paint_manager_example.cc revision 5821806d5e7f356e8fa4b058a389a808ea183019 
1// Copyright (c) 2011 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 "ppapi/c/pp_input_event.h"
6#include "ppapi/cpp/graphics_2d.h"
7#include "ppapi/cpp/image_data.h"
8#include "ppapi/cpp/input_event.h"
9#include "ppapi/cpp/instance.h"
10#include "ppapi/cpp/module.h"
11#include "ppapi/cpp/size.h"
12#include "ppapi/cpp/view.h"
13#include "ppapi/utility/graphics/paint_manager.h"
14
15// Number of pixels to each side of the center of the square that we draw.
16static const int kSquareRadius = 2;
17
18// We identify our square by the center point. This computes the rect for the
19// square given that point.
20pp::Rect SquareForPoint(int x, int y) {
21  return PP_MakeRectFromXYWH(x - kSquareRadius, y - kSquareRadius,
22                             kSquareRadius * 2 + 1, kSquareRadius * 2 + 1);
23}
24
25static void FillRect(pp::ImageData* image,
26                     int left, int top, int width, int height,
27                     uint32_t color) {
28  for (int y = std::max(0, top);
29       y < std::min(image->size().height() - 1, top + height);
30       y++) {
31    for (int x = std::max(0, left);
32         x < std::min(image->size().width() - 1, left + width);
33         x++)
34      *image->GetAddr32(pp::Point(x, y)) = color;
35  }
36}
37
38class MyInstance : public pp::Instance, public pp::PaintManager::Client {
39 public:
40  MyInstance(PP_Instance instance)
41      : pp::Instance(instance),
42        paint_manager_(),
43        last_x_(0),
44        last_y_(0) {
45    paint_manager_.Initialize(this, this, false);
46    RequestInputEvents(PP_INPUTEVENT_CLASS_MOUSE);
47  }
48
49  virtual bool HandleInputEvent(const pp::InputEvent& event) {
50    switch (event.GetType()) {
51      case PP_INPUTEVENT_TYPE_MOUSEDOWN: {
52        pp::MouseInputEvent mouse_event(event);
53        // Update the square on a mouse down.
54        if (mouse_event.GetButton() == PP_INPUTEVENT_MOUSEBUTTON_LEFT) {
55          UpdateSquare(static_cast<int>(mouse_event.GetPosition().x()),
56                       static_cast<int>(mouse_event.GetPosition().y()));
57        }
58        return true;
59      }
60      case PP_INPUTEVENT_TYPE_MOUSEMOVE: {
61        pp::MouseInputEvent mouse_event(event);
62        // Update the square on a drag.
63        if (mouse_event.GetButton() == PP_INPUTEVENT_MOUSEBUTTON_LEFT) {
64          UpdateSquare(static_cast<int>(mouse_event.GetPosition().x()),
65                       static_cast<int>(mouse_event.GetPosition().y()));
66        }
67        return true;
68      }
69      default:
70        return false;
71    }
72  }
73
74  virtual void DidChangeView(const pp::View& view) {
75    paint_manager_.SetSize(view.GetRect().size());
76  }
77
78  // PaintManager::Client implementation.
79  virtual bool OnPaint(pp::Graphics2D& graphics_2d,
80                       const std::vector<pp::Rect>& paint_rects,
81                       const pp::Rect& paint_bounds) {
82    // Make an image just large enough to hold all dirty rects. We won't
83    // actually paint all of these pixels below, but rather just the dirty
84    // ones. Since image allocation can be somewhat heavyweight, we wouldn't
85    // want to allocate separate images in the case of multiple dirty rects.
86    pp::ImageData updated_image(this, PP_IMAGEDATAFORMAT_BGRA_PREMUL,
87                                paint_bounds.size(), false);
88
89    // We could repaint everything inside the image we made above. For this
90    // example, that would probably be the easiest thing since updates are
91    // small and typically close to each other. However, for the purposes of
92    // demonstration, here we only actually paint the pixels that changed,
93    // which may be the entire update region, or could be multiple discontigous
94    // regions inside the update region.
95    //
96    // Note that the aggregator used by the paint manager won't give us
97    // multiple regions that overlap, so we don't have to worry about double
98    // painting in this code.
99    for (size_t i = 0; i < paint_rects.size(); i++) {
100      // Since our image is just the invalid region, we need to offset the
101      // areas we paint by that much. This is just a light blue background.
102      FillRect(&updated_image,
103               paint_rects[i].x() - paint_bounds.x(),
104               paint_rects[i].y() - paint_bounds.y(),
105               paint_rects[i].width(),
106               paint_rects[i].height(),
107               0xFFAAAAFF);
108    }
109
110    // Paint the square black. Because we're lazy, we do this outside of the
111    // loop above.
112    pp::Rect square = SquareForPoint(last_x_, last_y_);
113    FillRect(&updated_image,
114             square.x() - paint_bounds.x(),
115             square.y() - paint_bounds.y(),
116             square.width(),
117             square.height(),
118             0xFF000000);
119
120    graphics_2d.PaintImageData(updated_image, paint_bounds.point());
121    return true;
122  }
123
124 private:
125  void UpdateSquare(int x, int y) {
126    if (x == last_x_ && y == last_y_)
127      return;  // Nothing changed.
128
129    // Invalidate the region around the old square which needs to be repainted
130    // because it's no longer there.
131    paint_manager_.InvalidateRect(SquareForPoint(last_x_, last_y_));
132
133    // Update the current position.
134    last_x_ = x;
135    last_y_ = y;
136
137    // Also invalidate the region around the new square.
138    paint_manager_.InvalidateRect(SquareForPoint(last_x_, last_y_));
139  }
140
141  pp::PaintManager paint_manager_;
142
143  int last_x_;
144  int last_y_;
145};
146
147class MyModule : public pp::Module {
148 public:
149  virtual pp::Instance* CreateInstance(PP_Instance instance) {
150    return new MyInstance(instance);
151  }
152};
153
154namespace pp {
155
156// Factory function for your specialization of the Module object.
157Module* CreateModule() {
158  return new MyModule();
159}
160
161}  // namespace pp
162