【DFB】IDirectFBInputDevice 方式处理事件 --键盘移动一个图片显示

#include <stdio.h>
#include <unistd.h>

#include <directfb/directfb.h>

static IDirectFB *dfb = NULL;
static IDirectFBSurface *primary = NULL;
static IDirectFBSurface *tux = NULL;
static int screen_width = 0;
static int screen_height = 0;
//全局变量

static IDirectFBInputDevice *keyboard = NULL;

int main (int argc, char **argv)
{
    DFBSurfaceDescription   dsc;
    IDirectFBImageProvider *provider;
    DFBInputDeviceKeyState escape = DIKS_UP;//先声明一个DFBInputDeviceKeyState枚举变量，
                                            //并将其值定为DIKS_UP,即默认没有按下
   
    int sprite_x, sprite_y, max_x, max_y;//定义四个整形值，其中max_x, max_y用于记录前面坐标允许的最大值，
                                        //sprite_x, sprite_y用于记录图片左上角的坐标值，
                                        //sprite_x在[0, max_x]，sprite_y在[0, max_y]范围内

    DirectFBInit (&argc, &argv);
    DirectFBCreate (&dfb);

    dfb->SetCooperativeLevel (dfb, DFSCL_FULLSCREEN);
    dsc.flags = DSDESC_CAPS;
    dsc.caps = DSCAPS_PRIMARY | DSCAPS_FLIPPING;
    dfb->CreateSurface( dfb, &dsc, &primary );
    primary->GetSize (primary, &screen_width, &screen_height);

    dfb->GetInputDevice (dfb, DIDID_KEYBOARD, &keyboard);

    dfb->CreateImageProvider (dfb, "./my.jpg", &provider);
    provider->GetSurfaceDescription (provider, &dsc);
   
    dfb->CreateSurface (dfb, &dsc, &tux);//创建一个平面tux，此平面的大小即为图片的大小，信息记录在dsc中

    provider->RenderTo (provider, tux, NULL);//将图片Render到tux上，而图片与tux大小一致，则即便使用了NULL，也不会有缩放发生
    provider->Release (provider);

    //设定4个int变量的值，以保证图片显示在屏幕正中心
    max_x = screen_width - dsc.width;
    max_y = screen_height - dsc.height;
    sprite_x = (screen_width - dsc.width) / 2;
    sprite_y = (screen_height - dsc.height) / 2;


    DFBInputDeviceKeyState state;

        //primary->SetColor(primary, 0x0, 0x0, 0x0, 0xff);               
        //primary->FillRectangle(primary, 0, 0, screen_width, screen_height);
    while (escape == DIKS_UP){


        //将tux显示在primary上面
        primary->FillRectangle (primary, 0, 0, screen_width, screen_height);   
        primary->Blit (primary, tux, NULL, sprite_x, sprite_y);
        primary->Flip (primary, NULL, DSFLIP_WAITFORSYNC);

        //开始图片移动策略，如果想改变移动速度，可调整步进值
        keyboard->GetKeyState (keyboard, DIKI_LEFT, &state);
        if (state == DIKS_DOWN){
            printf("DIKI_LEFT-----------------/n");
            sprite_x--;
        }
        keyboard->GetKeyState (keyboard, DIKI_RIGHT, &state);

        if (state == DIKS_DOWN){
            printf("DIKI_RIGHT-----------------/n");
            sprite_x++;
        }

        keyboard->GetKeyState (keyboard, DIKI_UP, &state);
        if (state == DIKS_DOWN){
            printf("DIKI_UP-----------------/n");
            sprite_y--;
        }

        keyboard->GetKeyState (keyboard, DIKI_DOWN, &state);
        if (state == DIKS_DOWN){
            printf("DIKI_DOWN-----------------/n");
            sprite_y++;
        }

        //开始定义策略使图片始终在屏幕范围内
        if (sprite_x < 0)
        sprite_x = 0;
        else if (sprite_x > max_x)
        sprite_x = max_x;
        if (sprite_y < 0)
        sprite_y = 0;
        else if (sprite_y > max_y)
        sprite_y = max_y;

        keyboard->GetKeyState (keyboard, DIKI_ESCAPE, &escape);//检查DIKI_ESCAPE状态，为下一次循环做准备
       
        //sleep(1);
    }

    //由小到大的释放资源
    keyboard->Release (keyboard);
    tux->Release (tux);
    primary->Release (primary);
    dfb->Release (dfb);

    return 0;
}