别在MFC了,先分析下,上图
我们以左上角为坐标原点,用position_width和position_height来保存当前显示坐标。
根据msdn说明,滚动条默认情况下的值在0~100之间。
根据图可以知道positon_width的活动范围是0到canvas_width-screen-width,另一边类似。
所以有恒等式1:position_width/(canvas_width-screen_width) = hb_pos/100,其中hb_pos是水平方向滚动条当前值。
滚动块长度公式2:screen_width/canvas_width = 滚动块长度/滚动条可滚动区域长度,滚动条可滚动区域长度大概是screen_width-40差不多,可以设置大写留余地。
下面直接上完整代码,可以运行的,只实现了拖动滚动块事件,其他事件自己补充吧
[cpp] view plain copy
- #include <windows.h>
- #define IDC_CANVAS 200
- HWND hwnd_screen = NULL;//屏幕句柄,这里的屏幕既是我们创建的顶级窗口
- HWND hwnd_canvas = NULL;//画布句柄
- HINSTANCE Ghinstance = NULL;//程序实例
- //注意:以下提到的“屏幕”指的都是我们创建的模拟屏幕,也就是顶级窗口,而不是我们计算机的屏幕
- int canvas_width = 2000;//画布长度
- int canvas_height = 1500;//画布宽度
- int screen_width = 0;//屏幕长度
- int screen_height = 0;//屏幕宽度
- int position_width = 0;//当前位置的横坐标
- int position_height = 0;//当前位置的纵坐标
- int hb_pos = 0;//竖直方向滚动条当前位置
- int vb_pos = 0;//水平方向滚动条当前位置
- LRESULT CALLBACK ScreenProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam);//屏幕事件处理函数
- LRESULT CALLBACK CanvasProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam);//画布事件处理函数
- //入口函数
- int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
- //========================================创建屏幕begin==================================================
- WNDCLASSEX wc;
- MSG Msg;
- memset(&wc,0,sizeof(wc));
- wc.cbSize = sizeof(WNDCLASSEX);
- wc.lpfnWndProc = ScreenProc;
- wc.hInstance = hInstance;
- wc.hCursor = LoadCursor(NULL, IDC_ARROW);
- wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
- wc.lpszClassName = "WindowClass";
- wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
- if(!RegisterClassEx(&wc)) {
- MessageBox(NULL, "Window Registration Failed!","Error!",MB_ICONEXCLAMATION|MB_OK);
- return 0;
- }
- //程序实例和屏幕句柄放到全局变量里
- Ghinstance = hInstance;
- hwnd_screen = CreateWindowEx(WS_EX_CLIENTEDGE,"WindowClass","Caption",WS_VISIBLE|WS_OVERLAPPEDWINDOW | WS_HSCROLL | WS_VSCROLL,
- CW_USEDEFAULT,
- CW_USEDEFAULT,
- 800,
- 600,
- NULL,NULL,hInstance,NULL);
- if(hwnd_screen == NULL) {
- MessageBox(NULL, "Screen Creation Failed!","Error!",MB_ICONEXCLAMATION|MB_OK);
- return 0;
- }
- //========================================创建屏幕end==================================================
- //你也可以把创建画布的过程放到屏幕的WM_CREATE事件中,放这里是使读者思路能清晰些
- //========================================创建画布begin==================================================
- wc;
- memset(&wc,0,sizeof(wc));
- wc.cbSize = sizeof(WNDCLASSEX);
- wc.lpszClassName = "Canvas";
- wc.lpfnWndProc = CanvasProc;
- wc.hInstance = Ghinstance;//这里可以直接使用全局变量了
- wc.hCursor = LoadCursor(NULL, IDC_ARROW);
- wc.hbrBackground = (HBRUSH)(COLOR_BACKGROUND);
- if(!RegisterClassEx(&wc)) {
- MessageBox(NULL, "Canvas Registration Failed!","Error!",MB_ICONEXCLAMATION|MB_OK);
- return 0;
- }
- hwnd_canvas= CreateWindow(
- "Canvas",
- "",
- WS_CHILD | WS_VISIBLE | WS_BORDER,
- 0, 0, canvas_width, canvas_height,
- hwnd_screen,//这里可以直接使用全局变量了,注意,如果是放屏幕的WM_CREATE里面,这时候是还不能使用这个全局变量的,WM_CREATE事件结束后CreateWindow方法才会返回创建窗口的句柄
- (HMENU)IDC_CANVAS,
- Ghinstance,//这里可以直接使用全局变量了
- 0
- );
- if(hwnd_canvas == NULL) {
- MessageBox(NULL, "Canvas Creation Failed!","Error!",MB_ICONEXCLAMATION|MB_OK);
- return 0;
- }
- //========================================创建画布end==================================================
- //该显示的显示
- ShowWindow(hwnd_screen, nCmdShow);
- UpdateWindow(hwnd_screen);
- //该显示的显示
- ShowWindow(hwnd_canvas, SW_SHOW);
- UpdateWindow(hwnd_canvas);
- //消息循环
- while(GetMessage(&Msg, NULL, 0, 0) > 0) {
- TranslateMessage(&Msg);
- DispatchMessage(&Msg);
- }
- return Msg.wParam;
- }
- //屏幕的事件
- LRESULT CALLBACK ScreenProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam) {
- //只需要处理WM_SIZE、WM_HSCROLL、WM_VSCROLL三个消息
- switch(Message) {
- //窗口大小改变时,更新全局变量中的屏幕大小,更新滚动条上滚动块的位置
- case WM_SIZE: {
- //更新屏幕大小begin-----------------------------
- screen_width = LOWORD (lParam);
- screen_height = HIWORD (lParam);
- //更新屏幕大小end-----------------------------
- //更新滚动条上滚动块的位置begin----------------------
- hb_pos = position_width * 100 / (canvas_width - screen_width);//根据恒等式1
- vb_pos = position_height * 100 / (canvas_height - screen_height);
- SCROLLINFO si;
- si.cbSize=sizeof(SCROLLINFO);
- si.fMask=SIF_POS;
- si.nPos = vb_pos;
- SetScrollInfo(hwnd_screen,SB_VERT,&si,true);
- si.nPos = hb_pos;
- SetScrollInfo(hwnd_screen,SB_HORZ,&si,true);
- //更新滚动条上滚动块的位置end----------------------
- //其实还应该更新滚动条上滚动块的长度,这里先忽略吧
- //int hb_length = GValue::s_width * (GValue::s_width - 40) / GValue::c_width;//根据恒等式2
- //int vb_length = GValue::s_height * (GValue::s_height - 40) / GValue::c_height;
- break;
- }
- //水平方向滚动条事件
- case WM_HSCROLL : {
- SCROLLINFO si;
- si.cbSize=sizeof(SCROLLINFO);
- si.fMask=SIF_ALL;
- GetScrollInfo(hwnd_screen,SB_HORZ,&si);//先拿滚动条信息
- switch(LOWORD(wParam)){//这里只处理按下滚动条拖动的事件,其他滚动条事件自己实现吧
- //分析可知按住滚动条拖动过程中,需要修改当前位置、然后基于当前位置移动画布,最后修改滚动条位置(你不修改的话视觉效果上会弹回去的)、
- case SB_THUMBTRACK: {
- position_width = si.nTrackPos * (canvas_width - screen_width) / 100;//更改当前位置
- MoveWindow(hwnd_canvas, 0 - position_width, 0 - position_height, canvas_width, canvas_height, true);//移动画布
- si.nPos=si.nTrackPos;
- break;
- }
- //TODO 滚动条的其他事件
- default: {
- break;
- }
- }
- //回写滚动条滚动块的位置,时视觉上正常
- si.fMask=SIF_POS;
- SetScrollInfo(hwnd_screen, SB_HORZ, &si, true);
- break;
- }
- //竖直方向滚动条事件,与上面相似不解释了
- case WM_VSCROLL : {
- SCROLLINFO si;
- si.cbSize=sizeof(SCROLLINFO);
- si.fMask=SIF_ALL;
- GetScrollInfo(hwnd_screen, SB_VERT, &si);
- switch(LOWORD(wParam)){
- case SB_THUMBTRACK: {
- position_height = si.nTrackPos * (canvas_height - screen_height) / 100;
- MoveWindow(hwnd_canvas, 0 - position_width, 0 - position_height, canvas_width, canvas_height, true);
- si.nPos=si.nTrackPos;
- break;
- }
- default: {
- break;
- }
- }
- si.fMask=SIF_POS;
- SetScrollInfo(hwnd_screen, SB_VERT, &si, true);
- break;
- }
- //鼠标滚轮
- /* case WM_MOUSEWHEEL : {
- //向下
- if(HIWORD(wParam) < 0) {
- vb_pos = vb_pos + 10;
- if(vb_pos > 100) {
- vb_pos = 0;
- }
- } else {
- vb_pos = vb_pos - 10;
- if(vb_pos < 0) {
- vb_pos = 0;
- }
- }
- break;
- }
- */
- case WM_CLOSE: {
- DestroyWindow(hwnd);
- break;
- }
- case WM_DESTROY: {
- PostQuitMessage(0);
- break;
- }
- default:
- return DefWindowProc(hwnd, Message, wParam, lParam);
- }
- return 0;
- }
- //窗口的事件
- LRESULT CALLBACK CanvasProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam) {
- switch(Message) {
- //从画布左上角到右下角画一条线,以便观察滚动效果
- case WM_PAINT: {
- PAINTSTRUCT ps;
- HDC hdc;
- RECT rc;
- GetClientRect(hwnd_canvas, &rc);
- hdc = BeginPaint(hwnd_canvas, &ps);
- MoveToEx(hdc, 0 , 0 , NULL);
- LineTo(hdc, rc.right, rc.bottom);
- EndPaint(hwnd_canvas, &ps);
- break;
- }
- case WM_CLOSE: {
- DestroyWindow(hwnd);
- break;
- }
- case WM_DESTROY: {
- PostQuitMessage(0);
- break;
- }
- default:
- return DefWindowProc(hwnd, Message, wParam, lParam);
- }
- }
时间: 2024-10-16 21:57:39