PPAPI插件的绘图与输入事件处理

在[PPAPI插件与浏览器的交互过程](http://blog.csdn.net/foruok/article/details/50494061)一文中学习了PPAPI插件与浏览器的交互流程、渲染逻辑、输入事件的处理逻辑，这次我们改造一下graphics_2d_example示例，加入处理鼠标事件的逻辑，演示一下PPAPI插件想要处理输入事件时的代码流程。 > foruok原创，如需转载请关注foruok的微信订阅号“程序视界”联系foruok。 # 工程 新建一个Win32项目，类型选DLL，去掉预编译头文件stdafx.h和stdafx.cpp，并且在项目属性–>配置属性–>C/C++–>预编译头，把预编译头选项的值设置为不使用预编译头。 使用UNICODE字符集，运行库选择MT。 项目名就叫ppapi_simple吧，把ppapi的上一级目录添加到附加包含目录里。 把graphics_2d_example.c拷贝过来，改名为ppapi_simple.c。内容修改成下面的样子： ~~~ /* Copyright (c) 2012 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. * * 2016-1-10, edited by foruok. * 如需转载，请关注微信订阅号“程序视界”，回复foruok获取其联系方式 * */ #include <stdint.h> #include <stdlib.h> #include <string.h> #include <Windows.h> #include <tchar.h> #include "ppapi/c/pp_completion_callback.h" #include "ppapi/c/pp_errors.h" #include "ppapi/c/pp_instance.h" #include "ppapi/c/pp_module.h" #include "ppapi/c/pp_rect.h" #include "ppapi/c/pp_var.h" #include "ppapi/c/ppb.h" #include "ppapi/c/ppb_core.h" #include "ppapi/c/ppb_graphics_2d.h" #include "ppapi/c/ppb_image_data.h" #include "ppapi/c/ppb_instance.h" #include "ppapi/c/ppb_view.h" #include "ppapi/c/ppp.h" #include "ppapi/c/ppp_instance.h" #include "ppapi/c/ppb_input_event.h" #include "ppapi/c/ppp_input_event.h" PPB_GetInterface g_get_browser_interface = NULL; const PPB_Core* g_core_interface; const PPB_Graphics2D* g_graphics_2d_interface; const PPB_ImageData* g_image_data_interface; const PPB_Instance* g_instance_interface; const PPB_View* g_view_interface; // [1] const PPB_InputEvent *g_input_interface; const PPB_MouseInputEvent *g_mouse_interface; /* PPP_Instance implementation -----------------------------------------------*/ struct InstanceInfo { PP_Instance pp_instance; struct PP_Size last_size; PP_Resource graphics; struct InstanceInfo* next; }; /** Linked list of all live instances. */ struct InstanceInfo* all_instances = NULL; /** Returns a refed resource corresponding to the created graphics 2d. */ PP_Resource MakeAndBindGraphics2D(PP_Instance instance, const struct PP_Size* size) { PP_Resource graphics; graphics = g_graphics_2d_interface->Create(instance, size, PP_FALSE); if (!graphics) return 0; if (!g_instance_interface->BindGraphics(instance, graphics)) { g_core_interface->ReleaseResource(graphics); return 0; } return graphics; } void FlushCompletionCallback(void* user_data, int32_t result) { /* Don't need to do anything here. */ } unsigned int g_colors[4] = { 0xFF0000FF, 0xFFFF00FF, 0xFF00FFFF, 0xFFEA00FF }; unsigned int g_color_index = 0; void Repaint(struct InstanceInfo* instance, const struct PP_Size* size) { PP_Resource image; struct PP_ImageDataDesc image_desc; uint32_t* image_data; int num_words, i; /* Ensure the graphics 2d is ready. */ if (!instance->graphics) { instance->graphics = MakeAndBindGraphics2D(instance->pp_instance, size); if (!instance->graphics) return; } /* Create image data to paint into. */ image = g_image_data_interface->Create( instance->pp_instance, PP_IMAGEDATAFORMAT_BGRA_PREMUL, size, PP_TRUE); if (!image) return; g_image_data_interface->Describe(image, &image_desc); /* Fill the image with blue. */ image_data = (uint32_t*)g_image_data_interface->Map(image); if (!image_data) { g_core_interface->ReleaseResource(image); return; } num_words = image_desc.stride * size->height / 4; // [6] g_color_index++; if (g_color_index >= sizeof(g_colors) / sizeof(g_colors[0])) g_color_index = 0; for (i = 0; i < num_words; i++) image_data[i] = g_colors[g_color_index]; /* Paint image to graphics 2d. */ g_graphics_2d_interface->ReplaceContents(instance->graphics, image); g_graphics_2d_interface->Flush(instance->graphics, PP_MakeCompletionCallback(&FlushCompletionCallback, NULL)); g_core_interface->ReleaseResource(image); } /** Returns the info for the given instance, or NULL if it's not found. */ struct InstanceInfo* FindInstance(PP_Instance instance) { struct InstanceInfo* cur = all_instances; while (cur) { if (cur->pp_instance == instance) return cur; cur = cur->next; } return NULL; } PP_Bool Instance_DidCreate(PP_Instance instance, uint32_t argc, const char* argn[], const char* argv[]) { struct InstanceInfo* info = (struct InstanceInfo*)malloc(sizeof(struct InstanceInfo)); info->pp_instance = instance; info->last_size.width = 0; info->last_size.height = 0; info->graphics = 0; /* Insert into linked list of live instances. */ info->next = all_instances; all_instances = info; // [5] g_input_interface->RequestInputEvents(instance, PP_INPUTEVENT_CLASS_MOUSE); g_input_interface->RequestFilteringInputEvents(instance, PP_INPUTEVENT_CLASS_MOUSE); OutputDebugString(_T("Instance_DidCreate\r\n")); return PP_TRUE; } void Instance_DidDestroy(PP_Instance instance) { /* Find the matching item in the linked list, delete it, and patch the * links. */ struct InstanceInfo** prev_ptr = &all_instances; struct InstanceInfo* cur = all_instances; while (cur) { if (instance == cur->pp_instance) { *prev_ptr = cur->next; g_core_interface->ReleaseResource(cur->graphics); free(cur); return; } prev_ptr = &cur->next; cur = cur->next; } } void Instance_DidChangeView(PP_Instance pp_instance, PP_Resource view) { struct PP_Rect position; struct InstanceInfo* info = FindInstance(pp_instance); if (!info) return; if (g_view_interface->GetRect(view, &position) == PP_FALSE) return; if (info->last_size.width != position.size.width || info->last_size.height != position.size.height) { /* Got a resize, repaint the plugin. */ Repaint(info, &position.size); info->last_size.width = position.size.width; info->last_size.height = position.size.height; } OutputDebugString(_T("Instance_DidChangeView\r\n")); } void Instance_DidChangeFocus(PP_Instance pp_instance, PP_Bool has_focus) { } PP_Bool Instance_HandleDocumentLoad(PP_Instance pp_instance, PP_Resource pp_url_loader) { return PP_FALSE; } static PPP_Instance instance_interface = { &Instance_DidCreate, &Instance_DidDestroy, &Instance_DidChangeView, &Instance_DidChangeFocus, &Instance_HandleDocumentLoad }; // [3] PP_Bool InputEvent_HandleInputEvent(PP_Instance instance, PP_Resource input_event) { struct PP_Point pt; TCHAR szLog[512] = { 0 }; switch (g_input_interface->GetType(input_event)) { case PP_INPUTEVENT_TYPE_MOUSEDOWN: pt = g_mouse_interface->GetPosition(input_event); _stprintf_s(szLog, 512, _T("InputEvent_HandleInputEvent, mouse down at [%d, %d]\r\n"), pt.x, pt.y); OutputDebugString(szLog); break; /* case PP_INPUTEVENT_TYPE_MOUSEUP: OutputDebugString(_T("InputEvent_HandleInputEvent, mouse up\r\n")); break; case PP_INPUTEVENT_TYPE_MOUSEMOVE: OutputDebugString(_T("InputEvent_HandleInputEvent, mouse move\r\n")); break; case PP_INPUTEVENT_TYPE_MOUSEENTER: OutputDebugString(_T("InputEvent_HandleInputEvent, mouse enter\r\n")); break; case PP_INPUTEVENT_TYPE_MOUSELEAVE: OutputDebugString(_T("InputEvent_HandleInputEvent, mouse leave\r\n")); break; */ default: return PP_FALSE; } struct InstanceInfo* info = FindInstance(instance); if (info && info->last_size.width > 0) { Repaint(info, &info->last_size); } return PP_TRUE; } // [3] static PPP_InputEvent input_interface = { &InputEvent_HandleInputEvent }; /* Global entrypoints --------------------------------------------------------*/ PP_EXPORT int32_t PPP_InitializeModule(PP_Module module, PPB_GetInterface get_browser_interface) { g_get_browser_interface = get_browser_interface; g_core_interface = (const PPB_Core*) get_browser_interface(PPB_CORE_INTERFACE); g_instance_interface = (const PPB_Instance*) get_browser_interface(PPB_INSTANCE_INTERFACE); g_image_data_interface = (const PPB_ImageData*) get_browser_interface(PPB_IMAGEDATA_INTERFACE); g_graphics_2d_interface = (const PPB_Graphics2D*) get_browser_interface(PPB_GRAPHICS_2D_INTERFACE); g_view_interface = (const PPB_View*) get_browser_interface(PPB_VIEW_INTERFACE); // [2] g_input_interface = (const PPB_InputEvent*)get_browser_interface(PPB_INPUT_EVENT_INTERFACE); g_mouse_interface = (const PPB_MouseInputEvent*)get_browser_interface(PPB_MOUSE_INPUT_EVENT_INTERFACE); if (!g_core_interface || !g_instance_interface || !g_image_data_interface || !g_graphics_2d_interface || !g_view_interface || !g_input_interface || !g_mouse_interface) return -1; OutputDebugString(_T("PPP_InitializeModule\r\n")); return PP_OK; } PP_EXPORT void PPP_ShutdownModule() { } PP_EXPORT const void* PPP_GetInterface(const char* interface_name) { if (strcmp(interface_name, PPP_INSTANCE_INTERFACE) == 0) { OutputDebugString(_T("PPP_GetInterface, instance_interface\r\n")); return &instance_interface; } // [4] else if (strcmp(interface_name, PPP_INPUT_EVENT_INTERFACE) == 0) { OutputDebugString(_T("PPP_GetInterface, input_interface\r\n")); return &input_interface; } return NULL; } ~~~ # 代码改动说明 ppapi_simple.c相对graphics_2d_example.c来讲，主要有6处改动，已在前面的源代码中使用[1]、[2]之类的符号标注出来了。大部分改动是为处理鼠标事件加入的代码，有两处是绘图相关的改动。 先说要处理鼠标事件需要添加的代码及流程。 [1] 这里声明了两个全局变量，g_input_interface和g_mouse_interface，它们将会在PPP_InitializeModule方法中被初始化（标号为[2]处的改动）。g_input_interface是浏览器暴露出来的输入事件接口，插件要请求处理某类事件就通过它。g_mouse_interface是鼠标事件，可以根据事件资源ID获取对应的详细信息，如位置、按下的鼠标按键等。 [3] 这处改动声明了插件测的输入处理接口。一个结构体，一个函数。 [4] 这里会被浏览器调用到，我们新添加的PPP_InputEvent就是在这里返回给浏览器。浏览器拿到PPP_InputEvent后就可以把事件传递给这个接口的HandleInputEvent方法，也就是我们实现的InputEvent_HandleInputEvent方法。在InputEvent_HandleInputEvent方法里，鼠标左键按下时我们调用Repaint()来重绘。 [5] 当插件对象实例创建时，我们向浏览器的输入事件接口请求处理鼠标事件。浏览器收到这个请求，才会派发事件给我们的插件实例对象。 [6] 渲染（绘图）函数。绘图过程，在[**PPAPI插件与浏览器的交互过程**](http://blog.csdn.net/foruok/article/details/50494061)中已介绍过了，不多说了。这里添加的代码，主要是为了让示例随着鼠标点击有变化。通过一个颜色数组和索引，变换插件实例对象对应视图区域的颜色。 我还在关键处插入了一些日志代码，可以通过DbgView来查看。 下面是运行效果图：  通过CEF运行时使用的命令参数如下： –ppapi-out-of-process –register-pepper-plugins=”D:\projects\cef_binary_3.2357.1271.g8e0674e_windows32\Release\stub.dll;application/x-ppapi-simple” –url=file:///d:/projects/cef_binary_3.2357.1271.g8e0674e_windows32/Release/simple.html simple.html和stub.html类似，改了下title和embed标签的type。 好啦，新的示例主要就这些内容了，处理输入事件的流程应该也清楚了。 相关文章参考： - [**CEF Windows开发环境搭建**](http://blog.csdn.net/foruok/article/details/50468642) - [**CEF加载PPAPI插件**](http://blog.csdn.net/foruok/article/details/50485448) - [**VS2013编译最简单的PPAPI插件**](http://blog.csdn.net/foruok/article/details/50485461) - [**理解PPAPI的设计**](http://blog.csdn.net/foruok/article/details/50486788) - [**PPAPI插件与浏览器的交互过程**](http://blog.csdn.net/foruok/article/details/50494061) - [**Windows下从源码编译CEF**](http://blog.csdn.net/foruok/article/details/50498740) - [**编译PPAPI的media_stream_video示例**](http://blog.csdn.net/foruok/article/details/50498873)