java实现菜单滑动效果

菜单滑动效果的实现

public class menuscrolleractivity extends basegameactivity implements iscrolldetectorlistener, ionscenetouchlistener, iclickdetectorlistener {
    
    // ===========================================================
    // constants
    // ===========================================================
    protected static int camera_width = 480;
    protected static int camera_height = 320;
 
    protected static int font_size = 24;
    protected static int padding = 50;
     
    protected static int menuitems = 7;
     
 
    // ===========================================================
    // fields
    // ===========================================================
    private scene mscene;
    private camera mcamera;
 
    private font mfont; 
    private bitmaptextureatlas mfonttexture;   
     
    private bitmaptextureatlas mmenutextureatlas;    
    private textureregion mmenulefttextureregion;
    private textureregion mmenurighttextureregion;
     
    private sprite menuleft;
    private sprite menuright;
 
    // scrolling
    private surfacescrolldetector mscrolldetector;
    private clickdetector mclickdetector;
 
    private float mminx = 0;
    private float mmaxx = 0;
    private float mcurrentx = 0;
    private int iitemclicked = -1;
     
    private rectangle scrollbar;    
    private list<textureregion> columns = new arraylist<textureregion>();
 
    // ===========================================================
    // constructors
    // ===========================================================
 
    // ===========================================================
    // getter & setter
    // ===========================================================
 
    // ===========================================================
    // methods for/from superclass/interfaces
    // ===========================================================
 
    @override
    public void onloadresources() {
        // paths
        fontfactory.setassetbasepath("font/");
        bitmaptextureatlastextureregionfactory.setassetbasepath("gfx/");
 
        // font
        this.mfonttexture = new bitmaptextureatlas(256, 256);
        this.mfont = fontfactory.createfromasset(this.mfonttexture, this, "plok.ttf", font_size, true, color.black);
        this.mengine.gettexturemanager().loadtextures(this.mfonttexture);
        this.mengine.getfontmanager().loadfonts(this.mfont);
         
        //images for the menu
        for (int i = 0; i < menuitems; i++) {        
          bitmaptextureatlas mmenubitmaptextureatlas = new bitmaptextureatlas(256,256, textureoptions.bilinear_premultiplyalpha);
          textureregion mmenutextureregion = bitmaptextureatlastextureregionfactory.createfromasset(mmenubitmaptextureatlas, this, "menu"+i+".png", 0, 0);
           
          this.mengine.gettexturemanager().loadtexture(mmenubitmaptextureatlas);
          columns.add(mmenutextureregion);
           
           
        }
        //textures for menu arrows
        this.mmenutextureatlas = new bitmaptextureatlas(128,128, textureoptions.bilinear_premultiplyalpha);
        this.mmenulefttextureregion = bitmaptextureatlastextureregionfactory.createfromasset(mmenutextureatlas, this, "menu_left.png", 0, 0);
        this.mmenurighttextureregion = bitmaptextureatlastextureregionfactory.createfromasset(mmenutextureatlas, this, "menu_right.png",64, 0);
        this.mengine.gettexturemanager().loadtexture(mmenutextureatlas);
      
    }
 
    @override
    public engine onloadengine() {
        this.mcamera = new camera(0, 0, camera_width, camera_height);
 
        final engineoptions engineoptions = new engineoptions(true, screenorientation.landscape, new fillresolutionpolicy(), this.mcamera);
        engineoptions.gettouchoptions().setrunonupdatethread(true);
 
        final engine engine = new engine(engineoptions);
        return engine;
    }
 
    @override
    public scene onloadscene() {
        this.mengine.registerupdatehandler(new fpslogger());
 
        this.mscene = new scene();
        this.mscene.setbackground(new colorbackground(0, 0, 0));
        
        this.mscrolldetector = new surfacescrolldetector(this);
        this.mclickdetector = new clickdetector(this);
 
        this.mscene.setonscenetouchlistener(this);
        this.mscene.settouchareabindingenabled(true);
        this.mscene.setonscenetouchlistenerbindingenabled(true);
 
        createmenuboxes();
 
        return this.mscene;
 
    }
 
    @override
    public boolean onscenetouchevent(final scene pscene, final touchevent pscenetouchevent) {
        this.mclickdetector.ontouchevent(pscenetouchevent);
        this.mscrolldetector.ontouchevent(pscenetouchevent);
        return true;
    }
 
    @override
    public void onscroll(final scrolldetector pscolldetector, final touchevent ptouchevent, final float pdistancex, final float pdistancey) {
 
        //disable the menu arrows left and right (15px padding)
        if(mcamera.getminx()<=15)
           menuleft.setvisible(false);
         else
           menuleft.setvisible(true);
         
         if(mcamera.getminx()>mmaxx-15)
           menuright.setvisible(false);
         else
           menuright.setvisible(true);
           
        //return if ends are reached
        if ( ((mcurrentx - pdistancex) < mminx) ){          
          return;
        }else if((mcurrentx - pdistancex) > mmaxx){
           
          return;
        }
         
        //center camera to the current point
        this.mcamera.offsetcenter(-pdistancex,0 );
        mcurrentx -= pdistancex;
           
        
        //set the scrollbar with the camera
        float tempx =mcamera.getcenterx()-camera_width/2;
        // add the % part to the position
        tempx+= (tempx/(mmaxx+camera_width))*camera_width;   
        //set the position
        scrollbar.setposition(tempx, scrollbar.gety());
         
        //set the arrows for left and right
        menuright.setposition(mcamera.getcenterx()+camera_width/2-menuright.getwidth(),menuright.gety());
        menuleft.setposition(mcamera.getcenterx()-camera_width/2,menuleft.gety());
         
        
         
        //because camera can have negativ x values, so set to 0
        if(this.mcamera.getminx()<0){
          this.mcamera.offsetcenter(0,0 );
          mcurrentx=0;
        }
         
 
    }
 
    @override
    public void onclick(clickdetector pclickdetector, touchevent ptouchevent) {
        loadlevel(iitemclicked);
    };
 
    // ===========================================================
    // methods
    // ===========================================================
     
    private void createmenuboxes() {
       
       int spritex = padding;
       int spritey = padding;
       
       //current item counter
       int iitem = 1;
 
       for (int x = 0; x < columns.size(); x++) {
         
         //on touch, save the clicked item in case it's a click and not a scroll.
         final int itemtoload = iitem;
         
         sprite sprite = new sprite(spritex,spritey,columns.get(x)){
           
           public boolean onareatouched(final touchevent pscenetouchevent, final float ptoucharealocalx, final float ptoucharealocaly) {
             iitemclicked = itemtoload;
             return false;
           }           
         };         
         iitem++;
         
         
         this.mscene.attachchild(sprite);         
         this.mscene.registertoucharea(sprite);         
  
         spritex += 20 + padding+sprite.getwidth();
      }
       
       mmaxx = spritex - camera_width;
       
       //set the size of the scrollbar
       float scrollbarsize = camera_width/((mmaxx+camera_width)/camera_width);
       scrollbar = new rectangle(0,camera_height-20,scrollbarsize, 20);
       scrollbar.setcolor(1,0,0);
       this.mscene.attachchild(scrollbar);
       
       menuleft = new sprite(0,camera_height/2-mmenulefttextureregion.getheight()/2,mmenulefttextureregion);
       menuright = new sprite(camera_width-mmenurighttextureregion.getwidth(),camera_height/2-mmenurighttextureregion.getheight()/2,mmenurighttextureregion);
       this.mscene.attachchild(menuright);
       menuleft.setvisible(false);
       this.mscene.attachchild(menuleft);
    }
     
     
 
    @override
    public void onloadcomplete() {
 
    }
 
    //here is where you call the item load.
    private void loadlevel(final int ilevel) {
        if (ilevel != -1) {
            runonuithread(new runnable() {
                @override
                public void run() {
                       
                    toast.maketext(menuscrolleractivity.this, "load item" + string.valueof(ilevel), toast.length_short).show();
                    iitemclicked = -1;
                }
            });
        }
    }
}

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