Android编程之书架效果背景图处理方法

public class myGridView extends GridView { private Bitmap background; private Bitmap newBackGround; public myGridView(Context context, AttributeSet attrs) {  super(context, attrs);  //加载做为背景的图片  background = BitmapFactory.decodeResource(getResources(), R.drawable.bookcase_bg); } protected void dispatchDraw(Canvas canvas) {  //取得加载的背景图片高，宽  int width = background.getWidth();  int height = background.getHeight();  //取得手机屏幕的高，宽，这里要注意，不要在构造方法中写，因为那样取到的值是0  int scWidth = this.getWidth();  int scHeight = this.getHeight();  //计算缩放率，新尺寸除原始尺寸,我这里因为高不用变，所以就是原大小的比例1  //这里一定要注意，这里的值是比例，不是值。  float scaleWidth = ((float) scWidth) / width;  float scaleHeight = 1;  //Log.v("info", "width:" + width + "height:" + height + "scWidth:" + scWidth + "scaleWidth:" + scaleWidth + "scaleHeight:" + scaleHeight);  // 创建操作图片用的matrix对象  Matrix matrix = new Matrix();  // 缩放图片动作  matrix.postScale(scaleWidth, scaleHeight);  //生成新的图片  newBackGround = Bitmap.createBitmap(background, 0, 0,    width, height, matrix, true);  int count = getChildCount();  //Log.v("myGridView-Count", count + "");  int top = 185;  //Log.v("getChildAt", getChildAt(0).getTop() + "");  int backgroundWidth = newBackGround.getWidth();  int backgroundHeight = newBackGround.getHeight();  for (int y = top; y<scHeight; y += 223){   //for (int x = 0; x<scWidth; x += backgroundWidth){    canvas.drawBitmap(newBackGround, 0, y, null);   //}  }  super.dispatchDraw(canvas); } //禁止滚动 条滚动 public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {   int expandSpec = MeasureSpec.makeMeasureSpec(Integer.MAX_VALUE >> 2,    MeasureSpec.AT_MOST);   super.onMeasure(widthMeasureSpec, expandSpec);  }}