ppapi/examples/2d/paint_manager_example.cc

   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.
  18 static 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.
  22 pp::Rect SquareForPoint(int x, int y) {
  23   return PP_MakeRectFromXYWH(x - kSquareRadius, y - kSquareRadius,
  24                              kSquareRadius * 2 + 1, kSquareRadius * 2 + 1);
  25 }
  26
  27 static 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
  40 class 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
 149 class MyModule : public pp::Module {
 150  public:
 151   virtual pp::Instance* CreateInstance(PP_Instance instance) {
 152     return new MyInstance(instance);
 153   }
 154 };
 155
 156 namespace pp {
 157
 158 // Factory function for your specialization of the Module object.
 159 Module* CreateModule() {
 160   return new MyModule();
 161 }
 162
 163 }  // namespace pp