A talk on C language (ii) image display windows and Linux

There are many libraries available for image display, Windows has GDI,GDI+,D3D and so on, Linux has X window and wayland, in addition to opengl, SDL and other graphics libraries and various GUI Libraries.

Understanding the most primitive way is still helpful for deepening your understanding. The following is the simplest example of displaying bitmaps under Windows and Linux:

Examples of Windows displaying images with Gdi:

1 /*2 * FILENAME:IMAGE_WIN.C3 * Usage:tcc-luser32-lgdi32-run image_win.c4 */5 6#include <windows.h>7#include <stdlib.h>8 //9typedef unsignedChar byte;Ten  onetypedefstruct { a     intWidth; -     intHeight; -     byte*Data; the } Image; -  - LRESULT CALLBACK WndProc (hwnd hwnd, UINT msg, WPARAM w, LPARAM l) - { + HDC hdc; - rect rect; + Image img; a bitmapinfo bmi; at paintstruct ps; -     intirowlength; -     // -ZeroMemory (&bmi,sizeof(bitmapinfo)); -Bmi.bmiHeader.biSize =sizeof(bitmapinfoheader); -Bmi.bmiHeader.biPlanes =1; inBmi.bmiHeader.biBitCount = -; -Bmi.bmiHeader.biCompression =bi_rgb; to     // +     Switch(msg) { -      casewm_destroy: thePostQuitMessage (1); *          break; $      casewm_paint:Panax NotoginsengHDC = BeginPaint (hwnd, &ps); -GetClientRect (hwnd,&rect); theImg. Width = rect.right-rect.left; +Irowlength = ((img. width*8*3+ to) & ~ to) >>3; aImg. Height = rect.bottom-rect.top; theImg. Data = (byte*)malloc(irowlength*Img. Height); +          for(intI=0; i<irowlength*img. height;i++) -Img. data[i] = Rand ()% the; $Bmi.bmiHeader.biWidth =Img. Width; $Bmi.bmiHeader.biHeight =Img. Height; -SetDIBitsToDevice (hdc,0,0, Img. Width, Img. Height, -                           0,0,0Img. Height, Img. Data, &bmi, dib_rgb_colors); the          break; -     default:Wuyi         returndefwindowproc (hwnd, msg, w, l); the     } -     return 0; wu } -  about intMainintargcChar*Argv[]) $ { -     StaticTCHAR szappname[] = TEXT ("Randcolor"); - hwnd hwnd; - msg msg; a wndclass wndclass; +     intIcmdshow =1; theHINSTANCE hinstance =NULL; -     // $Wndclass.style = Cs_hredraw |cs_vredraw; theWndclass.lpfnwndproc =WndProc; theWndclass.cbclsextra =0; theWndclass.cbwndextra =0; theWndclass.hinstance =hinstance; -Wndclass.hicon =LoadIcon (NULL, idi_application); inWndclass.hcursor =loadcursor (NULL, idc_arrow); theWndclass.hbrbackground =(hbrush) getstockobject (white_brush); theWndclass.lpszmenuname =NULL; aboutWndclass.lpszclassname =szappname; the     if(! RegisterClass (&WNDCLASS)) { theMessageBox (NULL, TEXT ("This program requires Windows nt!"), szappname, mb_iconerror); the         return 0; +     } -hwnd = CreateWindow (szappname, TEXT ("Image"), ws_overlappedwindow^ws_thickframe, the cw_usedefault, cw_usedefault, cw_usedefault, cw_usedefault,Bayi null, null, hinstance, null); the     //the message Loop. the ShowWindow (hwnd, icmdshow); - UpdateWindow (hwnd); -  the      while(GetMessage (&msg, NULL,0,0)) { theTranslateMessage (&msg); theDispatchMessage (&msg); the     } -     return 0; the}

　　

Example of using X window to display images under Linux:

1 /*2 * FILENAME:IMAGE_LINUX.C3 * Usage:tcc-lx11-run image_linux.c4 */5#include <X11/Xlib.h>6#include <X11/Xutil.h>7 8#include <stdlib.h>9 Ten #defineWIDTH 640 one #defineHEIGHT 480 a  - intMainintargcChar**Argv) - { the     intwin_b_color; -     intwin_w_color; - XEvent xev; - window window; +Visual *visual; -XImage *ximage; + GC gc; a      at     Char*buffer= (Char*)malloc(width*height*4*sizeof(Char)); -      -Display *display =Xopendisplay (NULL); -Win_b_color =blackpixel (display, defaultscreen (display)); -Win_w_color =blackpixel (display, defaultscreen (display)); -window = Xcreatesimplewindow (display,defaultrootwindow (display),0,0, WIDTH, HEIGHT,0, win_b_color, win_w_color); invisual = Defaultvisual (display,0); -     //xselectinput (display, window, exposuremask | keypressmask); to Xmapwindow (display, window); + XFlush (display); -GC = XCREATEGC (display, window,0, NULL); the     //XEvent event; *      while(1) { $          for(inti =0; I < width*height*4; i + +)Panax Notoginsengbuffer[i] = Rand ()% the; -Ximage=xcreateimage (display, visual, -, zpixmap,0, buffer,width, HEIGHT, +,0); theXputimage (display, window,gc, ximage,0,0,0,0, WIDTH, HEIGHT); +     } a     return 0; the}

The next one will introduce the knowledge of vector diagrams, which are mainly explained by Emf,svg and Postscript.

A talk on C language (ii) image display windows and Linux