卡马克缓冲算法代码及演示

package redduke.game.j2me; import javax.microedition.lcdui.Graphics; import javax.microedition.lcdui.Image; /** * 缓冲类 * @author redduke1202 * */ public class ReddukeBuffer { private int width,height; private Paintable p; private Image buf; private Graphics g; //缓冲区左上角相对Layer的偏移 private int offx,offy; //缓冲区当前偏移量 private int _offx,_offy; //显示区相对缓冲区的偏移量 private int offx2,offy2; /** * 构造方法 * @param p 需要缓冲的绘制对象 * @param w 宽度 * @param h 高度 * @param w2 缓冲2边的宽度 缓冲宽度=宽度+w2*2 * @param h2 缓冲上下的高度 缓冲高度=高度+h2*2 */ public ReddukeBuffer(Paintable p,int w,int h,int w2,int h2) { if(w2<0 || h2<0 || w<1 || h<1 || w+w2>p.getWidth() || h+h2>p.getHeight()) throw new IllegalArgumentException(); this.width=w; this.height=h; this.p=p; buf=Image.createImage(w+w2,h+h2); g=buf.getGraphics(); bufferImpl(0,0,buf.getWidth(),buf.getHeight()); } /** * 将此缓冲绘制到g */ public final void paint(Graphics g,int x,int y) { int tempx=offx%buf.getWidth(); int tempy=offy%buf.getHeight(); drawRegion(g,buf,tempx+offx2,tempy+offy2,buf.getWidth()-tempx-offx2,buf.getHeight()-tempy-offy2,0,x,y,0); drawRegion(g,buf,0,tempy+offy2,width-(buf.getWidth()-tempx-offx2),buf.getHeight()-tempy-offy2,0,x+width,y,Graphics.RIGHT|Graphics.TOP); drawRegion(g,buf,tempx+offx2,0,buf.getWidth()-tempx-offx2,height-(buf.getHeight()-tempy-offy2),0,x,y+height,Graphics.BOTTOM|Graphics.LEFT); drawRegion(g,buf,0,0,width-(buf.getWidth()-tempx-offx2), height-(buf.getHeight()-tempy-offy2),0,x+width,y+height,Graphics.RIGHT|Graphics.BOTTOM); } private void drawRegion(Graphics g,Image img,int x_src,int y_src,int width,int height,int transform,int x_dest,int y_dest,int anchor) { if(width<=0 || height<=0) return; if(width>this.width) width=this.width; if(height>this.height) height=this.height; g.drawRegion(img,x_src,y_src,width,height,transform,x_dest,y_dest,anchor); } /** * 卷动绘制对象，根据需要进行缓冲 */ public void scrollTo(int offx,int offy) { scroll(offx-this._offx,offy-this._offy); } /** * 卷动绘制对象，根据需要进行缓冲 */ public void scroll(int dx,int dy) { if(_offx+offx2+dx<0) dx=-offx2-_offx; else if(_offx+offx2+dx>p.getWidth()-width) dx=p.getWidth()-width-offx2-_offx; if(_offy+offy2+dy<0) dy=-offy2-_offy; else if(_offy+offy2+dy>p.getHeight()-height) dy=p.getHeight()-height-offy2-_offy; int w2=buf.getWidth()-width; int h2=buf.getHeight()-height; if(dx!=0) { int _offx2=offx2; offx2+=dx; if(offx2<0 || offx2>w2) { offx2=w2>>1; dx=_offx2+dx-offx2; if(_offx+dx<0) { offx2+=_offx+dx; dx=-_offx; } else if(_offx+dx>p.getWidth()-buf.getWidth()) { offx2-=p.getWidth()-buf.getWidth()-_offx-dx; dx=p.getWidth()-buf.getWidth()-_offx; } } else dx=0; } if(dy!=0) { int _offy2=offy2; offy2+=dy; if(offy2<0 || offy2>h2) { offy2=h2>>1; dy=_offy2+dy-offy2; if(_offy+dy<0) { offy2+=_offy+dy; dy=-_offy; } else if(_offy+dy>p.getHeight()-buf.getHeight()) { offy2-=p.getHeight()-buf.getHeight()-_offy-dy; dy=p.getHeight()-buf.getHeight()-_offy; } } else dy=0; } if(dx!=0 || dy!=0) { _offx+=dx; _offy+=dy; buffer(); } } private void bufferImpl(int x,int y,int w,int h) { int tempx=_offx%buf.getWidth(); int tempy=_offy%buf.getHeight(); // A { g.setClip(tempx,tempy,buf.getWidth()-tempx,buf.getHeight()-tempy); p.paint(g,tempx-_offx,tempy-_offy); } // B if(tempx>0) { g.setClip(0,tempy,tempx,buf.getHeight()-tempy); p.paint(g,tempx-_offx-buf.getWidth(),tempy-_offy); } // C if(tempy>0) { g.setClip(tempx,0,buf.getWidth()-tempx,tempy); p.paint(g,tempx-_offx,tempy-_offy-buf.getHeight()); } // D if(tempx>0 && tempy>0) { g.setClip(0,0,tempx,tempy); p.paint(g,tempx-_offx-buf.getWidth(),tempy-_offy-buf.getHeight()); } } public int getWidth() { return width; } public int getHeight() { return height; } private void buffer() { if(offx==_offx && offy==_offy) return; if(Math.abs(offx-_offx)>=buf.getWidth() || Math.abs(offy-_offy)>=buf.getHeight()) bufferImpl(0,0,buf.getWidth(),buf.getHeight()); else { int minX=Math.min(_offx%buf.getWidth(),offx%buf.getWidth()); int maxX=Math.max(_offx%buf.getWidth(),offx%buf.getWidth()); int minY=Math.min(_offy%buf.getHeight(),offy%buf.getHeight()); int maxY=Math.max(_offy%buf.getHeight(),offy%buf.getHeight()); if(_offx/buf.getWidth()==offx/buf.getWidth() && _offy/buf.getHeight()==offy/buf.getHeight()) { if(minX==maxX) bufferImpl(0,minY,width,maxY-minY); else if(minY==maxY) bufferImpl(minX,0,maxX-minX,buf.getHeight()); else { bufferImpl(minX,0,maxX-minX,minY); bufferImpl(0,minY,buf.getWidth(),maxY-minY); bufferImpl(minX,maxY,maxX-minX,buf.getHeight()-maxY); } } else if(_offx/buf.getWidth()==offx/buf.getWidth()) { bufferImpl(0,0,buf.getWidth(),minY); bufferImpl(minX,minY,maxX-minX,maxY-minY); bufferImpl(0,maxY,buf.getWidth(),buf.getHeight()-maxY); } else if(_offy/buf.getHeight()==offy/buf.getHeight()) { bufferImpl(0,0,minX,buf.getHeight()); bufferImpl(minX,minY,maxX-minX,maxY-minY); bufferImpl(maxX,0,buf.getWidth()-maxX,buf.getHeight()); } else { bufferImpl(0,0,buf.getWidth(),minY); bufferImpl(0,minY,minX,maxY-minY); bufferImpl(maxX,minY,buf.getWidth()-maxX,maxY-minY); bufferImpl(0,maxY,buf.getWidth(),buf.getHeight()-maxY); } } offx=_offx; offy=_offy; } /** * 返回偏移量横坐标 * @return */ public int getOffx() { return offx+offx2; } /** * 返回偏移量纵坐标 * @return */ public int getOffy() { return offy+offy2; } //以下方法仅做测试用 /* 返回缓冲图片 */ public Image getBuffer() { return buf; } /* 返回缓冲区横坐标偏移量 */ public int getBufOffx() { return offx; } /* 返回缓冲区纵坐标偏移量 */ public int getBufOffy() { return offy; } }