ppapi: Add support for touch events.

ppapi/c/dev/ppb_touch_event_dev.h

+/* Copyright (c) 2011 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.
+ */
+#ifndef PPAPI_C_DEV_PPB_TOUCH_EVENT_DEV_H_

[brettw, 2012/06/19 21:20:52]

You should convert this file to IDL and then generate .h file from that using
ppapi/generator/generator.py

[sadrul, 2012/06/20 20:19:03]

Done.

+#define PPAPI_C_DEV_PPB_TOUCH_EVENT_DEV_H_
+
+#include "ppapi/c/pp_bool.h"
+#include "ppapi/c/pp_point.h"
+#include "ppapi/c/pp_resource.h"
+#include "ppapi/c/pp_stdint.h"
+
+#define PPB_TOUCH_INPUT_EVENT_DEV_INTERFACE_0_1 "PPB_TouchInputEvent(Dev);0.1"
+#define PPB_TOUCH_INPUT_EVENT_DEV_INTERFACE PPB_TOUCH_INPUT_EVENT_DEV_INTERFACE_0_1
+
+/**
+ * Represents a single touch point.
+ */
+struct PP_TouchPoint_Dev {
+  /**
+   * The identifier for this TouchPoint. This corresponds to the order
+   * in which the points were pressed. For example, the first point to be
+   * pressed has an id of 0, the second has an id of 1, and so on. An id can be
+   * reused when a touch point is released.  For example, if two fingers are
+   * down, with id 0 and 1, and finger 0 releases, the next finger to be
+   * pressed can be assigned to id 0.
+   */
+  uint32_t id;
+
+  /**
+   * The x-y coordinates of this TouchPoint, in DOM coordinate space.

[brettw, 2012/06/19 21:20:52]

One thing that we need to clarify is the coordinate space here. I don't know
what the DOM coordinate space is. Is it relative to the upper left of the
plugin? I assume not.

We're working on high DPI and the coordinate spaces can get kind of confusing,
so we should be very clear about what we mean here.

Probably relative to the plugin so that touch events match mouse events would
seem to make the most sense to me. I'm not sure if that's what the current spec
does.

[sadrul, 2012/06/20 20:19:03]

These values are indeed in the same coordinate space as the mouse-events. I have
updated the docstring here to be similar to the docstring for
PPB_MouseInputEvent::GetPosition.

+   */
+  struct PP_FloatPoint position;
+  /**
+   * The elliptical radii, in screen pixels, in the x and y direction of this
+   * TouchPoint.
+   */
+  struct PP_FloatPoint radius;
+  /**
+   * The angle of rotation in degrees of the elliptical model of this TouchPoint
+   * clockwise from "up."
+   */
+  float rotation_angle;
+  /**
+   * The pressure applied to this TouchPoint.  This is typically a
+   * value between 0 and 1, with 0 indicating no pressure and 1 indicating
+   * some maximum pressure, but scaling differs depending on the hardware and
+   * the value is not guaranteed to stay within that range.
+   */
+  float pressure;
+};
+
+PP_INLINE struct PP_TouchPoint_Dev PP_MakeTouchPoint() {
+  struct PP_TouchPoint_Dev result = { 0, {0, 0}, {0, 0}, 0, 0 };
+  return result;
+}
+
+typedef enum {
+
+  /**
+   * The list of all TouchPoints which are currently down.
+   */
+  PP_TOUCHLIST_TYPE_TOUCHES,
+
+  /**
+   * The list of all TouchPoints whose state has changed since the last
+   * TouchInputEvent.
+   */
+  PP_TOUCHLIST_TYPE_CHANGEDTOUCHES,
+
+  /**
+   * The list of all TouchPoints which are targeting this plugin.  This is a
+   * subset of Touches.
+   */
+  PP_TOUCHLIST_TYPE_TARGETTOUCHES
+} PP_TouchListType;
+
+struct PPB_TouchInputEvent_Dev {

[brettw, 2012/06/19 21:20:52]

I think we will want a "create" function like we have for the other input
events. These ended up being important for testing, and it will be a pain to rev
the interface later to add.

[sadrul, 2012/06/20 20:19:03]

Done. I have currently left CreateTouchInputEvent unimplemented, and it only
returns NULL. I plan on adding implementation for this in the next CL (since it
looks like it also requires adding to the ResourceCreationAPI interface). Does
that sound acceptable?

+  /**
+   * Determines if a resource is a touch event.
+   *
+   * @return PP_TRUE if the given resource is a valid touch input event.
+   */
+  PP_Bool (*IsTouchInputEvent)(PP_Resource resource);
+
+  /**
+   * @return The number of TouchPoints in the given list
+   */
+  uint32_t (*GetTouchCount)(PP_Resource resource, PP_TouchListType list);
+
+  /**
+   * @return The TouchPoint at the given index, or an empty TouchPoint if the
+   * given index is out of range
+   */
+  PP_TouchPoint_Dev (*GetTouchByIndex)(PP_Resource resource,
+                                       PP_TouchListType list,
+                                       uint32_t index);
+
+  /**
+   * @return The TouchPoint with the given identifier, or an empty TouchPoint
+   * if this TouchList does not contain a TouchPoint with that identifier.
+   */
+  PP_TouchPoint_Dev (*GetTouchById)(PP_Resource resource,
+                                    PP_TouchListType list,
+                                    uint32_t id);
+};
+
+#endif  /* PPAPI_C_DEV_PPB_TOUCH_EVENT_DEV_H_ */