Android进阶篇Canvas Bitmap

1.Canvas上以一定收缩比例贴一张图

    headBgBmp = BitmapFactory.decodeResource(context.getResources(), R.drawable.class_bg_sha1);
    headBmp = Bitmap.createBitmap(view.getWidth(),headBgBmp.getHeight(),Config.ARGB_8888);
    Canvas canvas2 = new Canvas(headBmp);
    Matrix matrix = new Matrix();
    float xScale = (float) view.getWidth()/headBgBmp.getWidth();
    matrix.setScale(xScale, 1.0f);
    canvas2.drawBitmap(headBgBmp, matrix, null);

2.Canvas上贴9.png的图

首先你要讲图片进行9.png处理

        NinePatchDrawable drawable = (NinePatchDrawable) context.getResources().getDrawable(R.drawable.class_bg_sha2_2);
        frameBg = drawableToBitmap(drawable, width, height);

drawableToBitmap方法:

    public Bitmap drawableToBitmap(Drawable drawable, int w, int h) {  
        // 取 drawable 的颜色格式  
        Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888  
                : Bitmap.Config.RGB_565;  
        // 建立对应 bitmap  
        Bitmap bitmap = Bitmap.createBitmap(w, h, config);  
        // 建立对应 bitmap 的画布  
        Canvas canvas = new Canvas(bitmap);  
        drawable.setBounds(0, 0, w, h);  
        // 把 drawable 内容画到画布中  
        drawable.draw(canvas);  
        return bitmap;  
    }