paint_manager_example.cc revision 8bcbed890bc3ce4d7a057a8f32cab53fa534672e 
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 <algorithm>
6
7#include "ppapi/c/pp_input_event.h"
8#include "ppapi/cpp/graphics_2d.h"
9#include "ppapi/cpp/image_data.h"
10#include "ppapi/cpp/input_event.h"
11#include "ppapi/cpp/instance.h"
12#include "ppapi/cpp/module.h"
13#include "ppapi/cpp/size.h"
14#include "ppapi/cpp/view.h"
15#include "ppapi/utility/graphics/paint_manager.h"
16
17// Number of pixels to each side of the center of the square that we draw.
18static const int kSquareRadius = 2;
19
20// We identify our square by the center point. This computes the rect for the
21// square given that point.
22pp::Rect SquareForPoint(int x, int y) {
23  return PP_MakeRectFromXYWH(x - kSquareRadius, y - kSquareRadius,
24                             kSquareRadius * 2 + 1, kSquareRadius * 2 + 1);
25}
26
27static void FillRect(pp::ImageData* image,
28                     int left, int top, int width, int height,
29                     uint32_t color) {
30  for (int y = std::max(0, top);
31       y < std::min(image->size().height() - 1, top + height);
32       y++) {
33    for (int x = std::max(0, left);
34         x < std::min(image->size().width() - 1, left + width);
35         x++)
36      *image->GetAddr32(pp::Point(x, y)) = color;
37  }
38}
39
40class MyInstance : public pp::Instance, public pp::PaintManager::Client {
41 public:
42  MyInstance(PP_Instance instance)
43      : pp::Instance(instance),
44        paint_manager_(),
45        last_x_(0),
46        last_y_(0) {
47    paint_manager_.Initialize(this, this, false);
48    RequestInputEvents(PP_INPUTEVENT_CLASS_MOUSE);
49  }
50
51  virtual bool HandleInputEvent(const pp::InputEvent& event) {
52    switch (event.GetType()) {
53      case PP_INPUTEVENT_TYPE_MOUSEDOWN: {
54        pp::MouseInputEvent mouse_event(event);
55        // Update the square on a mouse down.
56        if (mouse_event.GetButton() == PP_INPUTEVENT_MOUSEBUTTON_LEFT) {
57          UpdateSquare(static_cast<int>(mouse_event.GetPosition().x()),
58                       static_cast<int>(mouse_event.GetPosition().y()));
59        }
60        return true;
61      }
62      case PP_INPUTEVENT_TYPE_MOUSEMOVE: {
63        pp::MouseInputEvent mouse_event(event);
64        // Update the square on a drag.
65        if (mouse_event.GetButton() == PP_INPUTEVENT_MOUSEBUTTON_LEFT) {
66          UpdateSquare(static_cast<int>(mouse_event.GetPosition().x()),
67                       static_cast<int>(mouse_event.GetPosition().y()));
68        }
69        return true;
70      }
71      default:
72        return false;
73    }
74  }
75
76  virtual void DidChangeView(const pp::View& view) {
77    paint_manager_.SetSize(view.GetRect().size());
78  }
79
80  // PaintManager::Client implementation.
81  virtual bool OnPaint(pp::Graphics2D& graphics_2d,
82                       const std::vector<pp::Rect>& paint_rects,
83                       const pp::Rect& paint_bounds) {
84    // Make an image just large enough to hold all dirty rects. We won't
85    // actually paint all of these pixels below, but rather just the dirty
86    // ones. Since image allocation can be somewhat heavyweight, we wouldn't
87    // want to allocate separate images in the case of multiple dirty rects.
88    pp::ImageData updated_image(this, PP_IMAGEDATAFORMAT_BGRA_PREMUL,
89                                paint_bounds.size(), false);
90
91    // We could repaint everything inside the image we made above. For this
92    // example, that would probably be the easiest thing since updates are
93    // small and typically close to each other. However, for the purposes of
94    // demonstration, here we only actually paint the pixels that changed,
95    // which may be the entire update region, or could be multiple discontigous
96    // regions inside the update region.
97    //
98    // Note that the aggregator used by the paint manager won't give us
99    // multiple regions that overlap, so we don't have to worry about double
100    // painting in this code.
101    for (size_t i = 0; i < paint_rects.size(); i++) {
102      // Since our image is just the invalid region, we need to offset the
103      // areas we paint by that much. This is just a light blue background.
104      FillRect(&updated_image,
105               paint_rects[i].x() - paint_bounds.x(),
106               paint_rects[i].y() - paint_bounds.y(),
107               paint_rects[i].width(),
108               paint_rects[i].height(),
109               0xFFAAAAFF);
110    }
111
112    // Paint the square black. Because we're lazy, we do this outside of the
113    // loop above.
114    pp::Rect square = SquareForPoint(last_x_, last_y_);
115    FillRect(&updated_image,
116             square.x() - paint_bounds.x(),
117             square.y() - paint_bounds.y(),
118             square.width(),
119             square.height(),
120             0xFF000000);
121
122    graphics_2d.PaintImageData(updated_image, paint_bounds.point());
123    return true;
124  }
125
126 private:
127  void UpdateSquare(int x, int y) {
128    if (x == last_x_ && y == last_y_)
129      return;  // Nothing changed.
130
131    // Invalidate the region around the old square which needs to be repainted
132    // because it's no longer there.
133    paint_manager_.InvalidateRect(SquareForPoint(last_x_, last_y_));
134
135    // Update the current position.
136    last_x_ = x;
137    last_y_ = y;
138
139    // Also invalidate the region around the new square.
140    paint_manager_.InvalidateRect(SquareForPoint(last_x_, last_y_));
141  }
142
143  pp::PaintManager paint_manager_;
144
145  int last_x_;
146  int last_y_;
147};
148
149class MyModule : public pp::Module {
150 public:
151  virtual pp::Instance* CreateInstance(PP_Instance instance) {
152    return new MyInstance(instance);
153  }
154};
155
156namespace pp {
157
158// Factory function for your specialization of the Module object.
159Module* CreateModule() {
160  return new MyModule();
161}
162
163}  // namespace pp
164