = Java_TouchPoint_getPressure(env, pt);
  45
  46   // TODO(djsollen): WebKit stores touch point size as a pair of radii, which
  47   // are integers.  We receive touch point size from Android as a float
  48   // between 0 and 1 and interpret 'size' as an elliptical area.  We convert
  49   // size to a radius and then scale up to avoid truncating away all of the
  50   // data. W3C spec is for the radii to be in units of screen pixels. Need to
  51   // change.
  52   const static double PI = 3.1415926;
  53   const static double SCALE_FACTOR = 1024.0;
  54   const int radius = static_cast<int>(
  55       (sqrt(Java_TouchPoint_getSize(env, pt)) / PI) * SCALE_FACTOR);
  56   wtp.radiusX = radius / dpi_scale;
  57   wtp.radiusY = radius / dpi_scale;
  58   // Since our radii are equal, a rotation angle doesn't mean anything.
  59   wtp.rotationAngle = 0.0;
  60
  61   // Add the newly created WebTouchPoint to the event
  62   event.touches[idx] = wtp;
  63   ++(event.touchesLength);
  64 }
  65
  66 }  // namespace
  67
  68 namespace content {
  69
  70 void TouchPoint::BuildWebTouchEvent(JNIEnv* env,
  71                                     jint type,
  72                                     jlong time_ms,
  73                                     float dpi_scale,
  74                                     jobjectArray pts,
  75                                     WebKit::WebTouchEvent& event) {
  76   event.type = static_cast<WebTouchEvent::Type>(type);
  77   event.timeStampSeconds =
  78       static_cast<double>(time_ms) / base::Time::kMillisecondsPerSecond;
  79   int arrayLength = env->GetArrayLength(pts);
  80   // Loop until either all of the input points have been consumed or the output
  81   // array has been filled
  82   for (int i = 0; i < arrayLength; i++) {
  83     jobject pt = env->GetObjectArrayElement(pts, i);
  84     MaybeAddTouchPoint(env, pt, dpi_scale, event);
  85     if (event.touchesLength >= event.touchesLengthCap)
  86       break;
  87   }
  88   DCHECK_GT(event.touchesLength, 0U);
  89 }
  90
  91 static void RegisterConstants(JNIEnv* env) {
  92    Java_TouchPoint_initializeConstants(
  93        env,
  94        WebKit::WebTouchEvent::TouchStart,
  95        WebKit::WebTouchEvent::TouchMove,
  96        WebKit::WebTouchEvent::TouchEnd,
  97        WebKit::WebTouchEvent::TouchCancel,
  98        WebKit::WebTouchPoint::StateUndefined,
  99        WebKit::WebTouchPoint::StateReleased,
 100        WebKit::WebTouchPoint::StatePressed,
 101        WebKit::WebTouchPoint::StateMoved,
 102        WebKit::WebTouchPoint::StateStationary,
 103        WebKit::WebTouchPoint::StateCancelled);
 104 }
 105
 106 bool RegisterTouchPoint(JNIEnv* env) {
 107   if (!RegisterNativesImpl(env))
 108     return false;
 109
 110   RegisterConstants(env);
 111
 112   return true;
 113 }
 114
 115 }  // namespace content