Android进阶2之 阴影制作（Shadow）

阴影制作：包括各种形状（矩形，圆形等等），以及文字等等都能设置阴影。阴影制作是什么原理呢？其实很简单，你需要设置阴影的东西被看作一个主层。然后在主层下面画一个阴影层。阴影制作涉及到一个重要函数：public   void   setShadowLayer (float radius, float dx, float dy, int color)radius：阴影半径dx：X轴方向的偏移量dy：Y轴方向的偏移量color：阴影颜色注意：如果半径被设置为0，意思就是去掉阴影。具体实现：

package xiaosi.textShadow;import android.app.Activity;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.os.Bundle;import android.view.View;public class TextShadowActivity extends Activity{@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(new drawCanvas(this));}class drawCanvas extends View{private Bitmap  bitmap = null;public drawCanvas(Context context){super(context);bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.i_skinprocess);}@Overrideprotected void onDraw(Canvas canvas){super.onDraw(canvas);// 建立Paint 物件Paint paint1 = new Paint();// 设定颜色paint1.setColor(0xFFFFFF00);// 设定阴影(柔边, X 轴位移, Y 轴位移, 阴影颜色)paint1.setShadowLayer(5, 3, 3, 0xFFFF00FF);// 实心矩形& 其阴影canvas.drawText("我很爱你", 20,40,paint1);Paint paint2 = new Paint();paint2.setColor(Color.GREEN);paint2.setShadowLayer(10, 5, 2, Color.YELLOW);canvas.drawText("你真傻", 20,60,paint2);Paint paint3 = new Paint();paint3.setColor(Color.RED);paint3.setShadowLayer(30, 5, 2, Color.GREEN);canvas.drawCircle(50, 130,30, paint3);Paint paint4 = new Paint();paint4.setShadowLayer(5, 8, 7, Color.DKGRAY);canvas.drawBitmap(bitmap, 50, 200, paint4);}}}