Add a mouselock example.

examples/mouselock/mouselock.cc

+// 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.
+
+#include "examples/mouselock/mouselock.h"
+
+#include <cmath>
+#include <cstdlib>
+#include <assert.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+// Indicate the direction of the mouse location relative to the center of the
+// view.  These values are used to determine which 2D quadrant the needle lies
+// in.
+typedef enum {
+    kLeft = 0,
+    kRight = 1,
+    kUp = 2,
+    kDown = 3
+} MouseDirection;
+
+namespace {
+const int kCentralSpotRadius = 5;
+const uint32_t kReturnKeyCode = 13;
+const uint32_t kBackgroundColor = 0xff606060;
+const uint32_t kLockedForegroundColor = 0xfff08080;
+const uint32_t kUnlockedForegroundColor = 0xff80f080;
+}  // namespace
+
+namespace mouselock {
+
+MouseLockInstance::~MouseLockInstance() {
+  free(background_scanline_);
+  background_scanline_ = NULL;
+}
+
+bool MouseLockInstance::Init(uint32_t argc,
+                             const char* argn[],
+                             const char* argv[]) {
+  RequestInputEvents(PP_INPUTEVENT_CLASS_MOUSE |
+                     PP_INPUTEVENT_CLASS_KEYBOARD);
+  return true;
+}
+
+bool MouseLockInstance::HandleInputEvent(const pp::InputEvent& event) {
+  switch (event.GetType()) {
+    case PP_INPUTEVENT_TYPE_MOUSEDOWN: {
+      is_context_bound_ = false;
+      if (fullscreen_.IsFullscreen()) {
+        // Leaving fullscreen mode also unlocks the mouse if it was locked.
+        // In this case, the browser will call MouseLockLost() on this
+        // instance.
+        if (!fullscreen_.SetFullscreen(false)) {
+          Log("Could not leave fullscreen mode\n");
+        }
+      } else {
+        if (!fullscreen_.SetFullscreen(true)) {
+          Log("Could not set fullscreen mode\n");
+        } else {
+          pp::MouseInputEvent mouse_event(event);
+          if (mouse_event.GetButton() == PP_INPUTEVENT_MOUSEBUTTON_LEFT &&
+              !mouse_locked_) {
+            LockMouse(callback_factory_.NewRequiredCallback(
+                &MouseLockInstance::DidLockMouse));
+          }
+        }
+      }
+      return true;
+    }
+
+    case PP_INPUTEVENT_TYPE_MOUSEMOVE: {
+      pp::MouseInputEvent mouse_event(event);
+      mouse_movement_ = mouse_event.GetMovement();
+      Paint();
+      return true;
+    }
+
+    case PP_INPUTEVENT_TYPE_KEYDOWN: {
+      pp::KeyboardInputEvent key_event(event);
+      // Lock the mouse when the Enter key is pressed.
+      if (key_event.GetKeyCode() == kReturnKeyCode) {
+        if (mouse_locked_) {
+          UnlockMouse();
+        } else {
+          LockMouse(callback_factory_.NewRequiredCallback(
+              &MouseLockInstance::DidLockMouse));
+        }
+      }
+      return true;
+    }
+
+    case PP_INPUTEVENT_TYPE_MOUSEUP:
+    case PP_INPUTEVENT_TYPE_MOUSEENTER:
+    case PP_INPUTEVENT_TYPE_MOUSELEAVE:
+    case PP_INPUTEVENT_TYPE_WHEEL:
+    case PP_INPUTEVENT_TYPE_RAWKEYDOWN:
+    case PP_INPUTEVENT_TYPE_KEYUP:
+    case PP_INPUTEVENT_TYPE_CHAR:
+    case PP_INPUTEVENT_TYPE_CONTEXTMENU:
+    case PP_INPUTEVENT_TYPE_IME_COMPOSITION_START:
+    case PP_INPUTEVENT_TYPE_IME_COMPOSITION_UPDATE:
+    case PP_INPUTEVENT_TYPE_IME_COMPOSITION_END:
+    case PP_INPUTEVENT_TYPE_IME_TEXT:
+    case PP_INPUTEVENT_TYPE_UNDEFINED:
+    default:
+      return false;
+  }
+}
+
+void MouseLockInstance::DidChangeView(const pp::Rect& position,
+                                      const pp::Rect& clip) {
+  int width = position.size().width();
+  int height = position.size().height();
+
+  // When entering into full-screen mode, DidChangeView() gets called twice.
+  // The first time, any 2D context will fail to bind to this pp::Instacne.
+  if (width == width_ && height == height_ && is_context_bound_) {
+    return;
+  }
+  width_ = width;
+  height_ = height;
+
+  device_context_ = pp::Graphics2D(this, pp::Size(width_, height_), false);
+  waiting_for_flush_completion_ = false;
+  free(background_scanline_);
+  background_scanline_ = NULL;
+  is_context_bound_ = BindGraphics(device_context_);
+  if (!is_context_bound_) {
+    Log("Could not bind to 2D context\n");
+    return;
+  }
+  background_scanline_ = static_cast<uint32_t*>(
+      malloc(width_ * sizeof(*background_scanline_)));
+  uint32_t* bg_pixel = background_scanline_;
+  for (int x = 0; x < width_; ++x) {
+    *bg_pixel++ = kBackgroundColor;
+  }
+  Paint();
+}
+
+void MouseLockInstance::MouseLockLost() {
+  if (mouse_locked_) {
+    mouse_locked_ = false;
+    Paint();
+  } else {
+    PP_NOTREACHED();
+  }
+}
+
+void MouseLockInstance::DidLockMouse(int32_t result) {
+  mouse_locked_ = result == PP_OK;
+  mouse_movement_.set_x(0);
+  mouse_movement_.set_y(0);
+  Paint();
+}
+
+void MouseLockInstance::DidFlush(int32_t result) {
+  waiting_for_flush_completion_ = false;
+}
+
+void MouseLockInstance::Paint() {
+  if (waiting_for_flush_completion_) {
+    return;
+  }
+  pp::ImageData image = PaintImage(width_, height_);
+  if (image.is_null()) {
+    Log("Could not create image data\n");
+    return;
+  }
+  device_context_.ReplaceContents(&image);
+  waiting_for_flush_completion_ = true;
+  device_context_.Flush(
+      callback_factory_.NewRequiredCallback(&MouseLockInstance::DidFlush));
+}
+
+pp::ImageData MouseLockInstance::PaintImage(int width, int height) {
+  pp::ImageData image(this, PP_IMAGEDATAFORMAT_BGRA_PREMUL,
+                      pp::Size(width, height), false);
+  if (image.is_null() || image.data() == NULL)
+    return image;
+
+  ClearToBackground(&image);
+  uint32_t foreground_color = mouse_locked_ ? kLockedForegroundColor :
+                                              kUnlockedForegroundColor;
+  DrawCenterSpot(&image, foreground_color);
+  DrawNeedle(&image, foreground_color);
+  return image;
+}
+
+void MouseLockInstance::ClearToBackground(pp::ImageData* image) {
+  assert(image);

[cstefansen, 2011/11/11 19:44:43]

Any reason not to use the 'Log("..."); return;' patterns you've used elsewhere?
(I'm all in favor of asserts normally, but in NaCl/Chrome if you run this on
Windows, it'll be hard to actually set it up so you can see the error because
the console tends to go to NUL:.)

[der Springer, 2011/11/11 21:21:37]

Done.

+  if (background_scanline_ == NULL)
+    return;
+  int image_height = image->size().height();
+  int image_width = image->size().width();
+  for (int y = 0; y < image_height; ++y) {
+    uint32_t* scanline = image->GetAddr32(pp::Point(0, y));
+    memcpy(scanline,
+           background_scanline_,
+           image_width * sizeof(*background_scanline_));
+  }
+}
+
+void MouseLockInstance::DrawCenterSpot(pp::ImageData* image,
+                                       uint32_t spot_color) {
+  assert(image);

[cstefansen, 2011/11/11 19:44:43]

Ditto.

[der Springer, 2011/11/11 21:21:37]

Done.

+  // Draw the center spot.  The ROI is bounded by the size of the spot, plus
+  // one pixel.
+  int center_x = image->size().width() / 2;
+  int center_y = image->size().height() / 2;
+  int region_of_interest_radius = kCentralSpotRadius + 1;
+
+  for (int y = center_y - region_of_interest_radius;
+       y < center_y + region_of_interest_radius;
+       ++y) {
+    for (int x = center_x - region_of_interest_radius;
+         x < center_x + region_of_interest_radius;
+         ++x) {
+      if (GetDistance(x, y, center_x, center_y) < kCentralSpotRadius) {
+        *image->GetAddr32(pp::Point(x, y)) = spot_color;
+      }
+    }
+  }
+}
+
+void MouseLockInstance::DrawNeedle(pp::ImageData* image,
+                                   uint32_t needle_color) {

[cstefansen, 2011/11/11 19:44:43]

Nit: you *could* check that image is not null like you did in the other
functions. (Or you could remove some of the checks; your call.)

[der Springer, 2011/11/11 21:21:37]

Done.

+  if (GetDistance(mouse_movement_.x(), mouse_movement_.y(), 0, 0) <=
+      kCentralSpotRadius) {
+    return;
+  }
+
+  int abs_mouse_x = std::abs(mouse_movement_.x());
+  int abs_mouse_y = std::abs(mouse_movement_.y());
+  int center_x = image->size().width() / 2;
+  int center_y = image->size().height() / 2;
+  pp::Point vertex(mouse_movement_.x() + center_x,
+                   mouse_movement_.y() + center_y);
+  pp::Point anchor_1;
+  pp::Point anchor_2;
+  MouseDirection direction = kLeft;
+
+  if (abs_mouse_x >= abs_mouse_y) {
+     anchor_1.set_x(center_x);
+     anchor_1.set_y(center_y - kCentralSpotRadius);
+     anchor_2.set_x(center_x);
+     anchor_2.set_y(center_y + kCentralSpotRadius);
+     direction = (mouse_movement_.x() < 0) ? kLeft : kRight;
+     if (direction == kLeft)
+       anchor_1.swap(anchor_2);
+  } else {
+     anchor_1.set_x(center_x + kCentralSpotRadius);
+     anchor_1.set_y(center_y);
+     anchor_2.set_x(center_x - kCentralSpotRadius);
+     anchor_2.set_y(center_y);
+     direction = (mouse_movement_.y() < 0) ? kUp : kDown;
+     if (direction == kUp)
+       anchor_1.swap(anchor_2);
+  }
+
+  for (int y = center_y - abs_mouse_y; y < center_y + abs_mouse_y; ++y) {
+    for (int x = center_x - abs_mouse_x; x < center_x + abs_mouse_x; ++x) {
+      bool within_bound_1 =
+          ((y - anchor_1.y()) * (vertex.x() - anchor_1.x())) >
+          ((vertex.y() - anchor_1.y()) * (x - anchor_1.x()));
+      bool within_bound_2 =
+          ((y - anchor_2.y()) * (vertex.x() - anchor_2.x())) <
+          ((vertex.y() - anchor_2.y()) * (x - anchor_2.x()));
+      bool within_bound_3 =
+          (direction == kUp && y < center_y) ||
+          (direction == kDown && y > center_y) ||
+          (direction == kLeft && x < center_x) ||
+          (direction == kRight && x > center_x);
+
+      if (within_bound_1 && within_bound_2 && within_bound_3) {
+        *image->GetAddr32(pp::Point(x, y)) = needle_color;
+      }
+    }
+  }
+}
+
+
+void MouseLockInstance::Log(const char* format, ...) {
+  va_list args;
+  va_start(args, format);
+  char buf[512];
+  vsnprintf(buf, sizeof(buf) - 1, format, args);
+  buf[sizeof(buf) - 1] = '\0';
+  va_end(args);
+
+  pp::Var value(buf);
+  PostMessage(value);
+}
+
+}  // namespace mouselock
+
+// This object is the global object representing this plugin library as long
+// as it is loaded.
+class MouseLockModule : public pp::Module {
+ public:
+  MouseLockModule() : pp::Module() {}
+  virtual ~MouseLockModule() {}
+
+  // Override CreateInstance to create your customized Instance object.
+  virtual pp::Instance* CreateInstance(PP_Instance instance) {
+    return new mouselock::MouseLockInstance(instance);
+  }
+};
+
+namespace pp {
+
+// Factory function for your specialization of the Module object.
+Module* CreateModule() {
+  return new MouseLockModule();
+}
+
+}  // namespace pp
+