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Commit 43b5b06c authored by Kevin Schoedel's avatar Kevin Schoedel Committed by Alex Vakulenko
Browse files

Add synthetic back button to virtual touchpad/stylus. 

Also add a bit more error checking and documentation.

Test: added to VirtualTouchpad_test.cpp
Bug: 34673438
Change-Id: I3851a2ad79c5338cdd1db0c7d460aecfff082cc3
parent 6890d95e

services/vr/virtual_touchpad/VirtualTouchpad.cpp

+44 −4
Original line number Diff line number Diff line 
#include "VirtualTouchpad.h"



#include <android/input.h>

#include <cutils/log.h>

#include <inttypes.h>

#include <linux/input.h>



// References:

//  [0] Multi-touch (MT) Protocol,

//      https://www.kernel.org/doc/Documentation/input/multi-touch-protocol.txt



namespace android {

namespace dvr {



namespace {



// Virtual evdev device properties.

// Virtual evdev device properties. The name is arbitrary, but Android can

// use it to look up device configuration, so it must be unique. Vendor and

// product values must be 0 to indicate an internal device and prevent a

// similar lookup that could conflict with a physical device.

static const char* const kDeviceName = "vr window manager virtual touchpad";

static constexpr int16_t kDeviceBusType = BUS_VIRTUAL;

static constexpr int16_t kDeviceVendor = 0x18D1;   // Google USB vendor ID.

static constexpr int16_t kDeviceProduct = 0x5652;  // 'VR'

static constexpr int16_t kDeviceVendor = 0;

static constexpr int16_t kDeviceProduct = 0;

static constexpr int16_t kDeviceVersion = 0x0001;



static constexpr int32_t kWidth = 0x10000;

static constexpr int32_t kHeight = 0x10000;

static constexpr int32_t kSlots = 2;
@@ -32,18 +41,24 @@ int VirtualTouchpad::Initialize() { 
  injector_->ConfigureMultiTouchXY(0, 0, kWidth - 1, kHeight - 1);

  injector_->ConfigureAbsSlots(kSlots);

  injector_->ConfigureKey(BTN_TOUCH);

  injector_->ConfigureKey(BTN_BACK);

  injector_->ConfigureEnd();

  return injector_->GetError();

}



int VirtualTouchpad::Touch(float x, float y, float pressure) {

  int error = 0;

  if ((x < 0.0f) || (x >= 1.0f) || (y < 0.0f) || (y >= 1.0f)) {

    return EINVAL;

  }

  int32_t device_x = x * kWidth;

  int32_t device_y = y * kHeight;

  touches_ = ((touches_ & 1) << 1) | (pressure > 0);

  ALOGV("(%f,%f) %f -> (%" PRId32 ",%" PRId32 ") %d",

        x, y, pressure, device_x, device_y, touches_);



  if (!injector_) {

    return EvdevInjector::ERROR_SEQUENCING;

  }

  injector_->ResetError();

  switch (touches_) {

    case 0b00:  // Hover continues.
@@ -76,5 +91,30 @@ int VirtualTouchpad::Touch(float x, float y, float pressure) { 
  return injector_->GetError();

}



int VirtualTouchpad::ButtonState(int buttons) {

  const int changes = last_motion_event_buttons_ ^ buttons;

  if (!changes) {

    return 0;

  }

  if (buttons & ~AMOTION_EVENT_BUTTON_BACK) {

    return ENOTSUP;

  }

  ALOGV("change %X from %X to %X", changes, last_motion_event_buttons_,

        buttons);



  if (!injector_) {

    return EvdevInjector::ERROR_SEQUENCING;

  }

  injector_->ResetError();

  if (changes & AMOTION_EVENT_BUTTON_BACK) {

    injector_->SendKey(BTN_BACK,

                       (buttons & AMOTION_EVENT_BUTTON_BACK)

                           ? EvdevInjector::KEY_PRESS

                           : EvdevInjector::KEY_RELEASE);

  }

  last_motion_event_buttons_ = buttons;

  return injector_->GetError();

}



}  // namespace dvr

}  // namespace android

services/vr/virtual_touchpad/VirtualTouchpad.h

+36 −3
Original line number Diff line number Diff line
@@ -10,12 +10,39 @@ namespace dvr { 


class EvdevInjector;



// Provides a virtual touchpad for injecting events into the input system.

//

class VirtualTouchpad {

 public:

  VirtualTouchpad() {}

  ~VirtualTouchpad() {}



  // |Intialize()| must be called once on a VirtualTouchpad before

  // and other public method. Returns zero on success.

  int Initialize();



  // Generate a simulated touch event.

  //

  // @param x Horizontal touch position.

  // @param y Vertical touch position.

  //            Values must be in the range [0.0, 1.0).

  // @param pressure Touch pressure.

  //            Positive values represent contact; use 1.0f if contact

  //            is binary. Use 0.0f for no contact.

  // @returns Zero on success.

  //

  int Touch(float x, float y, float pressure);



  // Generate a simulated touchpad button state.

  //

  // @param buttons A union of MotionEvent BUTTON_* values.

  // @returns Zero on success.

  //

  // Currently only BUTTON_BACK is supported, as the implementation

  // restricts itself to operations actually required by VrWindowManager.

  //

  int ButtonState(int buttons);



 protected:

  // Must be called only between construction and Initialize().

  inline void SetEvdevInjectorForTesting(EvdevInjector* injector) {
@@ -23,17 +50,23 @@ class VirtualTouchpad { 
  }



 private:

  // Except for testing, the |EvdevInjector| used to inject evdev events.

  std::unique_ptr<EvdevInjector> owned_injector_;



  // Active pointer to |owned_injector_| or to a testing injector.

  EvdevInjector* injector_ = nullptr;

  std::unique_ptr<EvdevInjector> owned_injector_;



  // Previous (x,y) position to suppress redundant events.

  // Previous (x, y) position in device space, to suppress redundant events.

  int32_t last_device_x_ = INT32_MIN;

  int32_t last_device_y_ = INT32_MIN;



  // Records current touch state in bit 0 and previous state in bit 1.

  // Records current touch state (0=up 1=down) in bit 0, and previous state

  // in bit 1, to track transitions.

  int touches_ = 0;



  // Previous injected button state, to detect changes.

  int32_t last_motion_event_buttons_ = 0;



  VirtualTouchpad(const VirtualTouchpad&) = delete;

  void operator=(const VirtualTouchpad&) = delete;

};

services/vr/virtual_touchpad/VirtualTouchpadService.cpp

+6 −1
Original line number Diff line number Diff line
@@ -13,11 +13,16 @@ int VirtualTouchpadService::Initialize() { 
}



binder::Status VirtualTouchpadService::touch(float x, float y, float pressure) {

  // Permissions check added and removed here :^)

  const int error = touchpad_.Touch(x, y, pressure);

  return error ? binder::Status::fromServiceSpecificError(error)

               : binder::Status::ok();

}



binder::Status VirtualTouchpadService::buttonState(int buttons) {

  const int error = touchpad_.ButtonState(buttons);

  return error ? binder::Status::fromServiceSpecificError(error)

               : binder::Status::ok();

}



}  // namespace dvr

}  // namespace android

services/vr/virtual_touchpad/VirtualTouchpadService.h

+4 −0
Original line number Diff line number Diff line
@@ -8,6 +8,9 @@ 
namespace android {

namespace dvr {



// VirtualTouchpadService implements the service side of

// the Binder interface defined in VirtualTouchpadService.aidl.

//

class VirtualTouchpadService : public BnVirtualTouchpadService {

 public:

  VirtualTouchpadService(VirtualTouchpad& touchpad)
@@ -22,6 +25,7 @@ class VirtualTouchpadService : public BnVirtualTouchpadService { 
 protected:

  // Implements IVirtualTouchpadService.

  ::android::binder::Status touch(float x, float y, float pressure) override;

  ::android::binder::Status buttonState(int buttons) override;



 private:

  VirtualTouchpad& touchpad_;

services/vr/virtual_touchpad/aidl/android/dvr/VirtualTouchpadService.aidl

+7 −0
Original line number Diff line number Diff line
@@ -13,4 +13,11 @@ interface VirtualTouchpadService 
   * Position values in the range [0.0, 1.0) map to the screen.

   */

  void touch(float x, float y, float pressure);



  /**

   * Generate a simulated touchpad button state event.

   *

   * @param buttons A union of MotionEvent BUTTON_* values.

   */

  void buttonState(int buttons);

}